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SUMMARY:The invertebrate fauna associated with colonies of the bryozoan Schizoporella errata was studied at two sites differing in hydrodynamism in southeastern Brazil. Patterns of species distribution, abundance, and diversity were similar at both sites. Polychaetes dominated the assemblages, both in number of individuals and species, with 70 species distributed in 20 families. Decapod crustaceans were also abundant, mainly anomuran crabs and caridean shrimps. Cluster analysis separated the samples from each site, and further analysis indicated that an interaction between water movement and trophic structure could explain these differences. At the site with low water movement, more muddy sediments were found inside the colonies, and a greater proportion of deposit-feeders was found. At the other site, higher hydrodynamism resulted in less sediments within the colonies, and favoured the occurrence of more filter-feeders. The trophic structure of faunal assemblages can help understand the structure of assemblages associated with biogenic substrata, as already demonstrated for benthic communities.

The phytal assemblages change in response to variation in biological and environmental conditions. In the present study, we evaluated the temporal variation of amphipod assemblages associated with a Sargassum filipendula bed in a subtropical shore, in relation to variation of the host alga, its epiphytes and local environmental conditions. Samples of S. filipendula with associated amphipods, water temperature, water movement and suspended solids were obtained monthly from June 2000 to May 2001. We recorded 24 species of amphipods associated with S. filipendula. Species richness varied throughout the year, with maximum values in October 2000 and minimum in April 2001. Total amphipod density gradually increased during the sampling period, with the highest value in March 2001. Amphipod diversity and evenness were both positively influenced by epiphyte load and negatively by temperature, with higher values during summer months. Total density and tube-builder density were also positively influenced by temperature, whereas nestler density was influenced by epiphyte load. Individual amphipod species showed significant density fluctuations over the year. The canonical correspondence analysis performed explained 88.2% of the variation, with a strong correlation of water movement, temperature and suspended solids with the first axis, and a strong effect of epiphyte load on both the first and the second axes. The temporal structural variation of the studied algal bed strongly influenced amphipod diversity and assemblage composition, possibly through direct and indirect effects.

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Abstract:Monitoring wildlife responses is essential to assess restoration projects. Birds are widely used as bioindicators of ecosystem restoration, but most studies use only taxonomic descriptors to compare categories of reference and restoring sites. Here, we used forest structure as a continuous predictor variable to evaluate avifaunal taxonomic and functional indicators in riparian forest reference and restoration sites on southeastern Brazil. Reference sites were riparian forest remnants, and restoration sites were pasture before seedling reintroduction. Forest structure variables (mean tree height, canopy depth, mean diameter at breast height, basal area, tree layering, tree density, and grass cover) were reduced into two axes using a Principal Component Analysis (PCA), Forest Axis 1 (tree biomass vs. grass cover) and Forest Axis 2 (canopy depth vs. tree density). Bird species were classified in relation to five functional categories (i.e., diet, foraging stratum, nest height, cavity dependence for nesting, and forest dependence). Forest Axis 1 influenced the functional diversity of bird assemblages and the relative abundance within levels of each functional category (except for nest height). The relative abundance of all functional categories combined was also affected by Forest Axis 2. Therefore, forest structure affected the predominant functional traits of bird species in riparian sites under restoration. Sites with higher tree biomass were the richest, with canopy birds that were insectivores and frugivores of high forest dependence, whereas more open sites were associated with birds of low forest dependence and ground-foraging insectivores. Forest structures of similar-aged sites were strongly variable, due to natural and anthropic disturbances, so restoration age was a poor indicator of forest development. These unpredictable disturbances can change the development of sites under restoration, so that forest structure can be a better descriptor of the trajectory of these ecosystems.

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