Barroso, Hortência de Sousa, Lima, Isabelle de Oliveira, Bezerra, Antonia Diana Alves, Garcia, Tatiane Martins, Tavares, Tallita Cruz Lopes, Alves, Ravena Santiago, Souza Junior, Edmilson Ferreira de, Teixeira, Carlos Eduardo Peres, Viana, Michael Barbosa and Soares, Marcelo de Oliveira ORCID: https://orcid.org/0000-0002-4696-3166 (2022) Distribution of nutrients and chlorophyll across an equatorial reef region: Insights on coastal gradients. Ocean and Coastal Research, 71 (suppl 2). e23002. DOI https://doi.org/10.1590/2675-2824071.22016hdsb.

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Abstract

We evaluate how the concentrations of inorganic nutrients and chlorophyll a vary in a heterogeneous area (Equatorial SW Atlantic), covering a gradient from stations closer to the coast to others more distant associated or not with turbid-zone reefs. Vertical temperature (27.9 ± 0.10 °C; mean ± standard deviation) and salinity (36.2 ± 0.14) profles showed that the water column is well mixed (0-30 m depth). The oligotrophic condition was marked by low concentrations of phosphate (0.30 ± 0.22 µM) and dissolved inorganic nitrogen (0.64 ± 0.74 µM). Moreover, dissolved reactive silicon (DSi) was low in most samples (< 2.0 µM), but higher (>10 µM) in nearshore stations, probably related to continental runoff and/or resuspension of the bottom sediments. The pelagic phytoplankton biomass indicated that chlorophyll a (0.25 ± 0.08 µg L-1) was low, positively correlated with light and negatively correlated with nutrients, indicating possible phytoplankton uptake. Chlorophyll a concentrations were lower in stations closer to the coast and higher in some stations near the reefs, indicating that the latter could be more prone to phytoplankton development and depletion of nutrients, especially DSi. Therefore, although oligotrophy is present along this coast, we found some unexpected heterogeneity of nutrient and chlorophyll a distributions, which were probably infuenced by benthic-pelagic coupling due to the presence of extensive reefs, sponge gardens (18-30 m depth), and the proximity to the coast. These results highlight the importance of understanding the heterogeneity of ocean productivity, especially in lesser known low-latitude areas, which showed distinct nutrient and chlorophyll a levels related to the occurrence of tropical reefs that are capable of supporting important fsh stocks and unique biological communities.

Document Type:	Article
Programme Area:	PA2
Research affiliation:	Ecology > Reef Systems
Refereed:	Yes
Open Access Journal?:	Yes
DOI:	https://doi.org/10.1590/2675-2824071.22016hdsb
ISSN:	2675-2824
Related URLs:	Publisher
Date Deposited:	10 Nov 2022 12:33
Last Modified:	10 Nov 2022 12:33
URI:	http://cris.leibniz-zmt.de/id/eprint/5053

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