Soft-bottom macrobenthic community composition and biomass in a Posidonia oceanica meadow in the Ligurian Sea (NW Mediterranean)

• Published in: Estuarine, coastal and shelf science Vol. 70; no. 1; pp. 251 - 258
• Main Authors: Covazzi Harriague, Anabella, Bianchi, Carlo Nike, Albertelli, Giancarlo
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.10.2006; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Brackish water ecosystems; coastal area; Fundamental and applied biological sciences. Psychology; macrofauna; Marine; NW Mediterranean; Posidonia meadow; Posidonia oceanica; Siphonoecetes dellavallei; soft-bottom; Synecology; Mediterranean Sea; Ligurian Sea; MED, Ligurian Sea; soft-bottom; Posidonia meadow; macrofauna; NW Mediterranean; coastal area; Community structure; Brackish water environment; Monocotyledones; Composition; Benthic organism; Fauna; Soft substrate; Posidonia oceanica; Biomass; Potamogetonaceae; Marine environment; Macrofauna; Angiospermae; Spermatophyta; Community
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2005.10.017

A soft-bottom community (6–8 m depth) within a seagrass bed in Prelo Bay (Eastern Ligurian Sea) was studied between April 1990 and August 1991. Samples were collected using a suction device and were sieved through a 1-mm mesh size. Cluster analysis showed seasonal fluctuations in the macrofauna density with highest values in summer 1990 (maximum 2870.0 ± 2029.4 ind. m −2 in August 1990) and lowest in late spring 1991 (100.0 ± 37.8 ind. m −2 at the end of May 1991). On the whole, the community was characterised by a high number of species (184 species plus 17 higher taxa) but only 12 accounted for 78% of the total density, so diversity was relatively low. Dissimilarity between seasons was high (on average 74.7 ± 8.3) and the principal discriminating species was the amphipod Siphonoecetes dellavallei, whose successful recruitment dominated community density in summer 1990. Total macrofauna biomass ranged between 166.1 ± 67.8 mg AFDW m −2 (May 1991) and 2399.8 ± 1073.2 mg AFDW m −2 (June 1991); molluscs being the major contributors (ca. 61%) with single large individuals. Secondary production reached on average 0.4 ± 0.2 g C m −2 y −1. Notwithstanding the relative low biomass, deposit-feeders were the major contributors to secondary production (38%), indicating their high efficiency in utilizing their food resource (detritus-associated bacteria). The seagrass bed seems to play only an indirect role in the structure and function of macrofaunal assemblages.