The sea nettle Chrysaora quinquecirrha has become abundant in the Barnegat Bay estuary and frequently blooms in warm summer months. Various factors have been attributed to the increasing localized appearance of sea nettles and other jellyfish including eutrophication, overfishing, global warming, construction, and species introduction. Despite its abundance and frequent distribution within estuarine systems, very little work has been done to detect and quantify the early life history stages of this organism. Free-swimming larval stages of C. quinquecirrha can be detected and quantified using a quantitative polymerase chain reaction assay specific for the C. quinquecirrha 16S ribosomal (r)DNA locus of the mitochondrial DNA. This assay is species specific, linear over a 9-log range, and can detect as few as 10 copies of 16S rDNA. Twenty-liter field samples were sequentially filtered through 500- and 100-μm mesh to separate ephyra from planula larvae and gametes, respectively. Quantifiable levels of C. quinquecirrha 16S rDNA were detected at all eight paired locations in Barnegat Bay, with levels varying on both spatial and temporal scales. This research is apparently the first comprehensive field-based survey mapping, both spatially and temporally, the early life history stages of a scyphozoan in a major estuary using environmental DNA. Quantitative molecular data on the distribution of early stage C. quinquecirrha may prove useful in both understanding and managing blooms of sea nettles in Barnegat Bay.
- 16S rDNA