Use of RNA:DNA ratios for assessing secondary production of
planktonic food webs effects of temperature, salinity, food and
heavy metals / Abstract (Summary)Acartia tonsa is a dominant
copepod in coastal waters and is an important link in the food
web between microplankton and higher trophic levels. RNA:DNA
ratios have been used to describe growth and nutritional
condition of field collected copepods and to show strong
correlation between group egg production and RNA:DNA ratios. A
method was developed using a sensitive, nucleic acid fluorescent
dye and automated microplate fluorometer to measure RNA, DNA and
RNA:DNA ratio of individual A. tonsa. RNA, DNA, RNA:DNA ratios
and egg production were all significantly higher in copepods fed
Thalassiosira spp. compared to starved copepods. There was a
general trend toward an increase in RNA:DNA ratios with increase
in egg production, but due to the high degree of variation in
both RNA:DNA ratios and egg production of individual copepods no
significant correlation bet