Composition and abundance of benthic microalgae from the Estuarine Complex of Paranaguá Bay (southern Brazil) with special emphasis on toxic species

Angel Ramón Moreira-González,Luiz Laureno Mafra Junior,Marco Colossi Brustolin

doi:10.1590/s2675-28242020068276

Angel Ramón Moreira-González, Luiz Laureno Mafra Junior + Show 1 more

Open Access

https://doi.org/10.1590/s2675-28242020068276

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Abstract

Abstract This study addressed the occurrence and distribution of benthic microalgae, with emphasis on toxic species, on different substrates (macroalgae, seagrass and sediments) along the outer, euhaline zone of the Estuarine Complex of Paranagua Bay, southern Brazil, from July 2015 to May 2016. Canonical analysis of principal coordinates (CAP) was used to identify the potential environmental drivers of microphytobenthic assemblage structure. A total of 18 potentially toxic benthic microalgae species were reported, including 7 dinoflagellates, 9 cyanobacteria, one diatom and one euglenophyte. The abundance of all potentially toxic microalgae varied consistently along the investigated period. Dinoflagellates dominated the microalgae assemblage in July and September 2015. Mean densities on macrophytes ranged from 33.6 cells g-1 in May 2016 to 775.6 cells g-1 in September 2015, being positively correlated with dissolved nitrogen-nutrients, water transparency, salinity, and chlorophyll-a. Prorocentrum cf. lima was the most frequent and abundant dinoflagellate. Overall, the highest abundance of toxic species occurred in February 2016, when cyanobacterial mats dominated by Lyngbya cf. aestuarii were observed throughout the estuary associated with periods of heavier rainfall and higher turbidity (shallower Secchi depth). At that time, a selected microphytobenthic extract exhibited acute toxicity on nauplii of the brine shrimp Artemia salina in the laboratory.

Highlights

Microphytobenthos (MPB) is represented by phototrophic bacteria and eukaryotic algae, mainly diatoms and dinoflagellates, inhabiting sediment surface, and constitutesSubmitted on: 12/March/2019 Approved on: 7/October/2019 Editor: Rubens M
This study reported the occurrence of potentially toxic benthic microalgae in the Estuarine Complex of Paranaguá Bay (ECPB), southern Brazil, associated with different substrates such as green algae, red seaweed, seagrass and fine sediment
This work confirms the importance of benthic microalgae as primary producers in mud-sand flats of this large, tide-driven estuarine system, where mangrove and phytoplankton producers have received much more attention in past studies on ecosystem ecology

Summary

Introduction

Microphytobenthos (MPB) is represented by phototrophic bacteria (i.e., cyanobacteria) and eukaryotic algae, mainly diatoms and dinoflagellates, inhabiting sediment surface, and constitutesSubmitted on: 12/March/2019 Approved on: 7/October/2019 Editor: Rubens M. Lopes an important component of estuarine ecosystems (Semcheski et al, 2016) These organisms play an active role in the uptake of inorganic and organic nutrients and contribute to the primary productivity of shallow areas as basal components of the food web (Underwood and Kromkamp, 1999; Riekenberg et al, 2017). They produce extracellular polymeric substances (EPS) forming biofilms, which increase sediment stability (Tolhurst et al, 2002). Understanding the patterns of spatial distribution and temporal dynamics of MPB is pivotal

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