Habitat structure, resources and diversity: the separate effects of surface roughness and macroalgae on stream invertebrates

摘要: Habitat structure has pervasive effects on community composition and diversity, with physically complex habitats often containing more species than simple ones. What factors or mechanism drive this pattern is little understood, but a complicating problem that different sources of habitat can be confounded in both surveys experiments. In study, we carried out an experiment which two structure, attached macroalgae substrate surface texture, were separately manipulated to discern their joint separate upon the diversity colonizing macroinvertebrates stony, upland stream. Because stream algae vary markedly abundance space time, also sampled epilithon stones at spatial scales eight dates over 2 years gain some preliminary data how between individual substrata time. Experimental had either smooth (siltstones, sandstones, crystal-poor felsic volcanics, plain paving bricks) rough (granodiorites, crystal-rich sand-blasted surface. We allowed these colonized naturally by macroalgae, mostly filamentous red alga Audouinella hermannii. Half each selected random gently sheared off. All defaunated household insecticide field persistence, set randomly through study riffle, invertebrates colonize them for 14 days. Some immediately check efficacy faunal algal removals, proved successful. results showed texture increase richness independently other. Surface no effect densities, while increased colonization rarefaction above values expected simply basis numbers colonists. However, reference high macroalgal cover same as those low cover, suggesting are transient relative associated texture. Epilithon samples taken times suggest magnitude variation plant growth alters If plants generally recolonize surfaces quickly smooth, then ought strongest after major disturbances during growing seasons plants.