Three sea nettles of ~7-15 cm bell diameter were used in each "with-predator" mesocosm.
In the latter case, the results represented an extreme outlier as compared to all other data (the range for all six other replicates was 39-59% eaten), and we believe that the sea nettles may have been injured during handling.
At the end of each trial, sea nettles were removed with dip nets; bell diameter was measured to the nearest 0.
In order to determine whether the spatial distribution of sea nettles within mesocosms varied in direct response to dissolved oxygen treatments, we measured the position of sea nettles in six replicate mesocosms for each dissolved oxygen treatment.
We tested striped bass at higher dissolved oxygen concentrations than sea nettles because striped bass are less tolerant of low dissolved oxygen concentrations and tend to show at least partial avoidance at concentrations [is less than or equal to] 3 mg/L (Coutant 1985, Setzler-Hamilton and Hall 1991, Breitburg et al.
The short duration was designed to accommodate the higher predation rates of striped bass as compared to sea nettles.
We conducted small-scale predation experiments to determine how low oxygen affects predation by sea nettles on prey with lower swimming speeds (copepods) or with no escape behavior (bay anchovy eggs).
Sea nettles were held in 20-L buckets for 60-90 min before being placed in experimental containers.
To further battle sea nettles, DEP is providing funding for Montclair State University to conduct a research study to identify potential natural predators of sea nettle polyps.
Sea nettles, which are voracious eaters and thrive in nitrogen-rich waters, can be plentiful in these areas.
Property owners in lagoon communities are encouraged to remove floating docks during the winter or clean them using a non-wire scrub brush or by powerwashing manmade bulkheads and docks at and below the high tide line to remove sea nettles.
Sea nettle polyps prefer hard, smooth surfaces such as those found on bulkheads, floating docks, and even trash, said Joe Bilinski, Barnegat Bay Project Manager for DEPs Division of Science, Research and Environmental Health.