ORIGINAL ARTICLE Patterns of fish and crustacean community structure in a coastal lagoon system, Rio de Janeiro, Brazil WAGNER L.S. FORTES 1,2 , PEDRO H. ALMEIDA-SILVA 1,3 , LUANA PRESTRELO 1 & CASSIANO MONTEIRO-NETO 1 * 1 Departamento de Biologia Marinha, Laborato ´rio ECOPESCA, Nitero ´i, Rio de Janeiro, Brazil; 2 Biodina ˆ mica Engenharia e Meio Ambiente Ltda, Rio de Janeiro, Rio de Janeiro, Brazil, and 3 Instituto Federal de Educac ¸a ˜o, Cie ˆncia e Tecnologia  Campus Volta Redonda, Volta Redonda, Rio de Janeiro, Brazil Abstract Coastal lagoons are feeding and nursery habitats for fish and crustaceans and fishing grounds for some of these species. This work describes the fish and crustacean community structure of the PiratiningaItaipu lagoon system (Nitero ´i, Rio de Janeiro, Brazil), evaluating the importance of environmental factors in structuring spatial and temporal changes. Sampling was conducted using gill-nets, cast-nets, hoop-nets and fish traps during summer and winter of 2006. A total of 50 fish and 9 crustacean species were collected, amounting to 17,143 specimens. Few species dominated in abundance, frequency and biomass. The marineestuarine species Atherinella brasiliensis and Cetengraulis edentulus were most abundant in Piratininga and Itaipu, respectively. Analysis of Similarity, nMDS and Canonical Correspondence Analysis indicated a strong spacial segregation between Piratininga and Itaipu and to a lesser extent a seasonal component. Salinity was the main factor influencing species distribution, followed by water depth, water temperature and, to a lesser extent, organic matter in the sediment and bottom vegetation. A large number of occasional species occurring at sampling sites near the Itaipu channel, which connects the lagoon to the sea, suggests a high degree of communication between this lagoon and the adjacent marine coastal environment, unlike Piratininga lagoon, which has an indirect communication with the sea. Key words: spatial distribution, environmental factors, salinity, southeastern Brazil Introduction Coastal lagoons provide essential goods and services for human populations, including shoreline protec- tion, fisheries resources, habitat and food for migra- tory and resident animals. These highly productive ecosystems sustain a great diversity and high den- sities of organisms, with fish, crustacean and benthic assemblages playing an important role as biological indicators of human-induced changes (Ribeiro et al. 2008). The conservation of biodiversity and natural processes in coastal lagoons has become a challenge in recent decades due to increasing human pres- sures, including fisheries, recreational activities, tourism, demographic expansion and global climate change (Edgar et al. 2010). Many studies have shown the role of lagoons as nurseries and feeding areas (Maci & Basset 2009; Vasconcelos et al. 2010). Estuarine-resident, estuar- ine-dependent, opportunistic marine and occasional marine and freshwater fishes (Castro et al. 2009), as well as several shrimp (Pe ´rez-Castan ˜eda et al. 2010) and crab (Monteiro-Neto et al. 2003) species use coastal lagoons for food, shelter and reproduction. Salinity (Martino & Able 2003; Sosa-Lopez et al. 2007; Castro et al. 2009; Maci & Basset 2009), water temperature, dissolved oxygen and pH often regulate community structure in coastal lagoons, following seasonal dynamic and tidal variations (Maes et al. 2004; Pombo et al. 2005; Murphy & Secor 2006; Sosa Lopez et al. 2007). Estuaries and lagoons are especially affected by anthropogenic pressures, resulting in water quality impairment and loss of aquatic biota (Pe ´rez- Domı ´nguez et al. 2012). Human impacts on coastal lagoons include eutrophication through wastewater, *Correspondence: Cassiano Monteiro-Neto, Departamento de Biologia Marinha, Po ´ s Graduac ¸a ˜o em Biologia Marinha, Laborato ´rio ECOPESCA, Caixa Postal 100644, Nitero ´ i, Rio de Janeiro, 24001-970, Brazil. E-mail: monteiro@vm.uff.br Published in collaboration with the Institute of Marine Research, Norway Marine Biology Research, 2014 Vol. 10, No. 2, 111122, http://dx.doi.org/10.1080/17451000.2013.797645 (Accepted 26 March 2013; Published online 18 September 2013; Printed 3 October 2013) # 2014 Taylor & Francis