Biotic and abiotic factors in the distribution of resident fish species: a case study from two islets and an adjacent shoreline in Terceira Island, Azores, Portugal.

Abstract

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With this poster we aim to disclose the ecological characteristics of the resident ichthyofauna in three distinct SE- NW aligned sites off the S coast of Terceira Island, Azores, Portugal. We collected both direct and indirect data about those species near the shoreline – Serretinha, in a close by islet complex – Cabras and over an offshore rocky outcrop – Fradinhos. The work was divided into two parts: a) specimen’s collection for biological sampling, namely the determination of both hepatic and gonadossomatic indexes for the eventual detection of reproductive peaks; and b)stomach content’s analyses to describe the food habits of these most common coastal species. We also developed a series of underwater transects in order to count individuals and thus to describe the resident communities in these three sites regarding a) richness, b) evenness and c) diversity. Main abiotic factors were also registered in order to study possible correlations with the above mentioned data. Azorean ichthyofauna is still poorly known especially in terms of ecological interactions between coastal resident species in several substrates. The few available literature references do present several gaps when reporting to the region’s coastal fish communities. Here we describe resident coastal fish communities in the three study sites as well as the determination of their dominant species, checking significant correlations within biotic and abiotic facts in their distribution and reproductive periods and determine main indexes for diversity, evenness and richness. We also describe the diet of these same species and report the major reproductive peaks for the dominant ones.

Keywords

• Azores
• Ecology
• Biodiversity
• richness
• Ichtyological communities