Mangais como habitat de camarão, estudo comparativo: no saco da ilha da inhaca e península de Machangulo

Abstract

The study of mangroves as shrimp habitat in Saco da Inhaca and Machangulo Peninsula was carried out in October 2005. This research work compares the biomass and density of shrimp species, the specific diversity index in the two study areas and evaluates the influence of temperature, salinity, depth and structural complexity on shrimp density in different habitats. The collection of samples, in the previously selected sub-areas, was carried out during two consecutive spring tides, based on the methodology proposed by Ronnback et al (2002), which consists of placing 4 fixed nets inside the mangrove forest, covering each net an area of ​​9 m. The lower part of the net was buried at low tide, in order to allow an adequate sealing of the internal area to be sampled. At the peak of the high tide, the net was raised with the help of four people, and at low tide the following morning, after removing the water, the shrimp was manually captured. During this investigative work, 5 species of shrimp were captured, namely: Penaeus indicus, Penaeus semisulcatus, Metapenaeus monoceros, Hippolyte kraussiana and Alpheus deuteropus, of which the species Penaeus indicus was the most abundant with 92.59% in Saco da Inhaca and 85.95% in Saco da Inhaca and 85.95% in Saco da Inhaca. Peninsula of Machangulo. The largest biomass was recorded in Machangulo and the smallest in Saco with 13.20 and 0.66 grams, respectively. Machangulo Peninsula had the highest specific diversity index (0.55), compared to Saco da Inhaca (0.27). In the two areas, and their respective sub-areas, the organic matter content did not show significant differences, although there is a small variation in the data collected during the sampling period. There were significant differences between the mean carapace length of the species P. indicus in Saco da Inhaca and Machangulo Peninsula, with sub-area D, in both areas, which presented the largest carapace length of shrimp. Depth was the only factor that influenced the density of shrimp species, and the lowest values ​​were found in Machangulo Peninsula. Salinity and depth did not significantly affect the density of the species Penaeus indicus. This species was negatively correlated with depth, but positively correlated with temperature, structural complexity and salinity. (TRADUÇÃO NOSSA)