Influence of fluvial discharge on the dynamics of Chlorophyll-α in the continental shelf adjacent to the Recife Port Basin (Pernambuco-Brazil)

Abstract

This study was undertaken in the coastal zone of the state of Pernambuco adjacent to the Recife port area, which corresponds to the inner shelf. This research aimed to analyze the dynamics of chlorophyll-a and several other environmental variables. Sampling was undertaken bimonthly on the surface from September 11th to May 10th, thus including the rainy and dry periods, and during low tide in spring tide. The parameters analyzed were chlorophyll-a, salinity, temperature, transparency, dissolved oxygen, oxygen saturation rate, pH, suspended solids, dissolved inorganic nutrients. Phytoplankton biomass ranged from 13.48 to 145.09 mg m-3 in the estuarine area and on the inner shelf, the variation being from 0.24 to 19.29 mg m-3 in the dry season and from 0.78 to 5.20 mg m-3 in the rainy season. PCA showed a direct relationship of chlorophyll-a with ammonia, phosphate and transparency and an inverse relationship with suspended particulate matter and nitrate. Biomass did not vary significantly different as a result of seasonal or spatial dynamics. The estuary of the Capibaribe River is considered highly impacted, and as it forms the Recife port basin, it joins with two more strongly eutrophic water bodies, the Beberibe River and the Pina Basin, leading to an amplification of its influence on the adjacent shelf. In terms of the river plume's dispersion in the Port of Recife, the presence of a dike causes some disturbance in the direction of the current, limiting the plume to the area close to the coast and influences the oceanographic variables on the inner continental shelf.

Uncoupled changes in phytoplankton biomass and size structure in the western tropical Atlantic

“…In the southernmost area of the tropical Atlantic, a preeminence of recycling productivity was previously reported, with the new production representing between 16 and 30% of the total phytoplankton production (Metzler et al, 1997). Our results pointed out a predominance of recycled production, with a conspicuous coast-offshore gradient evidenced by the observed higher Fp in the shelf, J o u r n a l P r e -p r o o f which was double than in other regions, likely due to the influence of the riverine runoffs on the coast productivity (Ekau and Knoppers, 1999;Otsuka et al, 2018). In addition, a significant seasonal increase in the new production was observed in oceanic islands, although, the values remained low and did not surpass 0.09, suggesting a dominance of small cells also in punctual productivity peaks.…”

“…In this region, the variability of phytoplankton biomass has been previously ascribed to the seasonality of riverine nutrient inputs and upwelling events promoted by J o u r n a l P r e -p r o o f the Island Mass Effect and Taylor column effect (Ekau and Knoppers, 1999;Otsuka et al, 2018;Souza et al, 2013). Furthermore, TChl-a concentration in oligotrophic oceans is characterized by seasonal changes that follow the intensity of the mixed layer, thus increasing when the mixed layer is deeper and reaching the nutricline (Mignot et al, 2014;Signorini et al, 2015).…”

Genetic diversity and connectivity of Flaccisagitta enflata (Chaetognatha: Sagittidae) in the tropical Atlantic ocean (northeastern Brazil)

“…PR is inserted in a semi-closed basin, influenced by the coastal dynamics and bounded by a reef line that runs parallel to the littoral (Fig 1) [88]. This reef is a physical barrier capable of constraining the local water turnover ratio, limiting the flow of planktonic organisms outwards the port basin [89].…”

Phytoplankton Productivity and Hydrology in an Impacted Estuarine Complex in Northeastern Brazil

“…Opposite results were recorded by [63] in the estuary of the Jaboatão River, by [64] in the port region of Recife, and by [65] in the Pina basin (values > 100 mg•m −3 ). According to the aforementioned authors, these values indicated strong eutrophication, which was mainly influenced by untreated domestic and industrial effluents released in these ecosystems.…”