The structure of rocky reef fish assemblages across a nearshore to coastal islands' gradient in Southeastern Brazil

Abstract

Local assemblages of fishes associated with reefs are influenced by interactions among the availability of larvae and survival of recruits with subsequent biotic and abiotic forcing, as well as by periodic and episodic disturbances of varying natures and magnitudes. Therefore, besides being structurally heterogeneous and patchily distributed, reef systems are strongly contextdependent due to the influence of a broad array of ecological processes. In order to assess interactions of local factors that influence the distribution and abundance of reef fishes within a coastal mosaic of rocky reefs, we tested the null hypothesis of no significant variation in fish assemblage structure, by comparing 33 sites along the northern coast of the São Paulo State, Southeastern Brazil. Replicated stationary visual census samples (n = 396) were obtained at different distances from the coast, depths and wave exposures, including the mainland, three relatively small coastal islands, and the two margins of a wide channel between the mainland and the large São Sebastião Island (~350 km 2 ), totaling 225 h of SCUBA diving. The regional rocky shore fish fauna comprised 106 species (41 families), with preponderance of diurnal mobile-invertebrate feeders. Samples from the outer margin of the São Sebastião Island, together with those from Alcatrazes, Búzios, and Vitória islands were significantly dissimilar from samples from the coastal sites at the São Sebastião Channel. Species richness tended to increase in a gradient from the coast to the more offshore islands. Local conditions such as depth and other habitat characteristics also influenced fish assemblages' structure. Distance from coast and depth were the main predictors for fish assemblages, followed by water transparency, temperature and benthic cover. This study represents the first regional-scale assessment of fish assemblages associated with rocky reefs in the São Paulo State coast, filling a major geographic knowledge gap in the South Atlantic. As the study region is experiencing fast coastal development and growing threats from seaport expansion, oil and gas exploitation, as well as increasing fishing and tourism pressure, the understanding of the underlying factors that influence the distribution and abundance of the reef-associated biota comprises a relevant baseline for monitoring, conservation planning and management.Assembleias locais de peixes associados a recifes são influenciadas pela interação entre a disponibilidade de larvas e recrutas e as forças bióticas e abióticas que operam após o recrutamento, assim como por perturbações periódicas e episódicas de diversos tipos e magnitudes. Dessa forma, além de serem estruturalmente heterogêneos e irregularmente distribuídos, os sistemas recifais são altamente dependentes do contexto em que se inserem. Com o objetivo de compreender interações de fatores locais que influenciam a distribuição e abundância de peixes recifais em um mosaico costeiro de recifes rochosos, testamos a hipótese nula de inexistência de variação signi...

Reef fishes of the Anchieta Island State Park, Southwestern Atlantic, Brazil

“…For instance, we recorded comparatively more reef fish species than other surveys conducted in nearby areas, i.e. 106 species in Gibran & Moura (2012) and 67 species in Teixeira- Neves et al (2015). Island is a coastal site largely dominated by the warm and less saline (due to riverine inflow) Coastal Water (CW), as well as by the warm (>18 o C) and saline water from the south-flowing Brazil Current (BC) (Matsuura 1986).…”

“…In addition, the region is affected by upwellings of the cold (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) o C) South Atlantic Central Water (SACW) during the austral summer and spring (Matsuura 1986). Such frequent cold water intrusions, as well as the relatively wide depth range of the AISP, account for the presence of several reef fishes with subtropical and temperate affinities (Floeter et al 2001, Luiz Jr. et al 2008, Gibran & Moura 2012, Pinheiro et al 2015b. Furthermore, the high structural complexity of rocky shores , Dominici-Arosema & Wolf 2006, Gibran & Moura 2012, Teixeira-Neves et al 2015 and the broad depth range of coastal islands (Pereira-Filho et al 2011, Gibran & Moura 2012, Teixeira-Neves et al 2015, as well as the proximity to large estuaries and the protected status of the AISP, are responsible for the relatively high richness of fishes recorded herein.…”

“…Moura & Francini-Filho 2005, Gibran & Moura 2012, and may be considered biodiversity hotspots, akin to "marginal" areas of other biogeographic regions (Aburto-Oropeza & Balart 2001, Sala et al 2012. The Brazilian coralline reef area represent 0.4% of global reef area, with 20% of reef fishes endemism, which represent a priority in conservation (Moura 2003, Moura & Francini-Filho 2005, Gibran & Moura 2012.…”

“…Luiz Jr. , Bonaldo et al 2005, Floeter et al 2006, Luiz Jr. et al 2008, Gibran & Moura 2012, Teixeira-Neves et al 2015, Neves et al 2016. However, major geographic gaps still remain along this broad (~2,000 km) and highly threatened (e.g.…”

“…However, major geographic gaps still remain along this broad (~2,000 km) and highly threatened (e.g. Gibran & Moura 2012) extension of the coast, where the country´s population is concentrated within less than 100 km from shoreline (IBGE 2016) with several multiple and interacting environmental stressors (pollution, harbors, tourism and fishing) are observed. Such information gaps are particularly relevant for the ongoing development of management plans for the large multiple-use Marine Protected Areas (MPAs) that have been established along most of coast of the State of São Paulo.…”