Checklist of the brachyuran crabs (Crustacea: Decapoda) in the rocky subtidal of Vitória Archipelago, southeast coast of Brazil

The present study aims to contribute to the knowledge of the richness of the brachyuran crabs on subtidal rocky bottoms in the Vitória Archipelago and enable to mapping the biodiversity of crabs in the Brazilian coast. Abstract: Biodiversity can be useful as an ecosystem indicator for conservation and monitoring, through continuous assessment of its main properties including stability, primary productivity, exploitation tolerance and even global environmental changes. The main purpose of this study was to provide a checklist of the crabs associated with subtidal rocky bottoms at the Vitoria Archipelago, southeastern Brazilian coast. Monthly collections were carried out from February 2004 through January 2006 on three islands at the Vitória Archipelago (23°44’S-45°01’W). The crabs were hand-caught by SCUBA divers during the daytime, in rock subtidal. A total of 3084 individuals were caught, belonging to 42


Introduction
The Brazilian southeastern coast has two principal characteristics that make it an interesting area for studying marine biodiversity, 1) the interaction of two main water currents of the western Atlantic, the Brazil Current and the Malvinas (Falkland) Current, which in this region produce a hydrological and faunistic transition area (Coelho and Ramos 1972;Palacio 1982;Boltovskoy 1999;Boschi 2000a, b); and 2) a wide diversity of protected environments along the highly indented coastline of the states of Rio de Janeiro and São Paulo, which provide shelter for many marine species (Mahiques 1995).
However, despite the present perception of the necessity to conserve and preserve biodiversity, little has been done concerning the marine rocky-bottom (Witman and Dayton 2000). In addition, these authors also pointed to the urgency in increasing human understanding about subtidal environments, in both theory and practice, because most threats and impacts to marine biodiversity caused by fisheries, pollution, etc., will occur in regions along the tide line.
In marine environments, decapod crustaceans are among the most diverse and abundant animal groups. Human exploitation may disastrously impact this fauna, both through fisheries and through the aquarium trade (Calado et al. 2003;Costa et al. 2007;Balaji et al. 2009;Gregati et al. 2010). Often, laws regulating these activities are ignored, increasing the threat to this group. Continuous monitoring programs are required in order to evaluate the degree of conservation of these animals. Despite this, data concerning the crab biodiversity on rocky bottoms of the Brazilian southeastern coast remain sparse (Mantelatto et al. 2004a, b).
Abstract: Biodiversity can be useful as an ecosystem indicator for conservation and monitoring, through continuous assessment of its main properties including stability, primary productivity, exploitation tolerance and even global environmental changes. The main purpose of this study was to provide a checklist of the crabs associated with subtidal rocky bottoms at the Vitoria Archipelago, southeastern Brazilian coast. Monthly collections were carried out from February 2004 through January 2006 on three islands at the Vitória Archipelago (23°44'S-45°01'W). The crabs were hand-caught by SCUBA divers during the daytime, in rock subtidal. A total of 3084 individuals were caught, belonging to 42 species, 28 genera, and 12 families, highlighting Mithraculus forceps (1528) and Stenorhynchus seticornis (407) representing more than 60% of the sample. On the other hand, Dromia erythropus, Moreiradromia antilensis, Ebalia stimpsoni, Garthiope spinipes and Tumidotheres maculatus had only one individual sampled.
Checklist of the brachyuran crabs (Crustacea: Decapoda) in the rocky subtidal of Vitória Archipelago, southeast coast of Brazil female (OF) and juvenile (J). The brachyuran crabs were identified according to Melo (1996), and their taxonomic status was determined following Ng et al. (2008). All the crabs collected are deposited in the scientific collection of carcinology, Zoology Laboratory, University of Taubaté (UNITAU) and the carcinological collection of the Zoology Museum of the University of São Paulo (MZUSP).

Mithrax tortugae Rathbun, 1920
Geographic distribution: Western Atlantic -Florida, Antilles, Colombia, Venezuela and Brazil (Pará, Pernambuco, Alagoas, Bahia to São Paulo and Santa Catarina) (Coelho et al. 1990;Melo 1998;Rieger and Giraldi 2001;Coelho et al. 2002;Almeida et al. 2007). Material examined: 22 M, 11 F, 29 OF and 55 J, size range: 2.8 ≤ CW ≤ 60.0 mm. Average: CW = 22.5 ± 11.9 mm. UNITAU 201212. Figure  3C) Geographic distribution: Western Atlantic -South Carolina, Florida, Gulf of Mexico, Antilles, Venezuela and Brazil (Fernando de Noronha, Rocas and São Paulo) (Melo 1998;Nizinski 2003;Alves et al. 2006 The crab richness recorded for this region is the highest reported for this kind of habitat on the Brazilian coast, and comprises almost 20% of the total of species recorded from the entire Argentinean Biogeographical Province (see Boschi 2000a). Some studies have demonstrated the significant diversity of brachyuran crabs associated with unconsolidated bottoms on the southeastern Brazilian coast Braga et al. 2005;Bertini et al. 2010). Despite these available data, the ecology of brachyuran crabs of this region remains little explored, reinforcing the urgency of increasing the research effort to monitor this fauna on the Brazilian coast.

Mithrax verrucosus H. Milne Edwards, 1832 (
Areas of high species richness or areas that host endemic or threatened species are recognized as hotspots of diversity, and must be a priority for conservation policies (Myers et al. 2000;Margules et al. 2002;Fox and Beckley 2005;Tchouto et al. 2006). The large level of richness of crabs found in the Vitória Archipelago indicates its great degree of conservation, suggesting that the area must be recognized as an important region to be taken as a model for conservation management studies and policies along the southeastern Brazilian coast. The Vitória Archipelago is located near the port of São Sebastião, one of the most important Latin American ports, which moves about 400,000 tons/year (SET 2007), especially oil. Despite its potential for economic development, this region is seriously threatened by the constant risk of oil spills. For example, in 1978 the cargo ship Brazilian Marina spilled about 6000 tons of oil on the Brazilian southeastern coast, and other, smaller spills are frequent (SET 2007).
In addition, the port areas are "entrance doors" for non-indigenous species, which could be introduced by ballast water or encrusted on the hulls of ships, as reported by Mansur et al. (2003), Alves et al. (2006) and Thayer and Stahlnecker (2006). Introduction of exotic species, especially in already impacted environments, could significantly change community relationships and even result in local extinctions of indigenous species  (Levin et al. 2002;Tavares and Mendonça Jr. 2004;Weigle et al. 2005).
Recent reports extending the known geographical distributions for one porcellanid and nine brachyuran crabs (see Alves et al. 2006;Camargo et al. 2010) reinforcing the necessity to increase research efforts concerning the biodiversity on subtidal rocky bottoms of the Brazilian coast. In addition, for many of these newly recorded species, a large discontinuity of occurrence along this coast was observed (e.g. Teleophrys ornatus, Domecia acanthophora, Cataleptodius parvulus, Xanthodius denticulatus). These gaps may result from insufficient collecting efforts in this kind of environment, or may indicate introductions by unnatural means of transport such as ship ballast water.
The Vitória Archipelago offers shelter and food for a wide diversity of marine animals, with a potential for recognition as a marine biological reserve. This concept must be seriously considered by the local governments, because this region seems to be a key site, or even a hotspot for the conservation of marine biodiversity of the southeastern Brazilian coast.