Navegando por Palavras-chave "Replicatas"

Agora exibindo 1 - 1 de 1
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Distribuição vertical de foraminíferos em sedimentos estuarinos: aspectos metodológicos e suas implicações em estudos ecológicos
    (Universidade Federal de São Paulo, 2017-12-21) Kukimodo, Isabela [UNIFESP]; Semensatto, Decio Luis [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Methodological aspects of sample collection are discussed in all areas of Science, given their potential impacts on interpretations and conclusions. In the case of ecological studies based on recent foraminifera, there are variations on the depth of the sediment layer collected, counting living organisms versus dead versus living plus dead organisms (called total microfauna) and the collection of single samples versus replicates. This paper aimed to answer some of these questions, especially but not exclusively in the inter-tidal zone of tropical regions: (i) the adoption of the strategy of single sample collection or replicates can cause different results and interpretations? (ii) are there differences in results and interpretations generated from the count of living organisms versus living dead bodies?; and (iii) the depth of collection of the sediment layers influence the results and interpretations based on the foraminifera on their respective environments? For this purpose, three collection points were selected along the mangrove margins associated to the Itapanhaú River, in Bertioga (SP), and in each one three microcores with 20 cm depth were collected. In each microcore 3 ml of sediment was extracted in the layers of 0 to 1, 4 to 5, 9 to 10, 14 to 15 and 19 to 20 cm. All the samples were compared among themselves regarding absolute abundance and species composition and taxocenosis, diversity, and equitability, using single and multivariate statistical techniques. Also, the results obtained were compared with the set of live foraminifers at the time of collection and total (live + dead). Replicate collection is better than a single sample, both for the living and for the total, because they enable to capture the spatial variation of the foraminifera and thus, the application of more accurate inferential statistical analysis. There were substantial differences in ecological interpretations and their respective indicators between analyzes based on living and total only so that they should not be considered directly comparable to each other. Counting live foraminifera requires greater collecting and picking effort to reach the statistical minimum recommended. As for depth, the first centimeter should be sufficient to collect the vast majority of live foraminifera, especially for estimating species richness. In the case of total teak (living + dead), there were no significant differences for ecological interpretation as the depth of collection increased. However, thicker sediments result in a longer time interval integrated into the sample, which may be a study objective.