​Measurement of Trace Metals in Crustacea and Bivalve Molluscs in Support of the MV Jambo Environmental Monitoring Programme

Summary

Fisheries Research Services
McIntosh, A ; Devalla, S; Robinson, C; Davies, I

As part of the monitoring programme following the cessation of the recovery of the zinc sulphide cargo from the MV Jambo, samples of scallops (Pecten maximus) and the edible crab (Cancer pagurus), from sites near to (Black Rock and Tanera Beag) and remote from (Sgeirean Glasa and Horse Island) the wreck site (En a’ Char) in the Summer Isles, were collected in February 2005 by the Fisheries Research Services Marine Laboratory (FRS ML) on behalf of the Food Standards Agency (Scotland) (FSA(S)). Trace metal concentrations were determined separately and individually in whole tissue and gonad in scallops and the white and brown meat from crabs. Jambo location. Combined Summer Isles concentrations in whole scallops were similar to those found in an offshore reference location, NM12. These data are consistent with no zinc contamination from the MV Jambo

Zinc concentrations determined in whole scallop tissue were similar at sites within the Summer Isles near to, and remote from, the Jambo location. Combined Summer Isles concentrations in whole scallops were similar to those found in an offshore reference location, NM12. These data are consistent with no zinc contamination from the MV Jambo.

Notwithstanding the above, concentrations seen in whole scallops (near and remote sites combined) were significantly lower in 2005 than in 2004.

There was no significant difference between the zinc concentrations determined in scallop gonad tissue at the near and remote sites and the zinc concentrations determined in scallop gonad tissue from NM12 in January and February 2005. In addition, there was no difference in concentrations seen in scallop gonad tissues (near and remote sites combined) between 2005 and 2004.

There were no significant differences in zinc concentrations determined in white or brown crab meats from sites in the vicinity of the wreck. Concentrations were not significantly different from those found in the previous monitoring period.

There was no significant difference between the cadmium concentration determined in whole scallop tissue from the near and remote sites and the cadmium concentration determined in equivalent tissue from the offshore reference NM12 in January and February 2005. Cadmium concentrations in scallop gonad tissue from both near and remote sites showed a marked reduction in February 2005 compared to the previous monitoring period but the cadmium concentrations in scallop gonad tissue at the near sites remain greater than the scallop gonad cadmium concentrations from the offshore reference station, NM12.

Concentrations of cadmium in whole scallop tissue from all sampling locations exceeded the EC Regulation (221/2002/EC) limit of 1.0 mg kg-1. Concentrations in scallop gonad tissue did not exceed this limit. Measurement of Trace Metals in Shellfish in Support of the JAMBO monitoring programme.

Cadmium was barely detectable in crab white meat but was higher in crab brown meat. The EC Regulation (221/2002/EC) does not apply to the brown meat of crab.

There was no significant difference between the lead concentration determined in whole scallop tissue from the near and remote sites and the lead concentration determined in equivalent tissue from the offshore reference NM12 sample station in January and February 2005.

The lead concentration in scallop gonad tissue from the near sites in February 2005 was significantly greater than equivalent tissue from the remote sites.

The concentrations of lead in both whole scallop and gonad tissues showed a significantly marked reduction at both near sites in February 2005 compared to those sampled over the previous monitoring period.

Concentrations of lead in scallops were all less then the EC Regulation limit of 1.5 mg kg-1.

Lead concentrations in crab white and brown meat were, with one exception, below the limit of analytical detection (0.087 mg kg-1 wet weight tissue).

The concentrations of arsenic determined in whole scallops sampled in February 2005 were significantly lower at all sites compared to the previous monitoring period, except at Horse Island. The arsenic concentration in scallop gonad tissue in February 2005 was significantly lower than over the previous monitoring period, October 2003 to January 2004, at the Horse Island location only.

No spatial or temporal differences in arsenic concentrations were seen in the crab meats.

Project Code: S02023