Algal Epibionts as Co-Engineers in Mussel Beds: Effects on Abiotic Conditions and Mobile Interstitial Invertebrates

GUTIÉRREZ, JORGE; BAGUR, MARÍA; PALOMO, M.GABRIELA

Diversity

MDPI

Año: 2019 vol. 11

Musselsand macroalgae have long been recognized as physical ecosystem engineers that modulateabiotic conditions and resources and affect the composition of rocky shoreassemblages. Their spatial distributions in the intertidal zone frequentlyoverlap, as many algal species thrive as epibionts on mussel beds. Nonetheless,their potential for combined engineering effects has not been addressed todate. Here we illustrate that Porphyra sp.?a desiccation-resistant macroalga that developsmostly epiphytically onto mussel beds?affects temperature, desiccation levels,and mobile interstitial invertebrates in mussel beds. Specifically, we observedthat Porphyracover(a) reduced temperature at the surface of the mussel bed but not at their base,(b) reduced desiccation both at the surface and base of the mussel bed and, (c)increased the densities of an abundant interstitial species?the amphipod Hyale grandicornis?in several study sites/dates.Additionally, we found that the positive responses of these grazing amphipodsto Porphyraweredriven by physical habitat modification (engineering) rather than foodavailability. This suggests that co-engineering by Porphyra and mussels generates abiotic states andfocal species responses that would not be predictable from their individualeffects. We expect that increased appreciation of co-engineering aids ourunderstanding of complex ecological dynamics.