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Seaweeds play a key role in the rocky-shore fauna by providing shelter and food for many invertebrate species, which in turn compose the diet of benthic and pelagic predators. This study investigated the effect of the macroalgal host species on an assemblage of associated amphipods, and tested if the host mediates the vulnerability of amphipods to predation. The association of amphipods with the macroalgal hosts Dichotomaria marginata, Padina gymnospora, and Sargassum filipendula was evaluated seasonally for 1 year on a subtropical rocky shore on the southeastern coast of Brazil. The density of amphipods did not vary with season or host. However, the composition of amphipod species was sensitive to the host macroalgal species and varied temporally. A field experiment showed no clear effect of predation on the amphipod assemblage. Also, predation did not explain the spatial or temporal variation of the amphipod assemblage. Our results indicate that the identity of the macroalgal host drove the composition of the associated amphipods, while predation may have a minor role. Therefore, the loss of habitat-forming organisms such as seaweeds is expected to have drastic consequences for the composition of associated fauna, and consequently on the flow of matter and energy in coastal ecosystems. [ABSTRACT FROM AUTHOR]

Patterns of long-term changes in fouling communities developing on artificial substrates in the White Sea are reviewed. The most significant shifts occurring in these communities are caused by biological successions that can last for several decades. Terminal stages of succession are the communities of a mussel Mytilus edulis or a solitary ascidian Styela rustica which can periodically replace one another within a narrow range of depths: from 1-1.5 to 5 m. Sporadic local invasion of a sponge Halichondria panicea can transiently modify the composition and performance of fouling communities. Sudden invasion of species that are not a typical component of fouling communities (infaunal polychaetes and molluscs, crabs) is not rare phenomenon but these organisms do not play a significant role there. Representatives of the associated polychaete fauna in fouling communities show long-term cyclic fluctuations in their abundances. Duration of these cycles is 7-8, 11-14, or 20 years. [ABSTRACT FROM AUTHOR]

This study describes the distribution and abundance patterns of the associate fauna on the living surface of the corals Siderastrea stellata Verril, 1868 and Mussismilia hispida (Verril 1902) using a non-destructive method, on the northern coast of Rio de Janeiro State. For each coral species, infestation density and proportions of infested colonies, colonies attached and unattached to the substrate were estimated. A total of 474 colonies of S. stellata and 452 colonies of M. hispida were examined. The barnacle Ceratoconcha floridana (Pilsbry, 1931) was the dominant coral associate found, followed by gall-crabs of the family Cryptochiridae Paulson, 1875 and the bivalve Lithophaga bisulcata (d’Orbigny, 1842). Both coral species presented similar patterns of infestation dominance. S. stellata colonies were more commonly infested and showed a greater mean infestation density of 0.62 ind/cm2 at Armação dos Búzios, whereas M. hispida colonies had infestation densities of only 0.20 ind/cm2. Infestation density does not appear to impact negatively on corals of Armação dos Búzios. A clear negative relationship between the number of associates in the coral colony and coral size was found. Evidently abundance and frequency of occurrence of associated fauna is highly related to coral community structure and composition and the results highlight the importance of local scale studies. [ABSTRACT FROM AUTHOR]

The aims of this study were to investigate the structure and composition of the invertebrate community during the detritus decomposition (colonization features) of the two most abundant aquatic macrophytes Typha domingensis Pers. and Nymphaea ampla in Jurubatiba Lagoon and verify if the chemical composition of the substratum has any influence on invertebrate colonization and which are the functional groups possibly affected by these compounds. The substratum T. domingensis had higher percentages of cell wall fraction (F = 108.33; p < 0.0001) and organic matter (F = 225.77; p < 0.0001), while nitrogen (F = 408.61; p < 0.0001) and phosphorus (F = 224.59; p < 0.0001) contents were higher in N. ampla. These differences in the chemical composition of the substrata influenced the decomposition rate, and the detritus of N. ampla (4.37% DW day-1) decomposed approximately 26 times faster than the T. domingensis (0.17% DW day-1) detritus. The main groups of invertebrates that colonized both substrate were Chironomidae, with more than 50% of the total, followed by Oligochaeta, Nematoda, Copepoda and Cladocera. The results showed that the slow breakdown rate of T. domingensis detritus provided a higher probability for colonization and that the main driving force structuring the invertebrates' community was degradative ecological succession (DES). [ABSTRACT FROM AUTHOR]