Effects of human trampling on a rocky shore fauna on the Sao Paulo coast, southeastern Brazil

Increased tourist activity in coastal regions demands management strategies to reduce impacts on rocky shores. The highly populated coastal areas in southeastern Brazil are an example of degradation caused by development of industry and tourism. Among different shore impacts, trampling has been intensively studied, and may represent a significant source of stress for intertidal fauna. A randomised blocks design was applied to experimentally study the effects of two different trampling intensities on richness, diversity, density and biomass of the rocky shore fauna of Obuseiro beach, Guarujá, southeastern Brazil. Blocks were distributed in two portions of the intertidal zone, dominated respectively by Chthamalus bisinuatus (Cirripedia) and Isognomon bicolor (Bivalvia). Blocks were trampled over three months, simulating the vacation period in Brazil and were monitored for the following nine months. Results indicate that Chthamalus bisinuatus is vulnerable to trampling impacts. Richness, diversity and turn-over index tended to be higher in trampled plots four months after trampling ceased. In general, results agree with previous trampling studies, suggesting that even low intensities of trampling may cause some impact on intertidal communities. Management strategies should include isolation of sensitive areas, construction of boardwalks, visitor education and monitoring programmes. In Brazil, additional data obtained from experimental studies are necessary in order to achieve a better understanding of trampling impacts on rocky shore communities.

Barnacles (Cirripedia Balanomorpha) of the estuarine region of Recife, Pernambuco, Brazil.

As regiões estuarinas das grandes cidades litorâneas estão sujeitas a fortes agressões ambientais, especialmente de fontes poluidoras provenientes de esgotos domésticos, hospitalares e industriais. A fauna presente geralmente é muito resistente a estes fatores antrópicos e, particularmente entre os cirrípedes, existem muitas espécies utilizadas como indicadoras de poluição. O objetivo deste trabalho foi listar as espécies de cirrípedes que ocorrem nos rios Capibaribe, Pina, Jiquiá, Tejipió e Jordão, bem como aqueles presentes nas bacias do Pina e portuária da cidade do Recife, Pernambuco. Os cirrípedes foram coletados no período de janeiro de 2005 a outubro de 2006, por meio de espátula e martelo, em todos os substratos consolidados disponíveis. Foram identificadas as seguintes espécies: Euraphia rhizophorae, Chthamalus bisinuatus, C. proteus, Tetraclita stalactifera, Amphibalanus amphitrite, A. eburneus, A. improvisus e A. venustus. Com exceção de C. bisinuatus e T. stalactifera, que são típicas de ambientes marinhos, todas as espécies são encontradas caracteristicamente em estuários tropicais, sendo reconhecidamente resistentes a baixas salinidades e citadas como tolerantes a diversas fontes de poluição. Palavras Chaves: Cirrípedes, estuário, ecologia, inventário.

Periwinkle (Gastropoda: Littorinidae) habitat selection and its impact upon microalgal populations

The present study examines habitat selection and grazing pressure of the periwinkle Nodilittorina lineolata (Gmelin, 1791) on the rocky shore of Arraial do Cabo, RJ, Brazil (lat. 23°S, long. 43°W). Transfer experiments suggest that periwinkles actively select the mid intertidal, where the cirripede Chthamalus bisinuatus Pilsbry is the dominant sessile invertebrate. We also conducted a caging experiment in the middle intertidal, manipulating grazers and light, to assess the impact of grazing upon microalgal density. Grazing pressure significantly reduced microalgal abundance at the mid-intertidal level, suggesting that food availability plays an important role in the habitat selection of periwinkles on the studied shore.