Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Adult intermolt blue crabs (Callinectes sapidus Rathbun) were stepwise acclimated to salinity at 22-25(DEGREES)C. Respiratory and circulatory responses were investigated in steady state salinity (5, 10, 20 and 30('o)/oo), diurnally fluctuating salinity (30-10-30('o)/oo, 10-30-10('o)/oo), and during 24-h exposure to water-soluble naphthalene at 0, 37.5% (0.9 ppm) and 75% (1.8 ppm) of the 24-h TL(,m) in a flow through system at 10 and 30('o)/ooS. No steady state salinity-related differences occurred in ventilation volume (V(,w)), oxygen extraction efficiency (E), oxygen uptake (VO(,2)), heartbeat frequency (F(,H)), stroke volume (SV), cardiac output (Q), post- and prebranchial oxygen tensions (PAO(,2), PVO(,2)) and oxygen contents. Protein and copper concentrations, pH and in vitro hemolymph P(,50) were higher in crabs at 10('o)/oo than at 30('o)/ooS. Responses to salinity fluctuation were affected by acclimation salinity. During 30-10-30('o)/oo fluctuations little change occurred in blood flow and oxygen content. V(,w) and VO(,2) changed inversely with salinity. PAO(,2) and PVO(,2) and hemocyanin oxygen affinity decreased. Salinity fluctuations of 10-30-10('o)/oo elicited decreased F(,H), SV and Q as salinity was increased from 10 to 30('o)/oo. After 96-h of fluctuation, mean F(,H), SV and Q were slightly elevated over 0-h controls. Percent oxygen extraction, VO(,2), blood O(,2) tension and content decreased during 10-30-10('o)/oo fluctuations, while hemocyanin O(,2) affinity remained constant. Protein and copper concentrations were unaltered during 96 hours of salinity fluctuation, regardless of direction. No salinity related difference existed in the TL(,m) of blue crabs. exposed to naphthalene. The pooled salinity 24-h naphthalene. TL(,m) was 2.4 ppm. Responses to naphthalene differed with. acclimation salinity. Crabs at 10('o)/ooS exhibited increased V(,w), VO(,2). and prebranchial pH, and decreased hemolymph O(,2) tension in 37.5. and 75% TL(,m). SV, Q and body water increased, while hemolymph. osmolality decreased 55-76 mOsm during exposure to 75% TL(,m) -. 10('o)/ooS. In vitro oxygen affinity was increased at 37.5 and 75% TL(,m). at 30('o)/oo and 37.5% TL(,m) at 10('o)/oo. C. sapidus at 30('o)/oo had. increased V(,w), VO(,2), F(,H), SV and W, and decreased PAO(,2) and PVO(,2). during exposure to 37.5 and 75% TL(,m) of naphthalene. Dose-. dependent alkalosis occurred in hemolymph of blue crabs. acclimated to 30('o)/ooS.