Epifaunal community composition in five macroalgal species - What are the consequences if some algal species are lost?

Anthropogenic disturbances such as eutrophication and climate change are affecting the distribution and coverage of macroalgae in coastal areas worldwide. How these changes will affect the littoral food webs is challenging to predict as we still lack basic knowledge of epifaunal communities in different macroalgal species. The aim of this study was therefore to compare the epifauna in five common macroalgal species in the northern Baltic Sea. Samples of macroalgae and the associated epifauna were collected in mesh bags at 2 m depth in July-August 2014. The epifaunal abundance data were analyzed with univariate and multivariate methods. The results revealed significant differences in the epifaunal composition among the studied macroalgal species. Ceramium tenuicorne hosted the significantly highest and Fucus vesiculosus the lowest abundance of epifauna per algal dry weight. When comparing the relative epifaunal abundances in percentage, we found that different epifaunal taxa representing different functional groups dominated Pylaiella littoralis (Chironomidae, deposit feeder), Cladophora rupestris (Gammarus spp., herbivorous/omnivorous) and Furcellaria lumbricalis (Mytilus trossulus, suspension feeder). However, most of the epifaunal taxa were found in all algal species studied. We conclude that the loss or decline of specific macroalgal species will affect the ecosystem functions and energy flows to the higher trophic levels, but that none of the studied algal species seems to be crucial for the existence of single taxa or functional group of epifauna. (C) 2017 Elsevier Ltd. All rights reserved.