Constructed wetlands...part 4

As I mentioned the other day, we've found 13 different frog and toad species that have colonized the constructed H-02 wetlands on site. So far no salamander species have shown up. We also have seen several snake species including garter snakes and banded water snakes (shown in photos). I've also seen marsh hawks hanging around and we usually see a good number of red winged blackbirds. I hadn't realized how many until we went to the wetlands the other night and as we walked around we were blown away by how many birds were in the bulrush in the wetlands. Literally had to be over 1,000 red-winged blackbirds. There have also been some ducks and quite the surprise this summer a juvenile alligator showed up for a while. It's clear that the wetlands have attracted a lot of wildlife, now our job is to figure out whether the habitat is ok for amphibian reproduction or whether it is an ecological trap. We've started looking at this question for three species: the southern leopard frog, the eastern narrowmouth toad, and the southern toad. Next we'll start talking about those studies.

Constructed wetlands....part 3

Mass of Eastern narrowmouth toads-

Southern toads-photos by D. Scott

As I mentioned the other day we've been studying some of constructed wetlands on the SRS.  One of the first goals was to see what species of amphibians would colonize the wetlands.  The wetlands are only 4 years old but we've seen quite a few species there.  Most often we see southern leopard frogs, bullfrogs, green frogs, southern toads and eastern narrowmouth toads---and we know that all of them have successfully reproduced there.  Less often we also see green treefrogs, barking treefrogs, squirrel treefrogs, cricket frogs, and Eastern spadefoot toads.  Check out the links for each species to see photos and hear their calls!  Of these species we have started studying southern leopard frogs, southern toads, and narrowmouth toads in detail. 

Constructed wetlands....part 2

The H-02 constructed wetlands were built in 2007.  This image shows the basic arrangement.  The water from the industrial facility first enters the retention pond then it goes to one of the two cells--the actual constructed wetlands that take the metals out of the water.  In this view the water enters the right end of the cells and exits the left side.  One of the major goals we have is determining if the wetlands may be "ecological traps" or "population sinks" for amphibians.  The concern is that adults would be attracted to the wetlands to breed--because they offer permanent water without fish--but then b/c of the high metal concentration the habitat may actually not be suitable for eggs and/or larvae to develop.  If that is the case reproductive success would be lowered and they would be considered a trap or sink and could have a negative effect on populations.  To start to look at this one of the first things SREL did was put in a partial drift fence in the woods just beyond the wetlands.  Just like the other drift fences we talk about with pitfall traps on both sides.  With the drift fence we can see what species of amphibians colonize the wetlands and then also see what metamorphs leave the wetland.  So far we've already seen 13 species come into the wetland!  We'll introduce those in the next entry.

Constructed wetlands....part 1

Given that we still aren't having much in the way of rain or amphibians I've decided to introduce the H-02 wetland system and will then spend a few entries talking about them and what we've got going on there.  Constructed wetlands can be used to prevent contaminants from getting into the rivers and streams.  At one spot on the Savannah River Site the storm water and process water coming out of an industrial facility was found to have too much copper and zinc, more than the EPA allows.  In 2007 a constructed wetland was created to remove the metals from the water.  The metals stick to the clay particles and organic matter (bits of dead and decaying plants and animals) and a suite of bacteria help move the metals from the water to the soils.  The H-02 wetland on site does a great job of this, by the time the water leaves the wetland and heads into to the stream system most of the zinc and copper are removed.  Just another way wetlands rock.  The wetland also tends to attract amphibians because it's a permanent body of water without fish.  Many amphibian species can't reproduce where fish live--the fish eat them--so the constructed wetland is pretty attractive.  The Savannah River Ecology Lab has been studying many aspects of the H-02 wetland since it was built.  over the next series of entries I'll start sharing the different work we've been doing and what we've learned from these wetlands. 

Turkeys everywhere!

Made it out to Rainbow Bay today and as we pulled up there we were greeted by a whole bunch of turkeys!  Probably about 15 or so that were moving over the drift fence into the (still dry) bay.  Unfortunately they were quicker to get away than I was to get a good  photo.  Tried to follow them through the bay but they cruised directly through to the other side, over the fence and off into the woods.  Walking around the inside and outside of the bay everywhere I looked there were signs of turkeys.  Looks like that group had been there a while rooting around in the leaf litter.  The picture on the bottom is my lame attempt to show what that looked like.  Basically it looked like the whole area had been ransacked by someone desperately trying to find something they lost in the leaf litter. 

We get a lot of wild turkeys on site.  In fact the population here is so strong is has been used as the source population of reintroductions of turkeys all over the southeast.  It is really common to see them while driving across site, but today it was great to be more up close and personal.

Icy bay

We got hit by a snow/ice storm on Sunday.  Very unusual for here--especially since we've already had snow here once this winter.  Ended up getting about 3 inches of snow then a day of freezing rain.  Not much compared to many parts of the country, but shuts everything down around here--seriously, everything.  Most importantly, it clearly shut down the amphibians.  Haven't seen anything at Rainbow Bay, not even the occasional juvenile bullfrog that we seem to get almost every day.  Hard to believe it was so warm the snakes were out just a bit ago!  Not even seeing inverts in the buckets now.    At least it's more water!  Still hoping the bays  may fill on site in February so the winter breeders will have a shot.  Have some research that depends on it so I need rain!

To stay in the wetland or hit the woods???

This lack of wetlands to play in is getting old.  Raining a little tonight and we actually have a winter weather advisory in place for Monday--not typical SC weather.  Anyway, since I knew Bay 100 had some water (see post from 12/1/10) a couple of us went there the other day to see what we kind find.  Neither of us had every explored that bay for amphibians so we weren't sure what would be there.  We ended up finding a decent number of paedomorphic mole salamanders (Ambystoma talpoideum).  Around here mole salamanders breed in the winter and the offspring can follow one of two life history paths.  On one path they develop and metamorphose in the spring, head out to the woods, and then return to the wetland the next year (or later) and breed.  The other option is to stay in the wetland for another year and develop their reproductive characteristics while still looking like a larvae (this is the basic idea of paedomorphosis--when adults retain juvenile characteristics), get a head start on breeding the next year and then metamorphose and leave as one year olds.  This is only an option if the wetland holds water through the summer.  Must be that Bay 100 held water all summer b/c we found a good number of these paedomorphic mole salamanders.  Take a look at the two photos--on top you have a metamorph that developed directly into the terrestrial form last spring and then the paedomorphs below---note they still have gills for their aquatic life.  Nature remains very cool.  Thanks to David Scott for the great photos.

Marbleds heading out, moles trickling in

Thought it would never happen again but it rained!  And warmed up! I think it reached 70 yesterday and was in the mid-60's today, with some nice rain overnight.  Seemed like it was just what the marbled salamanders were waiting for since several hundred of them left Rainbow Bay last night.  Brought 15 large bins of salamanders back to the lab--now they'll be "processed" (measured and photographed) and then we'll release them on the other side of the fence and we won't see them again until next fall.  A lot of the ones leaving today were females which means they've abandoned their nests this year.  Their eggs won't hatch until the bay finally fills, but who knows if that will even happen this winter!  The nests don't fare as well without the females there, but it gets to a point where the females seem to need to cut their losses and go forage and get ready for next year.  As the marbled salamanders were leaving the mole salamanders (Ambystoma talpoideum) were starting to come into the bay.  Just a few, probably about 10 or so came in today.  Too bad there's no water in the bay so they won't be able to breed yet.  Anyway, was great to have some action at the bay---oh and at H-02 wetlands there was a small banded water snake in a bucket, then when I got home a garter snake on my deck.  Guess everything was enjoying the change in weather!