Análises metagenômicas revelam a influência das camadas de profundidade na biodiversidade marinha em regiões tropicais e subtropicais

Abstract

About 71% of the Earth's surface ecosystem is covered by ocean, responsible for containing 97% of all the Earth's water, with plankton being its dominant life form. Microorganisms play an essential role in maintaining the planet's system, since they are sources of energy and nutrients for living beings, realize almost half of net primary production, maintain chemical balance in the atmosphere and export photosynthetically fixed carbon to the deepest layers of the ocean. Ocean ecosystem biology studies how biotic and abiotic factors determine ocean ecosystem properties. With the emergence of global-scale studies of open sea organisms, much has been discovered about the genomics of oceanic microbial communities. One of the main projects in this category today is Tara Oceans, a multidisciplinary project aiming to understand the diversity, interactions, functions and phenotypic complexity at taxonomic and spatial scales of plankton, through about 35000 samples with millions of organisms collected at depths of up to 2000 m in 210 stations across the oceans. The main objective of this work was to compare oceanic samples exploring the abundance, diversity, and function of microorganisms found in tropical and subtropical zones, in order to understand how these factors affect the biodiversity of these species. For this, only samples from collection stations that presented samples in the three depth layers (SRF, DCM and MES) simultaneously were selected. This filtering resulted in 8 stations with a sum of 76 samples. These data were processed through the MEDUSA pipeline, following the standard flow of a metagenomic analysis: pre-processing, sequence alignment with a reference protein bank, taxonomic classification and functional annotation. With the results obtained from this process, it was possible to compare the abundance and diversity of these samples and to note and analyze the results of this comparison. A greater diversity of organisms was observed in the deepest layer (MES) and there was no significant difference in abundance between the explored depth layers. Some biological functions are unique to each depth layer, indicating its particularities and functional diversity. No significant distinction of abundance, diversity or function was observed comparing exclusively samples from collection stations in different geographic points.