Effects of pesticides and metals on penaeid shrimps in Maputo Bay, Mozambique – A field study

Joachim Sturve,Mikael Gustavsson,Per-Olav Moksnes,Daniela C De Abreu

doi:10.1016/j.marpolbul.2021.112964

Joachim Sturve, Mikael Gustavsson + Show 2 more

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https://doi.org/10.1016/j.marpolbul.2021.112964

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Abstract

Estuaries are important nursery areas for many species and these habitats are often affected by anthropogenic activities. We investigate possible negative effects of pesticides and metals on penaeid shrimps in Maputo Bay, Mozambique. Shrimps and water samples were collected in three estuaries and one coastal area for biomarker and chemical analysis. Acetylcholinesterase (AChE) and glutathione-S transferase activities were analysed as biomarkers for pollutants. 37 different pesticides were analysed in water samples and shrimp muscle tissue was analysed for 10 metals. Risk assessment showed that the environmental thresholds were exceeded for several herbicides in three of four of the assessed nursery areas. Lower AChE activities were detected in shrimps captured close to an agriculture area and this location had the lowest shrimp densities. Metal analysis in shrimp showed low levels. Despite localized effects, results highlight the need to improve the regulation of pollutants in the Espírito Santo estuary in Maputo bay.

Highlights

Worldwide, anthropogenic activities affect estuarine and tropical shallow water systems such as mangrove forests
Bembe was originally selected as a reference site based on the low levels of anthropogenic activities in the area, but results suggest that this area is subjected to pesticide pollution
Even if earlier studies (Sturve et al, 2016) and the present results indicate that pesticides to some degree may contaminate the northern part of Espírito Santo estuary, and that the sediment in the same area is polluted by metals (Scarlet, 2015), densities of shrimp were very high in other parts of the estuary

Summary

Introduction

Anthropogenic activities affect estuarine and tropical shallow water systems such as mangrove forests. These impacts range from direct changes in species composition by harvesting and intro duction of exotic species, to physical changes resulting from activities like harbour dredging, streams channelization and land reclamation. Agricultural runoff and urban effluents discharged together with shipping activities contribute with toxic compounds (Khan et al, 2014) including, among others, a wide range of pesticides, polyaromatic hydrocarbons and metals. Mixtures of chemicals can be especially diverse in estuarine areas where aquatic organisms simultaneously can be exposed to chemicals from land-based and marine based activities. The toxicity of metals towards aquatic organisms, including invertebrates, is well documented (Mars den and Rainbow, 2004; Chiarelli and Roccheri, 2014). The most commonly used insecticides worldwide are organophosphates (OP), carbamates and synthetic pyrethroid sub stances (Grube et al, 2011)

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