Influence of environmental patterns on the population structure and secondary production of the fiddler crab Uca maracoani (Latreille) in the Amazon mangroves.

Uca maracoani is a fiddler crab found in estuaries along the western Atlantic coast, with a notable preference for euhaline environments. This study aimed to analyze the population structure and dynamics of this species in an estuary on the North Coast of Brazil, specifically in an area of the upper estuary where seasonal rainfall fluctuations result in significant changes in salinity. Monthly crab samples were taken from December 2013 to November 2015, together with measurements of environmental variables, such as water and climate parameters. The population maintains a balanced sex ratio; however, males are generally larger, with lower mortality rates and longer lifespans than females. Reproduction is continuous but mainly takes place in the dry season when salinity levels are higher (above 12‰). Higher crab densities have been observed during the rainy season when, despite lower salinity levels (below 10‰), the conditions for survival (food availability and milder climate) seem to be more favorable. The estimated average annual biomass and production for the population were 2.62 g AFDM m-2 and 5.43 g AFDM m-2 year-1, respectively, characterized by a high turnover rate (P/B = 2.10 year-1). Our results suggest that U. maracoani has thriving populations in the Amazon coast's mangroves, benefiting from the vast muddy intertidal zone and the high organic content delivered by the estuaries.

Harvesting the cockle Leukoma pectorina (Lamarck, 1818) on Algodoal-Maiandeua Island (Pará, Brazil): techniques, bio-ecology, and ethnoecological knowledge.

The ecological and ethnological aspects of the harvesting of the cockle, Leukoma pectorina (Bivalvia: Veneridae), were investigated on Algodoal-Maiandeua Island, on the Amazon coast of Brazil. Ethnobiological data were collected through informal conversations, semi-structured interviews, and observations of the harvesting and processing of bivalves on the island. Following the ethnobiology study, the cockle beds were surveyed to evaluate the density of L. pectorina, body size and the meat yield of the cockles in the months of dry and rainy seasons. In the study area, cockling is a manual and artisanal activity, and L. pectorina is typically harvested by mothers with little formal education. The cocklers make their own tools, cockles are prepared in the family environment, and the majority of the catch is sold to commercial establishments on the island. Cockling is a sporadic activity used to complement the family income, and is more common during the dry season, when tourism increases on Algodoal-Maiandeua Island. The cockles are also larger and population density is higher during this season, and the cocklers themselves recognize this period as providing the most productive harvest. These findings reinforce the value of traditional knowledge for both scientific research and the planning of the management of coastal fishery resources.