Influence of abiotic factors on phytoplankton diversity and distribution in an atoll environment

Marina C Jales,Fernando A N Feitosa,Manuel De Jesus Flores Montes,Vanessa B Pedrosa,Maria Luise Koening

doi:10.1590/0102-33062020abb0269

Marina C Jales, Fernando A N Feitosa + Show 3 more

Open Access

https://doi.org/10.1590/0102-33062020abb0269

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Abstract

Taxonomic investigations of phytoplankton community structure are very important for understanding the dynamics of these organisms in places like reefs, which present broad hydro-biological variation. This study aimed to determine and investigate phytoplankton community composition and biomass in natural pools of Atol das Rocas (3°51’ S; 33°49’ W), and to evaluate the possible influences of abiotic variables throughout different seasons. The oceanographic parameters used to assess the phytoplankton community and its biomass were chlorophyll a, salinity, water temperature, dissolved oxygen and dissolved inorganic nutrient content, namely ammonia, nitrate, nitrite, phosphate and silica. A total of 109 species were identified, distributed among four groups: Ochrophyta (52.3 %), Dinophyta (37.6 %), Cyanobacteria (7.33 %) and Haptophyta (2.75 %). Although none of the hydrological parameters were found to be statistically determinant, phytoplankton composition in all the studied pools was primarily associated with nutrient salts and there was a qualitative and quantitative increase in phytoplankton in the rainy season. This increase was due to the positive relationship between phytoplankton composition and nutrient salts when associated with local hydrodynamics, which provides more favorable conditions for the enrichment of diversity with emphasis on species that compose the benthic microflora.

Highlights

Phytoplankton are mainly autotrophic and very weak swimmers, and flow at the whim of currents
According to Vaulout (2001), marine phytoplankton colonize the upper part of the water column, above the limit of light penetration, and their community structure and abundance are mainly controlled by inorganic nutrients
The Atol das Rocas reef complex is influenced by the South Equatorial Current, which runs in a westward direction at an average speed of 30 cm s-1 (Richardson & Walsh 1986)

Summary

Introduction

Phytoplankton are mainly autotrophic and very weak swimmers, and flow at the whim of currents These organisms are mostly single-celled and the main photosynthetic living cells in the marine environment (Lubiana 2015). Understanding the factors that control the dynamics and composition of species is important to prevent environmental impacts on aquatic ecosystems (Winder & Sommer 2012). Environmental changes, such as to physical conditions, nutrient input (bottom-up control) and the Departamento de Oceanografia, Universidade Federal de Pernambuco, 50601-910, Recife, Pernambuco, Brazil 2 Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco, 52171-900, Recife, Pernambuco, Brazil

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