Large gaps in reef distribution may hinder the dispersal of marine organisms, interrupting processes vital to the maintenance of biodiversity. Here we show the presence and location of extensive reef habitats on the continental shelf between the Amazon Reef System (ARS) and the Eastern Brazilian Reef System (ERS), two reef complexes off eastern South America. Formations located 20–50 m deep include both biogenic and geogenic structures. The presence of diverse reef assemblages suggests the widespread occurrence of rocky substrates below 50 m. These habitats represent an expansion of both the ARS and ERS and the closure of the only remaining large-scale gap (~ 1000 km) among West Atlantic reef environments. This indicates that the SW Atlantic harbors a single, yet heterogeneous, reef system that stretches for about 4000 km, and thus, represents one of the largest semi-continuous tropical marine ecosystems in the world.

The reproductive cycle of Cardisoma guanhumi was described from the analysis of seasonal variation of the gonadal maturation stages. The first maturity for both sexes was determined based on three different tests: inflexion point on the curve; relevant character (morphometry); and histological analysis (physiology). In addition, some aspects of sexual dimorphism for the population were studied. A total of 353 individuals caught in north-eastern Brazil between December 2006 and November 2007 were analysed. The sex-ratio was statistically equal (P ≥ 0.05) and the carapace width (CW) of the females ranged from 4.34 to 8.56 cm and of the males from 2.84 to 9.22 cm. Mature females with fully developed gonads begin to appear in the dry season (August) and ovigerous females occurred from November to February, suggesting that spawning occurs mainly during the rainy season. The CW of first sexual maturity for females ranged from 5.87 cm to 6.70 cm and males from 6.22 cm to 7.20 cm. The highest percentage of individuals caught were juveniles, indicating the need for a targeted effort to preserve the species.

The nurse shark, Ginglymostoma cirratum, is considered an endangered species in Brazil and its capture by fisheries forbidden. Despite such legislation, nurse sharks continue to be caught as these laws are unenforced and fisheries are not monitored. The goal of the present study was to describe the population structure of nurse sharks caught off Ceará State, north-eastern Brazil, based on the following aspects: abundance and size, sex-ratio, fisheries incidence and seasonality of captures. Landings were monitored weekly during a two-year period. A total of 189 specimens were recorded. Total length (TL) varied between 73 and 274 cm. The male–female ratio did not differ significantly (1.19♀:1♂). TL of individuals landed as carcasses was estimated based on interdorsal length. The following equation was obtained for males and females: TL = 12.606ID + 14.24 (R² = 0.9505). Most of the landed sharks were juveniles (86.2%). No seasonal pattern of abundance and TL variation was observed. Management of this fishery is required in order to prevent localized over-fishing of nurse sharks.

The Haemulon plumieri is a typical reef-associated and tropical species found in warm and temperate waters of the Western Atlantic. Due to the large fishing effort directed to H. plumieri, the knowledge about its reproductive biology is essential for correct stock management and conservation. The aim of this study was to characterise reproductive biology with a focus on its seasonal variation of gonadal maturation stages, first maturation size and fecundity. Specimens were monthly collected and a total of 119 females and 136 males were analysed. The reproductive cycle of Haemulon plumieri is seasonal, with higher activity between March and May. Size at first maturity (L₅₀) was estimated at 16.86 and 18.55 cm for females and males, respectively. The total fecundity ranged between 17,816 and 120,333 mature oocytes per female and relative fecundity was 235 ± 63 oocyte.g⁻¹ whereas batch fecundity varied between 20 and 25% from total fecundity. Since the species is widely caught, we suggest a closed season from March to May and to establish a minimum catch size of 18.5 cm for both sexes, since there is no evident sexual dimorphism.