Occurrences of the Macroinvertebrates in the Alimentary Canal of the Mangrove Oyster Crassostrea tulipa (Family: Osteidea)

Abstract

The food contents of the mangrove oyster, Crassostrea tulipa (C. tulipa) from Tomaro mangrove swamp of the Lagos Lagoon were investigated monthly from January to December, 2022, using one hundred samples for each month. The stomachs were gutted and its contents examined under the microscope using frequency of occurrence and numerical methods for food items while the vacuity and fullness indices were calculated using standard formulae. The results revealed that the species feed on various food items of both plants and animal origins with dietary preference consisting of Closterium ehrenbergi, Detritus, Melosira varians, Navicula elliptica, Oscillatoria tenuis, Nitzchia gracilis and organic substrates. Of the 1200 stomachs examined, 346 were empty stomachs, 292 had quarter-full stomachs, 170 had half-full stomachs, 287 had three quarter-full stomachs and 107 had full stomachs, indicating that there were significant differences in different months (P

<0.05). The study on the food items in the stomachs of C. tulipa indicated that they ingested a variety of benthic and pelagic food resources, mainly phytoplankton, suggesting therefore that C. tulipa is a phytoplankton feeder, mainly consumes aquatic insects, algae, diatoms, and organic decay material with modest feeding throughout the year while animal derivatives, aquatic plants and gastropods were eaten accidentally.