Ocorrência e aspectos populacionais do bivalve invasor Electroma vexillum (Reeve, 1857) na Enseada do Mucuripe, Fortaleza - Ceará

Abstract

The introduction of invasive alien species is a long-standing problem that has affected coastal environments for centuries. Bioincrustation on ship hulls and the transport of ballast water are among the main causes of the introduction of these species into marine ecosystems. Electroma vexillum is a bivalve mollusk of the Vulsellidae family and its original distribution is in the Indian Ocean and the Red Sea. However, this species has already been found in the Mediterranean Sea and on the northeast coast of Brazil. In this context, the purpose of this study was to analyze the occurrence and spatial distribution of the species Electroma vexillum in Enseada do Mucuripe, in Fortaleza, Ceará. Data was collected at seven locations along the Mucuripe coast, with three replicates at each site, totaling 21 samples. Since the species tends to attach itself to seaweed, collection sites were decided in advance based on the presence of marine macroalgae on sandstone reefs and coastal groynes in Enseada do Mucuripe. Marine macroalgae were collected using a 10x10cm quadrant, with the assistance of a steel spatula. Subsequently, the samples were taken to the laboratory, where they were frozen and sorted to separate E. vexillum individuals and macroalgae. After that, the organisms were measured using a stereomicroscope. A total of 1,538 individuals were collected. The highest abundance was found on the sandstone reef at Mercado dos Peixes, with a total of 1,465 individuals, and the lowest abundance was found at Espigão João Cordeiro and Recife do Labomar, with 0 individuals. The Kruskal-Wallis test revealed a significant difference in the abundance of E. vexillum between the areas analyzed. Shell length and height showed a significant positive linear correlation (r = 0.8834). The shortest length observed was 0.962 mm and the longest was 4.48 mm, both found at the Mercado dos Peixes, which had a significantly longer length compared to the other study sites. The Kruskal-Wallis test was also applied to compare biomass and macroalgae richness between collection sites, but no statistically significant differences were found. These results indicate that the species is well established in the study site, with its abundance and size variating spatially. Furthermore, there is a clear need for long-term monitoring to investigate the factors that may influence the distribution of E. vexillum, enabling a better understanding of its population dynamics and its establishment in Enseada do Mucuripe.