Influences of Climate Change and Variability on Estuarine Ecosystems: An Impact Study in Selected European, South American and Asian Countries.

Walter Leal Filho,Ana Lígia Primo,Miguel A Pardal,Filipe Martinho,Mónica Gómez Erache,Chunlan Li,Mustafa Saroar,Gustavo J Nagy

doi:10.3390/ijerph19010585

Abstract

It is well-known that climate change significantly impacts ecosystems (at the macro-level) and individual species (at the micro-level). Among the former, estuaries are the most vulnerable and affected ecosystems. However, despite the strong relations between climate change and estuaries, there is a gap in the literature regarding international studies across different regions investigating the impacts of climate change and variability on estuaries in different geographical zones. This paper addresses this need and reviews the impacts of climate change, variability and extreme weather on estuaries. It emphasises the following: (i) a set of climate parameters governing estuarine hydrology and processes; and (ii) a sample of countries in Asia (Bangladesh), Europe (Portugal) and South America (Uruguay). We reviewed the influences of the climatic drivers of the estuarine hydrology, ecological processes and specific species in estuarine communities across the selected geographical regions, along with an analysis of their long-term implications. The key results from the three estuaries are as following: (i) Hilsa fish, of which the catches contribute to 10% of the total earnings of the fishery sector (1% of GDP), are affected by climate-forced hydrological and productivity changes in the Meghna; (ii) extreme droughts and short-term severe precipitation have driven the long-term abundance and spatial distribution of both fish larvae and juveniles/adults in the Mondego; and (iii) the river inflow and fluctuations increases since the early 1970s have contributed to variations in the salinity, the stratification, the oxygen, nutrient and trophic levels and the spatial pattern for the life stages of planktonic species, fish biomass and captures in the Rio de la Plata. The results suggested that immediate action is needed to reduce the vulnerability of estuaries to climate stressors, mainly the changing river flows, storms and sea-level rise. As a contribution to addressing current problems, we described a set of adaptation strategies to foster climate resilience and adaptive capacity (e.g., early-warning systems, dam management to prevent overflows and adaptive fisheries management). The implications of this paper are two-fold. Firstly, it showcases a variety of problems that estuaries face from changing climate conditions. Secondly, the paper outlines the need for suitable adaptive management strategies to safeguard the integrity of such vital ecosystems.

Highlights

An Overview of Climate Change Trends and Their Impacts on EstuariesRecent studies have revealed that increases in the average global temperature, erratic precipitation regimes and frequent and high-magnitude weather extremes [1,2] threaten the natural environment [3–5]
The assessment of Bangladesh’s climate-related vulnerability in terms of the change in fish capture focused on three components of exposure: (1) sea-level rise (SLR) leading to salinisation; (2) storms and cyclones resulting in an increased height of storm surges; and (3) consecutive wet days causing flash floods and riverine floods [32]
This decline in biodiversity and productivity affects the breeding/spawning ground of the anadromous planktivore Hilsa fish (Tenualosa ilisha), of which the catches contribute to 10% of the total earnings of the fishery sector (1% of GDP), because individual plankters are susceptible to changing hydrodynamics [41–44]

Summary

Introduction

Recent studies have revealed that increases in the average global temperature, erratic precipitation regimes and frequent and high-magnitude weather extremes [1,2] threaten the natural environment [3–5]. Averaged over the mid-latitude land areas of the Northern. Hemisphere, precipitation has increased (high confidence after 1951); for other latitudes, area-averaged long-term positive or negative trends have low confidence [6]. The global mean sea level (GMSL) very likely rose at a mean rate of 1.7 mm yr−1 between 1900 and 2010 and at a rate of 3.2 mm yr−1 from 1993 to 2010 [7]. The average rate of the sea-level rise (SLR) was 1.3 mm yr−1 between 1901 and 1971, increasing to 1.9 mm yr−1 between 1971 and 2006 and further increasing to 3.7 mm yr−1 between 2006 and 2018 (high confidence)

Objectives

Methods

Results

Discussion

Conclusion