Effects of salinity on respiration and nitrogen excretion in two species of echinoderms

• Published in: Marine biology 1981-01, Vol.65 (1), p.91-99
• Main Authors: Sabourin, T D, Stickle, W B
• Format: Article
• Language: English
• Subjects: Eupentacta quinquesemita; Marine; Strongylocentrotus droebachiensis
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/BF00397072

The 30-d survival limit of Eupentacta quinquesemita and Strongylocentrotus droebachiensis is 12-13ppt. S. The activity coefficient (1 000/righting time in seconds) of stepwise acclimated sea urchins declined from 16.3 at 30ppt. S to 3.5 at 15ppt. S. Oxygen consumption rates (QO sub(2)) of both species held at 30ppt. S and 13 degree C were highest in June and lowest in December. During the summer, when environmental salinity is most variable in southeastern Alaska, the QO sub(2) of both species held at 30, 20 and 15ppt. S varied directly with salinity. The QO sub(2) of both species varied directly with ambient salinity during a 30-10-30ppt. semidiurnal pattern of fluctuating salinity. Total nitrogen excretion of stepwise acclimated sea cucumbers declined significantly from 30 to 15ppt. S, but there was no salinity effect on total nitrogen excretion in sea urchins. The oxygen:nitrogen ratio of both species indicated that carbohydrate and/or lipid form the primary catabolic substrate. The O:N ratio did not vary as a function of salinity. Both species are more tolerant to reduced salinity than previously reported, however, rates of oxygen consumption and/or nitrogen excretion are modified by salinity as well as season.