Current Search: trophic ecology (x)
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(1 - 3 of 3)
- Title
- Fish and seagrass communities vary across a marine reserve boundary, but seasonal variation in small fish abundance overshadows top-down effects of large consumer exclosures.
- Creator
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Douglass, James, Paperno, Richard, Reyier, Eric A., Hines, Anson H.
- Abstract / Description
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A growing number of examples indicate that large predators can alter seagrass ecosystem structure and processes via top-down trophic interactions. However, the nature and strength of those interactions varies with biogeographic context, emphasizing the need for region-specific investigations. We investigated spatial and temporal variation in predatory fish and seagrass communities across a Marine Protected Area (MPA) boundary in the Banana River Lagoon, Florida (USA), assessing trophic roles...
Show moreA growing number of examples indicate that large predators can alter seagrass ecosystem structure and processes via top-down trophic interactions. However, the nature and strength of those interactions varies with biogeographic context, emphasizing the need for region-specific investigations. We investigated spatial and temporal variation in predatory fish and seagrass communities across a Marine Protected Area (MPA) boundary in the Banana River Lagoon, Florida (USA), assessing trophic roles of intermediate consumers, and performing a large-consumer exclusion experiment in the MPA. Large, predatory fishes were most abundant within the MPA, while some mid-sized fishes were more abundant outside it. Small, seagrass-resident fishes, epifaunal invertebrates, and macrophytes also differed across the MPA boundary, but varied more among individual sites and seasonally. We cannot conclusively attribute these patterns to MPA status because we lack data from prior to MPA establishment and lack study replication at the level of MPA. Nevertheless, other patterns among our data are consistent with hypothesized mechanisms of top-down control. E.g., inverse seasonal patterns in the abundance of organisms at adjacent trophic levels, coupled with stable C and N isotope and gut contents data, suggest top-down control of crustacean grazers by seasonal recruitment of small fishes. Large-consumer exclosures in the MPA increased the abundance of mid-sized predatory and omnivorous fishes, but had few impacts on lower trophic levels. Results suggest that large-scale variation in large, predatory fish abundance in this system does not strongly affect seagrass-resident fish, invertebrate, and algal communities, which appear to be driven more by habitat structure and seasonal variation in small fish abundance.
Show less - Date Issued
- 2018-10-01
- Identifier
- fgcu_ir_000920
- Format
- Citation
- Title
- Form–function relationships in a marine foundation species depend on scale: a shoot to global perspective from a distributed ecological experiment.
- Creator
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Douglass, James, Ruesink, Jennifer L., Stachowicz, John J., Reynolds, Pamela L., Boström, Christoffer, Cusson, Mathieu, Eklöf, Johan, Engelen, Aschwin H., Hori, Masakazu, Hovel,...
Show moreDouglass, James, Ruesink, Jennifer L., Stachowicz, John J., Reynolds, Pamela L., Boström, Christoffer, Cusson, Mathieu, Eklöf, Johan, Engelen, Aschwin H., Hori, Masakazu, Hovel, Kevin, Iken, Katrin, Moksnes, Per-Olav, Nakaoka, Masahiro, O’Connor, Mary I., Olsen, Jeanine L., Sotka, Erik E., Whalen, Matthew A., Duffy, J. Emmett
Show less - Abstract / Description
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Form–function relationships in plants underlie their ecosystem roles in supporting higher trophic levels through primary production, detrital pathways, and habitat provision. For widespread, phenotypically‐variable plants, productivity may differ not only across abiotic conditions, but also from distinct morphological or demographic traits. A single foundation species, eelgrass Zostera marina , typically dominates north temperate seagrass meadows, which we studied across 14 sites spanning 32...
Show moreForm–function relationships in plants underlie their ecosystem roles in supporting higher trophic levels through primary production, detrital pathways, and habitat provision. For widespread, phenotypically‐variable plants, productivity may differ not only across abiotic conditions, but also from distinct morphological or demographic traits. A single foundation species, eelgrass Zostera marina , typically dominates north temperate seagrass meadows, which we studied across 14 sites spanning 32–61°N latitude and two ocean basins. Body size varied by nearly two orders of magnitude through this range, and was largest at mid‐latitudes and in the Pacific Ocean. At the global scale, neither latitude, site‐level environmental conditions, nor body size helped predict productivity (relative growth rate 1–2% day‐1 at most sites), suggesting a remarkable capacity of Z. marina to achieve similar productivity in summer. Furthermore, among a suite of stressors applied within sites, only ambient leaf damage reduced productivity; grazer reduction and nutrient addition had no effect on eelgrass size or growth. Scale‐dependence was evident in different allometric relationships within and across sites for productivity and for modules (leaf count) relative to size. Zostera marina provides a range of ecosystem functions related to both body size (habitat provision, water flow) and growth rates (food, carbon dynamics). Our observed decoupling of body size and maximum production suggests that geographic variation in these ecosystem functions may be independent, with a future need to resolve how local adaptation or plasticity of body size might actually enable more consistent peak productivity across disparate environmental conditions.
Show less - Date Issued
- 2017-12-04
- Identifier
- fgcu_ir_000921
- Format
- Citation
- Title
- A high-resolution molecular method for identification of smalltooth sawfish prey.
- Creator
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Hancock, Taylor Lee
- Abstract / Description
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The foundation of food web analysis is a solid understanding of predator-prey associations. Traditional dietary studies of fishes have been by stomach content analysis. However, these methods are not applicable to Critically Endangered species such as the smalltooth sawfish (Pristis pectinata). Previous research using the combination of stable isotope signatures from fin clips and 18S rRNA gene sequencing of fecal samples identified the smalltooth sawfish as piscivorous at high taxonomic...
Show moreThe foundation of food web analysis is a solid understanding of predator-prey associations. Traditional dietary studies of fishes have been by stomach content analysis. However, these methods are not applicable to Critically Endangered species such as the smalltooth sawfish (Pristis pectinata). Previous research using the combination of stable isotope signatures from fin clips and 18S rRNA gene sequencing of fecal samples identified the smalltooth sawfish as piscivorous at high taxonomic levels. Here, we present a high taxonomic resolution molecular technique for identification of prey using opportunistically acquired fecal samples. To assess potential biases, primer sets of two mitochondrial genes, 12S and 16S rRNA, were used alongside 18S rRNA, which targets a wider spectrum of taxa. In total, 19 fish species, from 7 orders and 11 families, native to the Gulf of Mexico were successfully identified, including one ray, the southern stingray (Dasyatis americana). Silver perch (Bairdiella chrysoura), bay anchovy (Anchoa mitchilli), tidewater mojarra (Eucinostomus harengulus), spotted seatrout (Cynoscion nebulosus), ladyfish (Elops saurus), and spot (Leiostomus xanthurus) were most prevalent in our analysis. The sawfish prey identified comprised diverse taxa, indicating that this species is a generalist piscivore. These findings and the molecular approach used will aid recovery planning for the smalltooth sawfish and has the potential to reveal previously unknown predator-prey associations from a wide range of taxa, being specifically desirable for use with rare and hard to sample species.
Show less - Date Issued
- 2019-06-05
- Identifier
- fgcu_ETD_0296
- Format
- Document (PDF)
