THE USE OF INTRODUCED SPECIES 
(MYTILUS EDULIS) 
AS A BIOLOGICAL INDICATOR OF TRACE 
METAL CONTAMINATION 
IN AN ESTUARY 
D. K. Phelps and W. Galloway 
EPA, Environmental Research Laboratory 
Narragansett, R.l. 02882 
The use of introduced as well as indigenous marine species as biological 
monitors or indicators of water quality is being evaluated at the Environmental 
Research Laboratory, Narragansett (ERLN). This paper presents data that 
demonstrate the edible blue mussel, Mytilus edulis, to be an effective indicator 
of metal pollution when introduced along a gradient of anthropogenic stress. 
M. edulis were collected from a commercially-fished mussel bed in Narragansett 
Bay, Rhode Island, and held in a laboratory seawater system for six days. 
Sub-groups were deployed in polluted and clean sections of that estuary, 
respectively, for a period of four weeks. 
Atomic absorption analyses revealed that M. edulis from the polluted section 
had significantly higher levels of lead, nickel, and copper when compared to 
Mytilus from the clean part of the estuary and those retained in the seawater 
system at the laboratory as controls. No differences were apparent between the 
three groups in the case of cadmium, chromium, vanadium, and zinc; however, 
comparisons between introduced Mytilus and indigenous Mercenaria 
mercenaria, demonstrated Mytilus to be an effective surrogate biological 
monitor for M. mercenaria in the case of lead, nickel, and copper. 
INTRODUCTION 
The area of study is Narragansett Bay, Rhode Island, U.S.A. (Figure 3-1). 
The Bay has been described as “abnormally stressed” by man’s activities in its 
upper reaches, and as being divisible into a polluted upper Bay, a transitional 
zone, and a lower Bay having water of high quality (1). Bottom water salinities 
range 28-31°/oo in the upper reaches, and 30-32°/oo in the lower Bay. 
Temperature seasonally escalates from freezing to 26^C in various sections of 
the estuary. 
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