Date of Award

5-2011

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Richard Fulford

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

James Franks

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Bruce Comyns

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Cultured juvenile blue crabs ( Callinectes sapidus Rathbun) were held for up to 77 days and monitored for survival, growth and development in low salinity water containing various compositions of ions. ~rabs were isolated in separate containers and placed in thirty gallon aquaria containing 2ppt of ion solution. Temperature, ambient, humidity, and nitrite levels were monitored daily. Molts were measured to determine growth, and molt increments were recorded to determine rate of development. The first part of the study compared ratios of sodium chloride (NaCl) to commercial sea salt (SS) in five treatments: 100% NaCl, 100% SS, 25:75 NaCl/SS, 50:50 NaCl/SS, and 75:25 NaCl/SS. The second par! of the study examined mixed ion treatments in water containing solutions of NaCl; NaCl and calcium chloride (CaCl2); NaCl, CaCl2, and magnesium chloride(MgCl2); NaCl, MgCl2, CaCl2, and potassium Chloride 9KCl); and SS. Another set of treatments examined the addition of magnesium sulfate (MgSO4) to the mixed ion solutions. The results of these experiments indicate that acceptable yields of cultured blue crabs (>50% survival) can be achieved in solutions of up to 50% NaCl mixed with commercial sea salt. Mixed ion solutions containing NaCl, MgCl2, CaCl2, and KCl, with or without the presence of MgSO4, initially facilitated survival, growth and development, but delayed growth and development followed by unacceptably high mortality occurred within 12-42 days. A limiting ion or ions has yet to be identified for acceptable survival of juvenile blue crabs in a mixed ion solution.

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