2.1. Biological material
2.1.1. Animals from the field
Between July 1989 and July 1991, 153 cuttlefish
were collected on 6 dates in the bay of the Seine off
the harbour of Ouistreham (Normandy, France; 49°
20′ N and 0° 15′ E). The age of the animals was
estimated according to the previous works of Medhioub
(1986) and Boucaud-Camou et al. (1991)
using the model of seasonal growth established by
Pauly and Gaschütz (1979). According to their mantle
length (ML), the animals were pooled into estimated
age classes for heavy metal analysis as
follows:
– about 1 week old: 3 pools of 25 individuals (mean
ML=10±1 mm);
– about 2 weeks old: 4 pools of 8 individuals (mean
ML=18±3 mm);
– about 1 month old: 3 pools of 4 individuals (mean
ML=33±4 mm);
– about 2 months old: 4 pools of 4 individuals (mean
ML=59±6 mm);
– about 12 months old (immature cuttlefish): 3 pools
of 5 individuals (mean ML=133±19 mm);
– about 18 months old (mature cuttlefish): 3 pools of 1
individual (mean ML=215±5 mm).
The cuttlefish specimens were immediately frozen
on board and stored at −20 °C. After a short frozen
period (b1 month), each individual was dissected in
the laboratory: the digestive gland and cuttlebone
were removed from the remaining tissues and pooled
to allow metal analyses in minute organs and tissues.
Our sampling of cuttlefish is assumed to represent a
single cohort, at least for the individuals of the first
year.