2009 SOUTHEASTERN NATURALIST 8(2):267–276 Enneacanthus chaetodon (Blackbanded Sunfish): An Imperiled Element of Maryland’s Coastal Plain Ichthyofauna Jay V. Kilian1,*, Scott A. Stranko1, Richard L. Raesly2, Andrew J. Becker1, and Patrick Ciccotto1 Abstract - In 2002 and 2006, we conducted a survey of historical collection localities for Enneacanthus chaetodon (Blackbanded Sunfish) in Maryland. Blackbanded Sunfish were detected at only one of six historical localities. This locality consisted of 17 quarry ponds, but the Blackbanded Sunfish was collected in only three of these. These ponds were characterized by low pH (<4.9), dense submerged and overhanging vegetation, and the absence or low abundance of non-native piscivores. The acidic nature of these ponds may provide refuge from predation for Blackbanded Sunfish by limiting numbers of non-native piscivores such as Micropterus salmoides (Largemouth Bass) and Pomoxis nigromaculatus (Black Crappie). As a result of the surveys described herein, the Blackbanded Sunfish state status in Maryland was elevated from Threatened to Endangered. Introduction Enneacanthus chaetodon Baird (Blackbanded Sunfish) is a small centrarchid typically associated with heavily vegetated, tannin-stained dystrophic ponds, swamps, and slow-moving habitats of streams and rivers (Jenkins and Burkhead 1993, Lee et al. 1980). This species is sporadically distributed on the Atlantic Coastal Plain from New Jersey to Florida and on portions of the Gulf slope in Georgia (Lee et al. 1980). Throughout this range, the Blackbanded Sunfish is absent from many areas, resulting in many disjunct populations (Jenkins et al. 1975, Lee et al. 1980, Sweeney 1972). Peculiar absences of this species throughout portions of its range are hypothesized to be the result of saltwater inundation into freshwater habitats caused by sea-level rise during the Pleistocene epoch (Sweeney 1972). Competition with other centrarchids may also explain the absence of Blackbanded Sunfish in areas with otherwise suitable habitat (Jenkins et al. 1975). Although considered secure in New Jersey and South Carolina, the Blackbanded Sunfish is considered imperiled, vulnerable, or presumed extirpated in Pennsylvania, Delaware, Virginia, North Carolina, Georgia, and Florida (Arndt 2004, NatureServe 2008). Recent efforts to collect Blackbanded Sunfish in Florida were unsuccessful (Tate and Walsh 2005). The historical range of Blackbanded Sunfish in Maryland includes the Nanticoke, Wicomico, and Pocomoke river basins on the Delmarva Peninsula, in which the majority of historical collection localities are ponds or 1Maryland Department of Natural Resources, Monitoring and Non-tidal Assessment, 580 Taylor Avenue, Annapolis, MD 21401. 2Frostburg State University, Department of Biology, 101 Braddock Road, Frostburg, MD 21532-1099. *Corresponding author - jkilian@dnr.state.md.us. 268 Southeastern Naturalist Vol. 8, No. 2 impoundments in the Nanticoke and Wicomico river basins. The most recent collection of Blackbanded Sunfish was in 1999 from an unnamed pond in a quarry pond complex located along Marshyhope Creek in the Nanticoke River basin. There is only one record for a lotic population of Blackbanded Sunfish in Maryland. This collection was made from Old Mill Branch, a tributary to the Pocomoke River on the Delmarva Peninsula (Speir et al. 1976). Lotic systems within the historical range of Blackbanded Sunfish in Maryland were sampled extensively from 1994 to 2006. The Maryland Department of Natural Resources’ Maryland Biological Stream Survey (Kazyak et al. 2005) and others (McIninch 1994; Raesly 1995, 1996) have sampled over 185 stream sites in the Nanticoke, Wicomico, and Pocomoke river basins, including Old Mill Branch. Blackbanded Sunfish has not been collected from a stream or river in Maryland since 1976. Given the extensive effort that has been focused in lotic systems, and the dearth of effort in lentic habitats in Maryland, we conducted a survey of ponds and impoundments where Blackbanded Sunfish were historically collected. The objectives of this study were to determine the current distribution and status of Blackbanded Sunfish in Maryland and determine what factors may be correlated with the distribution of the species. Methods In the summer of 2002 and 2006, we attempted to collect Blackbanded Sunfish from six historical collection localities (Fig 1). These localities Figure 1. Locations of historical collection localities for Blackbanded Sunfish sampled in 2002 and 2006. 2009 J.V. Kilian, S.A. Stranko, R.L. Raesly, A.J. Becker, and P. Ciccotto 269 included Leonards Mill Pond, Williams Pond, Schumaker Pond, Tony Tank Lake, Smithville Lake, and the complex of quarry ponds where Blackbanded Sunfish was last collected in Maryland. We sampled all five impoundments and 17 ponds within the quarry pond complex using electrofishing. While electrofishing in dense vegetation, the vegetation was searched extensively for small fishes, and dip nets were used to sweep through and lift the plants to increase capture efficiency. A 14-foot jonboat outfitted with a Smith-Root Model KVA electrofisher was used to sample all non-wadeable habitats. The boat was positioned perpendicular to the shoreline and electroshocking was conducted moving from deepwater offshore to shallow inshore habitats. Backpack electrofishing (Smith-Root Model 12; Haltech Model HT-2000) was used in wadeable margins of ponds and impoundments. Sampling was conducted until all available habitats had been sampled and no new species of fish were captured for at least 600 seconds. With the exception of Schumaker Pond, Tony Tank Lake, and Smithville Lake, abundances of fish species were qualitatively assessed as rare, common, or abundant. In the summer of 2006, temperature (°C), pH, acid-neutralizing capacity (ANC; μeq/L), dissolved oxygen (mg/L), specific conductance (mS/cm), and dissolved organic carbon (DOC; mg/L), were recorded at 15 quarry ponds and two impoundments (Williams Pond and Leonards Mill Pond) in addition to fish sampling. With the exception of ANC and DOC, which were analyzed at the University of Maryland Appalachian Laboratory, all water chemistry parameters were measured using a Hydrolab Quanta. Principal component analysis was used to visualize potential patterns in these variables as they relate to the presence of Blackbanded Sunfish. Variables were tested for normality with a Kolmogorov-Smirnov test in SAS Enterprise Guide (SAS Institute 2006). Specific conductance was the only variable that failed the test for normality, and was subsequently log10(x) transfromed. A correlation matrix was used to run the principal component analysis in PC-ORD (Mc- Cune and Medford 2006). Results We collected 27 species of fishes, including all three species in the genus Enneacanthus, using electrofishing (Table 1). Blackbanded Sunfish were collected in very low abundances from only three ponds in the complex of quarry ponds. These ponds were characterized by low pH and ANC (less than 4.9 and 12.8, respectively; Table 2), an abundance of submerged logs and limbs, dense aquatic vegetation, and few non-native piscivores (i.e., Micropterus salmoides (Lacepède) [Largemouth Bass] and Pomoxis nigromaculatus (Lesueur in Cuvier and Valenciennes) [Black Crappie]). The pond with the largest collection of Blackbanded Sunfish (7 individuals) was the only habitat with an abundance of Ceratophyllum demersum L. (Coontail) along the entire shoreline. Principal component analysis illustrates the distinct chemical and biological nature of the lentic habitats where Blackbanded Sunfish were collected. 270 Southeastern Naturalist Vol. 8, No. 2 Table 1. Numbers of Blackbanded Sunfish collected and qualitative abundance of other fish species collected in 2002 and 2006. R = rare: comprising smallest proportion of total catch; C = common: well represented in the catch, but not rare or abundant; A = abundant: comprising largest proportion of total catch. X indicates that the species was present, but abundance was not recorded. WP = Williams Pond, LMP = Leonards Mill Pond, SP = Schumaker Pond, TTL = Tony Tank Lake, and SL = Smithville Lake. Quarry Pond Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 WP LMP SP TTL SL Ameiurus natalis (Lesueur) (Yellow Bullhead) R R R R C C C R R R X X Ameiurus nebulosus (Lesueur) (Brown Bullhead) R R X X Anguilla rostrata (Lesueur) (American Eel) C C C C C C C R C A R R C R X X Aphredoderus sayanus (Gilliams) (Pirate Perch) C R R C R R X X X Cyprinus carpio (L.) (Common Carp) C Dorosoma cepedianum (Leseuer) (Gizzard Shad) R C A C R R R Enneacanthus chaetodon (Blackbanded Sunfish) 1 1 7 Enneacanthus gloriosus (Holbrook) R R A A A C A C C C R C C C X X (Bluespotted Sunfish) Enneacanthus obesus (Girard) (Banded Sunfish) X Erimyzon oblongus (Mitchill) (Creek Chubsucker) R R R C C R R C A R R R X X X Esox americanus (Gmelin) (Redfin Pickerel) X Esox niger ((Leseuer) (Chain Pickerel) C R C R R C C C C C C R R R C X X X Etheostoma fusiforme (Girard) (Swamp Darter) R R R R R R R X X 2009 J.V. Kilian, S.A. Stranko, R.L. Raesly, A.J. Becker, and P. Ciccotto 271 Table 1, continued. Quarry Pond Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 WP LMP SP TTL SL Etheostoma olmstedi (Storer) (Tessellated Darter) R X X X Gambusia holbrooki (Girard) (Eastern Mosquitofish) R R X Lampetra aepyptera (Abbott) (Least Brook Lamprey) X X Lepisosteus osseus (L.) (Longnose Gar) R C R Lepomis hybrid R Lepomis gibbosus (L.) (Pumpkinseed) R R R R R C X X X Lepomis macrochirus (Rafinesque) (Bluegill) A A A A A C A A C A A R R C A A A X X X Morone americana (Gmelin) (White Perch) R R Micropterus salmoides (Largemouth Bass) A A A C R R A A C C R R C C A A X X X Notemigonus crysoleucas (Mitchill) (Golden Shiner) R C C R C C C C R C R R R A X X X Noturus gyrinus (Mitchill) (Tadpole Madtom) R R X X Perca fl avescens (Mitchill) (Yellow Perch) R R C Pomoxis annularis (Rafinesque) (White Crappie) C Pomoxis nigromaculatus (Black Crappie) R R C R C A C R C C R A C X X Umbra pygmaea (DeKay) (Eastern Mudminnow) R A R C R X X X 272 Southeastern Naturalist Vol. 8, No. 2 The eigenvalues of the first three principal component axes were all greater than their respective broken-stick eigenvalues (Table 3), and the first two principal components were plotted (Fig. 2). The first principal component axis accounted for 48% of the total variance and represented ANC, pH, and specific conductance gradients among historical sites. The second principal component axis accounted for 29% of the total variance and represented a dissolved organic carbon gradient (Table 3). Sites where Blackbanded Sunfish were collected and non-native centrarchids were not abundant had lower pH and ANC values (Fig. 2). Although the small sample size inhibits a rigorous statistical test of the data, we believe the principal component analysis identifies a pattern in the distribution of Blackbanded Sunfish. Discussion Although detection may be incomplete due to the application of a single sampling method (electrofishing) in this study, our results demonstrate that Blackbanded Sunfish are exceedingly rare in Maryland and the species’ range has declined dramatically. We did not detect Blackbanded Sunfish at five of the six historical collection localities. Only six other extant populations of this species were known in the entire Chesapeake Bay watershed at the time this study was conducted. All six of these are from the Nanticoke River drainage in Delaware (K. Kalasz and C. Martin, Delaware Division of Fish and Wildlife, Smyrna, DE, pers. comm.). Historically, Blackbanded Sunfish were likely widespread throughout the Nanticoke and Wicomico rivers in Maryland and Delaware, where they inhabited both lotic and lentic Table 2. Water chemistry of ponds and impoundments used in principal components analysis.T = temperature (ºC), ANC = acid neutralizing capacity (μeq/L), DO = dissolved oxygen (mg/L), SpCond = specific conductance (mS/cm), and DOC = dissolved organic carbon (mg/L). Pond/impoundment T pH ANC DO SpCond DOC Quarry Pond 1 21.1 5.96 70.3 3.5 0.026 6.1 Quarry Pond 2 20.3 6.38 168.2 2.2 0.039 2.5 Quarry Pond 3 18.9 6.29 308.6 3.4 0.085 5.8 Quarry Pond 4 21.6 6.30 146.9 5.0 0.051 5.5 Quarry Pond 5* 21.4 4.75 12.8 4.0 0.052 9.1 Quarry Pond 6* 20.6 4.87 -0.3 2.0 0.047 9.4 Quarry Pond 7 19.9 6.37 294.1 4.8 0.068 6.5 Quarry Pond 8 19.4 5.66 261.5 2.4 0.050 5.7 Quarry Pond 9 20.3 4.53 6.9 1.5 0.047 14.4 Quarry Pond 10 21.3 5.10 82.1 2.5 0.029 8.7 Quarry Pond 11 19.6 5.80 244.3 2.9 0.089 9.7 Quarry Pond 12* 24.3 4.66 -11.0 4.9 0.032 1.7 Quarry Pond 14 22.7 5.20 -10.0 3.4 0.038 2.6 Quarry Pond 16 22.5 5.07 64.1 5.7 0.025 5.6 Quarry Pond 17 22.7 5.56 64.6 4.3 0.027 7.0 Williams Pond 20.5 5.64 336.1 4.7 0.075 11.2 Leonards Mill Pond 21.1 6.08 370.7 4.8 0.093 10.2 *Blackbanded Sunfish detected. 2009 J.V. Kilian, S.A. Stranko, R.L. Raesly, A.J. Becker, and P. Ciccotto 273 systems. However, all known extant records are from isolated fragments of lentic habitat. Although somewhat cursory, the patterns observed in this study are consistent with other studies describing Blackbanded Sunfish habitat. Blackbanded Sunfish have occasionally been observed in bodies of water with pH levels above 7.0 and can successfully reproduce in neutral or alkaline waters (Graham 1978, Hoedeman 1974). However, they have most often been found Figure 2. Principal component analysis of water chemistry variables for Blackbanded Sunfish sampling sites. Dark circles (●) are sites where Blackbanded Sunfish were collected and non-native piscivores were not abundant; filled squares (■) are sites where Blackbanded Sunfish were not collected and non-native piscivores were abundant; and open squares (􀂅) are sites where Blackbanded Sunfish were not collected and non-native piscivores were not abundant. Eigenvectors associated with the axes are presented in Table 1. Table 3. Results of the principal component analysis for water chemistry variables. Eigenvectors are reported for the first 3 axes for each variable, as well as eigenvalues and percent of variance explained by the first 3 axes. Variable Axis 1 Axis 2 Axis 3 pH 0.51 0.33 0.42 Acid neutralizing capacity (μeq/L) 0.62 -0.02 0.05 Dissolved oxygen (mg/L) 0.17 0.52 -0.83 Specific conductance (mS/cm) 0.56 -0.29 -0.11 Dissolved organic carbon (mg/L) 0.11 -0.74 -0.35 Eigenvalue 2.39 1.45 0.79 Broken-stick eigenvalue 2.28 1.28 0.78 % of variance 47.87 29.04 15.82 274 Southeastern Naturalist Vol. 8, No. 2 in highly acidic habitats. Conversely, Graham and Hastings (1984) suggested that survival of Largemouth Bass and Black Crappie may be reduced by low pH. Graham (1993) documented a decline in Largemouth Bass and Black Crappie abundance as pH dropped below 6.0, and absence from waters more acidic than 4.5. Although our sample size was small and detection may be incomplete, Blackbanded Sunfish were found only in acidic ponds with few or no non-native centrarchids suggesting that acidic conditions may provide refuge from predation and/or competition. Due to pervasive alterations to the physical, chemical, and biological conditions of Delmarva streams and rivers, only a few suitable insular lentic habitats may remain for Blackbanded Sunfish in Maryland. The reduction of beaver and the removal of millponds have likely contributed to the decline of suitable habitat within lotic systems. Acidic, dystrophic habitats favored by this species have been further reduced by large-scale removal of forests, stream channelization, eutrophication, and liming of land for agriculture. Current conditions of the large majority of Delmarva freshwater habitats may be more suited to non-native centrarchids than to the native Blackbanded Sunfish. In addition, factors responsible for the insular nature of the current Blackbanded Sunfish distribution have made meta-population interactions all but impossible for this species. It has not been observed in any stream or river in Maryland since 1976 (Speir et al. 1976), nor in Delaware since 1995 (K. Kalasz and C. Martin, pers. comm.). The isolation of Maryland’s extant populations of Blackbanded Sunfish also makes the species vulnerable. With a maximum lifespan of only four years (Schwartz 1961), one poor recruitment year or even a minor disturbance of the few habitats where they occur could result in extirpation from Maryland. Without the connection of populations living in ponds via habitable river systems, conserving this species is likely to be challenging. Surveys for this species with additional gear types (e.g., seining and minnow traps) are needed to provide a more comprehensive determination of Blackbanded Sunfish presence in Maryland (MacKenzie et al. 2004). Estimating detection probabilities for Blackbanded Sunfish for each gear type would provide useful information to guide future surveys in Maryland as well (Albanese et al. 2007). Including additional habitat and chemical parameters in future surveys may also reveal other factors important in determining the current Blackbanded Sunfish distribution in Maryland. These surveys will also provide sufficient information for a more rigorous statistical examination of factors associated with this species. Such information will be important in managing this species. In the interim, however, the information provided by the results of this study reveal an immediate need for conservation action. Protection of the area surrounding the ponds where the species is currently known to occur is imperative. To the extent possible, Largemouth Bass and other non-native centrarchids should be relocated from these ponds, and stocking of these species therein should be discontinued. Depending on the results of 2009 J.V. Kilian, S.A. Stranko, R.L. Raesly, A.J. Becker, and P. Ciccotto 275 follow-up surveys and the status of Delaware populations, possible re-introduction of Blackbanded Sunfish may be explored in the future. As a result of the surveys described herein, the Blackbanded Sunfish state status in Maryland was elevated from Threatened to Endangered. The status of this species in nearby states, such as Delaware and Virginia indicate that it may be regionally imperiled. Along with our management effort in Maryland, we also plan to communicate our results to the natural resource management agencies in adjacent jurisdictions in hopes of initiating a region-wide collaboration for the conservation of this species and the unique coastal plain habitats it represents. Acknowledgments We thank Paul Kazyak for his work on earlier surveys and for providing the impetus for rare species surveys in Maryland. 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