Influence of river tide dynamics on phytoplankton variability and its ecological implications in three Brazilian tropical estuaries (Delta do Parnaíba Environmental Protection Area)

ABSTRACT

The Delta do Parnaíba Environmental Protection Area (EPA) represents one of the largest deltaic systems in the Americas. This study investigated the spatiotemporal variability of phytoplankton communities and their correlation with environmental factors and assessed their trophic status and water quality across three mesotidal estuaries (Parnaíba-PRE, Comum-CRE, and Bom Gosto-BGRE) over a year-long sampling period. Multivariate analyses explored the interplay between environmental parameters, phytoplankton communities, and trophic indices. Salinity has emerged as a key determinant in these estuaries. Trophic components influence nutrient dynamics, with Redfield ratios indicating colimitation by orthophosphate (${\mathrm{PO}}_4^{3-}$) and silicate (${\mathrm{SiO}}_2^{-}$). This study identified 355 taxa within the phytoplankton community, with Chlorophyta predominating in the PRE and diatoms dominating in estuaries with relatively high salinities (BGRE and CRE). Environmental drivers vary across estuaries, with temperature, dissolved oxygen (DO), total nitrogen (TN), chlorophyll-a (Chll-a), and the trophic index (TRIX) influencing the phytoplankton community in the PRE, while salinity, ${\mathrm{PO}}_4^{3-}$, total phosphorus (TP), and TN affect the CRE, and salinity and Chll-a influence the BGRE. The Delta do Parnaíba EPA exhibits eutrophic to hypertrophic conditions, emphasising the need for comprehensive environmental monitoring, nutrient management, and conservation efforts to safeguard biodiversity, water quality, and ecosystem health.

GRAPHICAL ABSTRACT

KEYWORDS:

• Microalgae
• trophic indices
• mesotidal estuary
• Brazilian equatorial margin

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Foundation for Research and Scientific and Technological Development of Maranhão – FAPEMA under grant number BM-02181/18 and the Brazilian Federal Agency for Support and Evaluation of Graduate Education– Finance Code 001 (CAPES). The authors thank the Chico Mendes Biodiversity Conservation Institute (ICMBio) for granting authorisation to obtain information from the Parnaíba Delta Environmental Protection Area (SISBIO N° 67397-1).

Notes on contributors

Marco Valério Jansen Cutrim

Marco V. J. Cutrim is a full professor in the Postgraduate Program in Science and Technology at the Federal University of Maranhão, Brazil. He obtained his Ph.D. in Biological Sciences from the University of Sao Paulo, Brazil. His research focuses on the phycology and aquatic ecology of marine and estuarine systems.

Quedyane Silva da Cruz

Quedyane Silva da Cruz is a Ph.D. student at Federal University of Pernambuco, Brazil. Her studies focus on phytoplankton community structure and dynamics.

Denise dos Santos Costa

Denise dos Santos Costa obtained her master’s degree in Oceanography from the Federal University of Maranhão. Her studies focused on the phytoplankton community structure, composition, and ecology of marine and estuarine systems.

Amanda Lorena Lima Oliveira

Amanda L. L. Oliveira obtained her master’s degree in Oceanography from the Federal University of Maranhão. Her studies focused on phytoplankton community structure and composition.

Ana Karoline Duarte dos Santos Sá

Ana Karoline D. S. Sá obtained her Ph.D. in Oceanography from the Federal University of Pernambuco, Brazil. Her studies focused on phytoplankton dynamics and aquatic ecology.

Lisana Furtado Cavalcanti-Lima

Lisana F. Cavalcanti obtained her Ph.D. in Oceanography from the Federal University of Pernambuco, Brazil. Her studies focused on the phytoplankton community structure and water quality of coastal environments.

Andrea Christina Gomes de Azevedo-Cutrim

Andrea C.G. Azevedo-Cutrim is an adjunct professor in the Department of Biology at the University of Maranhão State, Brazil. She obtained her Ph.D. in Oceanography from the Federal University of Pernambuco. Currently, she works with biological oceanography and phycology.

Taiza Pimentel Santos

Taíza Pimentel Santos is a Ph.D. student at Federal University of Pernambuco, Brazil. Her research focuses on plankton dynamics and taxonomy.