Metals in Crawfish - Aquaculture and the Environment: A Shared Destiny - page 210

concentration of 50.9 mg/kg in C. gariepinus and was the most abundant metal in fish; Cu,
with an average concentration of 0.3 mg/kg in O. niloticus , was the least abundant metal.
Biomagnification of most metals in both seasons varied widely from site to site. This was
confirmed by a coefficient of variation from 31 to 144% and 29 to 130% in wet and dry
seasons, respectively. Results showed that fish, crawfish, and sediment can be used to
monitor metal pollution in Nigerian coastal seawater.
Water quality assessment in the Aznalcollar area of Spain was attempted using multivariate
methods based on heavy metal concentrations in red swamp crawfish (Procambarus clarkii)
(Sanchez Lopez et al, 2004). Trace levels of four heavy metals, Cu, Zn, Cd, and Pb, were
detected in crawfish from 11 different stations. Principal component analysis (PCA)
highlighted a gradient of contamination between the sampling stations. Cluster analysis
(CA) distinguished three groups of stations. Discriminant analysis also differentiated three
groups. The group centroids of the first discriminant function were used to devise an index
that varies according to the source of the crawfish. These standardized values are proposed
for use as a water quality index. The ability of this index to successfully predict
environmental quality was proved with random samples.
Contamination of the American red crawfish from the Guadiamar riverside is due to the
disastrous toxic spill that occurred on April 25, 1998, in the mining area of Aznalcollar-Los
Frailes, Spain Sanchez Lopez et al 2003). A high concentration of heavy metals in the waters
from the mine pool and their spill to the River Guadiamar was the cause of the destruction
of a great number of animal and vegetable organisms. An inductively coupled plasma-mass
spectrometry (ICP-MS) method for the total determination of heavy metals (Cu, Zn, Pb, and
Cd) in whole bodies of American red crawfish (Procambarus clarkii) was used. Metals were
extracted from the matrix in a closed-vessel microwave digestion system with nitric acid
and hydrogen peroxide. A study of the uncertainty of the method for the determination of
metals was carried out; at a concentration of 5 mg/L, the uncertainty was below 34%.
10.4 Research from McNeese State University in Lake Charles, Louisiana
Due to a national emergency in the early 1940`s, Southwest Louisiana and Lake Charles was
chosen as a place for petrochemical refining and associated petrochemical industry.
Currently there are about fifty different petrochemical companies in this area. Due to the
lack of or enforced environmental laws and accidental spillage, the area was polluted ,
particularly with selected metals. While this has significantly improved since the 1970`s,
there is still a legacy of contamination. Lake Charles is situated around 50 miles from the
Gulf and can only be reached via a canal. This has to be continuously dredged which
disturbs dormant or at least less accessible metal pollutant. Further complicating this area
was a direct hit from Hurricane Rita in late September 2005 and to a lesser extent Hurricanes
Gustav and Ike in September 2008.
Initial work in this laboratory at McNeese State University in Lake Charles, Louisiana was
started back in 1997 when Dr. Joseph Sneddon was asked by a colleague, Dr. Mary G.
Heagler from the Environmental Sciences Department to assist with the determination of
lead using flame atomic absorption spectrometry with crawfish digestion via classical acid
reflux in the meat of locally caught crawfish (Briggs-Reed and Heagler, 1998). The authors'
data supported the hypothesis that the lead accumulated in the meat or digestive tract as an