Context-dependent interaction between an intertidal sponge and a green macroalgae in a variable temperate Patagonian bay

GASTALDI, M.; FIRSTATER, F.; NARVARTE, M.; DALEO, P.

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2017 vol. 581 p. 21 - 32

0171-8630

Thestress gradient hypothesis (SGH) states that positive interactionsbecome more important as physical stress increases. Organisms livingin Patagonian intertidal ecosystems are subjected to high desiccationstress due to elevated temperatures and strong winds. In coastalenvironments, sponges and macroalgae are common benthic organisms andthey occur from the subtidal to intertidal zones. As human pressurehas increased in these systems, both sponges and macroalgae havebecome more abundant, which has led to more frequent interactionsbetween them. To evaluate the interaction between Hymeniacidonperlevisand Ulvalactucain two contrasting environments, we sampled their abundance andconducted field factorial experiments consisting of spongetransplants and manipulation of algal presence. Our results show thatin harsher environments U.lactucafacilitates H.perlevislikely through the reduction of direct solar radiation or highsubstrate temperature beneath its canopy. Whereas, at milderenvironments, U.lactucanegatively affects H.perlevisthroughout other physical or chemical mechanisms (e.g., abrasion,feeding interference through changing currents dynamics, depletion ofoxygen, allelochemical compound production).