Mapeamento de micro habitats da plataforma continental interna da Praia de Iracema - Fortaleza – Ceará

Abstract

Habitat is a common term that defines the living space of plant and animal organisms, distributed by a set of factors other than the environment (Begon et al, 1990). In the continental shelf, the concept of habitat encompasses aspects guided by geology, such as substrate type, sedimentary texture, geomorphology and sedimentary processes, which function largely in the distribution and abundance of certain demersal and benthic organisms (Yoklavich et al. ., 2000, Love et al., 2006). The present work on the conclusion of the Oceanography course of the Institute of Marine Sciences (LABOMAR / UFC) allowed the characterization of the marine substrate of the internal platform, located near the Praia de Iracema Spigot, implanted between Carlos Vasconcelos (eastern boundary) and Senator Almino (west boundary). In general, the sedimentation mapped on the continental shelf of Ceará in the study area is characterized by terrigenous (allochthonous) and biogenic (autochthonous) deposits. According to Folk and Ward, 1957, in Suguio, 1973, the particle size analysis of the samples collected on the marine substrate of the study area indicated a fine distribution of the fine, medium and fine sand fractions. It is possible to observe the predominance of fine and very fine sand, while sands with a diameter of 0.250 to 0.500 mm, medium sand, occur strictly in the NW portion of the area. The concentrations of gravel (˃ 22mm) are represented only at station 16, with a percentage of 10 to 12%, corresponding to shell fragments of marine organisms (Filo Mollusca) and algae. The sands class (> 64 μm to <2 mm) are in isolated spots, with a percentage of 90 to 100%, containing in some fractions mica platelets. The fine fraction (silt and clays <64 μm) assume percentages of 30 to 50% in stations 8 and 19. The biogenic deposits correspond to sediments constituted by fragments of marine organisms and calcareous algae. The highlight of the biodiversity was found in sample 3, where we can see examples of the Echinodermata, Mollusca, Porifera and Annelida phyla. In the essentially sandy samples, the presence of benthic organisms was observed, mainly in sand classes (diameter of 1mm to 0.500mm), belonging to Filo Mollusca - Class Bivalvia. Regarding depth and morphology, minimum depths of around 2 meters and maximum values of 10 meters were observed. Four profiles were identified that identified rock formations in the study area.