Natural and Anthropogenic Influences on the Mount Hope Bay Ecosystem 2006 Northeastern Naturalist 13(Special Issue 4):1–26 Introduction to the Special Issue: Natural and Anthropogenic Influences on the Mount Hope Bay Ecosystem Rodney A. Rountree1,2 and Daniel G. MacDonald1,* Overview With the dramatic technological developments of the past two centuries and the increasing migration to urban centers over the last 100 years, the extent of the human impact on the natural environment has greatly increased. As many growing urban centers tend to be located along coastlines, coastal ecosystems in particular have been placed under an ever increasing stress. This special volume of the Northeast Naturalist focuses on one coastal ecosystem in the northeast United States that has been impacted by human presence and the collateral effects of human innovation for centuries. While it is essential to focus on many local aspects of an impacted ecosystem, as the papers in this volume do, it is important to keep in mind that the plight of Mount Hope Bay is not wholly unique, but is a situation repeated many times up and down coastlines around the globe. This introduction provides a brief overview of the natural and historical setting of Mount Hope Bay, including a summary of recent observed ecosystem changes, followed by a short discussion of the papers contained within the volume. Mount Hope Bay Mount Hope Bay is located in the northeast corner of the greater Narragansett Bay region, straddling the Massachusetts–Rhode Island state line (Fig. 1). The Bay covers an area of approximately 35 km2 and is oriented primarily along a northeast–southwest axis, with a length of approximately 10 km, as shown in Figure 2. A narrow channel—less than 900 m wide at its narrowest point—connects Mount Hope Bay to the East Passage of Narragansett Bay, and the Sakonnet River provides a direct connection to Rhode Island Sound. At its northern end, the Sakonnet River is constricted through two narrows, where the channel width is approximately 100 m. Mount Hope Bay is relatively shallow, with typical depths on the order of 5 to 8 meters. A shipping channel is dredged and maintained with depths on the order of 7 to 15 meters along the southeastern edge of the Bay, providing access to the city of Fall River. 1School for Marine Science and Technology, University of Massachusetts Dartmouth, New Bedford, MA 02744. 2Current address - Marine Ecology and Technology Applications, Inc. 23 Joshua Lane, Waquoit, MA 02536. *Corrresponding author – dmacdonald@umassd.edu. 2 Northeastern Naturalist Vol. 13, Special Issue 4 Figure 1. Locus map. Mt. Hope Bay is located in the northeast corner of the greater Narragansett Bay region along the Massachusetts–Rhode Island border. Figure 2. Plan view of Mt. Hope Bay showing location of tributaries and seaward connections. Shaded region corresponds to depths (at lower low water) less than 6 m. Source: NOAA Chart # 13221 (November 1989). 2006 R.A. Rountree and D.G. MacDonald 3 Five rivers discharge fresh water into the Bay, the largest of which is the Taunton River, draining a watershed of nearly 1500 km2, with an average annual discharge of approximately 30 m3s-1. Flow in the Taunton is highly seasonal, with an annual peak in late winter/early spring on the order of 55 m3s-1, and a minimum flow on the order of 10 m3s-1 during the summer and early fall as measured at USGS gauging station 0110800, located approximately 40 km upstream of Mount Hope Bay (Ries 1990). The combined flow of the four remaining rivers that discharge into the Bay is small in comparison with the Taunton flow. The Quequechan River, which runs culverted under the city of Fall River for most of its length, has the largest discharge of the four, but the Cole River is the only other gauged discharge, with an average flow of approximately 0.8 m3s-1 (Ries 1990). Runoff from the remaining rivers is likely to be of the same order or less. Mount Hope Bay and its watersheds have felt the impact of human activity for two centuries. The city of Fall River and the lower reaches of the Taunton have been the industrial heart of the region since the first cotton mill was established there in 1811, and the Fall River Ironworks was founded in 1821. The city thrived on the textile industry that quickly developed, until its rapid decline in the early 1900s (Rosebrock 1978). Many textile buildings were constructed along the Taunton River waterfront, and many other supporting industries have also had a presence there over the last two centuries. Significant industrial impacts, as well as municipal sewage discharges, were also made directly to the Quequechan River as the city of Fall River developed. In 1963, a fossil-fuel powered electric generating facility began operation on Brayton Point in Somerset, MA, across the mouth of the Taunton from the city of Fall River. Additional generating capacity was added at the Brayton Point Power Station (BPPS) in 1964, 1969, and again in 1984, bringing the generating capacity of the plant up to the present-day maximum of 1600 MW. In its present configuration, the power plant withdraws water from the Bay at a rate close to one billion gallons per day (46 m3s-1). This water is used for condensing steam that drives the electric turbines within the plant, and is discharged back to the Bay with an increase of temperature on the order of 5 to 10 ºC (USGEN 2001). The last several decades have also seen rapid growth in the population of the Mount Hope Bay watershed regions. For example, the population of the Taunton River watershed has increased on the order of 30 to 60% over the last 40 years, with a current population approaching 700,000 (US Census Bureau/ MassGIS). An increased watershed population puts greater pressure on Mount Hope Bay through an increase of paved and other impervious areas within the watershed, larger sewage loading to septic systems and municipal wastewater treatment facilities, and increased runoff of fertilizers, pesticides, and the like. Recently, public concern over the health of Mount Hope Bay has increased sharply due to the sudden collapse of the Pseudopleuronectus americanus Walbaum (winter flounder) fishery after 1984. Prior to this collapse, winter flounder had been the dominant commercial finfish in 4 Northeastern Naturalist Vol. 13, Special Issue 4 Mount Hope Bay. In an unpublished Rhode Island Department of Environmental Management (RIDEM) report, Gibson (1996) noted a temporal correlation between the fishery collapse and a boost in BPPS’s operations in 1984 and cited this as evidence that the Station’s cooling system was the cause of the winter flounder’s decline. Gibson (1998, 2002a, 2002b), followed up with more recent reports that continued to suggest that the decline in Mount Hope Bay winter flounder was caused by the power plant. The causative factor was suggested to occur either through the death of larvae entrained in the cooling waters pumped through the plant, or through the unknown effects of the heated waters being discharged into the Bay. However, others have pointed out in unpublished technical reports (see reviews in Rountree et al. 2003) that the decline of winter flounder was not unique to Mount Hope Bay, but occurred throughout Narragansett Bay, and indeed, throughout the species range in the Gulf of Maine, Georges Bank, southern New England, and the Mid-Atlantic Bight, and therefore could not be attributed simply to the power plant’s operations. Declines in Trinectes maculatus Bloch & Schneider (hogchoker) and other bottom fishes, and increases in Anchoa mitchilli Valenciennes (bay anchovy), Clupea harengus L. (Atlantic herring) and Brevoortia tyrannus Latrobe (Atlantic menhaden) in Mount Hope Bay have further stimulated debate over the health of Mount Hope Bay and the impact of BPPS. Public and management concern over the impact of BPPS on winter flounder and other fishes was further heightened by the publication of a study indicating that anthropogenic temperature modification of the surface temperature of Mount Hope Bay was as much as 0.8 oC above ambient during certain seasons of the year (Mustard et al. 1999). There has been significant debate among BPPS and others concerning the significance of these findings (see reviews in Rountree et al. 2003). From this brief review, it seems likely that the current state of the ecosystem in Mount Hope Bay may be the cumulative result of a wide range of impacts, for which the relative influences are poorly understood. These include the local industrial and population pressures discussed above, regional and global-scale impacts such as atmospheric warming, and natural, but poorly understood, cycles of variability at all scales. The challenge of distinguishing the effects associated which each of these many impacts requires an integrated and interdisciplinary approach with inputs from a wide variety of scientists. The 2003 Mount Hope Bay symposium and the production of this volume are attempts to further such collaboration. About the Symposium and this Volume The papers in this volume were presented as part of a day-long symposium on science in Mount Hope Bay that occurred in Fairhaven, MA, in May 2003. The symposium was entitled: “Natural and Anthropogenic Influences on the Mount Hope Bay Ecosystem” and was convened as part of a joint meeting of the New England Estuarine Research Society and the Southern New England Chapter of the American Fisheries Society. The purpose of the symposium was 2006 R.A. Rountree and D.G. MacDonald 5 to determine the state of knowledge of the Mount Hope Bay ecosystem and to examine how natural and anthropogenic factors affect estuarine systems. The organizers sought to bring scientists, resource managers, and industry and conservation representatives together to present their views, research, and findings in order to take the first step towards developing an understanding of how the major natural and anthropogenic factors influence the Mount Hope Bay ecosystem. Scientists from regional academic and professional institutions presented sixteen full papers and six posters of their research within Mount Hope Bay (Table 1, Appendix 1). All presenters were invited to contribute papers to this volume, but not all chose to do so. However, abstracts from all papers are provided in Appendix 1. The presenters were joined in the audience by representatives from regional management agencies, including the US Environmental Protection Agency (EPA), RIDEM, the Massachusetts Department of Marine Fisheries (MADMF), and the National Marine Fisheries Service (NMFS), and conservation groups such as Save the Bay. Representatives from BPPS and local municipalities were also present. The symposium resulted in an excellent exchange of ideas and information among all these constituents. A variety of topics were covered in papers presented at the symposium (Table 1, Appendix 1), ranging from habitat mapping and restoration to water quality, recovery of Phalacrocoraz auritus Lesson (cormorant) and seal populations, winter flounder tagging, and macrobenthos surveys. Many of the presentations and discussions focused on the controversial issues of BPPS’s impact on winter flounder and other fishes, and on the Mount Hope Bay heat budget. Because some of the presenters chose not to submit manuscripts to this volume, we provide a brief summary of the presentations and discussions below, as they occurred at the symposium. However, to provide balance to the views and conclusions drawn by the volume editors, who were also participants in the symposium, we asked Giancarlo Cicchetti of the Environmental Protection Agency to moderate one of the discussion sessions and to provide a critical review of the symposium and this volume from a regulatory perspective (Cicchetti 2006). The resulting volume should provide scientists and resource managers with useful insight into how interactions among local and national management agencies, conservation groups, industry and academic institutions contribute productively to management decision making. It is obvious that neither the Symposium nor this resulting volume has resolved the controversies surrounding Mount Hope Bay and that further research is needed to address them. Mount Hope Bay heat budget Several presentations at the symposium dealt directly with the Mount Hope Bay heat budget (see Table 1, Appendix 1). Scientists from various institutions presented observational and model simulation studies that suggested both strong (Mustard) and negligible (Fan and Brown, Swanson et al., Zhao et al.) impacts. The focal point of the heat-budget controversy can be assessed by reviewing the conclusions reached in both the Mustard and the Fan and Brown 6 Northeastern Naturalist Vol. 13, Special Issue 4 Table 1. Papers presented at the symposium “Natural and Anthropogenic Influences on the Mt. Hope Bay Ecosystem” held at a joint meeting of the New England Estuarine Research Society and the Southern New England Chapter of the American Fisheries Society, in Fairhaven, MA, 10 May 2003. (*Denotes presenter.) Author(s) Affiliation Presentation title Barrett*, S.B., H. Durey, and B.C. Graves Epsilon Associates, Inc. Mount Hope Bay tidal restriction atlas: Identifying man-made structures which alter tidal hydrology and degrade estuarine habitats in Mount Hope Bay Costello*, C.T. Massachusetts Department of Mapping and monitoring resources of Mt. Hope Bay Environmental Protection Deacutis*, C.F., D. Murray, W. Prell, L. Korhun, Narragansett Bay Estuary Program Hypoxic waters in Narragansett Bay, Rhode Island and E. Saarman DeAlteris*, J.T., T.L. Englert, University of Rhode Island Trends in fish abundance in Mount Hope Bay and J.A.D. Burnett DeLong*, A.K., and J.S. Collie Graduate School of Oceanography, Examining the decline of Narragansett Bay winter flounder, with a University of Rhode Island particular emphasis on Mount Hope Bay Englert*, T.L., and J.A.D. Burnett Lawler, Matusky and Skelly A RAMAS population model of winter flounder in Mount Hope Bay Engineers LLP Fan*, Y., and W.S. Brown SMAST, University of Massachusetts An estimated heat budget for Mount Hope Bay Dartmouth French McCay*, D.P., and J.J. Rowe Applied Science Associates, Inc. Estimated impacts of cormorants on fish populations in the Narragansett Bay estuary Gibson*, M.R. RI Department of Environmental Assessing the impacts of fishing and Brayton Point Power Station on Management, Division of Fish and local stocks of winter flounder using a nested, biomass dynamic Wildlife model Howes*, B.L., and D.R. Schlezinger SMAST, University of Massachusetts Nutrient related habitat quality of Mount Hope Bay Dartmouth Kincaid*, C.R. University of Rhode Island The exchange of water through multiple entrances to the Mt. Hope Bay Estuary. 2006 R.A. Rountree and D.G. MacDonald 7 Table 1, continued. Author(s) Affiliation Presentation title Lawrence*, D., and M. Scherer Marine Research, Inc. Macroalgae impacts on the nursery habitat of young-of-the-year winter flounder (Pleuronectes americanus), Mount Hope Bay Mustard*, J.F. Brown University The temperature of Mt. Hope Bay O’Neill*, R.J. and T.L. Englert, Lawler, Matusky and Skelly Effects of the Brayton Point Station thermal discharge on representative Engineers LLP important species in Mount Hope Bay Powell*, J.C. Rhode Island Division of Fish and A tagging study of winter flounder (Pseudopleuronectes aAmericanus) and Wildlife in Mt. Hope Bay, Rhode Island Pratt*, S.D. Graduate School of Oceanography, Aspects of macrobenthos in Mount Hope Bay University of Rhode Island Rountree*1, R.A., and D. Witting21SMAST/UMass Dartmouth and Spatial and temporal patterns of the fish assemblages in the greater 2NOAA Northeast Fisheries Science Narragansett Bay estuarine system: Is Mt. Hope Bay different? Center Swanson*, C., and H.-S. Kim Applied Science Associates, Inc. Simulated thermal variations in Mt. Hope Bay and application to assessing ecosystem effects Tate*, A., K. Weaver, and A. Fuda Roger Williams University Integration of a winter flounder habitat suitability index model and geographic information system to prioritize Narragansett Bay salt pond restorations Taylor*, D.L. University of Rhode Island, Graduate Predation of winter flounder eggs by the sand shirmp (Crangon School of Oceanography septemspinosa) in Mt. Hope Bay Webb*, P.M. Roger Williams University Assessment of the seal populations of Mt. Hope Bay and surrounding waters Zhao*, L., L. Goodman, C. Chen, B. Rothschild, SMAST, University of Massachusetts Simulating the effects of the heated water discharges from Brayton and R. Rountree Dartmouth Point Power Station to Mount Hope Bay in finite volume coastal model 8 Northeastern Naturalist Vol. 13, Special Issue 4 presentations. The impact of the Brayton Point thermal plume on the temperature structure was addressed through satellite observations by Mustard (see symposium abstract in Appendix 1, and Carney 1997, Mustard et al. 1999). The conclusions of this study suggest that the surface waters of Mount Hope Bay are increased in temperature during autumn by approximately 0.8 ºC, as compared to the surface temperature of the upper Narragansett Bay region, which is in many ways comparable to Mount Hope Bay. The reason for this increase is attributed to the presence of BPPS. Although satellite observations can be useful, it is important to remember that they are only capable of measuring the skin temperature of the Bay. Due to the buoyancy of the thermal plume during most of the year and its tendency to occupy only the top meter or two of the water column, focusing only on skin temperatures can provide a biased perspective of heating effects on the entire Bay. Fan and Brown reported on a study using available meteorological data and comprehensive measurements made by Applied Science Associates. Their analysis used a box-model approach to resolving the Mount Hope Bay heat budget, focusing on both late summer and winter periods. Their results suggest that during winter, all excess heat is lost across the surface of Mount Hope Bay to the atmosphere. In late summer, the amount of heat lost to the atmosphere is of the same order as the amount of heat advected out of Mount Hope Bay into Narragansett Bay and the Sakonnet River. One inference from this study is that most of the excess heat added to Mount Hope Bay through BPPS is lost directly to the atmosphere over the balance of the year, indicating that the heat has a relatively short residence time with respect to the flushing capacity of the Bay, and that the added heat may play a minor role in affecting the physics and overall temperature structure of the Bay. Interestingly, these two studies are largely consistent with each other in that the Fan and Brown results suggest that late summer (and possibly autumn) is the only period of time during the year where excess heat may remain in the system long enough to significantly affect the long-term temperature structure of the Bay. This finding is, of course, consistent with the results of Mustard's symposium presentation and Mustard et al. (1999), and it should be pointed out that the numerical modeling presentations (Swanson and Kim, Zhao et al.) provide no information to the contrary. Controversy does ensue, however, over interpretation of the results, and the significance of the limited autumn effects to the ecology of the Mount Hope Bay system in general, and to the winter flounder stocks in particular. This issue is discussed in more detail in the following section. Winter flounder decline Presentations arguing a direct cause and effect relationship between the Brayton Point Power Plant operations and winter flounder population collapse (Delong and Collie, Gibson) contrasted with others that suggested the collapse of winter flounder in Mount Hope Bay resulted from the same factors that caused the concurrent collapse of winter flounder throughout the 2006 R.A. Rountree and D.G. MacDonald 9 Narragansett Bay system (DeAlteris et al., Englert and Burnett, Englert et al., O’Neill and Englert, O’Neill et al., Rountree and Witting). Gibson (1996, 1998, 2000a, 2000b, and his symposium presentation) used fish abundance data collected from Brayton Point monitoring programs in the upper third of Mount Hope Bay and compared it to data collected in the annual RIDEM from throughout Narragansett Bay and coastal Rhode Island to show that declines in winter flounder and other finfishes were greater in Mount Hope Bay than in Narragansett Bay. He also reported that this decline was coincident with a large increase in water throughput at the Brayton Point Power Plant and thus claimed to demonstrate a cause and effect relationship. Primary arguments against this conclusion are 1) that similar declines in winter flounder abundances occurred throughout the species’ range at about the same time, 2) that Gibson’s use of data from only the upper portion of Mount Hope Bay is not representative of the entire Bay, and 3) that inclusion of coastal Rhode Island data (where stocks have not been as strongly depressed) with Narragansett Bay data invalidates the comparison with Mount Hope Bay (see arguments in DeAlteris et al. 2006 and Rountree et al. 2003). DeAlteris et al. (2006) attempt to correct for these issues by comparing standardized abundance trends from upper and lower Mount Hope Bay with those from Narragansett Bay. They conclude that abundance declines in Mount Hope Bay were not different from Narragansett Bay. However, there was some evidence that upper Mount Hope Bay had declined faster than the other areas. Modeling studies by Englert et al. (2006) and O’Neill et al. (2006) similarly conclude that there is little impact attributable to the Brayton Point Power Plant. We feel that spatial factors continue to cloud the analysis of Mount Hope Bay fish abundance trends, because these studies compare Mount Hope Bay in whole or in part to the entire Narragansett Bay. There are many reasons why a relatively isolated upper bay component (i.e., Mount Hope Bay) might show different abundance trends from a larger, more complex system such as Narragansett Bay. For a contrasting review of these papers see Cicchetti (2006). Collie and Delong (2001) and Delong and Collie's symposium presentation attempted to resolve the issue of spatial representation by comparing Mount Hope Bay to different subsets of the greater Narragansett Bay system. They analyzed time series of winter flounder abundance at several locations in Narragansett and Mount Hope Bays to identify potential mechanisms for winter flounder decline. In their analyses of 1973-1999 Mount Hope Bay winter flounder data (Marine Research, Inc.) and 1979-1999 RIDEM data, Collie and DeLong (2001) and DeLong and Collie's symposium presentation identified two “bottlenecks,” or periods of increased mortality, that are related to total winter flounder mortality: the egg-larvae period and the age- 1 fall to age-2 spring period. The correlation coefficient of age-1 fall to age-2 spring mortality with total mortality (r =0.80) was much larger than that of egg-larvae period (r = 0.37), or any other period examined, indicating that the age-1 fall to age-2 spring period is the period to which much of the 10 Northeastern Naturalist Vol. 13, Special Issue 4 decline in Mount Hope Bay winter flounder abundance can be attributed. Further, mortality rates at various stages (age-1 spring to age-1 fall, juveniles June to October) displayed significant positive correlation with bottom temperature, suggesting temperature-dependent mortality of Narragansett Bay winter flounder. Temperature-dependent juvenile winter flounder mortality may be either a direct physiological response or an indirect response to other temperature-related changes such as availability of prey (DeLong et al. 2001). Other findings of Collie and DeLong’s (2001) analyses include a recent (post-1988) trend of declining adult female winter flounder in Narragansett Bay relative to their abundance in Rhode Island Sound (although this analysis is based on a single station in each area), suggesting a relative depletion of Narragansett Bay winter flounder spawning stock. Spatial-temporal analyses of available winter flounder data (Collie and DeLong 2001) indicate that the habitat suitability of Mount Hope Bay (“sector 3” of their analyses) has increased for large and small winter flounder during the spring, but that fall habitat suitability has decreased. The Collie and Delong (2001) and Delong and Collie's symposium presentation studies raise some important questions and provide some of the strongest arguments for an impact of the Brayton Point Power Plant on winter flounder stocks in Mount Hope Bay. However, Rountree and Whitting's symposium presentation points out that their analysis is weakened by an unfortunate choice in how the Mount Hope Bay area was defined. Following an arbitrary spatial format used in old ichthyoplankton studies (Bourne and Govoni 1988), they used data from the middle third section of Mount Hope Bay as representative of “Mount Hope Bay,” while lumping data from the lower third portion of Mount Hope Bay in with the east passage portion of Narragansett Bay. (Note: data from the upper third of Mount Hope Bay was not available, as the Rhode Island survey does not cover the Massachusetts portion of Mount Hope Bay.) Rountree and Witting's symposium presentation also sought to remedy these spatial weaknesses by comparing winter flounder abundance patterns for Mount Hope Bay with abundance patterns from eight other estuarine areas within the greater Narragansett Bay estuarine system (inclusive of Mount Hope Bay and the Sakonnet River); hereafter referenced as Narragansett Bay. They argued that the RIDEM seasonal trawl survey was the only data set that provided sufficient spatial coverage of both Mount Hope Bay and other Narragansett Bay areas throughout the pre- and postperiod of collapse of winter flounder to conduct such an analysis. It consisted of over 1300 standard trawl tows collected from 1979–2001 (the latest year for which data was available). The RIDEM seasonal trawl survey data was partitioned into nine spatial areas following previous ichthyoplankton studies by Bourne and Govoni (1988) and Keller et al. (1999), and more recent studies of winter flounder by Collie and Delong (2001) and Delong and Collie (symposium presentation), but departed from these by separating the lower portion of Mount Hope Bay from the east passage of Narragansett Bay, and combining it with the middle portion of 2006 R.A. Rountree and D.G. MacDonald 11 Mount Hope Bay to create an area representing Mount Hope Bay based on data from the lower two-thirds of the Bay. A statistical comparison of abundance trends between Mount Hope Bay and the other eight sectors revealed that Mount Hope Bay was not significantly different from most other sectors, but rather exhibited an intermediate decline. The highest declines in winter flounder abundances occurred in the shallow embayments or the areas adjacent to semi-enclosed areas, including Greenwich Bay, Middle West Passage, Wickford Harbor, and Upper Sakonnet and Lower Sakonnet Rivers. Rountree and Witting's symposium presentation concluded that winter flounder abundances were shrinking away from all the shallow marginal embayments of the Narragansett Bay system (including Mount Hope Bay) into a core of the central deep areas of the Bay. Rountree and Witting (symposium presentation) conducted a similar spatial analysis for the entire fish assemblage sampled by the RIDEM seasonal trawl survey. This analysis indicated that the Mount Hope Bay fish community had undergone a dramatic shift from an assemblage dominated by benthic species such as Tautoga onitis L. (tautog), winter flounder, Scophthalmus aquosus Mitchill (windowpane), and hogchoker, to one dominated by pelagic species such as Atlantic menhaden, bay anchovy, and Atlantic herring. The same pattern was evident in all areas of Narragansett Bay. Rountree and Witting concluded, therefore, that changes in the fish assemblage of Mount Hope Bay, including the decline of winter flounder, were a reflection of similar changes occurring throughout the region. They further suggested that the pattern of fish assemblage shifting from benthic to pelagic species is consistent with shifts observed in other regional estuaries and attributed to eutrophication and habitat loss (e.g., Hughes et al. 2002, Wyda et al. 2002). One important weakness of the study by Rountree and Witting (Appendix 1) was again related to spatial coverage, as data from the upper portion of Mount Hope Bay could not be incorporated into the analysis (which was restricted to data available through the RIDEM trawl survey). Finally, we note that Rountree and Witting's symposium presentation study does not address the question of whether the decline in winter flounder and changes in the fish assemblage structure were influenced by the Brayton Point Power Plant, but merely suggests that the dominant factors influencing these observed changes are a reflection of a process or processes that operate on a regional scale (i.e., it is not possible to determine if the observed abundance changes in Mount Hope Bay were stronger than they would have been in the absence of the power plant). Cicchetti (2006) provides an alternative review of the presentations and discussions on the impact of the Brayton Point Power Plant on winter flounder and other fish populations in Mount Hope Bay, and it is clear that more work is needed to clarify the issue. Conclusions The intent of this collection of papers is to provide the reader with an understanding of the complex issues and controversy surrounding the 12 Northeastern Naturalist Vol. 13, Special Issue 4 environment of Mount Hope Bay. As we mentioned at the beginning of this introduction, the combination of factors observed in Mount Hope Bay is not exclusive to the region, but is played out repeatedly in other coastal regions. It is our hope that this volume, and the papers contained within it, will shed light not only on the situation in Mount Hope Bay, but on other coastal ecosystems and management issues as well. After reading the papers in this issue, the abstracts in Appendix 1, and the discussions presented by the editors in the introduction and conclusion papers, together with dissenting views presented by Cicchetti (2006), we believe the reader will be able to arrive at a good understanding of both the controversial issues and general state of knowledge on the ecosystem in Mount Hope Bay. Literature Cited Barrett, S.B., B.C. Graves, and B. Blumeris. 2006. The Mount Hope Bay tidal restriction atlas: Identifying man-made structures which potentially degrade coastal habitats in Mount Hope Bay, Massachusetts. Northeastern Naturalist 13(Special Issue 4):31–46. Bourne, D.W., and J.J. Govoni. 1988. Distribution of fish eggs and larvae and patterns of water circulation in Narragansett Bay, 1972–1973. American Fishery Society Symposium 3:132–148. Carney, M.A. 1997. Surface temperatures in Narragansett Bay: Seasonal dynamics and anthropogenic effects. B.Sc. Thesis. Center for Environmental Studies, Brown University, Providence, RI. Cicchetti, G. 2006. Fisheries in Mount Hope Bay: Notes on a special symposium from an invited regulatory perspective. Northeastern Naturalist 13(Special Issue 4):27–30. Collie, J.S., and A.K. DeLong. 2001. Examining the decline of Narragansett Bay winter flounder. Progress Report to RIDEM Division of Fish and Wildlife, Wakefield, RI. Deacutis, C.F., D. Murray, W. Prell, S. Saarman, and L. Korhun. 2006. Hypoxia in the upper half of Narragansett Bay, RI, during August 2001 and 2002. Northeastern Naturalist 13(Special Issue 4):173–198. DeAlteris, J.T., T.L. Englert, and J.A.D. Burnett. 2006. Trends in fish abundance in Mount Hope Bay: Is the Brayton Point Power Station affecting fish stocks? Northeastern Naturalist 13(Special Issue 4):95–116. DeLong, A.K., J.S. Collie, C.J. Meise, and J.C. Powell. 2001. Estimating growth and mortality of juvenile winter flounder, Pseudopleuronectes americanus, with a length-based model. Canadian Journal of Fisheries and Aquatic Sciences 58(11):2233–2246. Fan, Y., and W.S. Brown. 2006. On the heat budget for Mount Hope Bay. Northeastern Naturalist 13(Special Issue 4):47–70. Gibson, M.R. 1996. Comparison of trends in the finfish assemblage of Mount Hope Bay and Narragansett Bay in relation to operations at the New England Power Brayton Point Station. RI Division Fish and Wildlife Research Reference Document 1995/1. Gibson, M.R. 1998. Recent trends in abundance, recruitment, and fishing mortality for winter flounder in Narragansett Bay and Rhode Island coastal waters. Report to the RI Marine Fisheries Council. Resource Reference Document 98. RI Division of Fish and Wildlife, Wickford, RI. 2006 R.A. Rountree and D.G. MacDonald 13 Gibson, M. 2002a. Ex-vessel Value of Fishery Production Foregone in Mount Hope Bay as a result of Operations at USGEN of New England’s Brayton Point Station.RI Division of Fish and Wildlife, Marine Fisheries, Wakefield, RI. Gibson, M. 2002b. Winter flounder abundance near Brayton Point Station, Mount Hope Bay revisited: separating local from regional impacts using long term abundance data. Rhode Island Division of Fish and Wildlife, Marine Fisheries, Wakefield, RI. Hughes, J.E., L.A. Deegan, J.C. Wyda, M.J. Weaver, and A. Wright. 2002. The effects of eelgrass habitat loss on estuarine fish communities of southern New England. Estuaries 25(2):235–249. Kincaid, C. 2006. The Exchange of water through multiple entrances to the Mount Hope Bay estuary. Northeastern Naturalist 13(Special Issue 4):117–144. Keller, A.A., G. Klein-MacPhee, and J. St. Onge Burns. 1999. Abundance and distribution of ichthyoplankton in Narragansett Bay, RI, 1989–1990. Estuaries 22:149–163. Mustard, J.F., M.A. Carney, and A. Sen. 1999. The use of satellite data to quantify thermal effluent impacts. Estuarine, Coastal, and Shelf Science 49:509–524. O'Neill, R.J., T.L. Englert, and J.K. Ko. 2006. Effects of Brayton Point Station's thermal discharge on Mount Hope Bay winer flounder. Northeastern Naturalist 13(Special Issue 4):71–94. Ries, K.G. 1990. Estimating surface-water runoff to Narragansett Bay, Rhode Island and Massachusetts. US Geological Survey Water Resources Investigations Report 89-4164, Providence, RI. Rosebrock, E. F. 1978. Historic Fall River. The Preservation Partnership, Natick, MA. Rountree, R., D. Borkman, W. Brown, Y. Fan, L. Goodman, B. Howes, B. Rothschild, M. Sundermeyer, and J. Turner 2003. Framework for Formulating the Mount Hope Bay Natural Laboratory: A Synthesis and Summary. School for Marine Science and Technology Technical Report Number SMAST-03-0501, University of Massachusetts Dartmouth, New Bedford, MA. Available at: http:// www.smast.umassd.edu/MHBNL/report2003.php. Swanson, C., H.-Y. Kim, and S. Sankaranarayanan. 2006. Modeling of temperature distributions in Mount Hope Bay due to thermal discharges from the Brayton Point Station. Northeastern Naturalist 13(Special Issue 4):145–172. USGen New England, Inc. (USGen). 2001. Variance request application and partial demonstration under the Clean Water Act, section 316(a) and (b) in support of renewal of NPDES permit No. MA0003654 for USGen New England, Inc.’s Brayton Point Station, May 24. Somerset, MA. Wyda, J.C., L.A. Deegan, J.E. Hughes, and M.J. Weaver. 2002. The response of fishes to submerged aquatic vegetation complexity in two ecoregions of the Mid- Atlantic Bight: Buzzards Bay and Chesapeake Bay. Estuaries 25(1):86-100. 14 Northeastern Naturalist Vol. 13, Special Issue 4 Appendix 1. Titles, authors, and abstracts of papers presented at the symposium “Natural and Anthropogenic Influences on the Mount Hope Bay Ecosystem” held at a joint meeting of the New England Estuarine Research Society and the Southern New England Chapter of the American Fisheries Society, in Fairhaven, MA, 10 May 2003. For author affiliations, see Table 1. Note: for the presented papers which were then submitted and accepted for publication in this special issue, the titles, authors, and abstracts are given as they appear in this issue rather than as originally presented at the symposium. The Mount Hope Bay Tidal Restriction Atlas: Identifying Man-made Structures which Potentially Degrade Coastal Habitats in Mount Hope Bay, Massachusetts Stephen B. Barrett*, Brian C. Graves, and Barbara Blumeris Abstract - For nearly a decade, Massachusetts resource managers have been systematically inventorying, assessing and restoring coastal wetlands degraded by infrastructure crossings such as bridges and culverts, which, unless properly designed and constructed, restrict tidal flow to upstream areas. These crossings - known as tidal restrictions - alter the natural flooding and flushing dynamics of coastal estuarine and wetland habitats, causing damage to salt marshes, eelgrass beds, and other important shellfish and finfish habitats. The Mount Hope Bay Tidal Restriction Atlas, undertaken by the Massachusetts Wetlands Restoration Program and the US Army Corps of Engineers, is the most recent addition to the statewide inventory effort. The Atlas lists a total of 74 potential tidal restrictions that were initially identified on maps and aerial photographs, of which 25 sites were documented using rapid field assessment techniques. Each field-visited site was assessed for severity of restriction and habitat impacts, potential environmental benefits of restoration, and logistical feasibility for implementing restoration. Using these factors, sites were prioritized using a high/medium/low scale. A three-page Site Assessment Report, which includes data, maps, and photographs, was generated for each field-visited site. The final Atlas was presented in an interactive digital format to allow users to query its database and readily move between data fields, maps, and photographs. The Atlas was distributed to stakeholders as a tool for use in restoration planning and implementation. *Corresponding author - Epsilon Associates, Inc., 150 Main Street, Maynard, MA 01754; sbarrett@epsilonassociates.com. Mapping and Monitoring Resources of Mount Hope Bay Charles T. Costello* Abstract - The Massachusetts Department of Environmental Protection has developed a comprehensive GIS database of the wetlands and coastal submerged aquatic vegetation SAV) of the region, which includes a large scale change detection methodology. *Corresponding author - Massachusetts Department of Environmental Protection, One Winter Street, Boston, MA 02108;charles.costello@state.ma.us 2006 R.A. Rountree and D.G. MacDonald 15 Hypoxia in the Upper Half of Narragansett Bay, RI, During August 2001 and 2002 Christopher F. Deacutis*, David Murray , Warren Prell, Emily Saarman, and Larissa Korhun Abstract - Narragansett Bay, RI, is considered to be a relatively well-mixed estuary not subject to extensive seasonal stratification and hypoxia. However, results of surveys of dissolved oxygen (DO) for the upper half of Narragansett Bay on August 15, 2001 and on August 6, 2002 have documented evidence of wide-area intermittent subpycnoclinal hypoxia (􀂔 3 mg l-1). For the August 2001 survey, severe hypoxic to near-anoxic levels were confined to the Providence River, the western side of Greenwich Bay, and a small area of Mount Hope Bay, but hypoxic levels below 2 mg l-1 were also experienced on the western side of the Upper Bay in an extensive, shallow oxygen minimum. Hypoxic bottom waters (􀂔 3 mg l-1) extended from the Upper Bay into the upper West Passage. Hypoxic waters covered approximately 66 km2 (36%) of the survey area for August 15, 2001. A more extensive and severe hypoxic event occurred during the August 2002 survey, when near-bottom waters of the entire Providence River and a large area of the Upper Bay and upper East Passage were severely hypoxic to nearanoxic, while other parts of the Upper Bay, upper East Passage and upper West Passage were hypoxic at depths greater than 5 m. Limited data for Mount Hope Bay in August 2002 documented small hypoxic areas of the southern end of that subembayment. The total hypoxic area for August 6, 2002 was approximately 93 km2 (65%) of the total area surveyed. Decreased estuarine circulation due to a severe drought may have contributed to the wider extent of hypoxic and nearanoxic waters in large areas of the upper half of Narragansett Bay recorded in the August 6, 2002 survey as compared with the August 15, 2001 survey. Results of the oxygen surveys affirm sediment profile camera work and limited benthic studies that previously suggested parts of the Mid Bay have become subject to increased organic loading impacts. These impacts can take place even under drought conditions, when only point source nutrients are the major contributors to nutrient loadings entering the upper half of Narragansett Bay. *Corresponding author - Narragansett Bay Estuary Program, URI Graduate School of Oceanography, Narragansett, RI 02882; deacutis@gso.uri.edu. Trends in Fish Abundance in Mount Hope Bay: Is the Brayton Point Power Station Affecting Fish Stocks? Joseph T. DeAlteris*, Thomas L. Englert, and John A.D. Burnett Abstract - Trends in abundance for winter flounder (Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus), hogchoker (Trinectes maculatus), tautog (Tautoga onitis), and scup (Stenotomus chrysops) in upper and lower Mount Hope Bay were compared to trends in Narragansett Bay to assess the effect of natural and anthropogenic stressors, including Brayton Point Power Station, on Mount Hope Bay fishes from 1972 to 2001. Sources of data included the Rhode Island Division of Fish and Wildlife trawl survey for Narragansett Bay and lower Mount Hope Bay, the University of Rhode Island Graduate School of Oceanography trawl survey for Narragansett Bay, and the Marine Research, Inc. 16 Northeastern Naturalist Vol. 13, Special Issue 4 trawl and Brayton Point Station impingement surveys for upper Mount Hope Bay. Analysis of covariance and Tukey-Kramer multiple comparison tests were used to evaluate differences in the slopes of transformed abundance indices from 1972– 2001 and for two subsets of years, 1972 to 1985 and 1986 to 2001, periods of lower and higher power plant cooling water withdrawals, respectively. Trends in abundance of these species in both upper and lower Mount Hope Bay are not substantively different from those in Narragansett Bay during any of the three time periods evaluated. This is evident through either a high-level visual inspection of the slopes measured for each species, time period, and area or a more detailed inspection of the analysis of covariance results and Tukey-Kramer confidence intervals associated with each slope estimate. Natural and anthropogenic stressors unique to Mount Hope Bay, including Brayton Point Station, have not caused Mount Hope Bay fish stocks to change at rates different from those observed for the same stocks in Narragansett Bay. This supports the conclusion that large-scale factors such as overfishing, climate change, and increased predator abundance are more likely to be the cause of the observed declines in important species such as winter flounder in Mount Hope Bay and Narragansett Bay. *Corresponding author - University of Rhode Island, Building 50, East Farm, University of Rhode Island, Kingston, RI 02881; jdealteris@uri.edu. Examining the Decline of Narragansett Bay Winter Flounder, with a Particular Emphasis on Mount Hope Bay Allison K. DeLong* and Jeremy S. Collie Abstract - The Narragansett Bay winter flounder population has experienced a severe decline in abundance over the last two decades as evidenced by catches in the three standardized trawl surveys conducted in the Bay: the RI Division of Fish and Wildlife fall and spring surveys, the Marine Research, Inc. Mount Hope Bay survey, and the University of Rhode Island weekly trawl survey. These data indicate that winter flounder abundance in Mount Hope Bay, located in the northeast corner of Narragansett Bay, has declined more severely than in the bay as a whole. The objective of this study was to use field data to describe and compare the declines of winter flounder in Narragansett and Mount Hope Bays. For each region, we compared estimates of abundance and mortality rates between 7 life stages: egg, larval, young-of-the-year (YOY) spring, YOY fall, age-1 spring, age-1 fall, and age-2 spring. We used these data to determine the key factors, or those juvenile life-stages that best represent total juvenile mortality. Finally, we examined environmental variables that may have affected winter flounder abundance and mortality rates within Narragansett and Mount Hope Bays. The variables considered included ageclass abundance, year, water temperature, precipitation, fishing mortality, seal abundance, double-crested cormorant abundance, chlorine discharge from wastewater treatment facilities, dissolved oxygen, salinity, and power plant flow and heat load. Stepwise regression and regression tree analyses were performed to determine those environmental variables that best explain changes in stage-specific mortality rates. *Corresponding author - Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02818; adelong@limanda.gso.uri.edu. 2006 R.A. Rountree and D.G. MacDonald 17 A RAMAS Population Model of Winter Flounder in Mount Hope Bay Thomas L. Englert* and John A.D. Burnett Abstract - During the past two decades, independent finfish surveys of Narragansett Bay and adjacent water bodies have shown steep declines in abundance of several groundfish species, including the commercially and recreationally important winter flounder (Pseudopleuronectes americanus). To explore possible causes of the winter flounder decline, a model of winter flounder in Mount Hope Bay was developed using RAMAS population modeling software. The model assessed how winter flounder abundance is affected by fishing, cormorant predation, power plant operations, and ambient water temperatures through generated historical (1959–2001) and future (2002–2049) abundance trajectories. The historical trajectory shows strong agreement with abundance trends observed in finfish surveys and thereby provides model validation. Model results show that the decline in Mount Hope Bay winter flounder abundance through 2001 has been due primarily to overfishing. Future abundance trajectories indicate that Mount Hope Bay winter flounder will recover provided management targeted fishing rates are achieved notwithstanding the other sources of impact modeled. *Corresponding author - Lawler, Matusky, and Skelly Engineers LLP, Pearl River, NY 10965; tenglert@hdrinc.com. On the Heat Budget for Mount Hope Bay Yalin Fan* and Wendell S. Brown Abstract - A simple heat budget has been constructed for Mount Hope Bay (MHB) for two one-month periods: winter 1999 (February–March) and summer 1997 (August– September). The box model considered here includes the heat contributions to MHB from the Brayton Point Power Station (BPPS), the exchange across the air–water interface, the Taunton River, and the tidal exchange between MHB and both Narragansett Bay and the Sakonnet River (NB/SR). Comprehensive measurements of MHB temperature fields by Applied Science Associates, Inc., and meteorological data from T.F. Green Airport (Warwick, RI) were used to estimate the different heat flux component contributions. The box model results for winter show that the BPPS heating is balanced (within the uncertainty of the estimates) by air–water cooling alone. The simple winter balance does not hold during the summer, when heat losses due to tidal exchanges between MHB and NB/SR are important. The summer heat budget of MHB—including BPPS heating, air–water cooling and tidal exchange cooling—can be balanced (within the uncertainty of the estimates) by assuming that 3% of the colder NB/SR tidal input water is exchanged with the warmer MHB water during each tidal cycle. The air–water cooling accounts for 84.4% of the total cooling, and the tidal exchange accounts for 15.6% of the total cooling. Taunton River contributions to the heat budget were negligible in both seasons. Analyses show that the model temperature is most sensitive to uncertainty in the measurements used to estimate the air–water heat fluxes—the relative humidity in particular. Thus, local MHB measurements are important for accurate monitoring of the MHB heat budget in the future. *Corresponding author - School for Marine Science and Technology, University of Massachusetts Dartmouth, 706 South Rodney French Boulevard, New Bedford, MA 02744-1221. Current address - Graduate School of Oceanography, Unviersity of Rhode Island, Narragansett, RI; yfan@gso.uri.edu. 18 Northeastern Naturalist Vol. 13, Special Issue 4 Estimated Impacts of Cormorants on Fish Populations in the Narragansett Bay Estuary Deborah P. French McCay* and Jill J. Rowe Abstract - The potential impact of cormorant fish consumption on fish populations in the Narragansett Bay estuary (i.e., including Narragansett Bay, Mount Hope Bay, Sakonnet River, and Providence River) was evaluated and compared for Mount Hope Bay and the Sakonnet River versus Narragansett Bay. The local exponential increase in cormorant populations during the 1980s and 1990s coincided with the decline in fish abundance and with the lack of recovery of the populations after fishing pressure was decreased. The population increases were much higher on the east side of the greater Narragansett Bay system than on the west side in Narragansett Bay proper. A model was developed to estimate fish consumption by cormorants. The model includes estimation of fish consumption per bird, foraging areas utilized, and the number of birds feeding in each portion of the Narragansett Bay estuary. The amount of fish consumed annually per cormorant in the population (on average) was estimated using modeling of fish consumption per bird based on age and reproductive status, population age structure, and breeding rates. Estimated cormorant predation losses were compared to trends in fish populations and, for winter flounder, other sources of mortality. *Corresponding author - Applied Science Associates, Narragansett, RI 02882; dfrench@appsci.com. Assessing the Impacts of Fishing and the Brayton Point Power Station on Local Stocks of Winter Flounder Using a Nested, Biomass Dynamic Model Mark R. Gibson* Abstract - Assessing power plant impacts to aquatic resources subject to other stressors using conventional approaches inevitably bogs down in disagreements over data quality, model configurations, and uncertainty surrounding the compensatory reserve of the resource. Larval impacts from entrainment are often assessed using an empirical transport model (ETM), which estimates the proportion of larvae killed in the plant. Thermal degradation of habitat and direct impingement losses of juvenile and older life stages are generally inferred using time series analysis and before-after control-impact (BACI) analysis of abundance indices. These approaches are lacking in that they are purely statistical, with no underlying population dynamics, and it is difficult to interpret the overall impact of the facility in the context of other stressors such as fishing mortality. These deficiencies can be largely avoided by applying a biomass dynamic model (BDM) that includes explicit terms for fishing and plant mortality and is configured as an impacted subpopulation nested within the total population. The model is fit to abundance indices from fishery surveys conducted in both areas. BDM results indicate that power plant mortality is proportional to waste BTU output and is generally less than fishing mortality rate. Overfishing is occurring, with current fishing mortality rate about twice that needed for maximum sustainable yield. The results also show that the Mount Hope Bay subpopulation has declined more relative to its carrying capacity than has the greater Rhode Island population. Projections indicate that substantial reductions in both fishing and power plant mortality are needed to rebuild the Mount Hope Bay subpopulation. *Corresponding author - Rhode Island Department of Environmental Management, Division of Fish and Wildlife, Marine Fisheries Office, 3 Fort Wetherill Road, Jamestown, RI 02835; mgibson@dem.state.ri.us. 2006 R.A. Rountree and D.G. MacDonald 19 Nutrient Related Habitat Quality of Mount Hope Bay Brian L. Howes* and David R. Schlezinger Abstract - Mount Hope Bay is one of the largest estuarine systems in Massachusetts and a major tributary system to Narragansett Bay. Mount Hope Bay, like many estuaries throughout the US, has become nutrient enriched as the population of its watershed increases. At present, about 1/3 of the total watershed area has been developed. The shift from forest to urban and residential development has enhanced nutrient inputs through wastewater, fertilizers and runoff. The primary mechanism for watershed nitrogen to enter Mount Hope Bay is through surface fresh water inflows. Mount Hope Bay receives direct freshwater discharges primarily from the Cole River, Lee River, Kichamuit River, and the Taunton River system. Of these, the Taunton River system has the largest watershed (> 600 mi2), freshwater discharge, and nitrogen load. In addition, there are multiple direct discharges of treated wastewater to the Bay. At present, the central region of the lower estuary appears to be receiving nitrogen inputs beyond its capacity to assimilate them without declines in habitat quality. During summer, the central Bay periodically shows phytophankton blooms (> 30 􀂗g chl-a L-1) and low bottom water dissolved oxygen (< 4 mg L-1), indicative of eutrophic conditions. Analysis of the spatial and temporal distribution and composition of animal and plant communities and comparison with historic records supports the contention that the central bay is currently eutrophic. Quantitative evaluation and nitrogen management modeling of this system is part of the ongoing Massachusetts Estuaries Project. *Corresponding author - Coastal Systems Laboratory, School for Marine Science and Technology, University of Massachusetts Dartmouth, New Bedford, MA 02744; bhowes@umassd.edu. The Exchange of Water Through Multiple Entrances to the Mount Hope Bay Estuary Chris Kincaid* Abstract - Results are presented from a set of hydrographic surveys conducted within Mount Hope Bay, RI, during the summer of August, 1996. This sub-system of Narragansett Bay is interesting because it has two connections to the ocean and it has a source of thermal energy from the Brayton Point Power Plant. Data was collected on water velocity, salinity and temperature on days with relatively high (􀂧 2 m range) and relatively low (􀂧 1 m range) tidal forcing. Velocity data were collected along fixed transect lines defining the boundaries of the estuary and at fixed stations. Results show that flow through each of the oceanward entrances has significant horizontal and vertical structure. The source of fresh water is the Taunton River to the north, and at times, exchange through this interface exhibits vertically sheared flow. Exchange is dominated by flow through the interface with Narragansett Bay, where transports reach 3000 m3/s and 6000 m3/s under conditions of low and high amplitude tidal forcing, respectively. Peak velocities exceed 100 cm/s. Values for transport though the smaller of the two salt water connections, with the Sakonnet River, and the fresh water entrance, at the interface with the Taunton River, were 􀂧 10– 20% of those through the interface with Narragansett Bay. Velocities are relatively sluggish in the shallow northern shelf 20 Northeastern Naturalist Vol. 13, Special Issue 4 region of the estuary, peaking at < 10 cm/s and 􀂧 20 cm/s for the low and high tidal amplitude sampling periods, respectively. Temperature and salinity data reveal significant levels of stratification and suggest three end-member water sources including a deep Narragansett Bay source (cold, salty), a shallow river source (warm, fresh) and a source of water from the Brayton Point region (hot, intermediate salinity). A plug of warm water that evolves on the northern shelf over the ebb cycle of the tide is advected to the east–northeast into the shipping channel during the flood. Phase differences in total instantaneous transport through the two mouths of the system suggest that interactions with the Sakonnet River are dominated by the greater volume and efficiency of exchange with the East Passage of Narragansett Bay. Lateral variations in residual transport show East Passage water entering Mount Hope Bay through the deep central portion of the cross-section and exiting through confined regions along the edges of the interface. The pattern in residual exchange with the Sakonnet River shows water exiting and entering Mount Hope Bay through the western and eastern portions of the cross section, respectively. A conceptual model is suggested in which these lateral flow patterns combine with strong vertical mixing in the Sakonnet River Narrows to pump thermal energy downward in the water column and back northward into the bottom waters of Mount Hope Bay. *Corresponding author - Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI; kincaid@gso.uri.edu. Macroalgae Impacts on the Nursery Habitat of Young-of-the-year Winter Flounder (Pleuronectes americanus), Mount Hope Bay David Lawrence* and Michael Scherer Abstract - In the summer of 2002, we collected data on the density and distribution of the macroalgae Ulva lactuca in Mount Hope Bay to assess its potential impact on the nursery habitat of young-of-the-year winter flounder (Pseudopleuronectes americanus). Macroalgae was sampled from four tributaries in Mount Hope Bay that serve as nursery habitat for winter flounder, with four sites in the Kickmuit River, two sites in the Cole River, three sites in the Lee River, and eight sites in the Taunton River. Triplicate macroalgae samples were taken using a m2 quadrat to determine macroalgal biomass at each site. Winter flounder were sampled using a beach seine at the same time and sites as the macroalgae sampling. An estuary-“wide” survey of macroalgae was conducted in the four tributaries of Mount Hope Bay in August using a combination of visual and benthic grab observations in an effort to determine overall percent coverage of macroalgae in each system. Dissolved oxygen was monitored in each estuary using paired YSI units, one placed in an Ulva-dominated habitat, the other in a site with bare sediment. YSI units were deployed for 1-2 weeks at each station. Finally, benthic samples were collected from areas with heavy macroalgal beds and from areas with relatively clear bottom in each estuary to assess the impact of dense macroalgae accumulations on benthic communities. Overall, these data will be used to determine if the heavy macroalgal densities observed in Mount Hope Bay result in the loss of potential habitat for young-of-the-year winter flounder. *Corresponding author - Marine Research Inc., 141 Falmouth Heights Road, Falmouth, MA 02540; djlaw@u.washington.edu. 2006 R.A. Rountree and D.G. MacDonald 21 The Temperature of Mount Hope Bay John F. Mustard* Abstract - Temperature is a fundamental property of estuarine systems and imparts strong influences on biological function. We have completed detailed studies of the temperature of Mount Hope Bay as a function of season and tide using a combination of in situ and remotely sensed data. These show that the top 2 meters of Mount Hope Bay is on average 1 ºC warmer in the summer and fall than comparable regions elsewhere in the Narragansett Bay estuary, but that this anomaly increases to approximately 3 ºC near Brayton Point. The thermal anomaly can be directly tied to the effluent from the Brayton Point Power Station. During the winter and spring when Mount Hope Bay is typically stratified, the thermal effluent flux is small relative to the heat losses and mixing in the bay. During the summer and fall, the bay is well mixed and the plume from the power plant is observed at the surface over large regions of the Bay. The thermal effluent flux during these times of the year is a significant contribution to the overall heat budget of the Bay. The overall distribution of the thermal anomaly observed with these data is supported by 3-dimensional hydrodynamic modeling. *Corresponding author - Department of Geological Sciences, Brown University, Providence, RI 02912; john_mustard@brown.edu. [For further information on this topic: Fisher, J., and J.F. Mustard. 2004. High spatial resolution sea surface climatology from Landsat thermal infrared data. Remote Sensing of Environment 90(3):293-307. Mustard, J.F., M. Carney, and A. Sen. 1999. The use of satellite data to quantify thermal effluent impacts. Estuarine, Coastal, and Shelf Science 49:509-524.] Effects of Brayton Point Station’s Thermal Discharge on Mount Hope Bay Winter Flounder Robert J. O’Neill*, Thomas L. Englert, and Jee K. Ko Abstract - On behalf of Brayton Point Station, an electrical generating plant located on the shore of Mount Hope Bay, the authors performed an innovative biothermal modeling assessment to evaluate effects of heat load from the Station on 10 bay-resident fish and shellfish species. The assessment linked several biological functions (growth, reproduction, avoidance, migratory blockage, and thermal mortality) to hydrothermal simulations of the Station’s thermal plume under two plant operating scenarios and the no-plant scenario. The assessment methodology is described, and results are presented for Pseudopleuronectes americanus (winter flounder), the species with the lowest thermal tolerance temperatures of those studied. Based on the modeling approach and input assumptions, the effects of the Station’s thermal discharge on the winter flounder life stages and functions studied were found to be negligible, especially when compared to other effects such as fishing pressure. The largest plant effect observed was only 3.9 percentage points more than for the no-plant scenario (compared to a fishing effect of approximately 40–50%). Limitations of the model and potential future refinements to address additional biological effects are discussed and evaluated. The modeling methodology used to complete this study represents a novel and scientifically grounded approach to quantifying the Station’s thermal impacts on the biota of Mount Hope Bay. *Corresponding author - HDR|LMS, 1 Blue Hill Plaza, PO Box 1509, Pearl River, NY 10965; Robert.ONeill@hdrinc.com. 22 Northeastern Naturalist Vol. 13, Special Issue 4 A Tagging Study of Winter Flounder (Pseudopleuronectes americanus) in Mount Hope Bay, Rhode Island J. Christopher Powell* Abstract - As part of an ongoing population assessment of the winter flounder (Pseudopleuronectes americanus) in Rhode Island waters, the RI Division of Fish and Wildlife conducted a winter flounder tagging study in Mount Hope Bay from 1989 to 1991. The tagging effort had to be terminated during the 1991 season due to a lack of flounder available for tagging. One goal of this effort was to determine if Mount Hope Bay has a discrete population of winter flounder that return to this area to spawn. During the study, 914 winter flounder 280 mm TL and larger were collected by otter trawl and tagged with Peterson disk tags. Fourteen percent (114) were males and eighty-six percent (800) were females. Data collected on the reproductive condition of each fish collected indicated that peak spawning in Mount Hope Bay occurred during the months of February and March. Seventy-five tags were returned; 38 (51%) from the rod and reel fisheries, 34 (45%) from the otter trawl fishery, and three (4%) of unknown origin. Temporal distribution of the returns showed the greatest commercial fishing effort occurred during the month of April, with the recreational fishing effort concentrated in May. Spatial distribution of returns showed that about an equal number of returns came from the Mount Hope Bay area and the East Passage just north of the Newport Bridge. Tag return data indicate that adult winter flounder begin moving into Narragansett Bay by way of the East Passage in October. As bay waters cool they move up the bay, east of Prudence Island, and into Mount Hope Bay to spawn. Six tag recoveries from the Sakonnet River indicate that there is some movement into or through this area. In summary, data collected during this study indicate that there is probably a discrete winter flounder population in Mount Hope Bay and that seasonal migration patterns are similar to that of other winter flounder populations in Narragansett Bay. *Corresponding author - Rhode Island Division of Fish and Wildlife, Fort Wetherill Marine Laboratory, 3 Ft. Wetherill Road, Jamestown, RI 02835; Chris.Powell@dem.ri.gov. Aspects of Macrobenthos in Mount Hope Bay Sheldon D. Pratt* Abstract - Conclusions from two University of Rhode Island (Narragansett Bay Project) studies and a description of a long-term data set are offered as bases for understanding macrobenthic invertebrate populations in Mount Hope Bay (MHB). The URI studies allow comparison of MHB with other parts Narragansett Bay. A study of hard clams (Mercenaria mercenaria) in closed waters was carried out in 1985. In MHB hard clams were most abundant in shallow, sandy habitats; the presence of very large (old) individuals there contrasted with the Providence River and indicated acceptable conditions for growth over a long period of time. A survey of macrobenthos was carried out in 1992. In undredged portions of MHB, macrobenthos assemblages were similar to those in Greenwich Bay. Species found in 2006 R.A. Rountree and D.G. MacDonald 23 deep portions of Narragansett Bay extended into the MHB dredged channel. As part of Brayton Point Power Station effects monitoring, benthic samples were obtained in Mount Hope Bay over a 23-year period at intervals as short as three weeks. This valuable data set shows seasonal recruitment pulses with some interruptions and long-term changes in pattern. *Corresponding author - Graduate School of Oceanography, University of Rhode Island, Narragansett, RI; spratt@gso.uri.edu. Spatial and Temporal Patterns of the Fish Assemblages in the Greater Narragansett Bay Estuarine System: Is Mount Hope Bay Different? Rodney A. Rountree* and David A. Witting Abstract - Winter flounder abundances have experienced dramatic declines throughout the greater Narragansett Bay estuarine system, including within Mount Hope Bay. However, a controversy has developed as to whether or not the decline has been more severe in Mount Hope Bay. To address this issue, we chose to use data from the long-term Seasonal Trawl Survey conducted by the Rhode Island Department of Environmental Management (RIDEM). This is the only data set that both encompasses a time frame (1979-2001) that includes the period before and after the decline of winter flounder, and has good spatial coverage of all the greater Narragansett Bay system, including Mount Hope Bay. We analyzed the RIDEM Seasonal Trawl Survey data to examine time trends in the abundance of winter flounder and 28 other species from 9 different areas within the greater Narragansett Bay system. No significant difference was found in the decline of winter flounder in Mount Hope Bay compared to other areas. In fact, the trend for Mount Hope Bay was intermediate to other areas, with several areas exhibiting stronger decline trend. The fish assemblage was observed to have undergone a dramatic shift from benthic to pelagic species in all areas of Narragensett Bay. This pattern is strongest in the shallow embayments (Greenwich Bay, Sakonnet River, Mount Hope Bay, Wickford Harbor, and upper Narragansett Bay), and weakest in the deep central bay areas. In conclusion, we find that changes in winter flounder abundance and in the fish assemblage between 1979 and 2001 in Mount Hope Bay are similar to those observed in other parts of the greater Narragansett Bay system, and reflect processes operating on a Narraganset- Bay-wide scale. *Corresponding author - School for Marine Science and Technology, University of Massachusetts Dartmouth, New Bedford, MA 02744. Current address - Marine Ecology and Technology Applications, Inc. 23 Joshua Lane, Waquoit, MA 02536; rrountree@fishecology.org. Modeling of Temperature Distributions in Mount Hope Bay Due to Thermal Discharges from the Brayton Point Station Craig Swanson*, Hyun-Sook Kim, and Subbayya Sankaranarayanan Abstract - Brayton Point Station is a 1600-MW electrical generating station located on Brayton Point, in Somerset, MA. The Station draws water from Mount 24 Northeastern Naturalist Vol. 13, Special Issue 4 Hope Bay at the Taunton and Lee Rivers for cooling purposes, and discharges the water back into the Bay, through a discharge canal. Mount Hope Bay is a shallow estuary located on the boundary between Rhode Island and Massachusetts. In connection with the renewal of the permit authorizing the withdrawal and discharge of cooling water, a series of studies on Mount Hope Bay were initiated by the owners of Brayton Point Station. These studies included both field and computer modeling components. A hydrothermal model capable of simulating the effects of Brayton Point Station on the Mount Hope Bay waters under a variety of operating scenarios was calibrated using the observed data. Additional cases were run to evaluate the effects of reduced discharges of heated effluent incorporating a cooling tower (enhanced multi mode operation) as well as the case of no discharge. Model results indicated that the temporal temperature variations occur over tidal to annual time scales. Seasonal variations were most discernible in the shallow upper reaches of the Bay, showing warmer than average temperatures during summer and cooler during winter. The calibrated hydrothermal model was also used to estimate the bottom area and water column volume coverage versus temperatures, which helps to quantify the effects of station heat load on the biological functions of winter flounder in Mount Hope Bay. *Corresponding author - Applied Science Associates, Inc., 70 Dean Knauss Drive, Narragansett, RI 02882; cswanson@appsci.com. Integration of a Winter Flounder Habitat Suitability Index Model and Geographic Information System to Prioritize Narragansett Bay Salt Pond Restorations Andrew Tate*, Kristen Weaver, and Anthony Fuda Abstract - Declines in the commercial and recreational winter flounder fisheries of southern New England have been well documented. Many causes for the declines have been suggested, including overfishing, pollution, predation, and alteration of critical habitats. Shallow tidal wetlands and salt ponds are critical spawning and nursery sites for winter flounder. Unfortunately, over the past 50 years, many of these important sites have been altered, and in many cases made unavailable for winter flounder. Recent efforts have identified more than 100 restorable coastal sites in Narragansett Bay. Protocols, which take into account socioeconomic and environmental concerns, have been established to prioritize restoration of eelgrass beds, salt marshes, and anadromous fish runs. However, no formal process has been established to integrate winter flounder critical habitats into prioritizing salt pond restoration. This presentation reports on our efforts to develop a geographic information system (GIS) that: 1) integrates existing habitat component maps into a Habitat Suitability Index (HSI) map for Narragansett Bay, 2) can overlay the HSI map with an existing map of restorable sites, and 3) can prioritize restorable salt pond sites based on their overall HSI scores. *Corresponding author - Department of Biology, Roger Wiliams University, Bristol, RI 02809; atate@rwu.edu. 2006 R.A. Rountree and D.G. MacDonald 25 Predation of Winter Flounder Eggs by the Sand Shrimp (Crangon septemspinosa) in Mount Hope Bay David L. Taylor* Abstract - Predation on the early life stages of marine fish is recognized as one of the most important factors regulating recruitment. Winter flounder (Pseudopleuronectes americanus) spawn demersal, adhesive eggs that could experience high rates of epibenthic predation during incubation. The objective of this study was to determine if the sand shrimp (Crangon septemspinosa) is a source of predator-induced mortality of flounder eggs. Laboratory experiments quantified the ingestion rate of shrimp feeding on flounder eggs as a function of shrimp size (34 to 62 mm TL) and water temperature (2,4, 6, and 10°C). Shrimp were also collected from the Niantic River, CT (n = 600) during peak flounder spawning periods (Feb to Apr 2002), and their stomach contents were analyzed with the Öuchterlony double-diffusion immunoassay to detect the presence (or absence) of flounder eggs in the diet. Shrimp consumption of eggs significantly increased with increasing shrimp size. Moreover, elevated temperatures resulted in the significant increase in egg predation. Results from stomach content analysis revealed that, on average, 7.2% of the field-collected shrimp had flounder eggs within their guts. The incidence of shrimp egg predation was greatest in late February (20%) and decreased at a decelerating rate over time (< 1% by early Apr). Integrating results from this study with estimates of annual flounder egg production in Mount Hope Bay, RI, shrimp could consume 3.4 to 100% (average = 37.0 ± 8.0%) of the total eggs spawned in a given year. Thus, shrimp predation on flounder eggs may be a significant mortality factor and ultimately have important consequences for flounder year-class strength. *Corresponding author - Roger Williams University, Department of Biology and Marine Biology, Bristol, RI 02809;dtaylor@rwu.edu. Assessment of the Seal Populations of Mount Hope Bay and Surrounding Waters Paul M. Webb* Abstract - Seals have been protected in United States waters since the Marine Mammal Protection Act took effect in 1972. As a result of that protection, the number of seals found in southern New England has increased dramatically over the past few decades. While much of this increase has occurred on coastal areas and nearshore islands, increasing numbers of seals have been seen in estuarine regions, including Narragansett Bay and Mount Hope Bay in Rhode Island. The most common seal species in these areas are harbor seals (Phoca vitulina), while increasing numbers of gray seals (Halichoerus grypus), and some ice-breeding seals including harp seals (Pagophilus groenlandica) and hooded seals (Cystophora cristata), are becoming more common, with a few hundred seals present in the area at peak abundances. The seals are most abundant in these areas during the winter and early spring months, where they will remain before moving north to breed in the summer. While the exact diet of these seals remains largely unknown, their increasing numbers may have the potential to impact local fish stocks. *Corresponding author - Department of Biology, Roger Williams University, Bristol, RI 02809; pwebb@rwu.edu. 26 Northeastern Naturalist Vol. 13, Special Issue 4 Simulating the Effects of the Heated Water Discharges from Brayton Point Power Station to Mount Hope Bay in Finite Volume Coastal Model Liuzhi Zhao*, Louis Goodman, Changsheng Chen, Brian Rothschild, and Rodney Rountree Abstract - Mount Hope Bay lies partially within both Massachusetts and Rhode Island. The bay is located in the northeast corner of Narragansett Bay and connected to the Narragansett Bay by the Narragansett Bay East Passage and the Sakonnet River. Using the finite volume coastal ocean model (called FVCOM) developed by Chen et al. (2002), the effects of the heated water discharges from the Brayton Point Power Station (BPPS) to Mount Hope Bay are being studied. This study involves exploration of the pre- and post- BPPS conditions, i.e., with and without the heated water discharges to the bay. The pattern of the water circulation in Mount Hope Bay and the water exchange between Mount Hope Bay and Narragansett Bay are also being explored in detail. *Corresponding author - The School for Marine Science and Technology, University of Massachusetts Dartmouth, 706 South Rodney French Boulevard, New Bedford, MA 02744; lzhao@umassd.edu.