Hábito alimentar do siri Callinectes ornatus (Ordway, 1863) (Crustacea: Brachyura: Portunidae) na Ilha de Itamaracá, Pernambuco, Brasil

Abstract

The swimming crab Callinectes ornatus (Ordway, 1863) is a crustacean belonging to the Portunidae family of great importance to the benthic community, given its important role in the trophic web of marine environments. The main objective of this study was to identify and provide information about the composition of the diet of C. ornatus Ordway, 1863 at Itamaracá Island, Pernambuco, Brazil in the period after the oil spill that occurred off the Brazilian coast in 2019, as well as to analyze the occurrence of possible changes in its feeding habits. The specimens analyzed came from accompanying fauna from fish collections carried out in August and September 2020. To obtain the material, a 20-meter long, 1.5-meter high trawl with a 5-millimeter mesh opening was used. Two different points were chosen, one in the surf zone at Jaguaribe beach (7°43'43"S 34°49'29"W) and the other at the mouth of the Jaguaribe River (7°43'19"S 34°49'32"W) on Itamaracá Island, Pernambuco, Brazil. After collection, the material was sent to the UFRPE/UAST Benthos Laboratory for analysis. After sorting, the material was identified, measured and sexed to extract the stomachs of the crabs and assess the degree of stomach filling. To analyze the contribution of each food item, the Point Method, the Frequency of Occurrence and the Food Index were applied. Twelve items were identified in the stomachs of the 104 crabs collected at the collection points. The results obtained indicate that Crustacea, Mollusca and Animal Organic Matter were the items that contributed most to the natural diet of the crabs collected in the surf zone of Jaguaribe Beach and Crustacea, Animal Organic Matter and Plant Organic Matter were the items that contributed most to the diet of the crabs collected at the mouth of the Jaguaribe River. As for the difference in the diet of males and females of the species, it was found that there were no major changes in the diet, with only small changes in the proportions of items. However, Crustacea continued to be the most representative item for both sexes. According to these results, the species' feeding habits are characterized as generalist and opportunistic, with a preference for organisms of animal origin. During the analysis of the material, the presence of oily substances was not identified, indicating the presence of oil in its structures or other internal organs, and the comparison with data from the literature shows that there was no change in the species' natural diet, even after the oil incident, with only the presence of plastic waste in some stomachs indicating exposure to anthropogenic activities along the coastal zone