Trophic interactions and metal transfer in marine ecosystems driven by the Peruvian scallop Argopecten purpuratus aquaculture

Iván Loaiza,Muriel Gómez‐Sanchez,Marleen De Troch,Juan Alcazar,Diego Campos,María Miglio,Susana Cárdenas‐Alayza,María Ganoza,Gudrun De Boeck

doi:10.1111/jwas.12822

Abstract

AbstractThis study investigates the trophic interactions and As and Cd transfer along seven marine ecosystems in Peru. Five of these ecosystems are driven by aquaculture of the Peruvian scallop Argopecten purpuratus. A southward increased gradient of δ15N was observed among the three examined regions along the Peruvian coast. The stable isotope analysis in R (SIAR)‐stable isotope mixing models helped to clarify the feeding ecology of A. purpuratus and its important predators (e.g., Bursa ventricosa, Romaleon setosum). The food items of A. purpuratus can be ranked in decreasing order of importance: seston > sediment > particulate organic matter (POM) > brackish‐and‐fresh water POM input, while A. purpuratus itself was found to be the main prey item for predators. The highest trophic magnification factors (TMFs) were 1.46 and 1.07 for As and Cd, respectively, and were both found at the location in front of the Illescas Reserve Zone (northern Peru). Metal biomagnification and non‐biomagnification effects were found in the Peruvian marine food webs, but A. purpuratus always fitted the trophic metal magnification or bio‐dilution regression model as intermediate consumer and/or prey. The TMFs and linear metal relationships implied that As contamination is a serious concern in marine ecosystems in Peru.

Highlights

The northern Humboldt Current system (NHCS) is one of the most productive eastern boundary upwelling systems, which leads to one of the highest fish productions worldwide
This study revealed a trend of increasing δ15N and δ13C from food sources to top consumers, by passing through the scallop A. purpuratus
This points at A. purpuratus' crucial role as intermediate consumer and main food item for predators in the studied marine food webs

Summary

Introduction

The northern Humboldt Current system (NHCS) is one of the most productive eastern boundary upwelling systems, which leads to one of the highest fish productions worldwide. Sechura Bay (SB) and Illescas Reserved zone (IRZ) are located in the north (5S) of Peru, in the Piura Region. These ecosystems are at the center of intensive scallop (Argopecten purpuratus) aquaculture. In the proximity of the southern (SL) SB (including IRZ), harbors, anthropogenic and industrial activities such as phosphate factories, the Norperuano oil pipeline, oil platforms, fishery factories, artisanal ports, and the industrial JPQ port are present, while in the northern part (NL) of the bay, fishery factories, artisanal ports, and fishing activities are found (IMARPE, 2007). It is worth noting that the Reserved Zone of Illescas is restricted to the land and the intertidal area, maritime, industrial, and human activities (including fisheries, aquaculture) are not regulated at sea (MINAM, 2010; SERNANP, 2019)

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