Wednesday, August 19, 2009
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....
Wednesday, June 3, 2009
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...
Saturday, May 9, 2009
Sampling season 2009 is underway!
Hello,
It has certainly been a busy winter and spring as the results of our 2008 season are still being analyzed. Hundreds of thousands of zooplankton have been counted and countless Excel graphs have been created. Our 2008 sampling season, however, is only one half of the picture. Data to be collected this year (from May through October) will add to our knowledge of ctenophores and other gelatinous zooplankton in Long Island estuaries. Last year at this time, we experienced a very large brown tide bloom, which likely had a large impact on the plankton dynamics in Great South Bay. Brown tides disrupt the normal ecosystem of marine environments by crowding out other, more nutritious algal species, diminishing the available food for zooplankton and benthic suspension feeders, such as clams and scallops. Brown tide also blocks out light available to the submerged aquatic vegetation resulting in large die-offs of eelgrass in Long Island waters. Although brown tide may not affect ctenophores such as Mnemiopsis leidyi directly, the impact on lower portions of the food web eventually impact the ability of larval and adult Mnemiopsis to feed efficiently and may have offset the timing of the 2008 M. leidyi bloom.
This year, our sampling season began on a cool, cloudy morning, but the waters of Great South Bay were clear with a tinge of green, and full of Acartia copepods - a good food source for M. leidyi. It will be interesting to see when M. leidyi blooms (in abundance) this year since the predatory ctenophore Beroe ovata came in towards the end of the summer and virtually wiped out M. leidyi from our sampling stations in Great South Bay. Since adult M. leidyi over-winter in the bay and serve as a source population for the ctenophore summer bloom, M. leidyi may reach peak abundance later in the season compared to years when B. ovata (which is an oceanic species) has entered the bay the season before.
The water is a cool 13.5 degrees (Celcius) and warming quickly. Our field experiments will soon be underway and I have a new team of eager undergraduates who will be assisting in the project this summer. So stay tuned!!!
It has certainly been a busy winter and spring as the results of our 2008 season are still being analyzed. Hundreds of thousands of zooplankton have been counted and countless Excel graphs have been created. Our 2008 sampling season, however, is only one half of the picture. Data to be collected this year (from May through October) will add to our knowledge of ctenophores and other gelatinous zooplankton in Long Island estuaries. Last year at this time, we experienced a very large brown tide bloom, which likely had a large impact on the plankton dynamics in Great South Bay. Brown tides disrupt the normal ecosystem of marine environments by crowding out other, more nutritious algal species, diminishing the available food for zooplankton and benthic suspension feeders, such as clams and scallops. Brown tide also blocks out light available to the submerged aquatic vegetation resulting in large die-offs of eelgrass in Long Island waters. Although brown tide may not affect ctenophores such as Mnemiopsis leidyi directly, the impact on lower portions of the food web eventually impact the ability of larval and adult Mnemiopsis to feed efficiently and may have offset the timing of the 2008 M. leidyi bloom.
This year, our sampling season began on a cool, cloudy morning, but the waters of Great South Bay were clear with a tinge of green, and full of Acartia copepods - a good food source for M. leidyi. It will be interesting to see when M. leidyi blooms (in abundance) this year since the predatory ctenophore Beroe ovata came in towards the end of the summer and virtually wiped out M. leidyi from our sampling stations in Great South Bay. Since adult M. leidyi over-winter in the bay and serve as a source population for the ctenophore summer bloom, M. leidyi may reach peak abundance later in the season compared to years when B. ovata (which is an oceanic species) has entered the bay the season before.
The water is a cool 13.5 degrees (Celcius) and warming quickly. Our field experiments will soon be underway and I have a new team of eager undergraduates who will be assisting in the project this summer. So stay tuned!!!
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