Shifts in Estuarine Macroinvertebrate Communities Associated With Water Quality and Climate Change

Thomas Goulding,Catarina Freitas,Paula Chainho,Gilda Silva,José Lino Costa,João Paulo Medeiros,Frederico Carvalho,Pedro M Sousa,Nuno Lopes,Inês Metelo

doi:10.3389/fmars.2021.698576

Abstract

The present work aims to identify changes in the macroinvertebrate community of the Tagus estuary (Portugal) due to improvements in water quality and to climate change. Data was collected over a period of 16 years (1998–2014) from different sites located along the estuarine gradient. The AZTI Marine Biotic Index (AMBI) was used to assess the ecological quality status based on benthic invertebrate communities and identify possible variations associated with changes in water quality. The overall distribution of each species was examined to detect possible changes associated with climate, based on species’ affinity for more temperate or subtropical climates. Results demonstrate that there was an overall improvement of AMBI scores during the assessment period. The analysis of the geographical distribution of benthic species seems to indicate that there has been an increase of species which prefer subtropical climates in the shallower waters of the estuary, whereas in the deeper estuarine sections the propensity is for species that prefer temperate climates.

Highlights

By straddling the transitional point between rivers and the oceans, estuaries play an essential role in nature and provide a wide variety of essential ecosystem services (Savage et al, 2012; Layman et al, 2014; Gittman et al, 2016)
Two types of data were obtained: time series that correspond to yearly samplings in Porto Buxo (PB); Portinho da Costa (PC); Parque das Nações Subtidal (PNS); and Parque das Nações Intertidal (PNI) but are spatially restricted; and spatial series which is restricted to two years (2003 and 2014) but whose sampling stations span the estuary consisting of Estuary Middle (EM), Estuary Bays (EB), and Estuary Lower (EL) (Figure 1)
The whole estuary data for 2003 and 2014 indicated that there was an improvement in the ecological status over that period with AZTI Marine Biotic Index (AMBI) values decreasing in different estuarine habitats (EM, EB, and EL)

Summary

Introduction

By straddling the transitional point between rivers and the oceans, estuaries play an essential role in nature and provide a wide variety of essential ecosystem services (Savage et al, 2012; Layman et al, 2014; Gittman et al, 2016). Due to these ecosystem services and sheltered nature, estuaries have attracted human settlements since prehistoric times (López-Romero et al, 2021). These settlements have evolved into great metropolises where millions of people live and work This rapid urban development in conjunction with the accompanying agricultural and industrial advances puts enormous pressure on estuaries (Lemley et al, 2017).

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Conclusion