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Willem M. Roosenburg - One of the best experts on this subject based on the ideXlab platform.
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Turtle soup, Prohibition, and the population genetic structure of Diamondback Terrapins (Malaclemys Terrapin).
2017Co-Authors: Paul E. Converse, J. Susanne Hauswaldt, Shawn R. Kuchta, Willem M. RoosenburgAbstract:Diamondback Terrapins (Malaclemys Terrapin) were a popular food item in early twentieth century America, and were consumed in soup with sherry. Intense market demand for Terrapin meat resulted in population declines, notably along the Atlantic seaboard. Efforts to supply Terrapins to markets resulted in translocation events, as individuals were moved about to stock Terrapin farms. However, in 1920 the market for turtle soup buckled with the enactment of the eighteenth amendment to the United States' Constitution-which initiated the prohibition of alcoholic drinks-and many Terrapin fisheries dumped their stocks into local waters. We used microsatellite data to show that patterns of genetic diversity along the Terrapin's coastal range are consistent with historical accounts of translocation and cultivation activities. We identified possible instances of human-mediated dispersal by estimating gene flow over historical and contemporary timescales, Bayesian model testing, and bottleneck tests. We recovered six genotypic clusters along the Gulf and Atlantic coasts with varying degrees of admixture, including increased contemporary gene flow from Texas to South Carolina, from North Carolina to Maryland, and from North Carolina to New York. In addition, Bayesian models incorporating translocation events outperformed stepping-stone models. Finally, we were unable to detect population bottlenecks, possibly due to translocation reintroducing genetic diversity into bottlenecked populations. Our data suggest that current patterns of genetic diversity in the Terrapin were altered by the demand for turtle soup followed by the enactment of alcohol prohibition. In addition, our study shows that population genetic tools can elucidate metapopulation dynamics in taxa with complex genetic histories impacted by anthropogenic activities.
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Turtle soup, Prohibition, and the population genetic structure of Diamondback Terrapins (Malaclemys Terrapin) - Fig 1
2017Co-Authors: Paul E. Converse, Susanne J Hauswaldt, Shawn R. Kuchta, Willem M. RoosenburgAbstract:(A) The Gulf and Atlantic seaboards of the Eastern United States. States harboring Terrapin populations along their coastlines are faded red. (B) All Terrapin populations under ΔK = 2. (C) All Terrapin populations under ΔK = 4. (D) All Terrapin populations under ΔK = 7. Subsections B,C, and D depict the same analysis, explored under different genotypic partitions. (E) Mid- and north Atlantic Terrapins under K = 2. In this scenario, NY and NJ Terrapins constitute a single population. (F) Mid- and north Atlantic Terrapins under K = 3. In this scenario, NY and NJ form separate populations. Subsections F and G depict the same analysis under two values of K with similar likelihood scores. (G) SC Terrapins investigated with Gulf populations. TX and FL form separate populations and SC1-6 constitute a single cluster. No substructure is present within SC1-6. TX, FL, SC, and MD are diagnosable clusters. If NY and NJ form a single cluster (subsection E), there are five total clusters. If NY and NJ form separate clusters (subsection F), there are six total clusters.
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Spatiotemporal analysis of gene flow in Chesapeake Bay Diamondback Terrapins (Malaclemys Terrapin).
2015Co-Authors: Paul E. Converse, Willem M. Roosenburg, Shawn R. Kuchta, Paula F. P. Henry, G. Michael Haramis, Tim L. KingAbstract:There is widespread concern regarding the impacts of anthropogenic activities on connectivity among populations of plants and animals, and understanding how contemporary and historical processes shape metapopulation dynamics is crucial for setting appropriate conservation targets. We used genetic data to identify population clusters and quantify gene flow over historical and contemporary time frames in the Diamondback Terrapin (Malaclemys Terrapin). This species has a long and complicated history with humans, including commercial overharvesting and subsequent translocation events during the early twentieth century. Today, Terrapins face threats from habitat loss and mortality in fisheries bycatch. To evaluate population structure and gene flow among Diamondback Terrapin populations in the Chesapeake Bay region, we sampled 617 individuals from 15 localities and screened individuals at 12 polymorphic microsatellite loci. Our goals were to demarcate metapopulation structure, quantify genetic diversity, estimate effective population sizes, and document temporal changes in gene flow. We found that Terrapins in the Chesapeake Bay region harbour high levels of genetic diversity and form four populations. Effective population sizes were variable. Among most population comparisons, estimates of historical and contemporary Terrapin gene flow were generally low (m ≈ 0.01). However, we detected a substantial increase in contemporary gene flow into Chesapeake Bay from populations outside the bay, as well as between two populations within Chesapeake Bay, possibly as a consequence of translocations during the early twentieth century. Our study shows that inferences across multiple time scales are needed to evaluate population connectivity, especially as recent changes may identify threats to population persistence.
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impact of a bycatch reduction device on diamondback Terrapin and blue crab capture in crab pots
2000Co-Authors: Willem M. Roosenburg, Jason P GreenAbstract:Bycatch in fisheries is receiving attention because of its impact on ecological diversity and resource sustainability. Male and juvenile female diamondback Terrapins, Malaclernys Terrapin, frequently drown as bycatch in crab pots, removing individuals with high reproductive value from the population and possibly skewing sex ratios. We tested a wire bycatch reduction device (BRD) to determine its ability to reduce Terrapin entrapment and to examine any effects the BRD has on the size and number of blue crabs, Callinectes sapidus, caught in crab pots. We tested three sizes of BRDs, a 4 X 10 cm BRD in 1996, and 4.5 x 12 cm and 5 x 10 cm BRDs in 1997. We equipped both standard crab pots and modified (tall) crab pots with BRDs, the latter were used to prevent Terrapin mortality in areas of high Terrapin density. Traps were checked and baited daily. In 1996, we caught no Terrapins in 14 crab pots equipped with the 4 x 10 cm BRDs and 21 Terrapins in 14 crab pots without BRDs. In 1997, the 4.5 x 12 cm BRD reduced Terrapin bycatch by 82%, whereas the 5 x 10 cm BRD reduced Terrapin bycatch by 47%. The 4 x 10 cm BRDs, however, reduced the size and number of large "Number One" and mature female crabs. Catch rate for standard crab pots with 4 x 10 cm BRDs was 2 crabs.pot- ' day- ' lower than standard crab pots fished without BRDs in 1996. Neither the 5 X 10 cm BRD nor the 4.5 x 12 cm BRD affected crab size or the number of crabs caught in crab pots. Standard crab pots with a 4.5 x 12 cm BRDs had the highest catch per unit effort (2.69 crabs.pot-'.day-'), followed by standard crab pots without BRDs (2.55 crabs-pot-'.day-') and standard crab pots with 5 x 10 cm BRDs (2.39 crabs.pot-'.day-'). The largest crab caught in 1997 was in a crab pot with a 4.5 X 12 cm BRD. We stress the importance of using the 4.5 x 12 cm BRD on crab pots fished commercially and recreationally to reduce Terrapin mortality and the need to integrate the use of BRDs on crab pots with other conservation practices such as protection of critical Terrapin habitat, particularly nesting beaches.
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Diamondback Terrapin (Malaclemys Terrapin) Mortality in Crab Pots
1997Co-Authors: Willem M. Roosenburg, William Cresko, Michael Modesitte, Matthew B. RobbinsAbstract:The entrapment of diamondback Terrapins (Malaclemys Terrapin) in crab pots frequently results in drowning and death of the trapped turtles. We determined the rate of capture, size, sex, and age of Terrapins cap- tured, and the potential impact crab pot mortality has on local Terrapin populations. We estimated Terrapin capture rates of 0.17 Terrapins/pot/day in shallow water areas of Chesapeake Bay (Maryland, USA). The sex ratio of Terrapins caught in crab pots was 3:2 male biased because female Terrapins become too large to enter crab pots by the time they reach 8 years of age. Males, however, remain vulnerable to entrapment throughout their life. Our estimates of capture rates and local population size suggest that 15- 78% of a local population may be captured in a single year. As a consequence, crab pots may be the major reason Terrapins are extir- pated in coastal, shallow water areas with heavy crab pot fisheries. Additionally, the selective removal of males may also contribute to female-biased sex ratios observed in this diamondback Terrapin population. We developed and tested a modified crab pot that increases Terrapin survival and does not reduce the number of crabs caught. Our modified crab pot maintained permanent access to air and prevented the drowning of ter- rapins. Additionally, our modified crab pot caught more crabs than standard commercial crab pots, suggest-
Amanda Southwood Williard - One of the best experts on this subject based on the ideXlab platform.
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Effects of temperature and salinity on body fluid dynamics and metabolism in the estuarine diamondback Terrapin (Malaclemys Terrapin)
2019Co-Authors: Amanda Southwood Williard, Leigh Anne Harden, T. J. Jones, Stephen R. MidwayAbstract:The diamondback Terrapin is the only temperate turtle species that exclusively inhabits estuarine habitats. Morphological, behavioral and physiological features contribute to the Terrapin9s ability to regulate body fluid osmotic pressure in a euryhaline environment. Low integument permeability combined with aquatic-terrestrial shuttling behavior limits passive exchange of water and salts with the environment, and Terrapins regulate active uptake of salts via alterations in drinking and feeding behavior. The lachrymal salt gland facilitates excretion of excess sodium (Na + ) and chloride (Cl − ) ions through active transport mechanisms. We investigated body fluid dynamics, oxygen consumption ( V O 2 ), and osmotic status of Terrapins exposed to an acute increase in salinity (12 to 35 psu) at 10°C and 25°C to gain insight into the relative importance of behavioral vs. physiological osmoregulatory adjustments over a range of seasonally-relevant temperatures. Linear mixed models were used to evaluate the effects of experimental temperature, salinity, and mass. Overall, temperature effects were stronger than salinity effects. Terrapins acclimated to 25°C had significantly lower blood osmolality and Na + , and higher water turnover rates, daily water flux (DWF), and V O 2 compared with Terrapins acclimated to 10°C. Salinity effects were restricted to DWF, which significantly decreased in response to acute exposure to 35 psu. Our results support the notion that behavioral adjustments predominate in the osmoregulatory strategy of Terrapins.
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the effects of bycatch reduction devices on diamondback Terrapin and blue crab catch in the north carolina commercial crab fishery
2017Co-Authors: Stephanie Chavez, Amanda Southwood WilliardAbstract:Abstract The diamondback Terrapin ( Malaclemys Terrapin ) is endemic to marshes, coves, and tidal creeks on the Atlantic and Gulf coasts of the United States. Currently, the Terrapin is listed as a species of special concern in several states where one of the prominent threats to populations is the drowning of Terrapins in commercial crab pots. Bycatch reduction devices (BRDs) that narrow the funnel opening on crab pots exclude Terrapins, but BRDs face opposition from the fishing industry due to fears that they will decrease target species catch. The primary goals of this research were to examine the efficacy of two sizes of BRDs in excluding Terrapins from crab pots and to assess the impact of BRDs on blue crab catch. Crab pots were deployed in paired and triplicate designs at estuarine sites along the central and southern coast of North Carolina in the summers of 2012 and 2013. A total of 4039 legal sized blue crabs and 14 Terrapins were captured over the course of the study. Bycatch reduction devices did not have a statistically significant effect on catch rates or carapace width of legal-sized blue crabs. Thirteen of the 14 captured Terrapins were in control pots, and one male Terrapin was captured in a pot equipped with a large size BRD. An integrated approach that combines data on the spatial ecology and demography of Terrapins with information on the most appropriate BRD dimensions for Terrapin exclusion is most likely to succeed in addressing the issue of Terrapin bycatch.
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The blood biochemistry of overwintering diamondback Terrapins (Malaclemys Terrapin)
2015Co-Authors: Leigh Anne Harden, Stephen R. Midway, Amanda Southwood WilliardAbstract:Abstract Estuarine ectothermic vertebrates, such as diamondback Terrapins (Malaclemys Terrapin, Schwartz 1955), inhabit a dynamic environment, and many aspects of their biology reflect their ability to withstand and respond to these environmental challenges. The physiological adjustments necessary to maintain water and salt balance and the metabolic adjustments that accompany seasonal changes in activity and behavior have not been well-characterized for overwintering Terrapins under field conditions. To investigate Terrapin osmotic and metabolic physiology during winter when activity levels are depressed, we obtained repeat blood samples from 10 radio-tagged female Terrapins maintained in a semi-natural, open-air salt marsh enclosure in southeastern North Carolina, USA. From November 2011 to April 2012, we measured monthly plasma osmolality, plasma concentrations of inorganic osmolytes (Na+, K+, Cl−), and protein catabolic indices (urea and uric acid), as well as monthly plasma concentrations of total Ca2 +, lactate, and glucose as metabolic indices. We used linear mixed models to determine the best predictors of blood chemistry, where time (i.e., day) and environmental variables were fixed factors and individual Terrapins were random factors. Day was a poor predictor of blood chemistry concentrations, indicating that the progression of winter did not elicit corresponding changes in biochemical indices as documented in other semi-aquatic turtles exposed to more severe winter and/or laboratory conditions. Carapace temperature was the most common predictor of blood chemistry concentrations in all models, underscoring its relative influence on physiology. In contrast to previous laboratory-based studies on the overwinter physiology of Terrapins, our study demonstrates that Terrapins in their natural environment are able to maintain biochemical homeostasis throughout winter. The use of evasive behavioral strategies may be an important factor for Terrapins to reduce the passive exchange of water and salts with the estuarine environment.
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total body water and water turnover rates in the estuarine diamondback Terrapin malaclemys Terrapin during the transition from dormancy to activity
2014Co-Authors: T. J. Jones, Leigh Anne Harden, Kimberley Anne Duernberger, Amanda Southwood WilliardAbstract:Abstract Water and salt concentrations in an animal’s body fluids can fluctuate with changing environmental conditions, posing osmoregulatory challenges that require behavioral and physiological adjustments. The purpose of this study was to investigate body water dynamics in the estuarine diamondback Terrapin ( Malaclemys Terrapin ), a species that undergoes seasonal dormancy in salt marsh habitats. We conducted a field study to determine the total body water (TBW%), water turnover rate (WTR), and daily water flux (DWF) of female Terrapins in southeastern North Carolina pre- and post-emergence from winter dormancy. Terrapins were injected with [ 2 H]deuterium on two occasions and washout of the isotope was monitored by taking successive blood samples during the period of transition from dormancy to activity. The WTR and DWF of ‘dormant’ Terrapins were significantly lower than those of ‘active’ Terrapins (WTR ’dormant’ = 49.70 ± 15.94 ml day -1 , WTR ’active’ = 100.20 ± 20.36 ml day -1 , DWF ’dormant’ = 10.52 ± 2.92 %TBW day -1 , DWF ’active’ = 21.84 ± 7.30 %TBW day -1 ). There was no significant difference in TBW% between ‘dormant’ and ‘active’ Terrapins (75.05 ± 6.19% and 74.54 ± 4.36%, respectively). Results from this field study provides insight into the Terrapin’s ability to maintain osmotic homeostasis while experiencing shifts in behavioral and environmental conditions.
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using spatial and behavioral data to evaluate the seasonal bycatch risk of diamondback Terrapins malaclemys Terrapin in crab pots
2012Co-Authors: Leigh Anne Harden, Amanda Southwood WilliardAbstract:Mortality of marine vertebrates due to incidental entanglement in fishing gear is of global concern. Trends in diamondback Terrapin Malaclemys Terrapin abundance and demogra- phy suggest that bycatch mortality associated with the blue crab Callinectes sapidus fishery may be contributing to population declines and demographic shifts of this estuarine turtle. Designing effective regulations to minimize Terrapin-crabbing interaction requires information on the spa- tial ecology and seasonal behavior of Terrapins. Our goals for this study were (1) to identify spatial and temporal patterns in the distribution of Terrapins and crab pots and (2) to determine bycatch risk based on seasonal shifts in Terrapin behavior and the degree of overlap between Terrapins and crab pots. We documented crab pot locations and monitored the movements and activity patterns of 29 Terrapins via radio telemetry in southeastern North Carolina from June 2008 to May 2009. To assess spatial overlap and resulting bycatch risk (BR), we calculated seasonal distributions and densities of crab pots and Terrapins and incorporated them into a spatial overlap index model (SOI) modified to include the seasonal aquatic behavior of Terrapins. Spatial overlap is greatest in warm months when Terrapins are swimming in the same shallow, near-shore habitat as blue crabs. When the seasonal and semi-aquatic behavior of Terrapins is incorporated into the spatial model, BR is reduced. This behaviorally modified SOI model may be applied to other geographic areas to identify areas and times of bycatch risk between fisheries and non-target species.
J. Susanne Hauswaldt - One of the best experts on this subject based on the ideXlab platform.
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Turtle soup, Prohibition, and the population genetic structure of Diamondback Terrapins (Malaclemys Terrapin).
2017Co-Authors: Paul E. Converse, J. Susanne Hauswaldt, Shawn R. Kuchta, Willem M. RoosenburgAbstract:Diamondback Terrapins (Malaclemys Terrapin) were a popular food item in early twentieth century America, and were consumed in soup with sherry. Intense market demand for Terrapin meat resulted in population declines, notably along the Atlantic seaboard. Efforts to supply Terrapins to markets resulted in translocation events, as individuals were moved about to stock Terrapin farms. However, in 1920 the market for turtle soup buckled with the enactment of the eighteenth amendment to the United States' Constitution-which initiated the prohibition of alcoholic drinks-and many Terrapin fisheries dumped their stocks into local waters. We used microsatellite data to show that patterns of genetic diversity along the Terrapin's coastal range are consistent with historical accounts of translocation and cultivation activities. We identified possible instances of human-mediated dispersal by estimating gene flow over historical and contemporary timescales, Bayesian model testing, and bottleneck tests. We recovered six genotypic clusters along the Gulf and Atlantic coasts with varying degrees of admixture, including increased contemporary gene flow from Texas to South Carolina, from North Carolina to Maryland, and from North Carolina to New York. In addition, Bayesian models incorporating translocation events outperformed stepping-stone models. Finally, we were unable to detect population bottlenecks, possibly due to translocation reintroducing genetic diversity into bottlenecked populations. Our data suggest that current patterns of genetic diversity in the Terrapin were altered by the demand for turtle soup followed by the enactment of alcohol prohibition. In addition, our study shows that population genetic tools can elucidate metapopulation dynamics in taxa with complex genetic histories impacted by anthropogenic activities.
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Population genetics of the diamondback Terrapin (Malaclemys Terrapin)
2005Co-Authors: J. Susanne HauswaldtAbstract:We examined the population genetic structure of the diamondback Terrapins ( Malaclemys Terrapin ), within and among estuaries. Based on mark-recapture studies, these estuarine turtles have high site fidelity that is likely to make them vulnerable to local extinctions. We tested if observed site fidelity of adults would be reflected in intraestuarine population genetic structure of six highly polymorphic microsatellite loci (five tetranucleotide and one dinucleotide). No evidence was found for population structuring within the Charleston estuary nor among three different estuaries in South Carolina. We then examined four other Terrapin populations from North Carolina to New York, as well as from the Florida Keys and from Texas. With increasing geographical distance, genetic differentiation increased from South Carolina through New York, but overall values were low. The dinucleotide locus contributed significantly more to the genetic differentiation of some population comparisons than any of the other loci. Interestingly, Terrapins from South Carolina to New York were much more genetically similar to those from Texas ( ρ = 0.154) than to those from Florida ( ρ = 0.357). We attribute this pattern to extensive translocations of Terrapins during the early 20th century to replenish diminished populations and to provide turtle farms with stocks. Terrapins collected in Texas were especially sought for shipment to the northeastern US because of their larger size. Our study indicates no population structure within or among adjacent estuaries. Thus, the mark-recapture information from adult and subadult feeding locations is a poor predictor of population genetic structure. Additionally, it appears that past human activities may have drastically altered the genetics of current populations. Finally, our data suggest that translocation of eggs or head starting of Terrapins within estuaries or among adjacent estuaries is acceptable from a genetic standpoint.
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Microsatellite DNA loci from the Diamondback Terrapin (Malaclemys Terrapin)
2003Co-Authors: J. Susanne Hauswaldt, Travis C GlennAbstract:We describe polymerase chain recation (PCR) primers and conditions to amplify one dinucleotide and five tetranucleotide microsatellite DNA loci isolated from the Diamondback Terrapin (Malaclemys Terrapin). The PCR primers were tested on 21 Terrapins from Cape Romain, SC, USA. The microsatellite primers developed yielded a high number of alleles (8–14) and high observed heterozygosities (0.57–1.0).
Tim L. King - One of the best experts on this subject based on the ideXlab platform.
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Spatiotemporal analysis of gene flow in Chesapeake Bay Diamondback Terrapins (Malaclemys Terrapin).
2015Co-Authors: Paul E. Converse, Willem M. Roosenburg, Shawn R. Kuchta, Paula F. P. Henry, G. Michael Haramis, Tim L. KingAbstract:There is widespread concern regarding the impacts of anthropogenic activities on connectivity among populations of plants and animals, and understanding how contemporary and historical processes shape metapopulation dynamics is crucial for setting appropriate conservation targets. We used genetic data to identify population clusters and quantify gene flow over historical and contemporary time frames in the Diamondback Terrapin (Malaclemys Terrapin). This species has a long and complicated history with humans, including commercial overharvesting and subsequent translocation events during the early twentieth century. Today, Terrapins face threats from habitat loss and mortality in fisheries bycatch. To evaluate population structure and gene flow among Diamondback Terrapin populations in the Chesapeake Bay region, we sampled 617 individuals from 15 localities and screened individuals at 12 polymorphic microsatellite loci. Our goals were to demarcate metapopulation structure, quantify genetic diversity, estimate effective population sizes, and document temporal changes in gene flow. We found that Terrapins in the Chesapeake Bay region harbour high levels of genetic diversity and form four populations. Effective population sizes were variable. Among most population comparisons, estimates of historical and contemporary Terrapin gene flow were generally low (m ≈ 0.01). However, we detected a substantial increase in contemporary gene flow into Chesapeake Bay from populations outside the bay, as well as between two populations within Chesapeake Bay, possibly as a consequence of translocations during the early twentieth century. Our study shows that inferences across multiple time scales are needed to evaluate population connectivity, especially as recent changes may identify threats to population persistence.
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Regional differentiation among populations of the Diamondback Terrapin (Malaclemys Terrapin)
2014Co-Authors: Kristen M. Hart, Margaret E. Hunter, Tim L. KingAbstract:The Diamondback Terrapin (Malaclemys Terrapin ) is a brackish-water turtle species whose populations have been fragmented due to anthropogenic activity such as development of coastal habitat and entrapment in commercial blue crab ( Callinectes sapidus ) fishing gear. Genetic analyses can improve conservation efforts for the long-term protection of the species. We used microsatellite DNA analysis to investigate levels of gene flow among and genetic variability within 21 geographically separate collections of the species distributed from Massachusetts to Texas. Quantified levels of genetic variability (allelic diversity, genotypic frequencies, and heterozygosity) revealed three zones of genetic discontinuity, resulting in four discrete populations: Northeast Atlantic, Coastal Mid-Atlantic, Florida and Texas/Louisiana. The average number of alleles and expected heterozygosity for the four genetic clusters were N_A = 6.54 and H_E = 0.050, respectively. However, the geographic boundaries of the populations did not correspond to accepted Terrapin subspecies limits. Our results illuminate not only the need to sample Terrapins in additional sites, specifically in the southeast, but also the necessity for allowing uninterrupted gene flow among population groupings to preserve current levels of genetic diversity.
Leigh Anne Harden - One of the best experts on this subject based on the ideXlab platform.
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Effects of temperature and salinity on body fluid dynamics and metabolism in the estuarine diamondback Terrapin (Malaclemys Terrapin)
2019Co-Authors: Amanda Southwood Williard, Leigh Anne Harden, T. J. Jones, Stephen R. MidwayAbstract:The diamondback Terrapin is the only temperate turtle species that exclusively inhabits estuarine habitats. Morphological, behavioral and physiological features contribute to the Terrapin9s ability to regulate body fluid osmotic pressure in a euryhaline environment. Low integument permeability combined with aquatic-terrestrial shuttling behavior limits passive exchange of water and salts with the environment, and Terrapins regulate active uptake of salts via alterations in drinking and feeding behavior. The lachrymal salt gland facilitates excretion of excess sodium (Na + ) and chloride (Cl − ) ions through active transport mechanisms. We investigated body fluid dynamics, oxygen consumption ( V O 2 ), and osmotic status of Terrapins exposed to an acute increase in salinity (12 to 35 psu) at 10°C and 25°C to gain insight into the relative importance of behavioral vs. physiological osmoregulatory adjustments over a range of seasonally-relevant temperatures. Linear mixed models were used to evaluate the effects of experimental temperature, salinity, and mass. Overall, temperature effects were stronger than salinity effects. Terrapins acclimated to 25°C had significantly lower blood osmolality and Na + , and higher water turnover rates, daily water flux (DWF), and V O 2 compared with Terrapins acclimated to 10°C. Salinity effects were restricted to DWF, which significantly decreased in response to acute exposure to 35 psu. Our results support the notion that behavioral adjustments predominate in the osmoregulatory strategy of Terrapins.
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The blood biochemistry of overwintering diamondback Terrapins (Malaclemys Terrapin)
2015Co-Authors: Leigh Anne Harden, Stephen R. Midway, Amanda Southwood WilliardAbstract:Abstract Estuarine ectothermic vertebrates, such as diamondback Terrapins (Malaclemys Terrapin, Schwartz 1955), inhabit a dynamic environment, and many aspects of their biology reflect their ability to withstand and respond to these environmental challenges. The physiological adjustments necessary to maintain water and salt balance and the metabolic adjustments that accompany seasonal changes in activity and behavior have not been well-characterized for overwintering Terrapins under field conditions. To investigate Terrapin osmotic and metabolic physiology during winter when activity levels are depressed, we obtained repeat blood samples from 10 radio-tagged female Terrapins maintained in a semi-natural, open-air salt marsh enclosure in southeastern North Carolina, USA. From November 2011 to April 2012, we measured monthly plasma osmolality, plasma concentrations of inorganic osmolytes (Na+, K+, Cl−), and protein catabolic indices (urea and uric acid), as well as monthly plasma concentrations of total Ca2 +, lactate, and glucose as metabolic indices. We used linear mixed models to determine the best predictors of blood chemistry, where time (i.e., day) and environmental variables were fixed factors and individual Terrapins were random factors. Day was a poor predictor of blood chemistry concentrations, indicating that the progression of winter did not elicit corresponding changes in biochemical indices as documented in other semi-aquatic turtles exposed to more severe winter and/or laboratory conditions. Carapace temperature was the most common predictor of blood chemistry concentrations in all models, underscoring its relative influence on physiology. In contrast to previous laboratory-based studies on the overwinter physiology of Terrapins, our study demonstrates that Terrapins in their natural environment are able to maintain biochemical homeostasis throughout winter. The use of evasive behavioral strategies may be an important factor for Terrapins to reduce the passive exchange of water and salts with the estuarine environment.
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total body water and water turnover rates in the estuarine diamondback Terrapin malaclemys Terrapin during the transition from dormancy to activity
2014Co-Authors: T. J. Jones, Leigh Anne Harden, Kimberley Anne Duernberger, Amanda Southwood WilliardAbstract:Abstract Water and salt concentrations in an animal’s body fluids can fluctuate with changing environmental conditions, posing osmoregulatory challenges that require behavioral and physiological adjustments. The purpose of this study was to investigate body water dynamics in the estuarine diamondback Terrapin ( Malaclemys Terrapin ), a species that undergoes seasonal dormancy in salt marsh habitats. We conducted a field study to determine the total body water (TBW%), water turnover rate (WTR), and daily water flux (DWF) of female Terrapins in southeastern North Carolina pre- and post-emergence from winter dormancy. Terrapins were injected with [ 2 H]deuterium on two occasions and washout of the isotope was monitored by taking successive blood samples during the period of transition from dormancy to activity. The WTR and DWF of ‘dormant’ Terrapins were significantly lower than those of ‘active’ Terrapins (WTR ’dormant’ = 49.70 ± 15.94 ml day -1 , WTR ’active’ = 100.20 ± 20.36 ml day -1 , DWF ’dormant’ = 10.52 ± 2.92 %TBW day -1 , DWF ’active’ = 21.84 ± 7.30 %TBW day -1 ). There was no significant difference in TBW% between ‘dormant’ and ‘active’ Terrapins (75.05 ± 6.19% and 74.54 ± 4.36%, respectively). Results from this field study provides insight into the Terrapin’s ability to maintain osmotic homeostasis while experiencing shifts in behavioral and environmental conditions.
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using spatial and behavioral data to evaluate the seasonal bycatch risk of diamondback Terrapins malaclemys Terrapin in crab pots
2012Co-Authors: Leigh Anne Harden, Amanda Southwood WilliardAbstract:Mortality of marine vertebrates due to incidental entanglement in fishing gear is of global concern. Trends in diamondback Terrapin Malaclemys Terrapin abundance and demogra- phy suggest that bycatch mortality associated with the blue crab Callinectes sapidus fishery may be contributing to population declines and demographic shifts of this estuarine turtle. Designing effective regulations to minimize Terrapin-crabbing interaction requires information on the spa- tial ecology and seasonal behavior of Terrapins. Our goals for this study were (1) to identify spatial and temporal patterns in the distribution of Terrapins and crab pots and (2) to determine bycatch risk based on seasonal shifts in Terrapin behavior and the degree of overlap between Terrapins and crab pots. We documented crab pot locations and monitored the movements and activity patterns of 29 Terrapins via radio telemetry in southeastern North Carolina from June 2008 to May 2009. To assess spatial overlap and resulting bycatch risk (BR), we calculated seasonal distributions and densities of crab pots and Terrapins and incorporated them into a spatial overlap index model (SOI) modified to include the seasonal aquatic behavior of Terrapins. Spatial overlap is greatest in warm months when Terrapins are swimming in the same shallow, near-shore habitat as blue crabs. When the seasonal and semi-aquatic behavior of Terrapins is incorporated into the spatial model, BR is reduced. This behaviorally modified SOI model may be applied to other geographic areas to identify areas and times of bycatch risk between fisheries and non-target species.
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Development of a rapid-assessment technique for diamondback Terrapin ( Malaclemys Terrapin ) populations using head-count surveys
2009Co-Authors: Leigh Anne Harden, J. Whitfield Gibbons, Shannon E. Pittman, Michael E. DorcasAbstract:Although diamondback Terrapins appear to be declining throughout much of their geographic range, more information is required to evaluate population trends. Unfortunately, sampling Terrapin populations is both time and labor intensive. We initiated studies to examine the efficacy of using head counts in tidal creeks as a rapid-assessment technique for monitoring Terrapin populations. From 2005 to 2007, we conducted headcount surveys in conjunction with regular aquatic sampling. Head-count surveys consisted of recording the number of Terrapins we observed from a boat going up (run 1) and down (run 2) tidal creeks. These surveys were conducted before aquatic sampling (i.e., low tide) as well as other times (e.g., high tide). We found the strongest positive relationship between the number of Terrapins observed in run 1 combined with run 2 and the number of Terrapins captured (R 2 = 0.538). We examined the effects of variables such as day of year, time of day, cloud cover, and creek location on the number of heads seen. Such models will allow effective monitoring of Terrapin population trends and improve implementation of appropriate conservation measures. We recommend a refinement of head-count surveys and the involvement of citizen scientists to aid in the establishment of a range-wide monitoring program that will greatly increase survey effort while saving time and money. © Koninklijke Brill NV, Leiden, 2009
