Undergraduate assistants Lauren Schnal, Madalyn Murray (and Mnemiopsis!)

Counting and measuring ctenophores

Frankel scholar (and undergraduate assistant) Madalyn Murray on the RV 'Three Quarter Time'

Jellyfishing

It's been a long, busy summer. "Cteam Ctenophore" (consisting of myself and several undergraduate assistants) has been running weekly plankton tows from the boat in Great South Bay and collecting ctenophores for numerous laboratory 'experiments', such as gut content analysis, growth rates, feeding rates, and egg production. The ctenophores bloomed in late July this year, about 2 weeks later than 2008, which agrees well with a general lag in Long Island waters of 2 weeks likely due to the very cool (and long) winter we had, followed by an unusually cool spring and summer. We ran a few large-scale mesocosm experiments in the bay, until the ctenophores became so abundant they infultrated all of our tanks, including the non-ctenophore treatments! We will continue boat sampling through October to monitor the population dynamics of Mnemiopsis leidyi as well as any other ctenophore species which may appear in the bay. The ctenophores decreased zooplankton abundance very quickly in the bay and subsequently declined in abundance themselves. Once zooplankton abundance increases, we suspect that we may get a second pulse, or bloom, of M. leidyi unless Beroe ovata, a predatory ctenophore that feeds on M. leidyi, arrives as it did in the fall of 2008. Stay tuned....

Rain, rain, go away

As we enter our fifth week of sampling, we have encountered some wet (and potentially dangerous) weather delaying this week's research trip. As we did last week, we do go out in some rough weather (although I prefer the term "adventurous"), but thunderstorms are another thing altogether. So far we have not caught a single ctenophore, although there are reports of the winter/spring sea gooseberry Pleurobrachia pileus in Peconic Bay, which is to our east. This makes sense since we witnessed a dramatic crash in Mnemiopsis at the end of the sampling season in 2008 due to predation by a third ctenophore Beroe ovata. With fewer ctenophores surviving in the bay, it is likely that the seasonal bloom will occur later this year than usual, although the term "usual" is something of a misnomer since Mnemiopsis seems to bloom two to three months earlier in recent years than in previous studies conducted 20 years ago. The waters now are teaming with copepods, a good food source for ctenophores and other gelatinous predators. We have been catching our fair share of the "lion's mane" jellyfish Cyanea capillata, which interestingly enough, also eats Mnemiopsis, and some small hydromedusae. The lack of Mnemiopsis is good news for now, since it gives us time to prepare for the busy experimental season ahead (once they appear). So stay tuned for new updates and photos...

Pleurobrachia pileus and its copepod prey

The "sea gooseberry" Pleurobrachia pileus in Long Island Sound