Grupos funcionais de copépodes em uma costa semiárida tropical

Abstract

Copepods has phenotypic characteristics relevant to their functions in ecosystems, called functional traits. From the traits you can define the functional groups and understand the trophic importance of the dominant group in planktonic pelagic environment. However, this knowledge is scarce on tropical semi-arid coasts. The objective was to analyze the distribution of the Copepoda functional groups in the Equatorial Southwest Atlantic, more specifically in the extreme west of the state of Ceará (Itarema). The region studied showed no differences in temperature and salinity. The results also indicated fourteen species of copepods. Paracalanus aculeatus, Paracalanus quasimodo, Paracalanus indicus, Parvocalanus scotti, Parvocalanus crassirostris, Centropages velificatus, Calanopia americana, Labidocera scotti, Labidocera fluviatilis, Temora turbinata e Temora stylifera, belonging to the order Calanoida. Corycaeus (Onchocorycaeus) giesbretchi and Ditrichocorycaeus amazonicus belonging to Cyclopoida. And the Euterpina acutifrons of the order Harpacticoida. The similarity analysis organized the species into four functional groups. There was no significant difference between groups in the density of sampled points between the years 2017 and 2018 and according to the distance from the coast. In Functional Group I (GF1) the species Temora spp and Euterpina acutifrons were grouped, they are omnivorous, filtering and do not present diurnal vertical migration. Functional Group II (GF2) includes the species Corycaeus (Onchocorycaeus) giesbretchi and Ditrichocorycaeus amazonicus, carnivorous species, they are active ambushes, retainers and do not present diurnal vertical migration. Functional Group III (GF3) is represented by the species Labidocera spp., Calanopia americana and Centropages velificatus, they are the omnivorous, filtering, egg dispersing species that perform diurnal vertical migration. In Functional Group IV (GF4), the species Parvocalanus spp. and Paracalanus spp. form the group of carnivores and herbivores they are filterers, egg dispersers and present diurnal vertical migration. As an oligotrophic environment with low food availability, it is necessary that species actively seek their prey. The species Temora turbinata was the most abundant in the study area and it’s his high density made GF 1 important in the trophic dynamics of the study area. This is an exotic species and how has the highest density in all the samples, indicates that there was stability of the species in the region. The portion of the internal platform studied present homogeneity in the distribution of groups of copepods, which may be an influence of the water bodies uniformity on the internal platform of the semiarid coast, once the copepods are sensitive to the physical-chemical changes of water. The results described here auxiliate to understand the coastal systems functions under extreme and unique conditions.