Endolithic invertebrate communities and bioerosion rates in Southwestern Atlantic intertidal consolidated sediments

BAGUR, M.; GUTIÉRREZ, J. L.; ARRIBAS, L. P.; PALOMO, M. G.

MARINE BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2014 vol. 161 p. 2279 - 2292

0025-3162

Organisms boring into intertidal consolidatedsediments generate bioerosion. It is generally unknown,however, whether they can significantly contribute tocoastline retraction. In this paper, we describe endolithiccommunities and estimate bioerosion and physical erosionrates at three southwestern Atlantic intertidal sites(37, 38, and 42°S; Argentina). In the northernmost site,we have also analyzed spatial variation in species richnessand abundance as a function of height within thetidal slope, orientation of the rock surface in relation tobreaking waves (i.e., facing or not), and rock hardness.The number of species and the combined abundance ofindividuals from the different species were larger at thelow intertidal level but did not differ between surfaceorientations. The density of chemically boring organismsincreased with increasing rock hardness and calciumcarbonate content. In contrast, no correlation was foundbetween rock hardness and the abundance of organismsthat bore by mechanical means. Endolithic communitycomposition and bioerosion rates differed among the threesites, the latter being higher at the site with the softersubstrate. Bioerosion estimates were two orders of magnitudelower than physical erosion estimates at each site.The bivalve Lithophaga patagonica was the species thatcontributed the most to bioerosion at all these locations.While results suggest that bioerosion contributes littleto overall coastal erosion at the three study sites, boringorganisms might still facilitate physical erosion by weakeningthe rock either via chemical or mechanical means.Besides, their apparently inconsequential direct action asbioeroders can have positive consequences for biodiversityvia increased habitat complexity.