Embriologia e ontogenia do aratu Goniopsis cruentata (Latreille, 1803) (Decapoda, Grapsidae) e os possíveis impactos populacionais do derramamento de óleo

Abstract

The crab Goniopsis cruentata is a non-digging crab, which roams the substrate between the mangrove roots during low tide, being considered a generalist feeder, ingesting organic sediments, algae, plants and molluscs. This feature represents an important link in the flow of energy to mangrove ecosystems, as well as an important role in the turnover of primary production in these environments and the structuring and function of the mangrove. From February 2019 to January 2020, 713 individuals were captured (378 males and 335 females) of which the ovigerous females were used for cultivation ( 16 females). The development and exploration of the embryonic event of the crab Goniopsis cruentata (Latreille, 1803) was studied and described in the laboratory through visual description and traditional and geometric morphometric techniques. These techniques were also used to determine variations in intraspecific perspective, in the juvenile and adult stages and to understand how human actions, oil spills in the oceans, act on the morphology of brachyura crabs (juveniles and adults) and the magnitude of how these events influence the stages. crab life initials The sequence of morphological changes observed initially in the egg and later in the embryo allowed the description of 9 embryonic phases from the moment of morula, a process reported for the first time for grapsids: pre-extrusion, pre-cleavage, post-cleavage, pre-naupliar, naupliar, metanaupliar, ocular and abdominal pigmentation, heartbeat and pre-hatch. The eggs were shown (ellipsoidal shape) only for eggs classified as I period. During embryogenesis the eggs showed an increase in their diameter and volume of 15% and 50% respectively. In the intraspecific analysis, males and females showed negative allometry (β0<1) for all linear relationships with ontogenetic difference (p<0.01) for all comparisons. In dorsal view, males were wider in the posterior region than females. In addition, in the abdominal region, young females are triangular in shape and adults are oval, a characteristic behavior of brachyurans. Regarding the shape of the chelipeds, we observed morphological separation in the sexual comparison (F x M) and laterality (R x L) (p<0.01), without ontogenetic variation (A x Y). In the comparison with the effect of anthropic actions, the patterns of size and shape distribution of G. cruentata showed noticeable differences, for linear morphometric techniques in all groups (FY, MY, FA and MA), however, this pattern was not noticed for the geometric, between the pre- and post-spill periods. After a period of 48 hours of exposure of the larvae to ASF, to evaluate the acute effect of the oil, the mortality percentages ranged from 0 to 100% with a mean of 19 21%. It was observed that a concentration of 12.5% FSA had the highest mean mortality (29% 26%), not differing from the control concentration (17 18%) and the other treatments (Dunn, p>0.05). Our data show that linear morphometric techniques associated with geometric morphometry are effective in identifying variations, even if not perceptible to the naked eye (as in determining the differentiation of different embryonic stages), and can be a useful and easily accessible tool in inference of possible environmental imbalances or, otherwise, of local consequences, in addition to helping to quantify disasters caused by incidents, given the size and complexity of aquatic systems. The results obtained in this will help to elucidate the understanding of ecological impacts caused by oil spills, used as a tool in political decision-making and in the environmental management of crab habitats to avoid environmental damage and risks.