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Entries in estuary (4)

Saturday
Apr102010

Field locations you have loved

In this thread I want to hear about field locations YOU have loved, and WHY.  Here's a couple of mine to get the ball rolling:

Kedron Brook, Brisbane, Australia.  A choked little stretch of suburban creek on the north east side of Brisbane Australia was a key field location for my PhD research, which was all about introduced (exotic) species and their parasites in rivers and streams in Australia.  At one point just above the tidal influence - stylishly named KB216 for its map reference - this creek is basically completely exotic: plants, invertebrates, fish, the whole shebang.  There aren't many parasites there, but those that were present were introduced hitchhikers.  Not sexy, but a veritable Shangri-La for a student on the hunt for ferals...
Heron Island, Queensland, Australia.  Where I met and fell in love with marine biology.  A patch of sand and guano-reeking Pisonia forest 800m long, on a reef 10 times that size, crawling with noddies, shearwaters, turtles, grad students and squinting daytrippers or more wealthy sunburned resort guests.  Too many firsts for me there to even list (but no, not that one - get your mind out of the gutter!).  Absolute heaven, hands-down.  How do I get back?

Throgs Neck, NY, USA.  You generally wouldn't think of the junction of Queens and the Bronx as a biologically interesting in any way (except maybe on the subway), but actually the western part of Long Island Sound was the epicenter of a lobster holocaust that started in (well, before, if you ask me) 1999.  When we were out on the RV Seawolf, the Throgs Neck bridge marked your entry into the East River and the start of one of the most unique and strangely beautiful urban research cruises around, right down the East side of Manhattan, past the Statue of Liberty and out into the Lower NY bays.  We would pass through on our way to do winter flounder spawning surveys off the beach at Coney Island (its that or go around Montauk).  Proof that not all interesting biology takes place in Peruvian rainforests...

In the comments, tell us about a field location YOU have loved and why.  Post links if you can find them.

Saturday
Mar272010

The ghost of fishers past

The folks you see out on their boats on the bay are not the only ones fishing; those who came before them still get a slice of the action, as this recent article about the retrieval of "ghost gear" from the Chesapeake Bay illustrates.  In many trap-based fishing industries, like lobsters and crabs, a significant number of traps are lost during the course of regular fishing efforts.  In addition, when a fishery turns bad, as happened in the Long Island Sound lobster fishery in 1999, some fishers cut their losses, and their marker floats, quit the fishery and just leave their gear where it is on the bottom of the bay.

The problem is, ghost gear like this keeps on fishing, long after the fisher has moved on to other endeavours.  The design of the trap continues to attract animals, even without bait, because the trap is basically a refuge or cave.  Those that enter are unable to leave and as they die they may act as bait to attract yet more animals to feed on their body.  In this way, the trap becomes a sort of "biomass black hole", sucking in animals from all around, for as long as the trap holds together.  Nets can ghost fish too, especially gillnets or any kind of trawl that can trap fish or strangle a reef

We used to trawl up ghost lobster gear all the time when I was working in Long Island Sound.  Indeed, few days on the water went by without snagging someone's old gear at some point, which speaks to the density of gear that's out there in some inshore waters.  I'm glad the fishers and the resource management agencies are working together to address the problem, because its one of those awful chronic out-of-sight, out-of-mind issues that can erode a fishery despite everyone's best efforts to manage things properly.  If you find ghost gear, call your local DEP or DEC, even the EPA, and let them know so they can come and retrieve it.

Picture of ghost gear on a coral reef from NOAA

Friday
Mar262010

Lionfish - more spectacular than your average invasive, but still a right pest.

When we think of invasive species, flamboyant fish from coral reefs are not usually the first thing that comes to mind.  Indeed, if you put together a list of characteristics of successful invasive species (like this one), "boring" would probably be close to the top, along with being quick to reproduce, not fussy about what you eat, having a large natural range, a great tolerance for extremes in the environment, and lacking natural enemies such as predators or parasites.  Think of some of the most successful invaders and decide for yourself if these predictions hold true: carp, starlings, mosquitofish, rats, sparrows, mice, rabbits, dogs, cane toads, cats, foxes, kudzu, chickweed... 

All this makes the invasion of the Atlantic seaboard by the Pacific lionfish, Pterois volitans, all the more remarkable.  Lionfish are flat-out spectacular!  Long prized as an aquarium specimen, they have bold stripes that spill over onto their fantastically long and showy fins; their scientific name even means "fluttering wings".  The sheer beauty of lionfish doubtless plays a role in how they came to invade the Atlantic in the first place; most likely they were an escaped or released aquarium species that found itself able to survive quite nicely in the conditions of the coastal Atlantic.  The beauty of lionfish conceals a dangerous secret - venomous spines on their dorsal (back) and pelvic (bottom) fins.  While they won't kill a person; they cause excruciating pain.  I've never been stung by one, but I have been stung by related scorpionfish (most recently the short-spined wasp fish) and the feeling is not one I'd care to go through again!

Over the course of just a few years, mostly since 2000, lionfish have spread dramatically along the coast of the Atlantic, from North Carolina down to the southern Caribbean and Mexico's beautiful Yucatan peninsula.  Typically considered to be a rocky or coral reef species, they've now been found swimming in the intracoastal waterway; that labyrinth of salt-marshes, channels and estuaries, engineered to allow safe passage of boats along the US coast in wartime.  This is sort of an unusual location, but it speaks to the adaptability of this remarkable fish.

So, what to do about such an animal??  Well, that's a tough one.  Invasive species (or more accurately, moving species around) are one of the greatest impacts humanity has had on natural environments, and there are very few cases where we have successfully eradicated or controlled an invasive (but see prickly pear in Australia), more often they just become part of the furniture and we get used to their impacts on the local ecosystem.  Introducing natural enemies (diseases, predators) like they did for prickly pear is a dangerous game; if you tried to get the Cactoblastus moth introduced to Australia in these days of stricter biosecurity, you'd almost certainly be denied.  You can easily get into a "spider to catch the fly" situation too; in fact that's how cane toads were introduced to many places - to control sugar cane beetles (which they suck at).  Perhaps the best approach is to do what we do best - create a market that will promote human efforts to exploit them, and then rely on the Tragedy of the Commons to do the work for you.  This has already been proposed with Asian carp.  Fortunately, it turns out that lionfish are not only spectacular aquarium fish, but also delicious in a white wine sauce.  I am sure that if we set our minds to it, we could do as good a job wiping out this species as we have with so many others.  So c'mon everyone and grab a fork; Save a reef - eat a lionfish, today!

(Photo and graphic from NOAA)

Monday
Mar222010

Fish as filters?

ResearchBlogging.org There's been a bit of press lately (see for example) surrounding a new paper from VIMS that concludes that the Atlantic menhaden or Bunker (Brevoortia tyrannus) is not very good at cleaning the Chesapeake Bay.  This seems an odd sort of paper but its actually not that crazy an idea.  Its turns out that lots of bivalve species like hard clams and soft clams actually pump enough water through their gills, sifting food as they go, that they can actually have a significant impact on the water clarity and nutrient content of the water.  Indeed, the zebra and quagga mussels that have invaded the Great Lakes have changed the entire ecosystem by doing exactly that.  With clearer water, there's less plankton productivity in the water column and more macrophytic plants and algae growing on the bottom.  Menhaden are filter feeders too, and they can occur in large schools, so perhaps its logical to think that they might be able to do the same sort of thing as the clams.  Alas, based on the VIMS experiments, it seems that they can't.

This is an interesting example of a negative result publication.  Often times you'll hear folks say we shouldn't publish negative results because, technically, you failed to prove that they clean the water, which is not the same as proving that they don't.  Well, as long as everybody is aware of that distinction, I still think negative results like that are useful to know, for two reasons.  One, its likely that they don't; if they do, then the effect is so minor that it was difficult to detect.  And two, it might save someone else from having the same idea and trying the same futile experiment.

The Chesapeake has some sporadic problems with hypoxia, which is ultimately a nutrient pollution issue, so I applaud the researchers for looking at a biological solution for what is otherwise a pretty intractable problem.