O objetivo deste trabalho foi conhecer a diversidade e alguns aspectos ecológicos dos caranguejos (Decapoda, Brachyura) nos estuários dos Rios Ariquindá e Mamucabas (PE), através da caracterização da estrutura de suas comunidades, com base na composição e diversidade desses crustáceos. As espécies foram amostradas mensalmente entre abril/2008 e março/2009. Foram coletados 8.394 exemplares, sendo 4.501 no manguezal do Rio Ariquindá (25 espécies e 14 gêneros) e 3.893 no manguezal do Rio Mamucabas (21 espécies e 12 gêneros). A maior frequência de espécies nesses manguezais foi dos representantes da Superfamília Ocypodoidea, em especial Uca spp. Comparando os dois estuários, nota-se que cinco espécies (Acantholobulus bermudensis, Austinixa leptodactyla, Callinectes exasperatus, Hexapanopeus caribbaeus e Uca maracoani) foram amostradas apenas no Rio Ariquindá, enquanto uma delas (Armases rubripes) foi encontrada apenas no Rio Mamucabas. A diversidade foi considerada média, de acordo com os índices ecológicos, com valores dentro do esperado para manguezais. Entretanto, nota-se que a diversidade foi menor no manguezal do Rio Mamucabas, resultado que pode estar relacionado aos impactos ambientais que esse estuário vem sofrendo nos últimos anos (represamento, desmatamento, deposição de resíduos sólidos e especulação imobiliária). O presente estudo, associado às medidas de proteção propostas, é de notável importância para a gestão dos crustáceos como recursos pesqueiros costeiros, especialmente se considerarmos que os crustáceos participam da teia trófica de diversos animais, entre eles o homem. A manutenção da diversidade de caranguejos em manguezais é considerada importante para a saúde dos ecossistemas costeiros.
It is important to study the diversity of a given area to comprehend the processes that rule the community and/or ecosystem. Several researches in tropical mangroves revealed that among the most abundant representatives, stand out the Crustacea Brachyura. The Brachyuran fauna of the littoral of Pernambuco (PE), Brazil, is well known, but the studies are mainly species lists. Thus, more detailed studies on the ecology of these communities are required, applying ecological indexes and multivariate analysis. The aim of this study was to know the biodiversity and some ecological aspects of crabs (Decapoda, Brachyura) found in the mangroves of Ariquindá and Mamucabas Rivers (PE), through the characterization of the structure of the community based on the composition and diversity of these crustaceans. For that, two hypothesis were proposed: H1 - The diversity of Brachyura is median for both mangroves, but it is higher at the Ariquindá River, due to its better state of conservation; and H2 - There are no dominant or very frequent species, indicating an environmental equilibrium in the communities. The species were monthly sampled from April 2008 to March 2009. A total of 8,394 individuals were sampled, being 4,501 in the mangrove of the Ariquindá River (25 species and 14 genera) and 3,893 in the mangrove of the Mamucabas River (21 species and 12 genera). The highest frequency of species in both mangroves is found in the Superfamily Ocypodoidea, especially Uca spp. Comparing both estuaries, it can be noticed that five species (Acantholobulus bermudensis, Austinixa leptodactyla, Callinectes exasperatus, Hexapanopeus caribbaeus and Uca maracoani) were sampled only at the Ariquindá River, while one of them (Armases rubripes) was found only at the Mamucabas River. The diversity was considered medium according to the ecologic index for both mangroves, and it is the expected for mangroves of Northeastern Brazil. However, it could be noticed that the diversity was lower at Mamucabas River, a result that might be related to the environmental impacts that this estuary has receiving in the last years (damming, deforestation, deposition of waste and housing occupation), which corroborates H1. The diversity was not high due to the dominance of one species, Uca thayeri, with 1,411 individuals at Ariquindá River and 1,300 at Mamucabas River, refuting H2. Besides, nine species were registered for the first time to the region of Tamandaré: Acantholobulus bermudensis, Armases rubripes, Austinixa leptodactyla, Hexapanopeus angustifrons, H. caribbaeus, Panopeus occidentalis, Sesarma curacaoense, Uca cumulanta and Uca victoriana. In the present study, it was possible to observe how the number of species of Brachyura behaves in the Brazilian coast. The highest number of species of crabs is observed in previous studies performed at mangroves of Pernambuco, with a tendency to decrease towards the South. The number of species recorded in the present study is expected for the Northeast region. In the Southern limit of the distribution of mangroves in South America (State of Santa Catarina), due to the colder climate, the development of mangroves is smaller, so as the diversity of crustaceans. With this, it is confirmed the greatest Brachyuran diversity in tropical areas, more stable ecosystems, such as the mangroves of Pernambuco. This study, coupled with the proposed protection measures, is of notable importance for the management of crustaceans as coastal fishery resources, especially considering that the crustaceans participate in the trophic web of various animals, including man. Maintaining the diversity of crabs in mangroves is considered important to the health of coastal ecosystems.
