Trophic relationships in tidepool fish assemblages of the tropical Southwestern Atlantic

Abstract

Trophic studies are fundamental to understanding the dynamics of assemblages and functional roles of species within ecosystems, contributing to the identification of factors responsible for the organization and structure of communities. This study aimed to analyse the trophic organization of tidepool fish assemblages in the tropical Southwestern Atlantic, based on the underlying idea that food resources are not limiting and that trophic guild formation is not driven by food competition. Diets were based on feeding index values of food categories for 12 representative species collected in six tidepools (20º49′ S, 40º36′ W) at quarterly intervals (2005 to 2007). The main food categories were small crustaceans, polychaetes and macroalgae. Multivariate techniques evidenced two multispecific trophic guilds: small‐prey carnivores, including Bathygobius soporator, Bathygobius geminatus, Malacoctenus delalandii and Halichoeres poeyi, and herbivores, including Sparisoma axillare and Acanthurus bahianus. Other species presented significantly different diets and were classified into the following guilds: omnivores feeding on filamentous algae and copepods (Abudefduf saxatilis); large‐prey carnivores (Labrisomus nuchipinnis); omnivores feeding on polychaetes and filamentous algae (Stegastes fuscus); and polychaete feeders (Ahlia egmontis). Gymnothorax funebris and Gymnothorax moringa were classified as carcinophagores and piscivores, respectively. Trophic organization appears related to species convergence toward the use of abundant food resources, driven by a combination of factors allowing some resource partitioning through inter‐specific differences in consumer size, microhabitat, behavior, and trophic specialization.

Seasonal and ontogenetic changes in the diet of blenny Hypleurochilus fissicornis: An estuarine mariculture as a model of the reef environment

“…Both prey items with the greatest IRI% (Campanulariidae and Balanomorpha) were very abundant in the studied area, fouling on the cultivated oysters (personal observation). Pimentel, Soares, Macieira, and Joyeux () found the same pattern in tide pools, where small fishes share the space and the same food resources, once these resources are abundant and can sustain the food chain at the tide pools. Concerning this statement, these small cryptic fishes could be showing an opportunistic feeding habit, feeding on the most available resource, as seen with H. fissicornis in the mariculture.…”

“…Furthermore, these items are preyed by other small cryptic fish in Guaratuba Bay, such as Ctenogobius shufeldti , which diet is based on ostracods (Zanlorenzi & Chaves, ). In tide pools, juveniles of diverse cryptic species also fed on ostracods and other small crustaceans (Pimentel et al, ). Hydrozoans are among the lowest energetic value marine organisms (Doyle, Houghton, McDevitt, Davenport, & Hays, ), and probably do not supply the basic energy needed for fish growth.…”

Niche-Relationships Within and Among Intertidal Reef Fish Species

“…For instance, typical territorial herbivorous reef fishes (e.g., Stegastes spp.) are able to compete for food with several other species acting as omnivorous (Zamprogno, 1989;Pimentel et al, 2018), FIGURE 1 | Intraspecific trophic pressure (ITP; fish silhouette color) in 3-D space defined from isotopic niche (δ 13 C and δ 15 N signatures on the x and y axes, respectively) and density (ind.m −3 ; z-axis) in six intertidal environments. The color scale indicates the relative ITP intensity at each site (low intensity = coldest color and high intensity = warmest color).…”

Partitioning fish communities into guilds for ecological analyses: an overview of current approaches and future directions

“…In this context, it can be used to identify groups of species that share similar attributes within the overall community. Previous studies have used cluster analysis in a variety of ways, including the exploration of dietary relationships (e.g., Pimentel et al 2018) and habitat preference (e.g., Spurgeon et al 2019). The results of a cluster analysis can be displayed in a dendrogram, or tree diagram, that can help to provide a better understanding of how the groups are structured.…”