Abstract
The polychaete Sabellaria alveolata (Linnaeus, 1767) is an important ecosystem engineer building reef structures which add to the topographic complexity in colonized areas. In Europe, the most extensive reef formation is located in the Bay of Mont-Saint-Michel (France). Since 2006, Sabellaria bio-constructions have developed on hard substrates along the west coast of the Cotentin Peninsula between Champeaux and Saint-Germain-sur-Ay on the northern part of the Bay of Mont-Saint-Michel. In this sector, two distinct types of bio-construction can be distinguished: platforms and reefs. The aim of this study is to analyse the patterns of the associated macrofauna on these platforms and reefs, as well as outside, and test for a correlation between the presence of Sabellaria bio-constructions and the richness of the benthic macrofauna. Univariate analyses are used to compare the macrofauna on four sites (Champeaux, Lingreville, Blainville-sur-Mer and Saint-Germain-sur-Ay). The results show a higher taxonomic richness on the platform-type than on the reef-type structures, and also a higher taxonomic richness outside the bio-construction areas. This suggests that, on the examined sites, the presence of S. alveolata bio-constructions does not contribute to higher levels of benthic macrofaunal richness on hard substrates. Temporary bio-constructions along this coast exhibit reefs of interest at some sites as well as in very small zones which merit special attention.
Highlights
Biogenic structures built by ecosystem engineers such as corals, molluscs and polychaetes provide favourable habitats for other benthic invertebrates and vertebrates; these structures can play an important role as nurseries for certain species of commercial interest and represent an essential source of food for birds and fishes (Commito and Rusignuolo 2000)
Spatial pattern of Sabellaria alveolata abundance Sabellaria alveolata is the most abundant species regardless of the site location or substrate type, apart from LING, where it does not appear among the dominant species and shows lower abundance on the degraded reef (Tables 2, 3)
The objective of this study is to estimate the macrofaunal Taxonomic Richness (TR) associated with Sabellaria bio-constructions on hard substrates along the west coast of the Cotentin Peninsula
Summary
Biogenic structures built by ecosystem engineers such as corals, molluscs and polychaetes provide favourable habitats for other benthic invertebrates and vertebrates; these structures can play an important role as nurseries for certain species of commercial interest and represent an essential source of food for birds and fishes (Commito and Rusignuolo 2000). The honeycomb worm S. alveolata, which belongs to the family Sabellaridae, is present in temperate regions of the world (India, North and South America), and is known in Europe, where it ranges from the Bristol Channel (Wilson 1974) to the coast of Portugal (Dias and Paula 2001). The bio-constructions correspond to polychaete colonies which build up sediment agglomerates composed of tubes. The initial tubes bind to the rock in the mid-intertidal zone, forming structures called platforms. These platforms develop throughout the life of the individuals, eventually creating more massive structures—referred to as reefs—in up to 3–5 years (Gruet 1982). In France (Fig. 1), the major bio-constructions in the Bay of Bourgneuf (Vendée, on the Atlantic coast) and in the Bay of Mont-Saint-Michel
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