Seasonal variation in the abundance and distribution ofAnomalocardia flexuosa(Mollusca, Bivalvia, Veneridae) in an estuarine intertidal plain

Abstract

Spatial and temporal density and biomass of the infaunal mollusk Anomalocardia flexuosa (Linnaeus, 1767) evaluated a tidal plain at Goiana estuary (Northeast Brazil). Three hundred and sixty core samples were taken during an annual cycle from three intertidal habitats (A, B and C). Shell ranged from 2.20 to 28.48 mm (15.08 ± 4.08 mm). Recruitment occurred more intensely from January to March. Total (0–1,129 g m−2) differed seasons (rainy and dry), with highest values in the early rainy season (221.0 ± 231.44 g m−2); and lowest values in the late dry season (57.34 ± 97 g m−2). The lowest occurred during the late rainy (319 ± 259 ind m−2) and early dry (496 ± 607 ind m−2) seasons. Extreme environmental situations (e.g., river flow, salinity and water temperature) at the end of each season also affected density ranges (late dry: 0–5,798 ind m−2; late rainy: 0–1,170 ind m−2). A. flexuosa in the Goiana estuary presented a dominance of juvenile individuals (shell length < 20 mm), with high biomass main the recruitment period. Average shell length, density and biomass values suggest overfishing of the stock unit. A. flexuosa is an important food and income resource along its whole distribution range. The species was previously also known as Anomalocardia brasiliana (Gmelin, 1791).

Rainfall effects on Anomalocardia flexuosa densities on the northeastern Brazilian coast using distributed lag models

“…This factor corroborates the success of bivalve recruitment in local population stock (Boehs et al, 2008). The high density of the group of large-sized individuals that occurred in the dry season was also similar to the result found by Silva-Cavalcanti et al (2018) for the species A. flexuosa in another extractive area in the state of Pernambuco.…”

“…This species occurs in the Atlantic Ocean from the West Indies down as far as Uruguay (Rios, 2009), but its commercial exploitation is concentrated on the Brazilian coast (Silva-Cavalcanti and Costa, 2011), where it inhabits different environments, including intertidal flats (Narchi, 1974). These areas are greatly influenced by rivers and estuaries (Rodrigues et al, 2013;Silva-Cavalcanti et al, 2018).…”

“…Among the environmental variables that are able to modify both the physical and biological factors of bivalves, rainfall is the variable that has the greatest influence (Silva-Cavalcanti et al, 2018;Almeida et al, 2021). Coupled with the absence of estimates of recruitment rates that can predict future densities, it is suggested that environmental variables that affect recruitment can be used in predictive analyses (Almeida et al, 2021).…”

“…Rainfall has a strong influence on the densities of A. flexuosa, as it can affect the fluctuations of salinity and fishing, among other factors (Belém et al, 2013;Rodrigues et al, 2013;Oliveira et al, 2014;Silva-Cavalcanti et al, 2018). In addition, it can also influence the different size classes of the species, which is a factor that is directly associated with fishing production (Oliveira et al, 2014;Rodrigues et al, 2018).…”

Qualidade da Água no Estuário do Rio Goiana, Nordeste do Brasil: Subsídios para a Conservação

“…Essas variáveis estão diretamente relacionadas com a dinâmica e abundância dos recursos pesqueiros extraídos na região da RESEX Acaú-Goiana, como no caso do crustáceo Cardisoma Guanhumi (LATREILLE, 1828) (Lima et al, 2021), e do molusco Anomalocardia flexuosa (LINNAEUS, 1767) (Silva-Cavalcanti et al, 2018). O pH é uma importante variável para o funcionamento do ecossistema, já quem em tores mais ácidos, vai prejudicar as dinâmicas populacionais dos organismos estuarinos (Mama et al, 2021).…”