The weirdness of 2012 continued

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This has been a bizarre year in the Gulf of Maine. A short time ago, Andy wrote an entry on the warm water anomaly in the Atlantic that has occurred this year.  It has been a basin-scale event that we'll probably be analyzing for many years to come. As I compose this entry, people are seeing all kinds of strange things up and down the coast of Maine.

In early November, there were reports of seahorses washed ashore and caught in traps in southern Maine. These charming fish are quite rare in the Gulf of Maine, with only a few reports off the Scotian Shelf. Initially, I suspected a connection with hurricane Sandy, or perhaps a warm-core ring. Earlier this week, however, I heard reports of seahorse sightings throughout the summer in midcoast Maine.

In October, I was out sampling with a group of Bowdoin students.  I had hoped to show them the wonders of copepods--an important lesson for all aspiring oceanographers.  However, our zooplankton samples were mysteriously devoid of them.  We even ran some 10-micron-filtered samples through a FlowCAM, and didn't see a single nauplius.  Instead, net after net came to the surface with voluminous orb-shaped ctenophores.


Ctenophore01.jpg

This beroe sp. was almost as large as my fist. The ecosystem we observed, with its large ctenophores and inscrutable lack of copepods, was quite different from what I had expected. Recently, I have heard reports of these large ctenophores throughout Casco Bay all autumn.

The question remains as to how significant these anomalies are.  Gelatinous species, like ctenophores, can bloom suddenly then vanish.  They can also settle in for the long term and dramatically reshape the ecosystem, as Mnemiopsis leidyi famously did in the Black Sea. Some ecologists have even forecast a "jelly ocean" following the collapse of global fisheries.  The basic idea is that gelatinous species out-compete fish for crustacean prey.

The "jelly-ocean" prediction is a debated one, as there are huge gaps in our knowledge of gelatinous species. They are undersampled, and there is much we don't know about them. Most models don't account for them, and they even thwart some the underlying assumptions in ocean ecosystem theory, such as the nice trophic size structure of marine ecosysems (that is, large eats small). For example, as you can see in the image below, ctenophores like beroe can be prey for tiny crustaceans.  We are even still discovering new families in the Gulf of Maine (see Pages et al. 2006, Scientia Marina). 

PagesEtAl.jpg

These changes often occur more quickly than we can understand or even sample them.  Keep your ears peeled for other strange happenings, and unexpected visitors.  And we encourage you to let us know what you happen upon.  We'll need many eyes on the sea if we hope to solve this puzzle.
  
-Nick Record, signing off


3 Comments

Seasoned biologists were apparently shocked by the lack of deep-dwelling dormant copepods throughout the Gulf of St-Lawrence during this fall's DFO monitoring cruise. I think 2012 may be the negative of the famous 1999 boom year in the North-West Atlantic...

Other unusual animals reported this summer and fall:
-sperm whales in the Bay of Fundy
-lots of squid in the Gulf of Maine
-salps in the Maine Coastal Current this fall

Comment emailed from Andrew Allyn:
I hope all is well. I just read Nick Record's recent blog post about the abundance of ctenophores this fall and your comment about other unusual observations in the Gulf of Maine. I wanted to chime in from the seabird angle, but had trouble logging in to post a comment. In "Fishes of the Gulf of Maine," Bigelow and Schroeder suggest that ctenophores are a primary food item for juvenile butterfish. At the monitored seabird colonies, observing large numbers of butterfish being brought to seabird chicks is generally a bad sign. Many of these seabirds have historically favored prey species such as herring and hake; large numbers of butterfish being brought back to the colonies suggests that these prey may not be available. The butterfish are so wide that small tern chicks are unable to swallow them, and in turn we see starvation and very low productivity rates. This past summer, however, was a very good year for seabirds throughout the Gulf of Maine. Forage watches documented a large number of herring and hake being brought back to chicks and productivity rates were relatively high (~ 1 chick fledged per nest). These observations are very interesting in the context of the SST anomaly map you showed, as well as Nick's observations. Prior to seeing the seabird colony monitoring results, and given your observations, I would have predicted a poor food and productivity year for the birds.

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About this Entry

This page contains a single entry by Nick Record published on November 19, 2012 3:32 PM.

Celebrating 10 years of Québec-Océan was the previous entry in this blog.

Bottom up vs. top-down or why the best evidence of bottom-up forcing is in Frank et al. 2005 is the next entry in this blog.

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