Differences in Trace Element Content between Non-Indigenous Farmed and Invasive Bivalve Mollusks of the South African Coast

Dmitry F Pavlov,Marina V Frontasyeva,Zoya I Goryainova,Jacques Bezuidenhout

doi:10.4236/ajac.2015.611084

Dmitry F Pavlov, Marina V Frontasyeva + Show 2 more

Open Access

https://doi.org/10.4236/ajac.2015.611084

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Abstract

contents of 23 trace elements (Sc, V, Cr, Mn, Fe, Co, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Sb, I, Ba, La, Ce, Sm, Eu, Hf, Ta) were quantitatively determined in soft tissues and shells of mass non-indigenous bivalve mussels—farmed Pacific oysters (Crassostrea gigas) and farmed and wild invasive Mediterranean mussels (Mytilus galloprovincialis) at the Atlantic coast of South Africa. The study revealed that the contents of the majority of elements in the soft tissues of both species were higher than those in the shells. The tissues of wild invasive Mediterranean mussels contain higher levels of a range of trace elements comparing to farmed mussels. The tissues of Pacific oysters contain much higher levels of almost all elements studied compared to the tissues of Mediterranean mussels. Higher content of zinc in the mussels and oysters from Saldanha Bay may evidence anthropogenic pollution of the bay’s ecosystem by this metal, which necessitates continued monitoring of levels of potentially toxic metals. Both alien species, and especially Pacific oysters, may serve as reliable biomonitors for trace elements in marine ecosystems. Both species are rich in essential elements and provide nutritionally-valuable seafoods.

Highlights

Aquaculture becomes a very important branch of economic activity worldwide
Pacific oyster was introduced to the Knysna Estuary in South Africa in the 1950s with the intention to use them for farming [1]
The contents of rare earth elements (REE) (La, Ce, Sm, Eu), hafnium and tantalum in shells and soft tissues of Mediterranean mussels from both sampling sites were below detection limits

Summary

Introduction

A number of species are propagated at the marine farms in South Africa. The roles of Pacific oyster (Crassostrea gigas) and Mediterranean mussel (Mytilus galloprovincialis) are especially noticeable. Pacific oyster was introduced to the Knysna Estuary in South Africa in the 1950s with the intention to use them for farming [1]. Mediterranean mussel has been commercially grown in Saldanha Bay since 1987 [Van Erkom Schurink and Griffiths, 1990], and the annual yield of mussels (primarily M. galloprovincialis) varies between approximately 500 and 3000 tons per annum [Anonymous, 2001]. Saldanha Bay of the South African Atlantic coast represents an area of intensive mollusk farming: the shellfish farms are covering 345 ha, or about 8% of the entire bay’s area and are playing a growing role for the local economy [3]

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