Northeast Natural History Conference 2011: Selected Papers 2012 Northeastern Naturalist 19(Special Issue 6):67–76 The Distribution of Cordulegaster (Odonata: Cordulegastridae) Nymphs in Seeps and Springs of Nelson Swamp (Madison County, NY) Barbara J. Hager1,*, Nina J. Kalantari1, and Van A. Scholten1 Abstract - Given the presence of foraging and reproducing adult Cordulegaster (spiketail) dragonflies in Nelson Swamp (Madison County, NY), we examined nymph distribution and abundance in the seeps and springs found within the swamp. From 9 September–4 November 2010, we surveyed 8 sites along Chittenango Creek in order to determine: (1) the species present and their distribution/occurrence among sites, (2) factors influencing species presence and abundances, and (3) patterns in size and age distribution among and within sites. For sites, we delineated habitat zones (inlet, middle, outlet), determined the benthic substrate, and measured shoreline perimeters. For nymphs, we measured head width, body length, and wing pad length and identified some to species. The majority of spiketails we identified were Cordulegaster diastatops (Delta-spotted Spiketail); Cordulegaster maculata (Twin-spotted Spiketail) was also present. Most nymphs occurred in inlets with muck and cobble bottoms and in water depths less than 10 cm. Spiketail densities ranged from 0.13–8.13 individuals/m of shoreline. Smaller individuals occurred in cobble substrate, while muck substrates had individuals of larger size and greater abundance. We demarcated at least 2 age cohorts of nymphs based on their body measurements in relation to growth patterns observed in other spiketail species. Introduction The 8 North American species of Cordulegaster (spiketail) dragonflies are geographically widespread yet only locally common inhabitants of streams, springs, and seeps (Nikula et al. 2007). In a review of Odonata literature, Corbet (1999) concluded that spiketail nymphs require microhabitats with particular sediment particle sizes—to permit the shallow burrowing by nymphs of different sizes—and with water flows of not more than 10–15 cm/sec. Recent studies of Cordulegaster erronea Hagen (Tiger Spiketail), Cordulegaster dorsalis Hagen (Pacific Spiketail), Cordulegaster sayi Selys (Say’s Spiketail), and Cordulegaster maculata Selys (Twin-spotted Spiketail) confirm that current, sediment size, and sediment composition influence presence and abundance (Burcher and Smock 2002, Glotzhober 2006, Marczak et. al. 2006, Stevenson et al. 2009). Thus, seeps and springs running into lentic waters as well as occurring alongside streams and rivers may support populations of spiketails. From 2006–2010, one of us (B.J. Hager) observed numerous adult Cordulegaster diastatops Selys (Delta-spotted Spiketail) and a few Twin-spotted Spiketails foraging along field edges at our study area (B.J. Hager, unpubl. data). Likewise, many Delta-spotted Spiketails were observed engaging in reproductive 1Environmental Studies Program, Cazenovia College, 22 Sullivan Street, Cazenovia, NY 13035. *Corresponding author - bhager@cazenovia.edu. 68 Northeastern Naturalist Vol. 19, Special Issue 6 activities in both the seeps and springs beside the branch of Chittenango Creek running through Nelson Swamp, and also in the creek itself. At the same time, only one Twin-spotted male was seen patrolling along Chittenango Creek itself and at the spring that was nearest the creek bed (site 6; Table 1). During the fall of 2010, we set out to examine spiketail nymph distribution within and among the seeps and springs at this locale. In particular, we focused on the following questions: (1) How are spiketail nymphs distributed among the individual seeps and springs? (2) Do the nymphs appear to prefer different microhabitats or substrates? (3) What are the sizes and abundances of the spiketail nymphs in the various seeps and springs? Methods Study area description Nelson Swamp Unique Area is a 607-ha (1500-acre) cedar/hemlock swamp located in west central Madison County, NY (roughly 42°53'N, 75°47'W). Two branches join to form the main channel of Chittenango Creek, which flows through the westernmost portion of the swamp (Fig. 1; NYSDEC Region 7 Management Team 2000). Classified as a fen by the New York State Natural Heritage Program, the area adjacent to the creek is underlain by Wayland silt-loam soil, and, upslope, the adjoining Carlisle-Palms muck soils (NYSDEC Region 7 Management Figure 1. Location of Madison County in New York State (shaded county on state map) and the seeps and springs (dashed line encircling creek) sampled along Chittenango Creek (CC) in Nelson Swamp Unique Area. A band of trees, ranging in width from 10–30 m, stretched north away from the creekbed. The dot indicates an open field where many teneral and adult Cordulegaster diastatops and a few Cordulegaster maculata occurred. LT indicates the Link Trail of Nelson Swamp and CBR stands for Constine Bridge Road. 2012 B.J. Hager, N.J. Kalantari, and V.A. Scholten 69 Team 2000). These soil types are well saturated year-round, and it’s likely that groundwater percolating from both of them contributes to the seeps and springs lining the creek. In the area we studied (northern side of the main branch of the creek near Constine Bridge Road, Town of Cazenovia; Fig. 1), Tsuga canadensis (L.) Carr (Eastern Hemlock) and Thuja occidentalis L. (Northern White Cedar) form the prominent canopy cover, while mats of Callitriche sp. (water starwort) dominate the aquatic vegetation. Seep/spring data We sampled 8 seeps and springs located along the northern edge of the main stem of Chittenango Creek. We distinguished seeps from springs by assessing whether the groundwater flowed from a single source (a spring) or appeared to have no source or multiple, very small trickle sources spread over a large area (a seep) (Dodson 2005). For each site, we measured the shoreline perimeter, delineated the inlet, middle, and outlet zones, and measured water depths near the shore (within 15 cm) in the inlets and outlets (when applicable) and at the deepest point. For each zone of a site, we classified the benthic substrate as large (>10 cm) or small (<10 cm) cobble, sand, muck (fine, black organic matter), clay, and vegetation (Table 1). The most common substrates—cobble and muck/sand— were later classified into cobble, muck, and mixed (cobble/muck) for analysis. Lastly, we recorded the presence of frogs (Lithobates clamitans Latreille [Green Frog]), fish (mostly Rhinichthyes spp. [daces]), and salamanders (Desmognathus spp.) encountered during our surveys. Spiketail sampling methods From 9 September to 4 November 2010, we surveyed each spring and seep for nymphs by systematically sifting the substrate by hand. All but two of the sites (sites 4 and 5) were sampled exhaustively for nymphs. The substrate of these latter two sites was predominantly clay and large cobble with a water depth greater than 0.5 m; therefore, we could not remove much material for sifting, although we did feel among the cobble for the nymphs. We placed the nymphs into separate shallow, water-filled pans corresponding to each zone. Using calipers, we measured head width, body length, and wing pad length of each spiketail to the nearest 0.05 mm. After processing, we released most of the nymphs where they were collected, except for those brought back to the laboratory for species identification. We brought 75 late instar (with headwidths greater than 5.5 mm) and 21 early instar spiketails back to the laboratory for species identification using the nymphal keys from Bright and O’Brien (1999) and Needham et al. (2000). These keys rely on 2 major characteristics of late-stadium nymphs to distinguish C. maculata from C. diastatops—frontal shelf shape and setae and epaulet shape; thus, we examined the early instar individuals to see if we could use the keys for individuals this young. Based on our observations, the differences in frontal shelf and epaulet shape of younger-stadium individuals were not as obvious as in older specimens, especially when trying to observe living individuals. Due to this level of uncertainty in identification, we decided not 70 Northeastern Naturalist Vol. 19, Special Issue 6 to include these individuals in our counts of determined species identification. All specimens were released the following week. Results We found a total of 296 nymphs, ranging in body length from 6.30 to 35.35 mm (Fig. 2), at 7 of the 8 sites (Table 1). The two sites with 0 or 1 nymph captured had clay-based bottoms, shallow or limited fine sediment, and extensive areas covered with large cobble. Of the 75 larger (head width > 5.5 mm and body length > 20 mm) individuals identified to species, 73 (97%) were C. diastatops, while the other two were C. maculata. The smaller individuals could not be identified to species with a high degree of certainty with the keys, but most appeared to be C. diastatops. Given that the keys are based on characteristics found in the last nymphal stadium, and that the relative appearance of these characteristics can change with nymphal age, it is possible that there could be more C. maculata at the sites. Spiketail density varied among the sites, but the overall average density of spiketails among sites did not differ (F1,7 = 0.324, P > 0.75). Studies on C. dorsalis showed that females may preferentially choose inlet areas for oviposition and as larval habitat (Marczak et al. 2006), so we examined nymph distribution by zone. More individuals occurred in the inlets (Fig. 3); spiketails in the inlets had smaller average head widths (hw) than those in other zones (inlet hw in mm: Figure 2. Frequency distribution of body-length size classes for Cordulegaster nymphs recovered from the eight sites within Nelson Swamp, NY. All sites with more than 6 spiketails had a mixture of size classes within them. 2012 B.J. Hager, N.J. Kalantari, and V.A. Scholten 71 4.33 ± 1.42 vs. 4.88 ± 1.33 in middle and 4.45 ± 1.65 in outlets; ANOVA F 2,294 = 3.86, P < 0.02). Because substrates and zones are confounded and sample sizes Table 1. Physical descriptions and select biological findings for the 8 springs and seeps along Chittenango Creek, Nelson Swamp, NY, sampled for the presence of Cordulegaster (spiketail) nymphs. The perimeter is the sum of the length of the shoreline of the spring or seep. For benthic substrate, m = muck, s = sand, lc = large cobble (>10 cm), sc = small cobble (<10 cm), cl = clay and v = vegetation. The density of Cordulegaster is the number of individuals per meter of shoreline perimeter. NA= Not applicable Water Cordulegaster Benthic substrate depths (cm) nymphs Presence of Perimeter Inlet/ Larval Fish or Site (m) Inlet Middle Outlet outlet Middle # Density salamanders frogs Springs 1 21.6 s/m m/sc m/v 50 56 30 1.38 No Yes (frogs) 3 15.5 m/v m/lc m/sc 10 90 124 8.00 Yes Yes (both) 4 7.7 m/cl cl/lc cl/sc 13 85 1 0.13 No Yes (fish) 5 8.1 cl/sc cl/lc cl/lc 11 88 0 0.00 No Yes (both) 6 11.1 m/sc m m/sc 7 7 66 5.94 Yes Yes (frogs) Seeps 2 15.2 NA m sc 10 43 5 0.33 Yes Yes (frogs) 7 7.5 sc m m 5 44 61 8.13 Yes Yes (frogs) 8 12.1 NA m NA 2.5 5 9 0.74 No No Figure 3. Abundances of Cordulegaster nymphs in the three habitat zones combined for all sites. 72 Northeastern Naturalist Vol. 19, Special Issue 6 are small, we could not determine the relative importance of each in influencing nymph distribution. However, we performed 2 preliminary analyses of substrate and nymphal age (as indicated by head width) with the data at hand. When we combined all sites and zones, more nymphs occurred in the muck substrates than in the cobble and mixed muck/cobble substrates (χ2 = 125.4, 2 df, P < 0.0001; Fig 4). Smaller individuals were found more often in the cobble substrate, while larger individuals occurred in muck, whether we combined all of the zones (inlet, outlet, and middle) (ANOVA: F 2,293 = 9.66, P < 0.009) or conducted the analysis for inlets only (ANOVA: F 2,174 = 8.48, P < 0.0003) (Fig. 5). Extrapolating from work done with other spiketail species (Glotzhober 2006), it appears that the Nelson Swamp sites supported at least 2 cohorts of nymphs (Fig. 6). Forty-eight individuals most likely belonged to the F-1 or F-0 stadium (F-1 is the penultimate and F-0 is the ultimate nymphal stadium before molting to adulthood) and were separated clearly from the younger nymphs by having a body length > 26 mm and a head width > 6 mm. Discussion Given the small number of sites (Table 1), we cannot draw conclusions about seep or spring preference by the spiketail species found in Nelson Swamp. However, we can make some initial assessments about habitat associations. Consistent Figure 4. Frequency of individuals found in the three major types of substrate. Expected numbers calculated by assuming equal abundances across the three substrates. More individuals were found in muck than expected (χ2 = 125.4, 2 df, P < 0.0001). 2012 B.J. Hager, N.J. Kalantari, and V.A. Scholten 73 Figure 5. Average head widths of Cordulegaster nymphs in relation to the substrate type of the inlets (ANOVA: F2,174 = 8.48, P < 0.0003). Figure 6. Correlation of body lengths and head widths for Cordulegaster nymphs in seeps and springs of Nelson Swamp, NY, all sites combined. The circle indicates nymphs of a separate age cohort. 74 Northeastern Naturalist Vol. 19, Special Issue 6 with other studies (Burcher and Smock 2002, Corbet 1999, Glotzhober 2006, Stevenson et al. 2009), spiketails in our sites use habitats with slow water currents and muck or sand substrates, both of which permit burrowing by the nymphs. One of us (B.J. Hager) has observed C. diastatops patrolling and ovipositing at 5 of the 7 sites over a 6-year period; in contrast, C. maculata was not seen foraging in the fields or at sites occupied by nymphs until the summers of 2010 and 2011 (B.J. Hager, unpubl. data). Whether or not these 2 species occupy different microhabitats within Nelson Swamp remains to be determined. Burcher and Smock (2002) and Corbet (1999) noted that C. maculata is more of a habitat generalist compared to many species within the genus Cordulegaster because, while also recorded as nymphs or ovipositing adults in small streams (Donnelly 1992, Dunkle, 2000, Glotzhober and McShaffery 2002), they are commonly found in the slower currents and backwaters of larger streams and along lake shorelines near inlets. Likewise, Santos and Stevenson (2011) reported in their study of perennial and non-perennial stream fauna in Massachusetts that C. maculata occurred only in perennial streams. We found both of the definitive specimens of C. maculata in site 6, a 1.5-m-wide spring that parallels Chittenango Creek and is separated from the creek at its nearest point by roughly 40 cm of land. In contrast, nymphs of C. diastatops are generally limited to smaller streams and are common in “puny streams” in “upland spring bogs” (Needham 1901) and small streams of forests and marshes (Donnelly 1992, Dunkle 2000). While many nymphs occupied the inlets (Fig. 3), we could not determine what influenced this distribution pattern. An initial analysis of the influence of substrate, using inlet data only, shows that nymph abundances and average sizes were greatest in muck (Figs. 4, 5). In contrast, the smallest individuals occurred in cobble (Fig. 5), which could be a consequence of one or more factors. First, female C. maculata and C. diastatops tend to oviposit in muck and vegetation in the shallowest portions of the water (Corbet 1999, Dunkle 2000, Nikula et al. 2007), where small and large cobble were common, and the nymphs might not have dispersed after egg hatch. Second, the narrower spaces among cobbles as well as the thinner sediment layer may prohibit larger individuals from burrowing here; Marczak et al. (2006) found that habitat particle size and body size were positively correlated for nymphs of C. dorsalis. Third, smaller nymphs may seek refuge from predators, including conspecifics, in the spaces among the cobble. Subsequent studies at the Nelson Swamp sites need to more carefully examine the distribution and density of nymphs in relation to muck depth, size of cobble, and size of sediments for each of the habitat zones (inlet, outlet, middle). Three of the 4 springs and seeps with the highest spiketail nymph densities also contained larval salamanders (Desmognathus spp.; Table 1). Cordulegaster erronea co-occurred with larval Pseudotriton ruber Latreille (Red Salamanders) in spring-fed stream habitats in Ohio (Glotzhober 2006), while larval Eurycea cirrigerra Green (Southern Two-lined Salamanders), Pseudotriton montanus Baird (Mud Salamanders), Red Salamanders, and larval and adult Desmognathus fuscus conanti Rossman (Spotted Dusky Salamander) inhabited 86% of C. sayi sites in Georgia (Stevenson et al. 2009). These investigators 2012 B.J. Hager, N.J. Kalantari, and V.A. Scholten 75 both suggest that salamanders might be important predators, prey, and/or competitors with the spiketail nymphs. We observed a spiketail nymph feeding on one of the larval salamanders. Most spiketail species are semivoltine and take from 2–5 years to reach maturity (Burcher and Smock 2002, Corbet et al. 1999, Ferreras-Romero and Corbet 1999, Glotzhober 2006). Assuming that growth and molting follow similar patterns among Cordulegaster species, we conclude that there are at least two age cohorts at our sites. Life-history studies of C. erronea (Glotzhober 2006), Cordulegaster boltonii Donovan (Golden-ringed Spiketail; Ferreras-Romero and Corbet 1999), and C. maculata (Burcher and Smock 2002) demonstrated clear, correlated changes in head width, body length, and wing pad length associated with the F-1 and F-0 stadia. These authors show that, when plotting the measurements in size classes, a clear separation from the younger individuals generally occurs for those near or entering the F-1 and F-0 stadia. Based on their findings, roughly 16% of our nymphs were probably at the F-1 or F-0 stadium (Fig. 6). Conversely, we had 14% with head widths of less than 3 mm. These latter individuals are likely to be from eggs laid and hatched in 2010, if we assume that all Cordulegaster eggs develop directly without overwintering, as is the case for the Golden-ringed Spiketail (Ferreras-Romero and Corbet 1999, Schutte 1997). Thus, with the information at hand, we cannot determine if there are more than 2 age cohorts in our sites. Repeated sampling and replacement of nymphs at these habitats over a more extended period of time, as done by Glotzhober (2006), is necessary to determine the specifics of the age cohorts in Nelson Swamp. Additionally, rearing of specimens should be conducted to determine life-history parameters and to obtain more precise information about the relative numbers and distributions of the two spiketail species using Nelson Swamp. Acknowledgments Partial funding for this project came from Cazenovia College’s Faculty Development Fund. The authors thank Erin White (NY Natural Heritage Program, NYS DEC) and Matthew Schlessinger (NY Natural Heritage Program, Chief Zoologist, DEC) for placement of B. Hager on the collection permit (for odonates) during 2010–2011. We gratefully acknowledge the statistical advice and editorial expertise of Dr. William M. Shields, manuscript editor Maria Aliberti Lubertazzi and two anonymous reviewers, who provided outstanding insights to improve this manuscript. Special thanks goes to the manuscript editor, Maria Aliberti Lubertazzi for her patience and excellent advice in revising this manuscript. We thank T. Yorks for confirming the fish identification. Literature Cited Bright, E., and M.F. O’Brien. 1999. Key to mature larvae of Michigan Cordulegaster. In Odonate Larvae of Michigan. Available online at: http://insects.ummz.lsa.umich.edu/ michodo/MOL/Home.htm. Accessed 10 September 2010. Burcher, C.L., and L.A. Smock. 2002. Habitat distribution, dietary composition, and life-history characteristics of Odonate nymphs in a blackwater coastal plain stream. American Midland Naturalist 148:75–89. 76 Northeastern Naturalist Vol. 19, Special Issue 6 Corbet, P.S. 1999. Dragonflies: Behavior and Ecology of Odonata. Cornell University Press, Ithaca, NY. 829 pp. Dodson, S. 2005. Introduction to Limnology. McGraw-Hill Publishers, New York, NY. 416 pp. Donnelly, T.L. 1992. The Odonata of New York. Bulletin of American Odonatology 1(1):1–27. Dunkle, S.W. 2000. Dragonflies through Binoculars. Oxford University Press, New York, NY. 266 pp. Ferreras-Romero, M., and P.S. Corbet. 1999. The life cycle of Cordulegaster boltonii (Donovan, 1807) (Odonata:Cordulegastridae) in the Sierra Morena Mountains (southern Spain). Hydrobiologia 405:39–48. Glotzhober, R.C. 2006. Life-history studies of Cordulegaster erronea Hagen (Odonata: Cordulgastridae) in the laboratory and field. Bulletin of American Odonatology 10(1):1–18. Glozthober, R.C., and D. McShaffrey. 2002. The Dragonflies and Damselflies of Ohio. Ohio Biological Survey, Columbus, OH. 364 pp. Marczak, L.B., J.S. Richardson, and M.C. Classen. 2006. Life-history phenology and sediment size association of the dragonfly Cordulegaster dorsalis (Odonata: Cordulegastridae) in an ephemeral habitat in southwestern British Columbia. The Canadian Field Naturalist 120(3):347–350. Needham, J.G. 1901. Aquatic insects of the Adirondacks. Bulletin of the NY State Museum 47:381–612. Needham, J.G., M.J. Westfall, Jr., and M.L. May. 2000. Dragonflies of North America. Scientific Publishers, Gainesville, FL. 939 pp. Nikula, B., J.L. Loose, and M.R. Burne. 2007. A Field Guide to Dragonflies and Damselfl ies of Massachusetts, 2nd Edition. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program, Westborough, MA. 196 pp. NY State Department of Conservation (NYSDEC) Region 7 Management Team. 2000. Nelson Swamp Unique Area stewardship management plan. Available online at: www.dec.ny.gov/docs/lands_forests_pdf/nelswp.pdf. Accessed 5 January 2011. Santos, A.N., and R.D. Stevenson. 2011. Comparison of macroinvertebrate diversity and community structure among perennial and non-perennial headwater streams. Northeastern Naturalist 18:7–26. Schutte, C. 1997. Early development and early instars in Cordulegaster boltonii immaculifrons Selys: A field study (Anisoptera: Cordulegastridae). Odonatologica 26:83–87. Stevenson, D.J., G. Beaton, and M.J. Elliott. 2009. Distribution, status, and ecology of Cordulegaster sayi Selys in Georgia, USA (Odonata: Cordulegastridae). Bulletin of American Odonatology 11:20–25.