Abstract

JERES, Pablo; ROMERO, María A  and  GONZALEZ, Raúl. Assessment of the structure of fish assembly of a North-Patagonian coastal reef subjected to different anthropic impacts. Ecol. austral [online]. 2018, vol.28, n.2, pp.325-338. ISSN 1667-782X.

The rocky reefs of the Patagonian coast are characterized by lower specific richness, but higher biomass and proportion of large fish than reefs in tropical regions. Rocky reefs have major seasonal changes that can affect fish abundance and diversity. Ecological studies on the North-Patagonian reef ecosystems are scarce. The aim of the present study was to evaluate the potential changes in the fish assemblage composition of a rocky reef in the San Matías Gulf. An abundance reduction of fish species is expected after more than 20 years of anthropogenic impacts. The assemblage variation and its relationship with environmental traits were evaluated over one year. Fish species abundance was recorded using scuba diving in the Parque Submarino Las Grutas. The newly obtained results were compared to a previous study by González (1993). The results showed that the fish assemblage composition is identical to that in the 1990s, consisting of five warm-tempered species (Diplodus argenteus, Pinguipes brasilianus, Acanthistius patachonicus, Serranus auriga and Pseudopercis semifasciata) and a single record of a cold-tempered species (Congiopodus peruvianus). However, in terms of abundance, an increase was observed for all species. Species such as D. argenteus and S. auriga nearly doubled and tripled their abundance, respectively, compared to the 1990 levels. Environmental factors such as sea temperature rise and primary production upturn could promote an increase in the fish population numbers and/or the migration of fish from nearby populations. Throughout the year, the species showed a tendency coupled with temperature, giving that all the species showed greater abundances at the end of the warm season (April). In this study, we demonstrate the need of long-tern ecological studies in order to evaluate the condition of our coastal ecosystems to help establish management and conservation measures that preserve them over time.

Keywords : Diversity; Human impacts; Coastal ecosystems.

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