Reproductive biology of Alitta succinea (Annelida: Nereididae) in a Brazilian tropical lagoon

Abstract

Alitta succinea is considered a cosmopolitan species in estuarine and coastal environments. It is also a model organism in marine chemical ecology and is used in ecotoxicological tests and molecular studies. We aimed to study the reproductive biology of the species in Lagoa de Maricá of Rio de Janeiro State, Brazil. For this purpose, monthly samples were taken from May 2015 to May 2016. The 653 individuals collected (sex ratio 1 male:1.5 female) were measured (width of the 20th chaetiger), sexed, and classified into stages by three criteria: the presence of gametes in the coelom; hypertrophy of the eyes; and modifications of the parapodia. From each identified female, the diameters of 30 randomly chosen oocytes were measured. Sediment samples were taken separately to analyze total organic matter and grain size. Salinity and temperature of the water were measured in situ each month. Our results show that individuals of this species reproduce through epitoky, with four stages of epitoky identified in both males and females. Parapodial modifications were more pronounced in males, in which some features such as the serrated papillae in the dorsal and ventral cirrus were exclusive.

Two-year survey of Alitta succinea (Annelida: Nereididae) in fouling communities with notes on morphology and reproduction

“…The population dynamics we observed seem to follow a pattern that is similar to one described in a tropical lagoon in Brazil (Aguiar and Santos, 2018). As the temperature increased from the spring to the summer, we saw a concurrent rise in population and a rise in the number of epitokes.…”

“…Morphologically, epitokes are longer and wider than atokes, and females tend to be larger than males. Furthermore, we were easily able to apply the staging system proposed by Aguiar and Gomes-Santos (2018) to a population from a different geographic region, which reaffirms the utility of presenting observations under this staging system.…”

“…This project aims to shed light on the population dynamics of the epitokus nereidid A. succinea throughout an annual seasonal cycle in a sub-tropical temperate environment. We anticipate that, similar to what happens when populations experience seasonal temperature variation, there will be two population peaks indicated by high numbers of small worms during the late spring and early fall (Gillet et al, 2011;Aguiar and Gomes Santos, 2018). These peaks will be preceded by an increase in late-stage epitokes during the early spring and late summer.…”

“…Some of the errant polychaetes found more commonly within fouling communities and soft bottoms in Southeast Texas are the nereidid worms, Alitta succinea (Leuckart, 1847) (Figure 1A) (Calnan et al, 1979). They live at the interface of sediment and water, both in shallow 'U'-shaped burrows, sometimes lined with mucus, and on the benthos, as epifauna (Gillet et al, 2011;Aguiar and Gomes Santos, 2018). A. succinea can survive in euryhaline and eurythermal environmental conditions and have a strong tolerance for changes in oxygen saturation, including hypoxic conditions Alitta succinea present epitoky, meaning they undergo a sexual metamorphosis before reproducing.…”

“…A pheromone exchange occurs, triggering the release of a plume of gametes by the males, then by the females (Bartels- Hardege and Zeeck, 1990;Ram and Hardege, 2005;Ram et al, 2008). After gametes are expulsed, individuals expire from metabolic exhaustion or from ruptured body walls due to gamete expulsion (Ram and Hardege, 2005;Aguiar and Gomes Santos, 2018). Then, the dead worms either sink to the sediment or are consumed by prey, contributing to an influx of organic material into the environment either way (Ram and Hardege, 2005).…”