Measurement of copepod predation on nauplii using qPCR of the cytochrome oxidase I gene
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A method to directly measure predation rates by older stage copepods upon copepod nauplii using species-specific primers for the mitochondrial cytochrome oxidase subunit one gene (mtCOI) and real-time quantitative PCR (qPCR) was developed. The general approach is to determine the mtCOI gene copy number of an individual prey organism and the copy number of the same gene in the stomachs of predatory copepods collected in the field. From the knowledge of DNA disappearance rates in the stomachs, ingestion rates can be calculated. In October 2006, laboratory experiments were carried out with Acartia tonsa N1 and N2 as prey and adult female Centropages typicus as predator. The copepods were collected in Narragansett Bay, USA. A. tonsa mtCOI copy numbers copepod−1 were determined for stages N1–C1 and for adults. A. tonsa DNA was detectable in the guts of the predators for as long as 3 h. Exponential rates of decline in prey DNA from the stomachs of the predators are similar to those measured for gut pigments. Because of the very small amount of DNA in an individual N1 or N2 nauplius, procedures were developed to maximize the quantitative extraction and recovery of DNA and to increase the sensitivity of the method. Two quite divergent haplotypes of A. tonsa were found in Narragansett Bay, which required separate qPCR primers; one was present in summer (July) and the other in fall and winter (October and February). With modification, the methods in this study can likely be applied to a range of predator–prey systems.
KeywordsPhytoplankton Microcentrifuge Tube Disappearance Rate Digestion Rate Naupliar Stage
We wish to thank the URI GSC Center for making their facilities available to us. This research was supported by NSF and NOAA.
- Durbin EG, Campbell RG (2007) Reassessment of the gut pigment method for estimating in situ zooplankton ingestion. Mar Ecol Progr Ser 331:305–307Google Scholar
- Folmer O, Black M, Hoeh W, Lutz R, Vrijenhoek R (1994) DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Mol Mar Biol Biotechnol 3:294–299Google Scholar
- Hebert PDN, Cywinska A, Ball SL, JdeWaard JR (2002) Biological identifications through DNA barcodes. Proc Roy Soc B 02PB0653.5Google Scholar
- Mauchline J (1998) The biology of plankton copepods. Adv mar biol vol 33 Academic, San DiegoGoogle Scholar
- Ohman MD, Sullivan BK, Durbin EG, Runge JA (2005) Relationship of predation potential to mortality for Calanus finmarchicus on Georges Bank, N.W. Atlantic. ASLO Summer Meeting, June 2005Google Scholar
- Popels LC, Cary SC, Hutchins DA, Forbes R, Pustizzi F, Gobler CJ, Coyne KJ (2003) The use of quantitative polymerase chain reaction for the detection and enumeration of the harmful alga Aureococcus anophagefferens in environmental samples along the United States East Coast. Limnol Oceanogr Methods 1:92–102CrossRefGoogle Scholar