Diversidade macrobentônica recifal: independência e esforço amostral

Abstract

The reef ecosystems sustain a great biodiversity, serving as substrate, forming one of the most complex ecosystems of the planet. However, access to such diversity becomes an increasing problem due to the difficult task of collecting species richness data that are representative in the areas studied. In addition, there are other associated substrates that can serve as shelter for various animal groups and which help to increase the quantification of species richness in reef environments, such as algae that offer important support to communities of marine organisms. Moreover, the structure of assemblages of benthic organisms is controlled by the results of competition for space, food availability and resistance to changes in environmental conditions over time. Thus, this dissertation had two distinct general objectives, the first of which was to test the spacing between collection points of the sample units, guarantee the independence of the data in relation to the sampled set, verifying the effect of the sample effort, in number of units, in the estimation of species richness with the lowest possible number of samples. To do this, the sampling was performed between April 2015 and May 2016, during low tide, in 10 transects, and the data were obtained using photographs of the reef substrate along each transect, with data recorded at 10 meters intervals, with a digital camera in macro mode, using a sample area of 2500 cm². We obtained a total of 767 sample units and recorded 40 species. The species did not show autocorrelation spatially with others that are 90 meters away, implying independence of the sample in relation to this distance. We also demonstrated that the sampling effort was sufficient to estimate the species richness at the study site. These general results compose a solution for the spacing between the samples, to establish a real distance between the collection points so that there is no pseudoreplication, thus increasing the number of spatial repetitions.