Science Serving Maryland's Coasts

Arthur Williams, Presbyterian College

Class Year: 

Project Title: 

Quantifying Growth Variation of Juvenile Blue Crab (Callinectes sapidus) using RNA:DNA in Response to Elevated Water Temperature and Nutritional Rations


The blue crab (Callinectes sapidus) is both ecologically and economically important in the Chesapeake Bay. It supports the most valuable fishery in the Chesapeake Bay and plays a key role in coupling energy flow between the benthic and pelagic ecosystems. As a result, future management is needed to maintain a sustainable habitat quality for the blue crab. To estimate the value of individual habitats, we must be able to estimate the production of blue crab. Yet, currently we lack knowledge on the growth of blue crab. The goal of this project is to evaluate the utility of a biochemical assay of nucleic acid concentrations as an index of growth. Although the amount of RNA and DNA in tissue varies between species, the quantity of DNA is constant in cells, but the level of RNA fluctuates with metabolic activity. This study explored the potential for RNA:DNA ratios to measure crab growth in laboratory settings, based on elevated water temperature and nutritional ration. Data indicated that concentrations of RNA, DNA, and RNA:DNA could be measured with precision. The experimental results showed a growth response to temperature and ration treatment. However, results indicated that the relationship between RNA:DNA and growth was equivocal. Based on these results RNA:DNA does not appear to be a valid index of growth in blue crab.