Browsing by Author "Peoples, Brandon K."
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- Context-dependent outcomes in a reproductive mutualism between two freshwater fish speciesFrimpong, Emmanuel A.; Peoples, Brandon K. (Wiley, 2016-01-25)1 The development of encompassing general models of ecology is precluded by underrepresentation of certain taxa and systems. Models predicting contextdependent outcomes of biotic interactions have been tested using plants and bacteria, but their applicability to higher taxa is largely unknown. 2 We examined context dependency in a reproductive mutualism between two stream fish species: mound nest-building bluehead chub Nocomis leptocephalus and mountain redbelly dace Chrosomus oreas, which often uses N. leptocephalus nests for spawning. We hypothesized that increased predator density and decreased substrate availability would increase the propensity of C. oreas to associate with N. leptocephalus and decrease reproductive success of both species. 3 In a large-scale in situ experiment, we manipulated egg predator density and presence of both symbionts (biotic context), and replicated the experiment in habitats containing high- and low-quality spawning substrate (abiotic context). 4 Contradictory to our first hypothesis, we observed that C. oreas did not spawn without its host. The interaction outcome switched from commensalistic to mutualistic with changing abiotic and biotic contexts, although the net outcome was mutualistic. 5 The results of this study yielded novel insight into how context dependency operates in vertebrate mutualisms. Although the dilution effect provided by C. oreas positively influenced reproductive success of N. leptocephalus, it was not enough to overcome both egg predation and poor spawning habitat quality. Outcomes of the interaction may be ultimately determined by associate density. Studies of context dependency in vertebrate systems require detailed knowledge of species life-history traits.
- Ethical Guidelines for Publication of Fisheries Research Publications Overview Committee, American Fisheries SocietyKocovsky, Patrick M.; Gaunt, Patricia S.; Peoples, Brandon K.; Frimpong, Emmanuel A. (2019-09)
- Modeling the predation dynamics of invasive blue catfish (Ictalurus furcatus) in Chesapeake BaySchmitt, Joseph D.; Peoples, Brandon K.; Bunch, Aaron J.; Castello, Leandro; Orth, Donald J. (2019-09-19)Blue catfish (Ictalurus furcatus) have been widely introduced throughout the United States and are invasive in Chesapeake Bay. Despite this proliferation, little is known about the diet of this large, predatory catfish. We used stratified random sampling to collect stomachs from 14,488 blue catfish in Chesapeake Bay. Canonical correspondence analysis (CCA) was used to identify key drivers of the diet of blue catfish, and generalized additive models (GAMs) were used to explore trends in rates of predation by blue catfish on depleted or commercially valuable native species, including American shad (Alosa sapidissima), blueback herring (A. aestivalis), alewife (A. pseudoharengus), American eel (Anguilla rostrata), and blue crab (Callinectes sapidus). Results of CCA reveal that diets were significantly correlated with season, salinity, and total length (TL) of blue catfish, and those from our GAMs reveal the circumstances associated with greater predation on these species. For example, we found that Alosa species were most susceptible to predation by large catfish (>600 mm TL) in freshwater areas during the month of April. This paper describes methods for identifying times, locations, and other circumstances that are associated with maximal predation rates upon certain taxa. The information gained from these approaches can be used to inform management strategies, with the goal of reducing effects of predation on specific organisms.
- Multiple dimensions of functional diversity affect stream fish taxonomic beta-diversityBower, Luke M.; Stoczynski, Lauren; Peoples, Brandon K.; Patrick, Christopher J.; Brown, Bryan L. (Wiley, 2023-03)When investigating metacommunity dynamics, functional differences among species are often assumed to be as important as environmental differences between sites in determining beta-diversity. However, few studies have examined the influence of functional diversity on beta-diversity. We examine the relative importance of regional functional diversity partitioned by niche dimensions and environmental variation in structuring taxonomic beta-diversity of stream fishes using a large dataset of stream fish assemblages (hereafter, simply beta-diversity). We predicted that both functional diversity and environmental variation play a role in determining beta-diversity. We tested this prediction by modelling the patterns of stream fish beta-diversity as a function of environmental variation, functional diversity and gamma-richness across 10,220 sites for 329 fish species using a series of conceptual path models. Environmental variation consistently affected beta-diversity across all models, whereas functional diversity and gamma-richness influenced beta-diversity only in some models. We show that including relevant trait differences among species in path models can improve their ability to explain beta-diversity, suggesting that functional traits influence beta-diversity. The ability of path models to explain beta-diversity varied depending on the trait grouping included in the model, demonstrating that specific path models representing different niche dimensions can improve the ability of a model to explain beta-diversity. In addition, parsing traits into different niche dimensions revealed alternative patterns of functional diversity-beta-diversity relationships that otherwise would have been missed. The selection of relevant traits and linked niche dimensions is critical for detecting relationships between functional diversity and beta-diversity. Using traits associated with different niche dimensions allows for the identification of niche dimensions most strongly associated with species sorting and the detection of patterns missed by focusing on a single niche dimension. Determining the niche dimensions that influence beta-diversity could provide insights into the processes driving biodiversity and metacommunity dynamics, improving our ability to conserve or restore aquatic communities.
- Size-structured habitat selection by arapaima in floodplain lakes of the Lower AmazonRichard, Jordan C.; Castello, Leandro; Gurdak, Daniel J.; Peoples, Brandon K.; Angermeier, Paul L. (2018-12)Human modification of floodplain ecosystems is widespread and a major threat to fish populations, particularly in the tropics where fish diversity and rates of floodplain degradation are high. Identifying measures to minimize the susceptibility of floodplain fishes to habitat modification requires understanding dry-season lake habitat selection for species of conservation concern. This study examined the effects of environmental factors on dry-season floodplain lake habitat selection by arapaima (Arapaima spp.) and determined the extent to which they differed across three size classes. In floodplain lakes of the lower Amazon River, variables were measured at locations representing habitat availability and compared with measurements taken where arapaima were observed during surface breathing. Regression models were used to account for between-lake variation in the presence of arapaima owing to nearby fishing communities. The probability of arapaima presence at each sample location was modelled based on the variables measured. The results indicated that arapaima expressed distinct habitat selection patterns, which differed significantly across size classes. The general pattern observed was that all arapaima were more likely to be found in deeper, more turbid, and higher conductivity locations, whereas smaller arapaima were more likely to remain near dense beds of floating macrophytes. The probability of arapaima presence differed among fishing community territories, reflecting differences in management schemes. Deeper, macrophyte-rich sections of floodplain lakes appear to provide key habitats for arapaima and deserve consideration for becoming priority targets for conservation of the rich diversity of fish species in these systems.