Habitat-Diversity Relations between Sessile Macrobenthos and Benthic Copepods in the Rocky Shores of a Marine Protected Area

Eleonora Grassi,Maria Balsamo,Federica Semprucci,Claudia Sbrocca,Marleen De Troch,Valentina Losi

doi:10.3390/w13081020

Eleonora Grassi, Maria Balsamo + Show 4 more

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https://doi.org/10.3390/w13081020

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Abstract

In rocky shore systems, sessile macrobenthic assemblages may act as “ecosystem engineers” for many smaller benthic organisms. Thus, the influence of macrobenthic coverage on the diversity and assemblage structure of the harpacticoid copepod fauna was investigated in the rocky shores of a Marine Protect Area (MPA) in the Ligurian Sea (NW, Mediterranean Sea). Two sampling sites were investigated in two seasons at three different depths on both sub-vertical and inclined reefs. A total of 61 species of copepods mainly represented by Miraciidae, Laophontidae, Longipediidae and Thalestridae were found. The complex micro-topography of these substrata provided a wide variety of niches for many species with different lifestyles that suggests the important role of rocky shores to ensure the functioning of coastal ecosystems. The harpacticoid assemblage structure seemed mainly influenced by season and depth. The temporal spread observed is likely one of the underlying mechanisms of niche segregation that allows many species to co-occur in this specific environment along with a subordinate spatial segregation corresponding to the depth gradient. The results seem to support the hypothesis that the different species composition of the “ecosystem engineer” (and consequently its structure changes) are relevant in structuring the copepod assemblages. The comparison with previous data on general meiofauna underlines that higher surrogacy of the taxonomic identification could be used to study rocky shore communities, but the rich diversity that these systems host can only be understood at the lower taxonomic levels. The same holds for future evaluations of impact of environmental changes (including MPA regulations) on meiofaunal assemblages.

Highlights

IntroductionRocky-shore-forming species, concurring to create variations in the water flow, sedimentation, nutrient fluxes and refuges, may act as ecosystem engineers for inconspicuous organisms such as meiofauna (40–1000 μm body size) [6,7,8,9]
The aim of this study was focused on the following questions: (1) are spatial or temporal variations of sessile macrobenthos relevant for harpaticoid abundance, diversity and assemblage structure? (2) does the structure and composition of sessile macrobenthos influence the harpacticoid community composition? In order to answer these questions, harpacticoid fauna associated to sessile macrobenthos along two infralittoral rocky substrata within the marine protected area (MPA) of Portofino
The structure of the macrobenthic assemblage was documented in Losi et al (2018) [9] and reported in Table S1 and exhibited significant variations between the two seasons (p < 0.05), and in particular, the taxa composition between summer and winter differed in both sites (p < 0.05)

Summary

Introduction

Rocky-shore-forming species, concurring to create variations in the water flow, sedimentation, nutrient fluxes and refuges, may act as ecosystem engineers for inconspicuous organisms such as meiofauna (40–1000 μm body size) [6,7,8,9]. Understanding how such ecosystem engineers may influence the benthic ecosystem functioning might contribute to clarify how these assemblages respond to natural and anthropogenic changes and how the associated ecosystem services might be modified [10,11]

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