Stable Isotope Analysis and Persistent Organic Pollutants in Crustacean Zooplankton: The Role of Size and Seasonality

Roberta Piscia,Michela Mazzoni,Roberta Bettinetti,Rossana Caroni,Davide Cicala,Marina Marcella Manca

doi:10.3390/w11071490

Roberta Piscia, Michela Mazzoni + Show 4 more

Open Access

https://doi.org/10.3390/w11071490

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Journal: Water	Publication Date: Jul 18, 2019
Citations: 5	License type: CC BY 4.0

Affiliation: Water Research Institute, National Research Council

Abstract

Zooplankton is crucial for the transfer of matter, energy, and pollutants through aquatic food webs. Primary and secondary consumers contribute to the abundance and standing stock biomass, which both vary seasonally. By means of taxa- and size-specific carbon and nitrogen stable isotope analysis, the path of pollutants through zooplankton is traced and seasonal changes are addressed, in an effort to understand pollutant dynamics in the pelagic food web. We analyzed zooplankton plurennial changes in concentration of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and its relatives (DDTs) and in taxa-specific δ15N signatures in two size fractions, ≥450 µm and ≥850 µm, representative of the major part of zooplankton standing stock biomass and of the fraction to which fish predation is mainly directed, respectively. Our work is aimed at verifying: (1) A link between nitrogen isotopic signatures and pollutant concentrations; (2) the predominance of size versus seasonality for concentration of pollutants; and (3) the contribution of secondary versus primary consumers to carbon and nitrogen isotopic signatures. We found a prevalence of seasonality versus size in pollutant concentrations and isotopic signatures. The taxa-specific δ15N results correlated to pollutant concentrations, by means of taxa contribution to standing stock biomass and δ15N isotopic signatures. This is a step forward to understanding the taxa-specific role in pollutant transfer to planktivores and of zooplankton enrichment in PCBs and DDTs.

Highlights

In lakes, crustacean zooplankton are low-order consumers and represent an important link between the base of the pelagic food web and the organisms at higher trophic levels, which may have economic or conservation value
While heterogeneity of the zooplankton community has been fairly well-documented in basic ecological studies, it is often overlooked in ecotoxicological ones, in models, which are usually focused mainly on sources and top-levels of pollution patterns, the latter being directly related to human health
Protists, monogonont rotifers, Cladocera, and Copepoda contribute to the zooplankton community, the latter with both individuals at their adult stage and a number of developmental stages that are different in size and trophic role

Summary

Introduction

Crustacean zooplankton are low-order consumers and represent an important link between the base of the pelagic food web and the organisms at higher trophic levels, which may have economic or conservation value. While heterogeneity of the zooplankton community has been fairly well-documented in basic ecological studies, it is often overlooked in ecotoxicological ones, in models, which are usually focused mainly on sources and top-levels of pollution patterns, the latter being directly related to human health. It is a crucial step in the flow of pollutants through aquatic ecosystems [2,3,4,5].

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