Serum ammonium (n=30), was sampled at all stages, but for posttransportation
was restricted to treatments with lids (i.e., ice & lid or lid
only, for both depurated and non-depurated fractions only). Each individual
sampled was considered a replicate. Haemolymph was removed
fromthe adductor muscle using a 21 gauge needle and syringe, and immediately
placed on ice. Samples were centrifuged (10,000 xg; 5 min)
on a portable microcentrifuge (Galaxy, VWR International LLC, USA)
with 100 μL aliquots frozen until further use. The ammonium assay
was performed with modifications on the Indophenol method after
Bolz and Howel (1978) with modifications for a 96 well plate. Serum
was defrosted and deproteinised with an equal amount of 5% TCA.
After further centrifugation, 100 μL of supernatant was diluted 5–20
fold in 3% sodiumchloride solution. To 100 μl diluted serumin triplicate,
50 μL of reagent 1 (phenol 1 g; sodium nitroprusside 5 mg; 50 mL
ddH2O) was added and shaken for 30 s; 50 μL of reagent 2 (sodium hydroxide
0.5 g; sodium hypochlorite 1 mL; 50 ml ddH2O) were then
added and the plate was incubated at 37 °C for 30 min. Optical density
was determined at 635 nm spectrophotometer (Sunrise, Tecan Group
Ltd, Switzerland). Ammonium content of the serum samples were then
calibrated against a standard curve of ammonium chloride (0–1 μg/mL).
For survival and mortality, individual mussels were extracted or
removed from bags after grading, depuration and transport (n= 100)
and 24 h after re-watering (n = 300) and checked for gaping and
death (defined as lack of adductor muscle contraction when tapped,
or shells broken due to physical trauma). Even though mussels with
broken shells are not dead, they are discarded because according to
the quality criteria used by the industry, these mussels are therefore
worthless. Each individual sampledwas considered a replicate. Changes
in biomass (difference in mass, post-transport or post-rewatering)were
calculated as a batch weight (n = 4–8 bags of mussels) weighed on a
bench scale (Ohaus Europe GmbH, Switzerland).