Daniel erther Center For Conservation And Research

Daniel erther Center For Conservation And Research

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Rypel A.L.,University of Wisconsin - Madison | Rypel A.L.,United Road Services | David S.R.,University of Wisconsin - Madison | David S.R.,Daniel erther Center For Conservation And Research
Ecosphere | Year: 2017

Empirically understanding spatial variation in secondary production rates is central to ecology. Yet for most taxa, such patterns are rarely examined, especially at different levels of ecological organization (e.g., species- vs. community-level patterns). We compiled data on biomass, production, and P/B rates of freshwater fish communities and species across latitudes and contrast patterns observed at the community level with those observed for species. At the community level, and at two distinct spatial scales (global vs. continental-North American), negative or neutral relationships were apparent between biomass, production, and P/B with latitude; however, there was substantial scatter in these data. Yet at the species level in North America, production was often closely linked to latitude, but in the opposite direction: Many species showed improved production with latitude. Latitudinal increases in species-level production rates were strongest for cool-And cold-water species, and species rarely showed the opposite trend. Species-level increases in production with latitude strengthened when production rates were normalized by the thermal opportunity for production, suggesting potential adaptations of individuals and populations to shorter growing seasons (i.e., "countergradient" production) at high latitudes. At the global scale, there were apparent unimodal relationships between community fish production measures and species richness; however, these patterns became linearized or non-significant at the continental scale. Decreased interspecific competition at northern latitudes combined with genetic adaptations (e.g., countergradient growth) could explain a tendency for increased species production in northern populations, while total community production remains reduced. Latitude has contrasting effects on fish production at different spatial scales and levels of biological organization. Thus while freshwater fish communities are somewhat more productive and diverse at lower latitudes, species production in northern populations is often surprisingly high. © 2017 Rypel and David.


Kough A.S.,University of Miami | Kough A.S.,Daniel erther Center For Conservation And Research | Claro R.,Institute Oceanologia | Lindeman K.C.,Florida Institute of Technology | Paris C.B.,University of Miami
Marine Ecology Progress Series | Year: 2016

Variability in environmental conditions and ocean currents can influence population connectivity and the exchange of larvae among locations. This is especially true for species that spawn in aggregations during a limited temporal window, such as many of the commercially and ecologically valuable species of snapper (Lutjanidae) in Cuba. Biophysical modeling has been used for over a decade to describe the pelagic pathways, sources, and sinks of lutjanid larvae. Here, we build on earlier studies by incorporating more advanced modeling techniques, higher resolution oceanography, and an expanded temporal scope using circulation from 2004 to 2013. Our goal was to revisit the relative linkages of Cuban snapper larvae among regions of the Cuban shelf and neighboring countries by investigating their interannual variability and spatial patterns. Biophysical simulations suggest the majority of larvae produced from snapper spawning aggregations are retained on-island, often within the region where they were spawned, with the exception of an aggregation in northwest Cuba. We used multinomial logistic regression to identify consistency in patterns of simulated biophysical larval transport, and to determine the number of years of simulation required to approximate connectivity. The best fit model correctly identified major connections from each spawning location to greater Caribbean destinations for each species. However, connections at smaller spatial scales were less predictable, and variance increased if fewer years of larval transport were considered. While the magnitude of settlement varies annually, the spatial arrangement of connectivity is relatively consistent such that modeled pathways from spawning aggregations can effectively inform connectivity planning, such as the placement of spawning reserves. © The authors 2016.


Loh T.-L.,Daniel erther Center For Conservation And Research | Loh T.-L.,University of British Columbia | Tewfik A.,Wildlife Conservation Society | Aylesworth L.,University of British Columbia | Phoonsawat R.,Gulf
Biological Conservation | Year: 2016

Unsustainable wildlife trade negatively impacts wild populations of traded species. Thus to assess these population impacts and manage trade, we need to find and characterize extant populations. Seahorses are one of the most heavily traded marine animals, with almost 6 million individuals exported worldwide annually. Thailand, the top exporter, is responsible for 88% of global export volumes of dried seahorses. Here, we sought to locate seahorse hotspots in Thailand - places where seahorses are still abundant, and elucidate predictors of these hotspots. Because seahorses have economic value, we included socio-economic parameters in addition to environmental parameters. From underwater surveys, 46 seahorses from three species were spotted at 13 of 46 sites, with Hippocampus spinosissimus most commonly observed. The highest seahorse densities were found off Chonburi province within the Gulf of Thailand. Seahorse density and presence were not significantly associated with habitat type, while access to market was the strongest predictor. Seahorses were less abundant in areas with a seahorse market, presumably because proximate seahorse resources in these areas are attractive commodities to extract for fishers. Intense fishing activity has already greatly impacted seahorse populations in Thailand, potentially obscuring natural habitat preferences and leading to population declines. For heavily traded species whose natural populations are already impacted, human processes may have a stronger effect on species distribution than habitat type or quality. Beyond identifying and protecting suitable habitats, the preservation of seahorse populations depends on changing human behavior in interacting with seahorses and the strict enforcement of existing fishing regulations. © 2016 Elsevier Ltd


Knapp C.R.,Daniel erther Center For Conservation And Research | Alvarez-Clare S.,North Central College
Journal of Tropical Ecology | Year: 2016

Herbivores are predicted to forage on a variety of plants in order to obtain a nutritionally sufficient diet. Most herbivores, however, forage non-randomly and may be influenced by morphological, chemical and physical traits in their food. We examined the influence of several leaf traits on food selection for the Exuma rock iguana (Cyclura cychlura figginsi). We expected the iguana to prefer leaves with higher nutrient concentration and lower physical defences, such as reflected by high N, P, Ca, K, Mg concentrations and low leaf density and per cent concentrations of cellulose, hemicellulose and lignin, respectively. We quantified selection by examining 30 faecal samples and analysing traits of leaves from the 10 most common plants on the island. Our results showed substantial variability in all measured traits among species but food preference only for less-dense leaves, a good indicator of low leaf toughness. Our results are the first to demonstrate that physical leaf traits can influence food selection in a true herbivorous lizard and offer a basis for future testing. Copyright © 2015 Cambridge University Press.


Loh T.-L.,University of North Carolina at Wilmington | Loh T.-L.,Daniel erther Center For Conservation And Research | McMurray S.E.,University of North Carolina at Wilmington | Henkel T.P.,Valdosta State University | And 2 more authors.
PeerJ | Year: 2015

Consumer-mediated indirect effects at the community level are difficult to demonstrate empirically. Here, we show an explicit indirect effect of overfishing on competition between sponges and reef-building corals fromsurveys of 69 sites across the Caribbean. Leveraging the large-scale, long-term removal of sponge predators, we selected overfished sites where intensive methods, primarily fish-trapping, have been employed for decades or more, and compared themto sites in remote or marine protected areas (MPAs) with variable levels of enforcement. Sponge-eating fishes (angelfishes and parrotfishes) were counted at each site, and the benthos surveyed, with coral colonies scored for interaction with sponges. Overfished sites had >3 fold more overgrowth of corals by sponges, and mean coral contact with sponges was 25.6%, compared with 12.0% at less-fished sites. Greater contact with corals by sponges at overfished sites was mostly by sponge species palatable to sponge predators. Palatable species have faster rates of growth or reproduction than defended sponge species, which instead make metabolically expensive chemical defenses. These results validate the top-down conceptual model of sponge community ecology for Caribbean reefs, as well as provide an unambiguous justification for MPAs to protect threatened reef-building corals. An unanticipated outcome of the benthic survey component of this study was that overfished sites had lower mean macroalgal cover (23.1% vs. 38.1% for less-fished sites), a result that is contrary to prevailing assumptions about seaweed control by herbivorous fishes. Because we did not quantify herbivores for this study, we interpret this result with caution, but suggest that additional large-scale studies comparing intensively overfished and MPA sites are warranted to examine the relative impacts of herbivorous fishes and urchins on Caribbean reefs. © 2015 Loh et al.


Knapp C.R.,Daniel erther Center For Conservation And Research | Hines K.N.,260 Crandon Boulevard | Zachariah T.T.,Brevard Zoo | Perez-Heydrich C.,Meredith College | And 5 more authors.
Conservation Physiology | Year: 2013

Deliberately feeding wildlife is an increasingly popular tourism-related activity despite a limited understanding of long-term impacts on the species being fed. As a result, tourist behaviours that may have adverse impacts on imperiled species have often been encouraged without the necessary evaluation or oversight. Here, we report the responses of Northern Bahamian Rock Iguanas (Cyclura cychlura) to human-visitation pressure and associated food provisioning. We compared a variety of blood chemistry parameters of iguanas subjected to supplemental feeding at popular tourist destinations with iguanas occurring on islands where supplemental feeding does not take place. We demonstrate that male and female iguanas inhabiting tourist-visited islands where supplemental feeding occurs do not differ in body condition or baseline stress and stress response (determined by corticosterone levels) compared with iguanas from non-visited islands. Both males and females from tourist-visited sites experienced a greater incidence of endoparasitic infection and atypical loose faeces. Indicators of dietary nutrition, including glucose, potassium, and uric acid values, also differed for both sexes from tourist-visited and unvisited islands. Male iguanas from visited islands differed significantly from those on non-visited islands in calcium, cholesterol, cobalt, copper, magnesium, packed cell volume, selenium, and triglyceride concentrations, whereas female iguanas from visited islands differed significantly in ionized calcium. Although the interpretation of these differences is challenging, chronic biochemical stressors could compromise individual health over time or decrease survivorship during periods of environmental stress. We suggest protocols that can be adopted throughout the region to ensure that supplemental feeding has fewer impacts on these long-lived iguanas. © The Author 2013.


Morrow K.,University of South Florida | Bell S.S.,University of South Florida | Tewfik A.,University of South Florida | Tewfik A.,Daniel erther Center For Conservation And Research
Marine Ecology Progress Series | Year: 2014

Using field surveys and stable isotope analyses of beach consumers and prey, we investigated whether the identity of dominant prey items of ghost crabs Ocypode quadrata differed across 3 barrier island beaches along the west coast of Florida, USA. Abundance of potential prey, mole crabs Emerita talpoida and coquina clams Donax variabilis, was determined from sediment cores collected from the swash zone at Anclote Key (ANC), Honeymoon Island (HI) and Cayo Costa (CC) from late April to September 2011. Concurrently, wrack-associated amphipods were gathered from supra-tidal areas, and ghost crabs were captured from these beaches. Stable isotopic signatures (δ13C and δ15N) of amphipods, mole crabs, coquinas and ghost crabs were identified and diets of ghost crabs compared across beaches using stable isotope analysis in R (SIAR) mixing models. Ghost crabs from CC and HI fed primarily on swash zone animals (mean contribution to diet = 67.6 and 68.4%, respectively), while those from ANC mainly consumed wrack-associated amphipods (mean contribution = 55.7%). ANC supported a comparatively low abundance of swash prey, contained moderate amounts of fine-grain sediments and retained a high biomass of seagrass wrack. In contrast, significantly greater abundances of swash prey were found on CC than on other beaches, and a low biomass of wrack was commonly recorded. This new information suggests that wrack may serve as an important marine subsidy and underlie a dietary shift observed for ghost crab consumers on some beaches. In addition to products transported onshore, beach morphology and features of inland habitats may contribute to variability in trophic structure of these subtropical beaches. © Inter-Research 2014.


Tewfik A.,Daniel erther Center For Conservation And Research
New Zealand Journal of Marine and Freshwater Research | Year: 2014

The distribution of Indo-Pacific spiny lobster populations is known to be influenced by oceanic hydrodynamics and terrestrially generated turbidity. The distinct pattern of artisanal landings for six lobster species (Panulirus homarus, P. longpipes longipes, P. ornatus, P. penicillatus, P. polyphagus, P. versicolor) on the west coast of Aceh Province is described. The observed pattern was influenced by availability of a variety of habitats and variability in environmental conditions affecting fisher access to lobster habitats. Relatively constant access to wave protected, soft sediment habitats and affiliated species (e.g. P. homarus) was in stark contrast to more wave exposed habitats and oceanic/reef species (e.g. P. pencillatus, P. versicolor) which may be difficult to access during the high wave energy dominated wet season. This study adds to the growing body of research on the impacts of weather on fishing fleets and potential changes in landings that may result as a consequence of climate change. © 2014 The Royal Society of New Zealand.


Hayes W.K.,Loma Linda University | Iverson J.B.,Earlham College | Knapp C.R.,Daniel erther Center For Conservation And Research | Knapp C.R.,San Diego Zoos Institute for Conservation Research | Carter R.L.,Loma Linda University
Biodiversity and Conservation | Year: 2012

Ample evidence confirms that large invasive mammalian competitors and predators can devastate endangered insular iguana populations. However, the impact of invasive rodents, particularly rats (Rattus rattus), has remained elusive. Tail autotomy occurs frequently in lizards, often as an antipredator tactic, but sometimes from intraspecific aggression. Tail autotomy can incur substantial locomotor, behavioral, energetic, and survival costs. Furcation (i.e., dividing into branches) of regenerated tails may also result from attempted predation but occurs much more rarely, and with unknown costs. To evaluate the potential impact of invasive rodents-primarily rats-on West Indian rock iguanas (genus Cyclura), we compared tail-break and tail-furcation frequencies among 19 insular iguana populations (3,537 individuals) representing three species in the Bahamian Archipelago (including the Turks and Caicos Islands). The findings supported our three hypotheses: (1) that tail-break and tail-furcation frequencies are significantly higher in populations coexisting with invasive rodents; (2) that tail-furcation results primarily from failed predation attempts rather than intraspecific aggression; and (3) that frequencies of tail breaks and tail furcation are associated with each other, suggesting a degree of commonality in cause-effect (i. e., failed predation attempts). Tail furcation, in contrast to tail breakage, never occurred on islands lacking invasive mammalian predators. We conclude that invasive rodents, particularly rats, may have a greater impact on endangered insular iguana species than previously recognized. © 2012 Springer Science+Business Media B.V.


PubMed | Meredith College, Earlham College, Brevard Zoo, PO Box N 8893 and 3 more.
Type: Journal Article | Journal: Conservation physiology | Year: 2016

Deliberately feeding wildlife is an increasingly popular tourism-related activity despite a limited understanding of long-term impacts on the species being fed. As a result, tourist behaviours that may have adverse impacts on imperiled species have often been encouraged without the necessary evaluation or oversight. Here, we report the responses of Northern Bahamian Rock Iguanas (Cyclura cychlura) to human-visitation pressure and associated food provisioning. We compared a variety of blood chemistry parameters of iguanas subjected to supplemental feeding at popular tourist destinations with iguanas occurring on islands where supplemental feeding does not take place. We demonstrate that male and female iguanas inhabiting tourist-visited islands where supplemental feeding occurs do not differ in body condition or baseline stress and stress response (determined by corticosterone levels) compared with iguanas from non-visited islands. Both males and females from tourist-visited sites experienced a greater incidence of endoparasitic infection and atypical loose faeces. Indicators of dietary nutrition, including glucose, potassium, and uric acid values, also differed for both sexes from tourist-visited and unvisited islands. Male iguanas from visited islands differed significantly from those on non-visited islands in calcium, cholesterol, cobalt, copper, magnesium, packed cell volume, selenium, and triglyceride concentrations, whereas female iguanas from visited islands differed significantly in ionized calcium. Although the interpretation of these differences is challenging, chronic biochemical stressors could compromise individual health over time or decrease survivorship during periods of environmental stress. We suggest protocols that can be adopted throughout the region to ensure that supplemental feeding has fewer impacts on these long-lived iguanas.

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