2.1. Clam collection and maintenance
Clams (approx. 100) were collected in February 2019thfrom a sampling site H45 located in the Gulf of GdaĆsk (southern Baltic
Sea) at 45m depth. The selected area has been reported to have the
highest prevalence of DN in L. balthica , as described in: Smolarz
et al. (2005bd) and Ogrodowczyk (2017) (Fig. 2.1 ). Clams
exceeding 10 mm in size (large enough for haemolymph withdrawal) were
selected from the sediment samples collected with a Van Veen grabber on
board of the rv Oceanograf. Transport and laboratory set-up were
adjusted to imitate in situ conditions. Bivalves were kept in 15
L tanks (approximately 50 clams per one tank) filled with seawater
collected at sea bottom from the sampling site for time not exceeding
five days. No sediment substrate was added to tanks with animals for
purification purposes.