A total of 272 species of brachyuran crabs are reported from marine and estuarine environments in northern and northeast Brazil. The checklist is derived from the literature published from 1847 to 2008, and includes all species that have been reported at least once from the study area. It is also partially supported by material deposited in the crustacean collection of the Departamento de Oceanografia, Universidade Federal de Pernambuco, city of Recife, Brazil (DOUFPE). The families containing the highest number of species in northern and northeastern Brazil are Majidae (31), Portunidae (22), Epialtidae (20), Panopeidae (20), and Xanthidae (18). The remaining species are distributed in 39 families. The analysis of the distribution of the species in the region, allows for identification of four patterns of longitudinal distribution (western Atlantic, Amphi-Atlantic, Amphi-American, and circumtropical species) and, in the western Atlantic, six patterns of latitudinal distribution (Virginian, Carolinian, Antillean, Central-South American, Boreal, and Endemic). Two non-indigenous species have also been reported. Most of the species represented in northern and northeastern Brazil have Antillean (94 species; 34.5%) and Carolinian (75 species; 27.6%) pattern of distribution.

The influence of abiotic factors on the spatial distribution of the fiddler crabs Uca leptodactyla, U. maracoani, U. rapax and U. thayeri was studied in a tropical mangrove of northeast Brazil. Eight transects were delimited in a mangrove area of the Pacoti River. On each transect, three 0.25 m2 squares were sampled during spring low tide periods from September 2003 to August 2004. The sediment of the squares at each transect was analysed for grain size, organic matter and humidity. Morphology of the second maxilliped was studied considering the number of spoon-tipped setae to help explain the ecological distribution of the species. U. leptodactyla and U. rapax were found living in medium sand, U. thayeri was collected in fine and very fine sand, while U. maracoani was found living in very fine sand. U. leptodactyla showed a negative correlation with organic matter and humidity while U. thayeri showed a positive correlations for both factors. U. maracoani and U. rapax were not correlated with organic matter or humidity. The analysis of the second maxilliped revealed that U. leptodactyla and U. rapax show a high quantity of spoon-tipped setae while U. maracoani and U. thayeri show a greater quantity of plumose setae.

The present study is the first major assessment of the marine decapod fauna of Ceará, northeastern Brazil, since contributions of J. Fausto-Filho in the 1960s–1970s. A fully updated checklist of all decapod crustaceans occurring in marine and estuarine habitats of Ceará is provided, based on literature records, specimens held in two carcinological collections of the Universidade Federal do Ceará (UFC), and material collected mainly by the authors between 2011 and 2014. A total of 337 decapod species are listed, distributed among the following taxa: Achelata (8 species), Anomura (42 species), Astacidea (1 species), Axiidea (11 species), Brachyura (162 species), Caridea (83 species), Dendrobranchiata (20 species), Gebiidea (9 species), and Stenopodidea (1 species). Among them, 23 species represent new records for Ceará, with 14 species, viz. Alpheus peasei (Armstrong, 1940), A. thomasi Hendrix & Gore, 1973, Ambidexter symmetricus Manning & Chace, 1971, Axianassa australis Rodrigues & Shimizu, 1992, Biffarius biformis (Biffar, 1971), B. fragilis (Biffar, 1970), Leptalpheus axianassae Dworschak & Coelho, 1999, L. forceps Williams, 1965, Lysmata bahia Rhyne & Lin, 2006, L. intermedia (Kingsley, 1878), Merhippolyte americana Holthuis, 1961, Neocallichirus maryae Karasawa, 2004, Ogyrides hayi Williams, 1981, and Typton carneus Holthuis, 1951, now having Ceará as the northern-most limit in their distribution range along the Brazilian coastline. One shrimp species, Lysmata lipkei Okuno & Fiedler, 2010, which was also found in the state of Rio Grande do Norte, possibly represents an invasive taxon in Brazil and the western Atlantic, originating from the Indo-West Pacific. Alpheus buckupi Almeida, Terossi, Araújo-Silva & Mantelatto, 2013, previously recorded from Ceará based on a colour photograph, is confirmed from this state, with specimens from several new localities. A few doubtful records from Ceará are briefly discussed. Colour photographs are provided for most of the taxa newly recorded from Ceará; some species are illustrated in colour for the first time.

The present study aimed to evaluate the current state of knowledge of marine and estuarine shrimp species from the suborder Dendrobranchiata and the infraorders Stenopodidea and Caridea, considering their diversity and distribution along the North and Northeast Brazilian coast (N/NE). The number of reported species rose from 124 to 169 since the Paulo S. Young’s Catalogue of Crustacea of Brazil, put out in 1998, which means an increase of 36.3%. Pernambuco (89 species) and Bahia (68 species) are the states that present the highest shrimp diversity, accounting for 53% and 40.5% of the total species registered for the N/NE regions, respectively. On the other hand, the states of Sergipe (21 species) and Piauí (13 species) contributed with only 12.5% and 7.7% of the total species registered at the moment.

Coastal reef environments support a great diversity of benthic species, which are physically arrayed according to their adaptations to biotic factors such as competition and to abiotic factors such as salinity and desiccation. Few studies have described adaptive strategies on rocky shores in tropical regions. This contribution deals with the spatial distribution of three species of zoanthids (Palythoa caribaeorum, Protopalythoa variabilis and Zoanthus sociatus) on flat sandstone reefs in north-eastern Brazil. Zoanthid distribution and abundances were determined as the percentage of cover along six transects, where 50 × 50 cm quadrats were sampled. Biotic data (influence of macroalgal cover) and abiotic data (relief, substrate type, temperature and salinity) were also taken along the transects to attempt to explain the zoanthid distribution. These species tended to colonize the middle and low intertidal zones, which are least exposed to air. Zoanthus sociatus apparently resists desiccation better than P. caribaeorum. Protopalythoa variabilis showed the highest abundance and frequency, occurring in the entire middle intertidal zone and colonized areas with high proportions of unconsolidated sediment. Desiccation was the main factor limiting the spatial distributions of the three species, although substrate composition and probably interspecific competition with macroalgae were also important. The results suggest that the zoanthids use a variety of these adaptive strategies, which account for their success on consolidated substrates. Continuous monitoring of changes in distribution patterns can be useful for indicating human impacts on marine biodiversity, providing insights for monitoring and conservation programmes.