Cave Ecosystems

As a cave lover, I have been on a lot of cave tours and during the tour, the cave ecosystem is always something that is discussed. They are very unique and fragile systems. The most important factor in depending on what the environment is like in the cave is what zone you are in. Caves are divided into 3 zones; the entrance, the twilight zone, and the dark zone. In the entrance, there might be green vegetation and there is a lot of light, the temperature is more variable. In the twilight zone, there is less light and minimal plant life. Finally, in the dark zone, there is no plant life and the temperature generally stays the small all year round. In most caves, it’s around 55 degrees Fahrenheit or so. All of the nutrients in this zone have to come from outside the cave.

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Lighthouse Cave in San Salvador, Bahamas, the 1st cave I ever explored 

Trogloxenes and Troglobites are also important terms to know for understanding cave ecosystems. A trogloxene is a species who uses caves but they don’t spend their entire life in one. An example of this is bears or raccoons. Bats also fall into this category as they must leave caves to find insects to consume. The material brought in by trogloxenes and their poop are the only resources that troglobites have to use besides debris that may wash into a cave during a storm. In a lot of caves, bat dropping can actually serve as the major source of nutrients. Troglobites spend their entire lives in caves. A lot of caves have unique species of troglobites because they don’t leave and therefore don’t have any other populations to breed with. These species generally have really interesting cave adaptions like lack of eyes or any pigment. Pigment is lost in the cave environment frequently because it doesn’t benefit the organism and is energetically expensive to produce. Common examples of these species are cave crickets, spiders, psuedoscorpions, salamanders, crawfish and more.

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Belize ecosystems

Belize is found within the tropics. The tropic is the region between the tropic of cancer and the tropic of Capricorn. More specifically Belize is found in the Neotropics which are the new world tropics (Central America, South America and the Caribbean). Between 80-90 percent of known species live within the tropics. Belize also has a wide diversity of habitats including savanna, rainforest, mangroves, and coral reefs. See the below photos, taken by yours truely, that show just some of the diversity Belize has to offer. It has one of the largest reefs in the world which is able to support a large number of species.

Within tropical forests, there are many ways in which a species can specialize. This is because a large number of nutrients and space resources are available. This type of environment can create endemic species which are species whose range is limited to a certain geographic area. When there is a high number of endemic species there is a high level of biodiversity.

In comparison to other nearby areas Belize has a high number of native forests, 65-70 percent of the country is covered by the native forest. In part this is because some areas are too remote to sustain development. Native forests are found to have greater diversity than secondary forests. A large area of the country is a part of reserves, about 26 percent of the land and sea, and 33 percent of the land. The average percent for land conserved across Latin America is 20 percent.

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A savannah in Belize, captured by Lauren Schramm

Belize contains 4000 species of flowering plants, 730 tree species, and 280 orchids. Its biodiversity is high compared to the surrounding regions because of the island biogeography theory. Basically what this means is that the level of species on a landmass is contrast (but not necessarily the same species) and species richness is positively correlated with landmass size. So the greater the landmass the more species there will be. Since the Caribbean is made up of islands then there cannot be as many species as a place on the mainland like Belize.

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The black orchid (Encyclia Cochleatum), the national flower of Belize, captured by Lauren Schramm

Indicator species are species that are heavily influenced by the quality of the environment in which they live. Because of this, they are often used to gauge the health of the ecosystem. Because amphibians breath through their skin they are considered an indicator species. In Belize, there are 37 species, in 10 families. In contrast, Bermuda only has 3 species of amphibians, in 2 families. This can be explained by the latitudinal diversity gradient. Belize is much closer to the equator than Bermuda and other Caribbean nations. The theory says that species richness declines the further away from the equator you move. Because there are many species in the tropics the species are often found in low abundances.

There are many theories on why diversity is high in the tropics including high speciation rate, low extinction rate, more net primary productivity, structurally complex ecosystems, and stable climate over time. In addition, there is lots of rain in the tropics which means that lots of water is available. Species like epiphytes greatly benefit from this. The environment has been stable over time so likely the species there today are similar to those in the past. However because there are a large number of species, none dominates. This means that each occurs in a low number. In areas with fewer species, there are often dominant species.

The San Marcos River

The San Marcos River is a spring-fed river located between Austin, Texas and San Antonio, Texas. The San Marcos River is only 75 miles long and eventually joins with the Guadalupe River. At the headwaters the river is crystal clear, thanks to the headwaters being spring fed. It is the crown jewel of Texas State University in San Marcos, Texas and is a popular site for tubing but few know about the interesting animals that live in the river. In fact, it’s considered one of the most diverse aquatic habitats in the southwestern United States.

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It’s home to an endemic species of river grass, called Texas Wild Rice (Zizania texana). Other inhabitants of the river include freshwater mussels (including the Golden Orb (Quadrula aurea)), turtles, prawns, Guadalupe bass (Micropterus treculii), and suckermouth catfish (Hypostomus plecostomus). The later as nonnatives, that were accidentally released into the river by humans. The river is also home to the endangered foundation darter (Etheostoma fonticola). It formerly was home to the endangered.  San Marcos Gambusia (Gambusia georgei) but the species hasn’t been seen in recent years. There are a few other endangered species you can read about here.

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A gar at the Meadows Center boardwalk, captured by Lauren Schramm

The headwaters of the river come from Spring Lake in San Marcos, which was originally created by a dam. You can watch the lake turn into the river from the patio at Saltgrass Steak house. The lake is fed by the Edwards Aquifer. You can actually dive in the lake, or take a glass-bottom boat  (at the Meadows Center) and see the aquifer producing water. If you park in this area and access the river via the culvert by the Freeman Aquatic Center the island is actually a great source of arrowheads after a large rain event.

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A bed of Texas Wild Rice

The Meadows Center is located where a former amusement park was located called Aquarena Springs. The park was home to “real” mermaids and a diving pig. Today you can still find pony beads from the former clown act and bottle caps from an act the mermaids did in which they drank coke underwater. Technically the beads and caps are artifacts so you are not supposed to take them but that doesn’t stop people.

 

Frog Taxonomy (with a focus on Georgia frogs)

Georgia currently has 30 native frog species and two introduced frog species that fall into six different families.

The most distinct of these families is Bufonidae or the true toads. All toads will be found in this family. All toads are frogs but not all frogs are toads. Toads are a specialized group of frogs who typically have warty dry skin, are short and stubby, and large glands on the sides of their heads that kind of look like shoulder pads and are called parotoid glands.  Toads can actually aim these glands at predators. The glands release a toxin, called bufo. That’s why it’s common to see toads hopping around during the day. The eggs are typically laid in long strands. Toads also have no teeth. Worldwide there are 604 species in this family.  In Georgia we have 4 species; American Toad (Anaxyrus americanus), Fowler’s Toad (Anasyrus fowleri), the Oak Toad (Anaxyrus quercicus), and the Southern Toad (Anaxyrus terrestris). In the Metro Atlanta area, it’s common to hear both American and Fowler’s toads calling. The Ameican toad sounds like a long musically thrill that lasts between 6 and 30 seconds. The Fowler’s Toad sounds like a harsh thrill, kind of like a nasally WAAAHHHH.

 

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Red-spotted toad (Anaxyrus punctatus, formerly Bufo punctatus), captured by Lauren Schramm

 

The largest family of frogs in Georgia is Hylidae or the tree frogs, chorus frogs, and cricket frogs. Worldwide the family has 710 species. They all shared a claw-shaped finger which is found at the end of their toe pad. The toe pads function not like suction cups, but via wet adhesion, similar to 2 pieces of wet glass sticking together. In Georgia we have the Northern Cricket Frog (Acris crepitans), Southern Cricket Frog (Acris gryllus), Bird-voiced Treefrog (Hyla avivoca), Cope’s Gray Treefrog (Hyla chrysoscelis), Green Treefrog (Hyla cinerea), Pine Woods Treefrog (Hyla femoralis), Barking Treefrog (Hyla gratiosa), Squirrel Treefrog (Hyla squirella), Cuban Treefrog (Osteopilis septentrionalis), Mountian Chorus Frog (Pseudacris brachyphona), BRimley’s Chorus Frog (Pseudacris brimleyi), Spring Pepper (Pseudacris cruicifer), Upland Chorus Frog (Pseudacris feriarum), Southern Chorus Frog (Pseudacris nigrita), Little Grass Frog (Pseudacris ocularis), and finally the Ornate Chorus Frog (Pseudacris ornata). The Cuban Treefrog is actually an invasive species that is twice as large as our native treefrogs and it consumes them! It’s really hard to find because it’s a treefrog and so there is not much we can do about it’s invasion. The upland chorus frog (sounds like running your finger along a comb), spring pepper (sounds like bird-like peeps), Cope’s gray treefrog (harsh, high pitched trill), green treefrog (nasally and duck-like), bird-voiced treefrog (like a bird call whit-whit-whit), squirrel treefrog (harsh repetitive, squirrel-like call), and northern cricket frog (sounds like two marbles being tapped together) can all be found in the Metro Atlanta area.

 

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Cope’s Grey Treefrog, captured by Lauren Schramm

 

The family Ranidae contains true frogs who have smooth and wet skin. Worldwide they have a large range. Generally, they are aquatic or live close to water. This family is probably what comes to mind when most people think of frogs. In Georgia you can find Gopher Frogs (Lithobates capito), Bullfrogs (Lithobates catesbeinanus), Green Frogs (Lithobates clamitans), Pig Frogs (Lithobates grylio), River Frogs (Lithobates heckscheri), Pickeral Frogs (Lithobates palustris), SOuthern Leopard Frogs (Lithobates sphenocephalus), Wood Frogs (Lithobates sylvaticus), and Carpenter Frogs (Lithobates virgatipes). Bullfrogs, green frogs, pickerel frogs, and Southern leopard frogs all have calls that can be heard in the metro Atlanta area. Respectively the calls sound like a repeated jug-o-ruummmm, like a banjo pluckling, a snoring person, and the sound of squeezing a balloon.

 

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Pickeral Frog, captured by Lauren Schramm

 

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Reducing your environmental impacts

Recently my household (my partner, a dog, and our four rabbits) have really tried to start reducing our personal impacts on the environment. Even though I am an environmental scientist is an area in which I have been slacking in. I have found that there are a lot of things you can do that are not only eco-friendly but also save money. Here is a rundown of the changes we’ve made in no particular order.

  • I have started to make a lot of the products we use including personal care and cleaning. The only thing I don’t make is dishwasher detergent (a request from my partner), soap (I don’t want to mess with lye), laundry soap (I use soap berries), toothpaste (not messing with fluoride) and deodorant (very hard to make correctly). A lot of what you end up paying for in these products is the water in them. You also have to pay for the water-filled products to be shipped around when you can just add tap water to basic ingredients to make basically everything. I keep a list of how I like to make everything on a list on the fridge. One of the best things I started making was a DIY version of the Lysol wipes. My kitchen gets a lot of use and therefore gets really dirty. I loved that they killed bacteria but hated throwing the wipes out after. Thyme oil actually kills a similar amount of bacteria. I found this recipe and love it! If there is interest I can do a more lengthy post on how to make everything.

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  • I have committed to not buying anything new unless I have to. This applies to household goods and clothing. Goodwill is a go-to store for me. While there are critics of Goodwill they do use their profits to help put people back to work. I also will buy clothes for work from Thredup. If you think about how many materials there are in the world already it’s crazy to buy everything new. Nextdoor also offers a lot of household things for sale.
  • I’ve greatly reduced the amount of junk mail/ past residence mail I have gotten. Whenever I get junk mail I make sure to unsubscribe from the companies mailings by filling out an online form if they have one, or calling/ emailing them. I also write return to sender on all mail not addressed to myself, my partner, or “current resident”. It may seem small but it has reduced the amount of resources being used to send me coupons I don’t want.

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The Georgia coast is key to shorebird conservation

A few months ago I attended the monthly Atlanta Aubdon Society meeting which was on the role of the Georgia coast and shorebird conservation. The talk was given by Brad Winn from Management center for conservation, Tim Keyes from the GeorgiaDepartment of Natural Resources and Abby Sterling from the University of Georgia.

Abby started the talk by giving a general overview of the habitat on the coast and the life history of shorebirds with a particular focus on Oystercatcher and Wilson’s plovers, the birds she did her doctoral studies on. The beaches on the Georgia coast are dynamic habitats as they do not have engineering typically found on beaches that hinder the natural movement of sand. These beaches are found on a chain of barrier islands that are formed from sediments that drain from the whole state. Shorebirds (at least these two species) lay their eggs in scrapes in the sand or sometimes in a horseshoe crab shells or flowers. The two species did not have an overlap of their nesting habitat which is important for conservation. The nests are typically hard to find and Abby said she had to follow the tracks of birds to find the nets. She monitored nests until they were successful or unsuccessful. This took about 28 days for Wilsons plovers. The chicks get fed by the parents. Abby would catch and band the birds and give the chicks a unique color band combination of ease of field identification.

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Wilson’s Plover

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Geology of Paraguay

Paraguay is a landlocked country in South America in which three ecoregions met; cerrado (a savannah), Atlantic forest, and chaco (a mix of the two). Areas in which ecoregions meet tend to have very high biodiversity. As an undergraduate I had plans, which sadly fell through, to travel to a research center in Paraguay. As part of the planning process, I did a lot of research on the country, including research related to the geology of the country.

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An example of the Chaco

The bedrock in Paraguay is mostly from the Quaternary age and Carboniferous age, though some may be Permian. In more northern parts of the globe, like western New York, you don’t find Quaternary age rocks because the last glaciation period stripped them away. Older rocks are found in the western part of the country. The country is very flat, particularly in the area in which the research center is located. Over about 1.5 miles I walked to class every day as an undergraduate there was a 112-foot change in elevation. Compared to a 48-foot change in elevation over the 0.8 miles it would have taken me to get to my study area.

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For reference, Paraguay is in red

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