The macrofauna of marine invertebrates of two photophilic algal communities on the Maresme coast (Barcelona, NE Spain) were studied. We evaluated how the type of algal substrate (soft or hard thallus algae) affects the distribution patterns of organisms living in them. Quantitative samples were collected in the months of October 2013 and February 2014 at 15-m depth by scraping standard surfaces of 400 cm2. A total of 164 specific or supraspecific taxa were obtained and grouped into two categories: unitary and modular organisms. Of the 118 taxa of unitary organisms, a total of 4587 specimens were counted: 2029 were arthropods (44.2%), 1284 were polychaete annelids (27.9%), and 1080 were mollusks (23.54%). The unitary organisms were counted and weighed and were used for most of the statistical and biodiversity analyses. For the modular organisms, 46 different taxa belonging to Porifera, Hydrozoa, Bryozoa, and Tunicata were identified. Modular organisms were studied only at a qualitative level. In soft thallus algae, a greater abundance of epibiont invertebrates was found, but with lower biomass than in calcareous algae, while the latter showed a greater species richness and Shannon-Wiener index. In general, we can conclude that the nature (soft or hard thallus) and architecture (branched or crusted) of the macroalgae can limit the size and abundance of the epibiont invertebrates and can condition the populations of organisms that settle in them. |
