Habitat complexity and community composition: relationships between different ecosystem engineers and the associated macroinvertebrate assemblages

SUEIRO, M.C.; BORTOLUS, A.; SCHWINDT, E.

HELGOLAND MARINE RESEARCH

SPRINGER

Año: 2011 p. 467 - 477

1438-387X

Several species of ecosystem engineers inhabitingcoastal environments have been reported structuringdifferent kinds of communities. The magnitude of thisinfluence often depends on the habitat complexity introducedby the engineers. It is commonly accepted that anincrease in habitat complexity will result in an increase indiversity and/or abundance in the associated fauna. Therocky salt marshes along the coast of Patagonia are dominatedby cordgrasses, mussels, and barnacles forming amosaic of engineered habitats with different complexity.This system allows us to address the following questions:how different is a macroinvertebrate assemblage whendominated by different ecosystem engineers? And, is therea positive relationship between increasing habitat complexityand the species richness, diversity and total densityof the assemblages? To address these questions, we comparedthe three ecological scenarios with decreasing habitatcomplexity: cordgrass?mussel, mussel, and barnacle-engineeredhabitats. We found a total of 22 taxa mostly crustaceansand polychaetes common to all scenarios. Thethree engineered habitats showed different macroinvertebrateassemblages, mainly due to differences in individualabundances of some taxa. The cryptogenic amphipodOrchestia gammarella was found strictly associated withthe cordgrass?mussel habitat. Species richness and diversitywere positively related with habitat complexity whiletotal density showed the opposite trend. Our study suggeststhat species vary their relative distribution and abundancesin response to different habitat complexity. Nevertheless,the direction (i.e., neutral, positive or negative) andintensity of the community?s response seem to depend onthe physiological requirements of the different species andtheir efficiency to readjust their local spatial distribution inthe short term.