Oduor, Nancy ORCID: https://orcid.org/0000-0002-9810-7628, Cristina, Sónia Claúdia and Costa, Príscila (2023) Sources of anthropogenic nutrients and their implications on nutrient chemistry and ecological conditions of Ria Formosa lagoon, Portugal. Regional Studies in Marine Science, 61 . p. 102843. DOI https://doi.org/10.1016/j.rsma.2023.102843.

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Abstract

Shallow coastal waters receive high anthropogenic nutrients (nitrogen-N and phosphorus-P) from land that can change their nutrient chemistry, algal composition, and food webs with serious effects on marine life, human health, and local livelihoods. Managing anthropogenic nutrient inputs is thus key to ensuring healthy and productive coastal ecosystems. This study conducted a bimonthly sampling for eight months between 2014 and 2015 to determine the influence of agriculture, sewage, and natural nutrient sources on nutrient chemistry, ecological status, and possible implications for aquaculture production in the western side of Ria Formosa lagoon. Ecological Quality Ratios (EQR) were calculated from nutrient ratios (N: P: Si) computed from nutrient concentrations with the Redfield ratio (N: P: Si =16:1:16) used as a reference for ecological status determination. A mean of 3.7, 1.0, and 4.6μmol/L; 6.7, 1.12, and 5.5μmol/L; and 4.6, 0.7, and 2.μmol/L were recorded for dissolved inorganic nitrogen, phosphorus and silicates concentrations at sewage, agriculture, and natural sites respectively. The site mean EQR values ranged between 0.55 and 0.69. The overall ecological status of the west part of the lagoon was ‘Moderate’, with all the sites grouped under ‘Good’/’Moderate’ and ‘Moderate’/’Poor’ classes based on nutrient ratios. This study demonstrates that the western part of the lagoon’s nutrient chemistry is highly influenced by the nutrient sources with agricultural run-off and sewage discharges associated with nitrates, and ammonia and phosphates respectively. The elevated ammonium and phosphates registered can transform the phytoplankton composition to non-diatomic species and affect the current ecological functions of the lagoon. We recommend further studies, including biological quality elements, to get more comprehensive results on the study area.

Document Type:	Article
Programme Area:	PA3
Research affiliation:	Biogeochemistry and Geology > Submarine Groundwater Discharge
Refereed:	Yes
Open Access Journal?:	No
DOI:	https://doi.org/10.1016/j.rsma.2023.102843
ISSN:	23524855
Date Deposited:	26 Jun 2023 11:58
Last Modified:	26 Jun 2023 11:58
URI:	http://cris.leibniz-zmt.de/id/eprint/5213

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