Population biology of two sympatric crabs: Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae) and Eriphia gonagra (Fabricius, 1781) (Brachyura, Eriphidae) in reefs of Boa Viagem beach, Recife, Brazil MARINA DE SÁ LEITÃO CÂMARA DE ARAÚJO¹*, DAVID DOS SANTOS AZEVEDO², JULIANE VANESSA CARNEIRO DE LIMA SILVA3, CYNTHIA LETYCIA FERREIRA PEREIRA1 & DANIELA DA SILVA CASTIGLIONI4,5 1. Universidade de Pernambuco (UPE), Coleção Didática de Zoologia (CDZ/UPE), Faculdade de Ciências, Educação e Tecnologia (FACETEG), Campus Garanhuns, Rua Capitão Pedro Rodrigues, 105, São José, CEP 55290-000, Garanhuns, PE. 2. Instituto Federal de Educação Ciência e Tecnologia de Pernambuco (IFPE), Av. Prof. Luiz Freire, 500, Cidade Universitária, CEP 55740-540, Recife, PE. 3. Universidade Federal de Pernambuco (UFPE), Programa de Pós-Graduação em Biologia Animal, Centro de Ciências Biológicas, Departamento de Zoologia, Av. Professor Moraes Rego, s-n, Cidade Universitária, CEP 50670-901, Recife, PE. 4. Universidade Federal de Santa Maria (UFSM), Departamento de Zootecnia e Ciências Biológicas, Campus de Palmeira das Missões, Avenida Independência, 3751, Bairro Vista Alegre, CEP 983000-000, Palmeira das Missões, RS. 5. Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria (UFSM), Prédio 17, sala 1140-D, Cidade Universitária, Camobi, km 9, Santa Maria, RS. *Corresponding author: [email protected] Abstract. This study characterizes the population biology of two crabs: Pachygrapsus transversus and Eriphia gonagra from reefs at Boa Viagem Beach, Pernambuco. Carapace width (CW) was measured and all animals were sexed. A total of 1.174 specimens of P. transversus and 558 specimens of E. gonagra were sampled. Carapace width for P. transversus males ranged from 3.46 to 18.37 mm and from 2.96 to 18.1 mm for females. As for the species E. gonagra, the CW ranged from 4.75 to 35.06 mm for males and from 2.8 to 35.85 mm for females. Males of P. transversus reached sexual maturity (CW50%) at 10.10 mm, and females at 9.50 mm. Males of E. gonagra reached CW50% at 14.50 mm, and females at 15.70 mm. Males and females attained sexual maturity at comparable sizes, fact that may favor the formation of couples. The reproductive period of P. transversus occurred in the fall, while the reproduction of E. gonagra was only in the warmer months of the year. The results of this study are important for an understanding of the life cycle and the population dynamics of both species in Boa Viagem Beach, as well as the simpatry between the species. Keywords: body size, sex ratio, breeding period, fecundity, crabs Resumo. Biologia populacional de dois caranguejos simpátricos : Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae) e Eriphia gonagra (Fabricius, 1781) nos recifes da praia de Boa Viahem, Recife, Brasil. Este trabalho caracteriza a biologia populacional dos caranguejos Pachygrapsus transversus e Eriphia gonagra dos recifes da Praia de Boa Viagem, Pernambuco. Os animais foram mensurados quanto à largura de carapaça e sexados. Um total de 1.174 exemplares de P. transversus e 558 exemplares de E. gonagra foram amostrados. A largura da carapaça (LC) dos machos de P. transversus variou de 3,46 a 18,37 Pan-American Journal of Aquatic Sciences (2016), 11(3): 197-210 198 M. DE S. L. CÂMARA DE ARAÚJO ET AL. mm e a das fêmeas variou de 2,96 a 18,1 mm. Já para a espécie E. gonagra, a amplitude na LC foi de 4,75 a 35,06 mm para os machos e de 2,8 a 35,85 mm para fêmeas. Os machos de P. transversus atingiram a maturidade sexual (LC50%) aos 10,10 mm e as fêmeas aos 9,50 mm. Já os machos de E. gonagra atingem o LC50% aos 14,50 mm e as fêmeas aos 15,70 mm. Machos e fêmeas atingiram a maturidade sexual com tamanhos comparáveis, fato que pode favorecer a formação de casais. O período reprodutivo de P. transversus ocorreu no outono, enquanto a reprodução de E. gonagra foi nos meses mais quentes do ano. Os resultados deste trabalho possibilitaram a constatação do equilíbrio populacional das referidas espécies na Praia de Boa Viagem, bem como a simpatria entre as espécies. Palavras-chave: tamanho corpóreo, proporção sexual, período reprodutivo, fecundidade, caranguejos Introduction occurs along the tropical-subtropical band of the The reef ecosystems are areas of great Brazilian coast (from state of Ceará to state of Rio biological interactions and productivity, serving as Grande do Sul), inhabiting rigid substrates typical of breeding area, shelter and food for many species of coastal regions (Melo 1996; Flores & animals (Correia & Sovierzoski 2005). Among the Negreiros-Fransozo 1999a, b). Besides its species that use the reefs as shelter, feeding and abundance, it is a key species in the intertidal zone reproduction are the decapod crustaceans, especially because of its generalist eating habits the crabs (Infraorder Brachyura). In the sandstone (Furtado-Ogawa 1977) and its role in energy transfer reefs from Boa Viagem Beach in Recife, state of to adjacent marine and terrestrial habitats (Abele et Pernambuco, 24 species of brachyurans were al. 1986). The crabs of the genus Eriphia Latreille, registered (Coelho et al. 2002; Nascimento & Torres 1817 are commonly found in rocky beaches and 2007). Among them, stand out Pachygrapsus reefs in tropical and subtropical regions (Koh & Ng transversus (Gibbes, 1850) and Eriphia gonagra 2008). As P. transversus, E. gonagra is a species (Fabricius, 1781), abundant species at the reef coast commonly found in the intertidal regions of rocky of Brazil (Melo 1996). coastline, whose distribution in Brazil extends from The reef environments are highly diverse in state of Pará to state of Santa Catarina (Melo 1996; natural resources and of great biological, economic Góes et al. 2005), being the only species of the and social importance (Sale 1991; Ferreira et al. genus occurring in the Brazilian coast. 1998). As open, fragile and complex ecosystems, Despite the abundance and importance of their structure, function and biodiversity are these species to maintain the trophic balance in the dependent on the dynamic interactions between intertidal zone, there are few studies related to their various species. population dynamics. Among the studies related to The population structure of marine and the grapsid P. transversus, we highlight Abele et al. estuarine crabs has been analyzed mainly by the (1986), Brossi-Garcia & Rodrigues (1997) and distribution of individuals in size classes, through Flores & Negreiros-Fransozo (1998, 1999 a, b), all comparison of males and females body size, sex addressing issues such as larval morphology, ratio, recruitment and reproductive period (Araújo & reproductive cycle, larval development and Calado 2008; Costa & Soares-Gomes 2009; population biology. Regarding the studies related to Castiglioni et al. 2010; Castiglioni et al. 2011; E. gonagra, we highlight Fransozo (1986), Fransozo Araújo et al. 2012; Menezes et al. 2012; Hirose et & Negreiros-Fransozo (1986, 1987), Góes & al. 2013; Lira et al. 2013; Ribeiro et al. 2013). These Fransozo (1997, 1998, 2000) and Góes et al. (2005), population data provide information about the where all analyzed morphological aspects, larval knowledge of the ecological stability of different development, relative growth and sex ratio of the species in a given habitat. In addition, many studies species. However, there are few published articles on have estimated the fecundity of Crustacea Brachyura these species for the North/Northeast region of (Mantelatto & Fransozo 1997; Graham et al. 2012; Brazil (for P. transversus, Ogawa & Rocha 1976 on González-Pisani & López Greco 2014). fertility and Furtado-Ogawa 1977 on biology The crabs of the genus Pachygrapsus Randall, population at state of Ceará). Thus, this study plans 1840 are the most common inhabitants of the to characterize the population biology of crabs P. intertidal zone of rocky coastline in warm, tropical transversus and E. gonagra in a reef area of Boa and subtropical temperate regions (Capparelli 2010). Viagem Beach, state of Pernambuco, northeast of In Brazil, there are the species P. gracilis (Saussure, Brazil. 1858) and P. transversus. The species P. transversus Pan-American Journal of Aquatic Sciences (2016), 11(3): 198-209 Biology of P. transversus and E.gonagra 199 Material and Methods The "b" of the equation is the allometric constant The Boa Viagem Beach, in the city of Recife, that expresses the relationship between the two state of Pernambuco (8º07'59,31" S and variables. It is used to determine the growth pattern: 34°53'59,25" W) is about 8 km long, with a b > 1, positive allometric growth, b = 1 isometric landscape set consisting of sandy beach, sea and growth and b <1, negative allometric growth. The sandstone reefs parallel to the coastline (Costa & value of "b" was tested through the Student t test ( Souza 2002; Costa & Kahn 2003). The littoral of = 0.05). Boa Viagem Beach is urbanized (Project Orla 2001) The determination of the size at and highly developed (Morgan 1999). During low morphological maturity for both species was based tide, pools are formed between the beach and the on the relationship between CL vs. CW in males and sandstone reefs and are used for recreation. AW vs. CW in females, based on Sampedro et al. The crabs were manually collected monthly (1999) and Araújo et al. (2012). Besides, the interval from March/08 to February/09 in an area of about 30 in which males and females of both species reached m² in sandstone reefs from Boa Viagem Beach sexual maturity was estimated using the size of the during 60 minutes, for each species, by the same largest immature individual and the size of the person during low tide. Individuals of all sizes were smallest mature individual. sampled. After collection, the crabs were placed in To determine the reproductive period of P.