Algae in Caves

Take a look at these two photographs and other than what they are pictures of see if you can see any major differences (Top picture from Carlsbad Caverns National Park [my post here] bottom picture from Mammoth Cave National Park [my post here]).

More photos from Carlsbad Caverns, more photos from Mammoth Cave.

What jumps out to me is the green stain on the wall in the picture from Mammoth Cave. This is something I really noticed while touring the cave and there was some really drastic growth on some of the walls in the New Entrance portion of the cave. According to Smith and Olson (2007) these are some of the 28 species of cyanobacteria, green algae, and/or diatoms. For the rest of this article I will refer to all of these groups as algae, because that is far easier than typing all those out every time. All of these groups are photosynthetic groups that need light as well as moisture to live and since they produce their own food they can grow on cave walls. Algae as well are known as pioneer species meaning, in this case, that they live on rocks, unlike plants which need soil to grow, and in the process they modify the rocks under them by producing weak acids during photosynthesis that break down the rocks they are on. On the surface where algae lives naturally this is a good thing, it is a form of chemical weathering that breaks the bonds that hold the rock together and forms soils in the long run, except in karst areas because it is hard to produce soil from limestone (not going to explain here if you want to know ask). In caves the algae are doing the same thing except that they naturally only occur where the sun shines so in order for them to grow deep down in caves is because we put lights down there.

So why so much more algae in Mammoth Cave than in Carlsbad Caverns? Some of it may have to do with the outside environments of the two areas. Carlsbad is in a desert and Mammoth Cave is in a temperate forest so it is going to be much more moist in Mammoth Cave. Carlsbad does, however, have algae that grows on the surface outside the cave. The main difference has to do with the type of lights that have been installed within the cave. Carlsbad Caverns has been moving toward lights that produce light at a wavelength that the algae cannot grow at (on a side note if you go to the link they talk about how they are changing the lights again and you can see some of that in my pictures). There is still some need to physically remove the algae as the Carlsbad website mentions:

Some of these algae live in the caves, too. Under normal light conditions, they will grow on walls or in pools as far into a cave as the sunlight penetrates (the twilight zone). In caves with artificial light sources of suitable wavelengths, such as Carlsbad Cavern, algae will grow in the dark zones near the lights. These algae are considered pest plants, and are kept under control periodically by park staff.

Smith and Olson (2007) point out that most of the work to remove the algae in Mammoth Cave has focused on physical removal using a weak sodium hypochlorite or bleach. This use of bleach can have physical effects on the cave but if the algae is not removed there can be other effects. Smith and Olson (2007) recommend the use of similar lights to what Carlsbad Caverns uses so the algae is unable to photosynthesize and therefore will not be able to produce food and will die without physical damage to the cave.

One other interesting thing the Smith and Olson (2007) paper is the only thing I can find about the removal of algae from Mammoth cave and they do not have anything about it on their website nor did they have any signs or did I hear from any of the rangers about it. Carlsbad on the other hand has the quote mentioned above and many of the rangers and signs throughout the cave mentioned the attempts to remove the algae. If I am wrong about this please let me know.

Source:
Smith, T. and R. Olson. 2007. A taxonomic survey of lamp flora (algae and cyanobacteria) in electrically lit passages within Mammoth Cave National Park, Kentucky. International Journal of Speleology. 36(2): 105-114.
(This source can be found here and is open access so the pdf is here)

A Future for Bats

So yesterday I had a post about Mammoth Cave National Park and I focused primarily on the geology of the park as I have with most of my National Park posts. Well shortly after I posted it I read a post over at Darren Naish's wonderful blog Tetrapod Zoology in his 20 part (holy crap 20) series on vesper bats, the link to the post will include links to the other 19 if you want. This was the last post in series and it is about the potential future for vesper bats and it included a pretty good summary of all of the troubles that the vesper bats are currently facing. This post won't focus on vesper bats in particular but bats in the more general sense

Now to tie the previous paragraph together. When I visited Mammoth Cave much of the discussion by the tour guides was not about the geologic history, although there was plenty of that, it was about the animals that live in the caves especially the bats. Bats seem to have some hold on people that seems to interest them greatly. They discussed two of the problems that Darren talks about in his post and how the National Park Service is trying to prevent the loss of bats. I will follow the two of them in the same order that Darren did and for simplicities sake I will be using the same section titles.

Disturbance and roost destruction
Many bats hibernate for the winter in caves and in hollow trees among other similar things. One of the things that can cause them not to come back or to leave their hibernation place too early is being disturbed while they hibernating. The U.S. Fish and Wildlife Service (FWS homepage) had this to say on the Indiana Bat, Myotis sodalis.

Indiana bats, because they hibernate in large numbers in only a few caves, are extremely vulnerable to disturbance. During hibernation, they cluster in groups of up to 500 per square foot. Since the largest hibernation caves support from 20,000 to 50,000 bats, it is easy to see how a large part of the total population can be affected by a single event. Episodes of large numbers of Indiana bat deaths have occurred due to human disturbance during hibernation.

It is obviously one thing to admit you have a problem and something else completely to do something about it. Well while at the park I was told that many of the other entrances, even the ones outside of the park, had gates put on them that would allow bats and other animals in and out but not allow humans in. The FWS page said this:

Public lands like National Wildlife Refuges, military areas, and U.S. Forest Service lands are managed for Indiana bats by protecting forests. This means ensuring that there are the size and species of trees needed by Indiana bats for roosting; and providing a supply of dead and dying trees that can be used as roost sites. In addition, caves used for hibernation are managed to maintain suitable conditions for hibernation and eliminate disturbance.

The National Park Service itself also talks about protection of the bats on page 12 of this report on the biological assessment for fiscal year 2007 prescribed fire plan says this:

There is a preference for standing dead trees and species that have loose bark, but Indiana bats may roost in any tree greater than six inches in diameter (they have occasionally been seen in smaller trees). The cave hibernacula are gated to prevent human disturbance during hibernation

Also in the report they mention not cutting down dead hollowed out trees and just trimming off some of the lower branches to keep the fire from spreading up the tree.

White-nose syndrome
While the previous section focused primarily on the Indiana bat this section applies more to bats in general. White nose syndrome (WNS) is a deadly disease that is described very well on Darren's post, but I have included the Wikipedia link just in case. WNS is devastating to bat populations and as such the NPS is greatly concerned with it hitting the bat populations within the park on a webpage with a lot of information on WNS:

The potential exists for the loss of hundreds of thousands more bats—and perhaps entire species—bad news for us as bats devour millions of insect pests and play a role in pollination.

The park, however, is being proactive and on that website they talk about what you should try to do to avoid spreading it. They also include a little check list explaining what you should try to avoid, as well as a small application that allows for a quick, you are good to go or you should see us about this. There were plenty of signs all over the visitors center about the harm white nose syndrome can do and a booth to go visit if you may have come in contact with it. They even have a plan in case your tour group happens across a potential exposure to WNS.

On the remote chance that you might come into contact with Geomyces destructans spores during your tour of Mammoth Cave, all participants in Mammoth Cave National Park cave tours will be required to walk on bio security mats after exiting the Cave. This will require each individual in your party to walk the length of a nylon mat saturated in a Lysol™ solution comparable to that used in home cleaning. Specific information on the active ingredients of Lysol IC™ and the concentration being used are available at the White-Nose Station at the Visitor Center. We also ask for your cooperation by washing your hands and changing clothes and footwear before visiting any other caves or mines.

I hope that between the efforts of the NPS in parks such as Mammoth Cave National Park and the efforts of the PWS throughout the United States could slow the spread of WNS and prevent many deaths from people disturbing colonies as possible.

Mammoth Cave National Park

Location: North-central Kentucky in portions of Edmonson, Hart, and Barren counties.

Introduction:
I was originally going to hold this post off till later but in honor of Earth Day and National Park week, many parks will allow you in for free or cheap through Sunday (April 24, 2011), I figured I would get this post done early.

Spring Break 2011 brought me to Nashville, TN and while Tennessee itself is home to many national parks this is the closest one to Nashville. About an hour and a half to two hour long drive from Nashville, Mammoth Cave is also close to other metropolitan areas such as Louisville, KY. Mammoth Cave (Wikipedia page) was the second of the cave systems within the National Parks that I visited, the first was Carlsbad Caverns National Park. Mammoth Cave National Park covers a large area and includes many different areas to hike around outside and enjoy the mountains and the forest. Obviously, however, what the park is most known for is the cave itself which includes at least two different entrances that lead down into the cave.

Unlike Carlsbad this cave system has been known for a long time and as you head through the cave you can see many of the markings made by some of the early visitors to the cave. These marks were made using candles on top of long sticks to allow visitors to write their names in the ash and smoke made from the candles on the roof, and since the cave environment changes very little and the marked areas do not have water in them many names that have been there since the mid-1800s are still visible. This cave has been in use in some form or another since the early 1800s and was originally used as a mine with many of the original settling basins and pipes that were worked by slaves are still visible. The one thing I didn't like about this park was that, also unlike Carlsbad, the only way to view the cave was the be led down by a National Park Service guide. This is due to the cave being more confusing than Carlsbad and the trails having been put in by the Civilian Conservation Corps (CCC) in the 1930's so the trail itself is not paved with railing around it. Overall though if you are in the area I recommend that you check out the cave.

Geology:
I have already covered how caves form from solid rock in the Carlsbad Caverns post (click that link if you want to read more) so the geology in this post will be more about the regional geology.

If you look at the mid-western portion of the United States on a geologic map there are a lot of Paleozoic aged rocks that form the bedrock for that area. This is because for most of the Paleozoic the Midwest was sitting under a shallow sea and the Appalachian Mountains were being uplifted, for the first time, which provided sediment to be deposited in this basin. During much of the Paleozoic North America sat on the equator which provided for a much warmer climate than what is found today especially in some of the more northern states such as Pennsylvania, you can see more of this in my Guadalupe Mountains (Guads) post. Many of the southern portions of this area were not receiving high amounts of sediment though and due to the way the crust bent in the area, the Cincinnati arch, these areas, seen really well from just south of Nashville to Ohio, were shallow seas. These shallow warm seas as we know today are home to calcite secreting organism and other reef organisms. This creates a vast area in the center of the country that is home to lots of limestone deposits which creates what is known as karst topography, which is pretty much lots of sink holes and caves. All of the rock that you see in and around Nashville is limestone or other similar calcite rich rocks.

During the Mississippian, early Carboniferous, the area that is now Mammoth Cave National Park was sitting in a shallow sea and was a highly productive reef system. Throughout many areas of the cave fossil organisms that are now primarily associated with reef systems, such as crinoids [image of a crinoid fossil from the new entrance to the left], are found as fossils in some of the less altered cave walls. This led to a lot of deposition of calcite which is where all of the portions of the cave are now found. During the Pennsylvanian, late Carboniferous, there was a subtle change in the flow of sediments into the basin and a river system began depositing sand in a deltaic system over the area. The sediment from this river would choke off the ability of the reef organisms to live and produce calcite, similar to why there are no reefs near the Mississippi River delta today, and would instead allow just for the deposition of sands and clays. These sands and clays do not erode away as quickly or easily nor are they effected by acidic water the same way that limestone is so they provide a sort of cap rock preventing water from entering the system and dissolving away the rocks below.

Eventually this area began to uplift as well as forms the western portion of the current Appalachian Mountains called the Appalachian Plateau. As this area was uplifted water did what it always does to areas that are uplifting, it started cutting away where rivers were flowing to form valleys, the speed of this uplift is really present in some of the eastern rivers such as the New River and the Shenandoah which appear to meander like river that are no longer down-cutting but they are still down-cutting forming deep valleys (I have the ability to cover that last one and might here soon). Within Mammoth Cave National Park is the Green River which cuts a valley and at one time was much higher up relative to where it is now. It was when it was still cutting a higher portion of this valley that most of the cave that visitors see was being formed. The cave system itself is actually part of the Green River watershed and there are vast underground flowing rivers that carry water from west of the area over to the current location of the river. At one point in the past some of the larger chambers in the upper portion of the cave did the same but as the water table fell, do to the uplift of the mountains, these portions of the cave became dry. In many places the Pennsylvanian sandstone [image at right is an outcrop of the Pennsylvanian sandstone] that formed the cap rock has been stripped away this has allowed water to continue to enter the cave and forms many of the sinkholes in the area. The places where the sandstone is still present form the ridge tops and locations within the cave that have no water dripping into them, because it cannot get through the sandstone, or does so too slowly to be noticed. This creates a stable environment that allowed for the preservation of mummies that first created the buzz for the area before it was a National Park.

More Pictures I have even more in the Mammoth Cave portion of my Flickr page.







Further Reading:

History of Geology's post on the mountains formed by prehistoric reefs (I should really have linked here in the Guads post as well).

National Park Service's webpage on the Natural Features and Ecosystems which has links to many more specialized sections of their webpage.

My post on how the NPS is trying to protect bats in the area.

National Park Service Series homepage