SALINITY INFLUENCES BODY-WEIGHT QUANTIFICATION IN THE SCYPHOMEDUSA AURELIA-AURITA - IMPORTANT IMPLICATIONS FOR BODY-WEIGHT DETERMINATION INGELATINOUS ZOOPLANKTON
Ag. Hirst et Ch. Lucas, SALINITY INFLUENCES BODY-WEIGHT QUANTIFICATION IN THE SCYPHOMEDUSA AURELIA-AURITA - IMPORTANT IMPLICATIONS FOR BODY-WEIGHT DETERMINATION INGELATINOUS ZOOPLANKTON, Marine ecology. Progress series, 165, 1998, pp. 259-269
Comparisons are made between bell diameter:weights (wet, dry, ash-free
dry, ash and elemental) relationships for the scyphomedusa Aurelia au
rita (L.). There are significant differences in the relationships betw
een bell diameter and dry, ash-free dry and ash weights at different s
alinities, with these weights increasing as the ambient salinity incre
ases. These trends are attributable to differences in the quantity of
both bound water (i.e. 'water of hydration') and ash content, both of
which vary with the size of medusae. Dry, ash-free dry and ash weights
change rapidly as the salinity of an individual's environment alters,
and these changes are associated with changes in the individual's buo
yancy. Unless salinity effects are appropriately considered, significa
nt errors may arise in the quantification of the biomass, production,
and other weight-dependent measurements of A. aurita. Similar errors a
rise in other gelatinous organisms, and studies of such groups must ma
ke allowances for these effects.