Abstract
Littoraria angulifera (Lamarck, 1822) is an estuarine gastropod of tropical occurrence, which lives mainly on trunks of mangrove tree species. This study aimed to evaluate the population attributes of this species, such as abundance, space-time distribution, sex ratio and recruitment in mangroves in Bahia State, northeastern Brazil. The specimens were collected monthly throughout 2018, on trunks of the red mangrove Rhizophora mangle L. at two heights and on two horizontal levels. Specimens that were on the marine grass Spartina alterniflora Loisel were also collected. After counting, biometrics and sexing, the specimens were returned alive to the environment. The average size and weight of L. angulifera was higher (p<0.05) in places with taller and less sparse trees and the vertical distribution on the trunks showed a preference for strata close to the soil. Both results are related to shading and protection against desiccation. Females were more abundant than males, at an approximate sex ratio F: M of 1.4: 1. Recruits were observed throughout the period, showing continuous reproduction of the species with a recruitment peak in spring (September to November). The study revealed the importance of keep the mangroves intact to allow the maintenance of the natural stocks of the species.
Highlights
Gastropods of the Littorinidae family are amphibious mollusks living on hard substrates, withstand long periods out of water, and feed on microscopic algae (Rios, 2009)
We aimed to investigate if: (i) the height of mangrove trees have an influence on the size and abundance of L. angulifera; (ii) larger animals occupy higher strata in the trees; (iii) males and females have a distinct spatial distribution; (iv) to facilitate the elimination of larvae, females are more concentrated near the water line; (v) the expected male to female sex ratio is 1: 1; (vi) as it is a tropical area, continuous reproduction of the species is expected, with peaks of reproduction in warmer periods of the year
Littoraria angulifera has continuous reproduction in the region, which was evidenced by the entry of new small individuals in practically every month of the year, but in the spring there was a greater input of recruits, which is probably related to a small increase in temperature at this time of year, an abiotic factor that stimulates reproduction (Galtsoff, 1961)
Summary
Gastropods of the Littorinidae family are amphibious mollusks living on hard substrates, withstand long periods out of water, and feed on microscopic algae (Rios, 2009). The species reaches 30 mm of shell height, whose surface is sculptured with very fine spiral striations (Rios, 2009), with color. Polymorphism, but with dark brown predominating (Zeidan et al, 2020) It presents detritivorous/ microphagic habit (Gutierrez, 1988), feeding mainly on lichens and fungi (Kohlmeyer and Bebout, 1986)
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Schedule a callMore From: Brazilian journal of biology = Revista brasleira de biologia
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