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Many species of tropical marine fish aggregate to spawn, and the dynamics of these aggregations make them especially susceptible to overfishing and habitat loss. Spawning aggregations tend to attract reproductive adults from a large geographic area, sites are traditionally used across generations, and larval dispersal can help supply regional fish stocks. Thus, anthropogenic impacts to spawning sites can have population-level consequences over local and regional scales. A critical component in the challenge to conservation of aggregation-spawning species is identification and subsequent protection of spawning sites. Here we summarize fieldwork conducted to create a protocol for identification of pre-spawning aggregation sites for bonefish, Albula vulpes, in The Bahamas. The mixed-methods, field-based protocol includes Traditional Ecological Knowledge, assessment of spawning readiness, tracking using acoustic telemetry, behavioral observations, and mark-recapture, that combined meet the requirements for identifying pre-spawning aggregation sites. Pre-spawning site identification, in conjunction with information on other life stages and habitats, is essential for successful spatial management strategies. Since bonefish and many other tropical fishes that form spawning aggregation are 'data poor' and occur in regions where enforcement of fishery regulations is lacking, spatial management is often the best conservation strategy. This protocol builds upon similar previous efforts to identify spawning sites for groupers and snappers, and will contribute to information needs for conservation is an essential component in the conservation of aggregation-forming species such as bonefish across broad spatial scales. [ABSTRACT FROM AUTHOR]

Indo-Pacific red lionfish (Pterois volitans) have invaded the western Atlantic, and most recently the northern Gulf of Mexico (nGOM), at a rapid pace. Given their generalist habitat affinities and diet, and strong ecological overlap with members of the commercially valuable snapper-grouper complex, increased density and abundance of lionfish could result in significant competitive interactions with nGOM commercially important species. We experimentally investigated the intensity of behavioral interactions between lionfish and indigenous, abundant and economically important juvenile nGOM red snapper (Lutjanus campechanus), and other increasingly abundant juvenile tropical snapper species (gray snapper—L. griseus and lane snapper—L. synagris) in large outdoor mesocosms to examine snapper vulnerabilities to lionfish competition. When paired with lionfish, red snapper swimming activity (i.e., time swimming and roving around experimental tank or at structure habitat during experiments) was significantly lower than in intraspecific control trials, but gray and lane snapper swimming activities in the presence of lionfish did not significantly differ from their intraspecific controls. Additionally in paired trials, red and lane snapper swimming activities were significantly lower than those of lionfish, while no significant difference in swimming activities was observed between lionfish and gray snapper. We found that red snapper prey consumption rates in the presence of lionfish were significantly lower than in their intraspecific 3-individual control trials, but when paired together no significant differences in prey consumption rates between red snapper and lionfish were observed. When paired with lane or gray snapper, lionfish were observed having comparatively higher prey consumption than snappers, or as observed in lionfish intraspecific 1-individual controls. However, lane and gray snapper consumption rates in the presence of lionfish did not significantly differ from those in intraspecific controls. These findings suggest that competition between juvenile snappers and invasive lionfish may be variable, with lionfish exhibiting differing degrees of competitive dominance and snappers exhibiting partial competitive vulnerability and resistance to lionfish. While the degree of intensity at which these interactions may occur in nGOM reefs may differ from those observed in our findings, this study enables greater understanding of the potential ecological effects of red lionfish on native reef fishes. [ABSTRACT FROM AUTHOR]

The article presents a study which aims at analyzing the behavior of fishes towards the quality of habitats in the oyster reef. The study was conducted by using the acoustic telemetry for quantifying the fish movement patterns in patch habitat at the Loxahatchee River in Florida. According to the results of the study, quality of habitat doesn't affects their living pattern and is not necessary for fitness maintenance.

Stable isotope analysis has emerged as one of the primary means for examining the structure and dynamics of food webs, and numerous analytical approaches are now commonly used in the field. Techniques range from simple, qualitative inferences based on the isotopic niche, to Bayesian mixing models that can be used to characterize food-web structure at multiple hierarchical levels. We provide a comprehensive review of these techniques, and thus a single reference source to help identify the most useful approaches to apply to a given data set. We structure the review around four general questions: (1) what is the trophic position of an organism in a food web?; (2) which resource pools support consumers?; (3) what additional information does relative position of consumers in isotopic space reveal about food-web structure?; and (4) what is the degree of trophic variability at the intrapopulation level? For each general question, we detail different approaches that have been applied, discussing the strengths and weaknesses of each. We conclude with a set of suggestions that transcend individual analytical approaches, and provide guidance for future applications in the field. [ABSTRACT FROM AUTHOR]