Wander With Wild Things

Friday Fun Fact!

Native freshwater mussels play a variety of important roles in any ecosystem, but perhaps the most important is water filtration. Mussels are filter feeders, that is, they get all of their food and oxygen from the flow over water over their internal gills, much like a fish. And they are REALLY REALLY GOOD AT IT - they can filter, on average, a gallon of water every hour. Observe a simple demonstration set up streamside:

Two small tanks filled with water from the stream in the background. Sediment has been stirred up, as would occur with stormwater flow or someone walking or driving across a stream. The tank on the right has about a dozen native mussels, the one on the left has nothing but water and substrate.



Elapsed time: 10 minutes



20 minutes



30 minutes



35 minutes



The difference is pretty dramatic. These animals are helping to keep your water clean by feeding on algae and bacteria that I'd prefer NOT to be in my glass of water! How effective are they in a large body of water? Take Chesapeake Bay for example: before we buggered it up, that particular gigantic estuary was FULL of oysters, a mussel relative, also a filter feeder. Those oysters kept that water crystal clear, filtering every single drop about every 2 days. In the whole estuary. Just to give you an idea, that's about 19 trillion gallons of water in that particular bay. 19,000,000,000,000 gallons. More than we can comprehend. In two days.

However, there is limit to their "mad filtering skillz." If the water has any toxic chemicals in it (for example, mussels are VERY sensitive to chlorine and ammonia, both commonly found in wastewater outfalls draining into streams and rivers), they cannot survive and typically, fatal levels of these chemicals are far lower than water quality standards set by states. Also, sediment can quickly smother a mussel if the source is ongoing. Think of it this way: if you make a cup of coffee and it has a few grounds in it, you will probably still drink it. However, if it's chockablock full of grounds, you will clam up (haha) and abstain. Same thing for mussels: they can filter out small amounts of sediment but if there is too much, they will be unable to breathe and they will die. Yet another reason to control sediment input into water, which I discussed here.

Helloooooooooo from Lake Waccamaw, wanderers! As promised I have lots of pictures from one of my favourite places in this lovely state. I am still working on sorting and uploading, but thought I would post this very silly little video of me saying hullo from my office. Bloggers are often shy of posting pictures of themselves for fear of IRL identification, but I have decided to just let 'er rip. ;-P



I will continue with my picture sorting, oh, I mean WORK and post more later today.

Ready or not, here they come....

This lake is one of our TWO natural lakes in North Carolina. The rest are all manmade reservoirs, i.e. dammed sections of rivers, a process that destroys the native life in the river and causes endless problems for the system. As a result, we almost never work in lakes (since we deal with native species and habitats, there is no point in working in reservoirs given that they are such heavily altered environments) so it's a unique experience to swim around in this one.

This type of lake is called a Carolina bay, named historically for the bay trees that line the shores of many of them. Carolina bays actually rarely have water in them year round, Waccamaw is the exception rather than the rule. About 1/3 of the shoreline is state park (easy to identify, it's the nice part NOT dotted with a bazillion houses and a thousand ugly docks and boathouses) and it is drop dead gorgeous. Sandy shores lines with beautiful cypress trees dripping with Spanish moss.



Here my boss searches for broadtail madtoms, a rare species in the catfish family.



We never did find any, but we DID find one tadpole madtom (Noturus gyrinus), a fiesty cousin found in the signature habitat of madtoms:



And he enjoys opera: "La...la...LAAAAAAAA!" Madtoms are just freakin' cute.



Waccamaw is also home to several endemic species (found no where else in the world!). One makes its home in maiden cane beds near the lake shore like this one (the cane is the grassy stuff).



It's the Waccamaw darter (Etheostoma perlongum) and you can see they are perfectly adapted to their habitat -- can you find the one in the first picture??





We wrangled other endemics that day including the Waccamaw killifish (Fundulus waccamensis), a lovely little tiger-striped fish,



...and the federally threatened Waccamaw silverside (Menidia extensa; yes, the folks down there ARE the most uncreative species namers in the world).



Another reason I LOVE working in this lake is that it is one of the few places left in the state where you can still find a LOT of native freshwater mussels. A LOT. As in, I can't take a step without landing on two or three of them. A LOT. I hope to put together a post just about mussels for you soon -- they are fascinating creatures with surprising levels of complexity to their lifestyle, definitely having more to them than meets the eye. When you are in the water, this what a mussel looks like, you can just see the water siphons they use to breathe and feed resembling a row of eyelashes.



Once you pull them out of the bottom, you can get a better look at them to identify them. This is my favourite species there, the rayed pink fatmucket (Lampsilis splendida; now THAT'S a good name!).



All in all, I spent two weeks down there, surveying for fish and mussels. We were happy to discover that many species are doing very well in the lake these days and populations are healthy. Now, if we can just find those pesky madtoms....we may have to start a campaign to get people to throw their empty bottles and cans into the water (I'm not kidding, these fish LOVE to hide in those things!) -- they've done too good a job picking up their trash!

I will leave you with this excited and curious school of coastal shiners (Notropis petersoni) who were intent on investigating me while I searched for darters. Wander in wonder!!

Sunset cuts across the lake surface. The water slapped the hull of my boat in two foot swells earlier today, but this evening it is smooth as glass after a 2:00 pm thunderstorm. An osprey circles overhead in air that smells renewed, cleared of humidity and rinsed by a breeze between soft evening clouds. I cut the motor and set up a pair of light traps to lower over the side. These traps are simple plexiglass boxes with carnival glow-sticks hung inside. They attract fish at night into a mesh net at the bottom, where they will be (hopefully!) held for us until tomorrow morning when we return to lift the traps and identify our prize. Before heading back to the dock, I pause for a moment, take a deep breath and can't help but smile in thanks to the universe, because I'm damn lucky that this is my office.

We are monitoring several imperiled endemic species in this lake -- they are found nowhere else in the world and so I feel priveledged to handle hundreds of them in a single day. Each is treated gently and released quickly to minimize stress so that they can return to their busy fishy lives no worse for wear. This lake is one of only two natural lakes in a state full of manmade reservoirs and as a result is chockablock full of unique fauna swimming, flying, crawling, and hopping all over the place.

These kinds of monitoring project sound routine, but they are really very important. Knowledge really IS power -- by learning about which areas and resources are most important to these fish, and others, and how population numbers change over time, we also learn which areas are most important to protect and thus get the most "bang for the buck." This data shapes a lot of decisions on a daily basis and can sometimes mean life or death for a population or even, in this particular location, an entire species.

Tomorrow, I dive into a blackwater river in hopes of collecting some baseline data about the types of freshwater mussels that live there. I hope this weekend or next week to have some pictures to share with you, wanderers -- this is an amazing place! Today's picture is from last year, one of the blackwater side canals near the boat ramp.

So who knows what the #1 pollutant in the US is?

I'll give you a hint:





Figured it out yet?

Yep, it's sediment. Dirt. Earth. Soil. Mud. Whatever you want to call it, it is carried by runoff and pulled from banks by erosion and our streams are FULL of it.

But, you say, dirt is part of nature, that's no pollutant! Well, you know the saying, "all things in moderation?" Well, that applies to ecology too.

Because of a variety of factors that have to do with channel shape, current speed, and stream path, a running body of water has a limit to the amount of sediment it can carry and move without becoming overloaded. Each stream, therefore, does have the ability to clear sediment out by carrying it and depositing it either along the bottom, on a bank or bar, or at its mouth. Likewise, the animals that live in the stream, mussels, fish, bugs, etc, each have their own tolerance to limited amounts of sediment for short periods of time.

It's when those tolerances are exceeded that this sediment becomes, in fact, a pollutant. When streams are frequently running muddy, when the bottom is nothing more than shifting mud or unconsolidated sand, when the banks are cut by erosion, dumping their clay into the water itself, problems abound.

Sediment smothers mussels so they cannot feed or breathe. Fish gills get clogged so the fish can no longer absorb oxygen. Many fish also rely on their excellent eyesight to find food; in muddy water, they are hungry and helpless. By blocking light, sediment also suffocates plant life beneath the surface that may be vital to fish and insect life. When all of this happens, it is an ecosystem in chaos and it also means the water supply is in trouble.

I mentioned that this sediment can come from bank erosion -- this erosion is often caused by a stream trying to channel more water than it is built for. This is usually due to our compulsion to pave and cover everything we can. Every square inch of ground we pave or harden with a rooftop is one less square inch that can absorb water. Thus, every drop of water that hits there will become runoff and we all have seen what a powerful force runoff can be.

In developed areas, most of the time, runoff is channeled into storm drains. Which usually then lead directly to a stream or other body of water, they ARE NOT filtered or cleaned in any way. This water also usually enters the stream at a single point -- it's like turning a fire hose on and blasting sediment right off of the banks, that's what kind of power this water has, especially during rain events. I remind you again, streams are your water supply, so anything you dump down that storm drain, you are effectively pouring into your glass of water. Sediment often enters the water supply here, running off from construction sites and yards. Most counties do have regulations about sediment control on construction sites, but the problem is that, even if these regulations are enforced (the enforcers are often far too few), the conventional technologies they require (silt fences, stormwater ponds) are very ineffective.

If you see a stream choked with sediment, especially if it is not raining, you can and should notify your county and notify your state water quality agency. A simple Google search can direct you right to them. Notice silt fences around a construction site are collapsed or leaking mud everywhere? Call and report it to your county, contractors and developers ARE required by law to maintain those. You have a right to clean water, wanderers, and it is up to each of us to stand up for that!