![]() ![]() We compared visual census, unbaited remote underwater video (mini-RUV), baited remote underwater video (mini-BRUV) and draining/collection methods, with the goal of quantifying the effectiveness of non-invasive methods over more typical invasive methods for quantifying rockpool fish assemblages. Rocky intertidal shores are diverse ecosystems that have been extensively studied, yet there is a surprising lack of knowledge on the methods best suited to quantifying species abundance, diversity and assemblages. © 2019 National Shellfisheries Association. This indicates that sites may play a more important role in the structure of molluscan assemblages in rock pools than the association with pools. Results indicated a clear local difference in the structures of the assemblages however, they did not differ according to the size of the pools. The most relevant species for discriminating among the assemblies were Eulithidium affine, Cerithium atratum, Tegula viridula, and Ischnochiton striolatus. A total of 43 species of molluscs belonging to the classes Bivalvia, Gastropoda, and Polyplacophora were identified. The molluscan assemblages were characterized by ecological diversity descriptors (abundance, species richness, diversity, and evenness). The size parameters evaluated were surface area, depth, and volume of pools and pool-ocean distance. The study was carried out in three sandstone reefs on the west coast of Ceará in northeast Brazil. This study investigated the variability of molluscan assemblages of rock pools according to location and pool size. The tide pool from Baleeiro's Point was intermediate in size, but was covered by a complex algae community and supported the most diverse fish assemblage, suggesting that habitat complexity may contribute to the diversity of fish. Bathygobius soporator was the dominant species in most of the tide pools, corresponding to 66% of all recorded fish. However, assemblages from the sampled tide pools differed from each other in composition and relative abundance of species, resulting in four distinct assemblage structures. Density and richness of fish were almost constant during the studied period, except for a reduction in fish density in São Francisco's Beach during a cold period. We observed 13 species of fishes (10 families), which belong to five trophic guilds (roving herbivores, territorial herbivores, mobile invertebrate feeders, omnivores and carnivores). Tide pools showed significant environmental differences, mainly in area, volume and complexity of substrata. Environmental and fish data were compared among tide pools and periods throughout the year (warm and cold) using both univariate and multivariate analyses of variance. Monthly, from January to December 2011, we sampled four tide pools (12 samples per pool), applying a standard protocol to record environmental variables, and visual censuses to record abundance, richness and composition of fish assemblages. In this study, we described the environmental conditions and the fish diversity and composition from four tide pools at the continental margin of the São Sebastião Channel, São Sebastião (23✤1'-23✥4'S 45✡9'-45✣0'W), in southeastern Brazil. Fish assemblages in tide pools are usually very different from those in surrounding areas resident species exhibit morphological and ecological adaptations to deal with such a variable environment. Organisms living in tide pools in the intertidal zone are exposed to daily and abrupt changes in temperature, dissolved oxygen, pH and salinity, during tidal cycles. We also highlight the uniqueness status of beach rocks in the Brazilian tropical region. ![]() Substrate heterogeneity was correlated to depth, highlighting the role of local features as filters to organize the fish fauna vertically in tidepools, especially a cultivation of algae that influences the local assembling. We explained spatial-temporal variation in: alpha diversity, taxonomic and functional community composition as well as temporal variation in functional, beta and gamma diversities.We found an annual stability in fish diversity and composition, and that fish biota was assembled mainly per tidepools’ depths. Traits of fish species were retrieved from Fishbase and beta diversity was assessed by the dispersion of abundance, presence-absence and functional diversity in the multivariate space. Here, we describe the functional and taxonomic assembling of fishes in beach rocks of northeastern Brazil. However, natural and anthropogenic actions that alter negatively marine ecosystems functioning (e.g., algal exploitation) are causing homogenization of fish biodiversity. Tidepools are considered ecosystems of high interchangeable fish biota.
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