Yeager L.A.,Florida International University |
Stoner E.W.,Loxahatchee River District |
Peters J.R.,Portland State University |
Layman C.A.,North Carolina State University
Journal of Experimental Marine Biology and Ecology | Year: 2016
Terrestrial-aquatic food web subsidies are known to affect food web structure, ecosystem productivity, and stability of recipient habitats. This study describes a prey flux across the land-water interface associated with a behavioral response to multiple predators. Specifically, mangrove tree crabs (Aratus pisonii, hereafter Aratus) are primarily arboreal, but may jump off mangrove trees to escape avian predators, making them vulnerable to fish predation. Mesocosm experiments, field observations, and tethering assays were used to investigate behavioral responses, habitat shifts, and risk for Aratus associated with these two predator types. In the field, Aratus spent most of their time above the water on mangroves, where risk is lowest. In response to simulated bird strikes in mesocosm trials, crabs jumped off trees to escape imminent risk, and spent more time in and near the water, enhancing risk of fish predation. Fish attacks on crabs were nearly three times greater in treatments with simulated bird attacks. In addition, empirical diet data was used to examine the importance of Aratus as a prey item for a fish predator. Aratus represented up to 29% of diet by volume for one of the most common mesopredators in the Caribbean (gray snapper Lutjanus griseus), with the proportion varying greatly across space. Because Aratus consume mangrove-derived carbon, their consumption by aquatic predators represents another pathway by which mangrove production may be incorporated into aquatic food webs. These data suggest how the nexus of behavioral and food web ecology may provide for new perspectives on energy flow between ecosystems. © 2015 Elsevier B.V.
Montoya J.V.,Texas A&M University |
Arrington D.A.,Loxahatchee River District |
Winemiller K.O.,Texas A&M University
Journal of Natural History | Year: 2014
We studied seasonal and diel changes of shrimp abundance in sandbanks of the Cinaruco River, a tropical floodplain tributary of the Orinoco River. Paired diurnal and nocturnal samples were collected from seven river-channel sandbanks during different periods of an annual hydrological cycle. We collected 3730 shrimp representing two families: Sergestidae (Acetes paraguayensis) and Palaemonidae (six species). Patterns of temporal and spatial variation of shrimp abundance on sandbanks of the Cinaruco indicated responsiveness to both diurnal cycles and the annual hydrological regime. The presence of submerged vegetation and the absence of ridge-and-trough topography on sandbanks were the factors most strongly associated with high shrimp abundance. We conclude that the river's seasonal flow regime and geomorphology create the heterogeneity of hydraulic habitats that is essential for diel movements of shrimp between areas used for nocturnal foraging and diurnal refuge. © 2013 © 2013 Taylor & Francis.
Jordan F.,Loyola University New Orleans |
Arrington D.A.,Loxahatchee River District
Restoration Ecology | Year: 2014
Evaluation of the success of ecosystem restoration projects requires identification of appropriate ecological metrics. Comparison of reconstructed food webs (or subsets thereof) from restored and non-restored habitats may be a valuable tool to evaluate restoration success because food webs help identify critical predator-prey relationships, keystone species, relative importance of direct and indirect trophic interactions, and other aspects of ecological function. We compared the diets of apex predatory fishes collected from enhanced and non-enhanced portions of the channelized Kissimmee River, Florida, USA to determine whether food web structure responded to experimental hydrologic manipulations. Diets were reconstructed for black crappie (Pomoxis nigromaculatus), bowfin (Amia calva), chain pickerel (Esox niger), Florida gar (Lepisosteus platyrhincus), largemouth bass (Micropterus salmoides), and warmouth (Lepomis gulosus) collected from enhanced and non-enhanced portions of the Kissimmee River. Prey eaten by apex predatory fishes in the enhanced portion of the Kissimmee River were quantitatively and qualitatively different from prey eaten in non-enhanced portions of the river. Predators in the enhanced portion of the river had fewer empty stomachs, more prey items per individual, more prey types per individual, more fish prey per individual, greater overall richness of prey, and a multivariate suite of prey distinct from predators in non-enhanced portions of the river. Results from hydrologic manipulations suggest that large-scale restoration of hydrologic linkages between the main channel and floodplain habitats will positively affect food web structure and ecosystem function in the Kissimmee River. © 2014 Society for Ecological Restoration 22 3 May 2014 Published 2014.
Freeman C.J.,Smithsonian Marine Station |
Stoner E.W.,Loxahatchee River District |
Easson C.G.,University of Alabama at Birmingham |
Matterson K.O.,University of Alabama at Birmingham |
Baker D.M.,University of Hong Kong
Marine Ecology Progress Series | Year: 2016
Symbiotic interactions in the marine environment have long been represented by mutualisms between photosymbionts and benthic marine invertebrates like corals and sponges. Although -upside-down- epibenthic jellyfish in the genus Cassiopea also derive a substantial metabolic benefit from abundant communities of the dinoflagellate symbiont Symbiodinium, comparatively little is known about the efficiency of carbon (C) and nitrogen (N) assimilation within the Cassiopea holobiont. Using standardized 6 h incubations with 13C- and 15N- enriched compounds, we assessed symbiont C and N assimilation in both oral arm and bell tissue of C. xamachana under light and dark conditions. Carbon fixation was light dependent and highest in the photosymbiont-rich oral arm tissue. In contrast, 15NO3 assimilation was light independent in both tissue types and was highest in bell tissue that was sparsely colonized by photosymbionts. This, coupled with higher bell tissue 15N enrichment under dark conditions, implicates nonphotosynthetic microbes in Cassiopea N metabolism. This zonation of microbial activity may allow C. xamachana to simultaneously fix C and assimilate ambient or porewater N released during Cassiopea pumping activity. Although C. xamachana may utilize symbiont-derived N, lower 15N enrichment relative to C fixation suggests that Cassiopea may also rely on exogenous sources of N for growth. This study provides initial evidence that the efficiency of symbiont metabolism within Cassiopea jellyfish is comparable to, or exceeds, that of other common benthic marine invertebrates, sup porting the contention that Cassiopea have an important role in the productivity and nutrient dynamics within their local environment. © Inter-Research 2016.
Culp J.J.,University of Alabama |
Haag W.R.,U.S. Department of Agriculture |
Arrington D.A.,Loxahatchee River District |
Kennedy T.B.,University of Alabama
Journal of the North American Benthological Society | Year: 2011
We examined seasonal patterns of abundance of mussel larvae (glochidia) in stream drift in a diverse, large-stream mussel assemblage in the Sipsey River, Alabama, across 1 y. We used recently developed techniques for glochidial identification combined with information about mussel fecundity and benthic assemblages to evaluate how well observed glochidial abundance corresponded to expected abundance based on glochidial production. Glochidia from short-term brooding species (Amblema plicata, Elliptio arca, Fusconaia cerina, Pleurobema decisum, Obliquaria reflexa, and Quadrula asperata) were abundant from May to August but did not occur in drift between November and the end of April. Long-term brooders (Lampsilis spp., Medionidus acutissimus, Obovaria unicolor, and Villosa spp.) occurred in several short peaks in spring, summer, and autumn, but generally were less abundant than short-term brooders. We estimated that the benthic assemblage at our study site produced >500,000 glochidia/m 2 annually and production varied widely among species. Abundance of species in the drift was positively related to benthic abundance but was only weakly related to glochidial production. The poor relationship between glochidial production and abundance in the drift suggests that release and transport of glochidia are influenced by a wide variety of abiotic and biotic factors. © 2011 The North American Benthological Society.