Reproductive cycle and embryonic development of the gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) in the Brazilian Northeast

Abstract

Melampus coffeus belongs to a primitive group of pulmonate mollusks found mainly in the upper levels of the marine intertidal zone. They are common in the neotropical mangroves. Little is known about the biology of this species, particularly about its reproduction. The aim of this study was to 1) characterize the morphology and histology of M. coffeus´ gonad; 2) describe the main gametogenesis events and link them to a range of maturity stages; 3) chronologically evaluate the frequency of the different maturity stages and their relation to environmental factors such as water, air and sediment temperatures, relative humidity, salinity and rainfall; and 4) characterize M. coffeus´ spawning, eggs and newly hatched veliger larvae. Samples were collected monthly between February, 2007 and January, 2009 from the mangroves of Praia de Arpoeiras, Acaraú County, State of Ceará, northeastern Brazil. The characterization of the gonad development stages was carried out using routine histological techniques. The results of this study show that Melampus coffeus is a simultaneous hermaphrodite. The follicles have masculine and feminine elements, interleaved within the gonad. M. coffeus presents a well-defined synchronous reproductive cycle, showing successive maturation, release and resting periods. The average diameter of the oocytes was negatively correlated with salinity and positively correlated with rainfall. The results show that no reproductive activity occurs during periods of drought. After the dry season, the increasing rainfall levels and reduced salinity lead to the appearance of very dense populations, predominantly composed of small individuals.Keywords: hermaphroditism, histology, mangrove, pulmonata, reproduction. Ciclo reprodutivo e desenvolvimento embrionário do gastrópode Melampus coffeus (Linnaeus, 1758) (Ellobiidae) no Nordeste do Brasil ResumoMelampus coffeus encontra-se em um grupo primitivo de moluscos pulmonados, primordialmente marinhos, habitantes dos níveis superiores da zona entremarés, comum em manguezais do Oceano Atlântico. Pouco se sabe sobre a biologia da espécie, em especial, sobre a sua reprodução. Os objetivos deste trabalho foram: 1) caracterizar morfo-histologicamente a gônada de M. coffeus; 2) descrever os principais eventos da gametogênese e associá-los a uma escala de estágios de maturidade; 3) avaliar temporalmente a frequência dos estágios de maturidade e sua possível relação com os fatores ambientais, como a temperatura da água, do ar e do sedimento, a umidade relativa, a salinidade e a pluviosidade, e 4) caracterizar a postura, os ovos e a véliger recém-eclodida de M. coffeus. Foram realizadas coletas mensais de fevereiro de 2007 a janeiro de 2009, no manguezal da Praia de Arpoeiras, município de Acaraú-Ceará, na Região Nordeste do Brasil. A caracterização das fases de desenvolvimento da gônada foi realizada utilizando-se técnicas histológicas de rotina. Os resultados deste estudo mostram que Melampus coffeus é um hermafrodita simultâneo. Os folículos apresentam elementos m...

The effects of salinity on the density, shell size and survival of a mangrove gastropod: laboratory and field evidence

“…During the rainy season, when salinity decreases, the populations were denser and small individuals predominated. Our results agree with those of other studies that indicate that salinity is one of the main factors determining the distribution and abundance of species in the Melampus genus, which is found at higher densities in areas of high salinity in estuaries (Kerwin, 1972; Fell & Williams, 1985; Burnham & Fell, 1989; Martins, 2001; Maia et al , 2012).…”

“…The gastropod Melampus coffeus (Linnaeus, 1758) belongs to a primitive group of mainly marine pulmonate molluscs commonly found at the upper levels of the intertidal zone of mangroves in the Atlantic Ocean (Martins, 1996a, b). The regulation of snail populations in mangroves or tropical estuaries is subjected to processes that are density dependent and independent such as competition and predation, and temperature, rainfall, and salinity, respectively (Roach & Lim, 2000; Maia et al , 2012). In the case of Melampus , predation and food competition seem to be the main density-dependent regulatory factors (Joyce & Weisberg, 1986; Lee & Silliman, 2006), whereas seasonal fluctuations in water salinity and temperature, which can lead to significant mortality of young animals and eggs, are the most important density-independent factors (Apley, 1970; Price, 1980; McMahon & Russell-Hunter, 1981; Maia et al , 2012).…”

“…Some species in Melampus can display an elaborate succession of temporal adjustments in their reproductive and embryonic development, which correspond to submersion during spring tides (Apley, 1970; Russell-Hunter et al ., 1972; Spelke et al ., 1995). Maia et al (2012) show that, in Melampus coffeus , no reproductive activity occurs during the dry season, after which, increasing rainfall and reduced salinity result in very dense populations of predominantly small individuals.…”

Gonad characterization and reproductive seasonality in Siphonaria lessonii (Gastropoda: Heterobranchia) from the southwestern Atlantic Ocean

“…The same trend was found by measuring oocyte diameter in several other gastropod species, such as Buccinum isaotakii (Ilano et al 2003), Megalobulimus abbreviatus (Horn et al 2005), Anodontites trapesialis (Callil & Mansur 2007), and Melampus coffeus (Maia et al 2012). The mean oocyte area also increased from proliferation to evacuation stages, when oocytes grew from 226.8 (AE165.1) lm 2 to 1007.6 (AE988.7) lm 2 .…”

“…The mean oocyte area also increased from proliferation to evacuation stages, when oocytes grew from 226.8 (AE165.1) lm 2 to 1007.6 (AE988.7) lm 2 . The same trend was found by measuring oocyte diameter in several other gastropod species, such as Buccinum isaotakii (Ilano et al 2003), Megalobulimus abbreviatus (Horn et al 2005), Anodontites trapesialis (Callil & Mansur 2007), and Melampus coffeus (Maia et al 2012). After evacuation, oocyte size decreased in the post-evacuation stage, although non-evacuated mature oocytes could still be found within acini.…”