An investigation of protein variation in Ulva lactuca and Ulva rigida under high nitrogen culture conditions

In the light of findings that abalone achieve higher growth rates when fed on high protein diets, this study attempts to increase the protein content of two macroalgae under culture conditions. Ulva lactuca and U rigida were grown in saturating NH₄⁺ - N (1 mM) and PO₄³⁻P (70 μM ) concentrations. Of the two, protein levels of U. lactuca showed the greatest increase over time. Natural populations had a content of 3.7 % of dry weight. This increased significantly (p <0.05) to a maximum value of 4.5 % after 8 days growth in nutrient enriched conditions. The protein content of U. rigida increased significantly from 3.3 % to 3.9 % after 6 days of growth in nutrient enriched conditions. An interspecies comparison was made using the intertidal species Porphyra capensis, Ulva capensis and Gracilaria gracilis. The highest protein content was found in P. capensis (11.5 %), followed by U capensis (3.0 %) and G. gracilis (2.7 %). Results indicate the suitability of P. capensis as a high-protein abalone fodder. Furthermore, results suggest that the protein content of abalone fodder may be optimized under aquaculture conditions.

Grantor dc:publisher.institution

Department of Biological Sciences

Year dc:date.issued

2001

Author dc:creator

• Wilkinson, Sarah

Advisor dc:contributor.advisor

• Bolton, John J

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/25786

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/25786