Quantifying New York's Diamondback Terrapin Habitat

Browne, James P.; Kanonik, Alexandra; Vanek, John P.; Crown, Crystal A.; Burke, Russell L.

doi:10.1656/045.022.0316

Cited by 3 publications

(3 citation statements)

References 16 publications

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Section: Discussionmentioning

confidence: 99%

“…Diamondback terrapins are a keystone species that are thought to be declining in parts of their range [32][33][34]. Accurate population estimates remain difficult to obtain for this species, but terrapin headcounts [17] and P. malaclemys cyst abundance measures [24] offer two new affordable and potentially reliable alternatives to more traditional survey methods [34]. The accuracy of each of these techniques has only been demonstrated once in a single test case in a small area: terrapin headcount surveys (as per [17]) at Kiawah Island, South Carolina, and P. malaclemys cyst abundance on mud snails (as per [24]) at 12 sites along the coast of Georgia.…”

Section: Discussionmentioning

confidence: 99%

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Poor Correlation between Diamondback Terrapin Population Estimates Using Two New Estimation Methods

Prowant

Burke

2020

Diversity

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Reliable estimates of animal and plant population sizes are necessary to track trends in populations through time. Diamondback terrapins are an ecologically unique keystone species that are globally declining. Conservation efforts for this species rely on accurate estimates of population sizes; however, diamondback terrapin population size estimates are difficult to measure with precision or accuracy. Terrapin collection methods are often labor-, time-, and cost-intensive. The present study compares two recently developed rapid assessment methods for measuring diamondback terrapin abundances. Since mark–recapture or similar data were unavailable, we could not test the accuracy of either method directly; instead, we compared the two methods. If the methods produce similar estimates of terrapin population size, this would increase confidence in these methods. We measured the abundance of diamondback terrapins at 77 sites in Long Island, New York, using headcount surveys and surveys of parasitic trematodes that can be used as a proxy for terrapin abundance. We used random forest analyses to test whether the variation in diamondback terrapin abundance measured using headcount surveys could be explained by either the prevalence or the abundance of trematode parasites. The most variation explained by any of the models was 7.77%, indicating that trematode prevalence and abundance could not explain the variation in terrapin abundance measured using headcounts. This poor correlation between terrapin census methods indicates that one, or both, of the census measures are inaccurate, at least in the habitats found across Long Island, NY. A technique that accurately estimates the abundance of diamondback terrapin populations is critical to understanding their population fluctuations and trends. The only way to evaluate the status of the species is to have information on population numbers and trends across the species’ range, which might not be possible without a more accessible survey method.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Poor Correlation between Diamondback Terrapin Population Estimates Using Two New Estimation Methods

Prowant

Burke

2020

Diversity

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“…Terrapins inhabit Atlantic and Gulf of Mexico coastal regions from Cape Cod, MA, to Corpus Christi, TX (Figure 2; Browne et al, 2015; Ernst & Lovich, 2009). Terrapin populations have been decreasing range‐wide as a result of anthropogenic activities such as coastal development, pollution, marsh degradation, bycatch in crab traps, and the increase in human‐subsidized predators (Maerz et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Of mudsnails, terrapins, and flukes: Use of trematodes as a field‐based project in parasitology research

Eugene

Burke

Williams

2021

Invertebrate Biology

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We present an exercise for counting trematode cysts on mudsnails that can be implemented as a field‐based project in course work by students or by volunteers. The exercise involves the digenetic trematode Pleurogonius malaclemys, which infects diamondback terrapins (Malaclemys terrapin) as its definitive host, and eastern mudsnails (Tritia obsoleta) as its intermediate host. The trematode forms macroscopic metacercarial cysts on the shells and opercula of the mudsnails, and the life cycle is completed when terrapins ingest the intermediate hosts with cysts. Previous research has suggested that quantifying cysts on mudsnails can be a relatively simple method to estimate terrapin population sizes where terrapins co‐occur with mudsnails. Three non‐professional scientist groups (including students and volunteers) were tested in their estimates of prevalence and intensity data compared to verified cyst counts. Prevalence data were relatively accurate (~76–78%) and reliable (68–89%) across the groups. The intensity of cysts (on shells and opercula of mudsnails) were mostly within 12% of the verified counts (total mean intensity of 1.81–2.97 cysts/parasitized mudsnail) but varied significantly in two cases due to false positives (likely due to sand grains or debris scored as cysts) or negatives (likely due to missed cysts behind the operculum). The exercise can be completed as a lab or series of labs in courses, and data from such projects could be used in terrapin conservation efforts, particularly in helping scientists determine where terrapins occur. We discuss modification of the exercise for other trematode species in regions around the world and hope this expands recognition by the public of the important role of parasites in ecosystems.

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Satellite telemetry reveals space use of diamondback terrapins

Lamont,

Price,

Catizone

2023

Anim Biotelemetry

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Movement and space use information of exploited and imperiled coastal species is critical to management and conservation actions. While satellite telemetry has been successfully used to document movements of marine turtles, the large tag sizes available have limited use on smaller turtle species. We used small Argos-based satellite tags to document movement patterns of diamondback terrapins (Malaclemys terrapin), the only estuarine turtle species in North America. Movement data from ten terrapins in St. Joseph Bay, Florida were gathered between July 13, 2018 and July 22, 2021. We estimated seasonal space use using the daily locations generated from a Bayesian hierarchical state-space model to calculate minimum convex polygons (95% MCP) and kernel density estimates (50% and 95% KDE). Mean tracking duration was 125 days and mean home range size was 9.4 km2 (95% MCP) and 8.1 km2 (95% KDE). Seagrass habitat comprised 55.8% of all home ranges on average, whereas salt marsh comprised a mean of 3.0%. Mean elevation used by terrapins was − 0.13 m (95% MCP) and -0.35 m (95% KDE). Satellite telemetry provided broad-scale spatiotemporal movement and space use data; however, Argos error produced considerable noise relative to true terrapin movements given their size, speed, and behavior. Terrapin home ranges were greater than previously reported and three of the ten terrapins exhibited repeated long-distance, directed movements within the bay. Small patches of salt marsh habitat were centralized within home ranges, despite comprising only a small percentage for each terrapin. Moreover, the percentage of salt marsh present in each core use area was positively correlated with terrapin mass. Although considered an estuarine species, seagrass habitat comprised a large portion of terrapin home ranges; however, our data did not provide the detail necessary to understand how terrapins were using this habitat. As northward-expanding mangroves continue to infringe upon salt marsh habitat, there is potential for negative impacts to terrapin populations across the northern Gulf of Mexico. As salt marsh habitat continues to be infringed upon by northward-expanding mangroves impacts to terrapins across the northern Gulf of Mexico.

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Quantifying New York's Diamondback Terrapin Habitat

Cited by 3 publications

References 16 publications

Poor Correlation between Diamondback Terrapin Population Estimates Using Two New Estimation Methods

Poor Correlation between Diamondback Terrapin Population Estimates Using Two New Estimation Methods

Of mudsnails, terrapins, and flukes: Use of trematodes as a field‐based project in parasitology research

Satellite telemetry reveals space use of diamondback terrapins

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