Monday, August 30, 2010

Something's Fishy

At the Audubon Center at Francis Beidler Forest, we don't often see the fish in the swamp.  However, in May when dissolved oxygen levels were low in the water, we spied multiple fish species lurking near the surface.  Longnose Gar (Lepisosteus osseus) and Bowfin (Amia calva) were present, but their ability to gulp atmospheric oxygen allows them to survive longer than other fish species in low-oxygen conditions.  Unfortunately, a low-oxygen water is but one of the threats facing fish in South Carolina.

Bluegill (Lepomis macrochirus)

Redbreasted Sunfish (Lepomis auritus)

Spotted Sunfish (Lepomis punctatus)

Warmouth (Chaenobryttus gulosus)

Previously, we have noted that fish in the Coastal Plain, especially in Four Holes Swamp, are contaminated with mercury introduced into environment as a result of burning coal to generate electricity or to power industrial operations.

The Post and Courier reported that an Alligator Gar (Atractosteus spatula) was killed by a bow angler on Lake Wateree.  The fish is not native to South Carolina and was likely placed into the lake.  Although the caught fish was only four feet long and 27 pounds (more the size of the native Longnose Gar), the Alligator Gar can grow to 10 feet and 200 pounds!  Hold on to your children!  In the article, SC DNR's Scott Lamprecht is quoted as saying, "Just one more complication to our ecosystem.  It just creates an ecological disaster."  Sound familiar?  Humans need to stop dumping species into ecosystems that have not co-evolved and generated some checks and balances.  It is why South Carolina made it illegal to transport wild hogs.

Longnose Gar

Now, back to what is in the native fish.  As noted above, mercury is present Coastal Plain fish, which accumulates up the food chain to be deposited into the tissues of the top predators (man, otters, alligators, etc.).  Besides Alligator Gar, Lake Wateree also has a polychlorinated biphenyl (PCB) problem.  PCBs, used in fire retardants and insulators, have been banned in the United States since the late 1970s due to their cancer-causing risk in humans.  However, PCBs spilled or dumped on the land or in the water persist in the environment.  As land is developed, especially around lakes, PCBs can be exposed and carried away with eroded soils.  PCBs will settle into the lake's sediment, but can work up the food chain as sediment-living organisms are consumed by predators which are in turn consumed by larger predators.

Maybe this is a preview of next summer's blockbuster..."Ten feet and 200 pounds of toxic terror!  Alligator Gar of Wateree!"

Images by Mark Musselman

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