Estudi de la biodiversitat epifaunal associada a comunitats algals dominades per Cystoseira mediterranea i Halopteris scoparia

Abstract

Cystoseira mediterranea is a canopy-forming seaweed, a macroalgae that functions as an ecosystem engineer and provides a great number of habitats and ecosystem services, favouring the establishment of a greater biodiversity. However, there is little knowledge of the macroinvertebrates communities associated with C. mediterranea. This study aims to determine the number of macroinvertebrates taxa and individuals (epifauna) associated with the algae communities dominated by C. mediterranea, and at the same time, to compare the results with the ones of the algae communities dominated by Halopteris scoparia. For this purpose, samples were collected on two beaches of Cadaqués (Platja de sa Confitera i d’es Caials), subsequently, separation, measurement, identification and counting of macroinvertebrates and algae present in the samples were done. An analysis of variances (ANOVA) was performed with the data obtained to determine significant differences and, using the PRIMER 6 software, similarity and dissimilarity percentages analysis were performed to observe how similar samples were between each other and what caused the differences between the two communities. Both communities showed high numbers of taxa and individuals. The results show differences in the distribution of macroinvertebrates between the two communities: H. scoparia presents a greater number of individuals than C. mediterranea. On the other hand, the number of taxa is the same in both communities. Although no experiments were carried out in this experiment to verify the exact factors that caused this higher number of individuals in H. scoparia, three were suggested: the stability of calm waters, the “bush” morphology of H. scoparia and the marked seasonal cycle of C. mediterranea. This study (pilot program of a CEAB-CSIC project) has allowed to learn the epifauna biodiversity associated with C. mediterranea and H. scoparia. At the same time, it has also provided information that will allow the project to use an efficient methodology, thus achieving a greater knowledge of marine ecosystems. This knowledge is crucial, since the Marine Strategy Framework Directive (EC 2008) currently requires to address the lack of knowledge of marine ecosystems (both algae and benthic invertebrates), in order to develop indicators to protect, preserve and restore the marine environment