lauren schramm

Asian clams: the most successful aquatic invaders

Some scientist considers Asian clams (Corbicula fluminea) to be the most successful aquatic invasive species, as evidenced by their being found on every continent except for Antarctica (1, 2, 3, 4, 5, 6). In addition, the species results in the loss of a billion dollars a year in the U.S. from clogging intact pipes (7). The clams are small, typically ranging from the size of a penny to a quarter, brownish yellowish, and triangular oval. They have distinctly raised growth groves. The species may be confused with native finger clams, but native species are more oval, found buried entirely, and have very fine growth ridges (8). While multiple species of Asian clams are invading aquatic systems, the most common species is C. fluminea (9, 10).

Biology

Asian clams are filter feeders but can also feed on the substrate called pedal feeding (11). The clam has one of the highest rates of filter-feeding of any bivalve (8). Unfortunately, the high filtration rate also means that they excrete many nutrients that can cause algal blooms (12,13).

The clams are found in the bottoms of water bodies, often buried in the substrate. Consequently, they are adapted to a wide range of substrates. Clams can also survive up to 36 days without being submerged in water (11).

The clams are prone to die-offs due to silt load from spring runoff, temperatures extremes, and low dissolved oxygen, which is usually associated with low water flows (12, 14). In these conditions, the clams will die and start to decompose, releasing compounds that may be harmful to other aquatic life, like native freshwater mussels (15).

Life Cycle

Asian Clam. Photo credit Lauren Schramm

Asian clams can reproduce in large numbers as they can start reproducing at around 3 to 6 months (8). The adult lives 3 to 4 years and can produce 100,000 juveniles per year (8). Adults can self fertilize, and the fertilized eggs develop into juveniles in the gills in 4 to 5 days. (8)

Range

In the United States, Asian clams can be found throughout 44 states but have the highest numbers in the southeast, Texas, and southwest. Significant populations globally can be found in South America, Europe, and Asia. Native populations also exist in Africa and Australia.

Researchers have found that various climate change models will increase the suitable habitat for Asain clams from 6.6 percent of aquatic habitats to 12.7 percent by 2050 in the U.S. (16).

Map of significant populations of Asain Clams (solid circles), sourced from Mackie & Brinsmead, 2017.

Introduction history

It is widely theorized that they were introduced as a food source on the west coast of the United States and were first discovered in the country in 1938 in California (17, 18). Another theory is that they were hitchhikers with imported Giant Pacific oysters (Crassostrea gigas) (8). Several factors have led to successful invasions of Asian clams, including its ability to produce a high number of offspring, self-fertilization, rapid sexual maturity, lack of a parasitic life stage (most other freshwater clams have this), filter-feeding, and the ability to disperse across long distances (11). In addition, juvenile clams can travel long distances using mucus “parachutes” (8).

Management options

Unfortunately, there are limited management options as once an invader enters an aquatic system, there are several different pathways it can travel. For example, Asian clams can be disturbed via fish eating them and then being excreted in waste (19). Other dispersal methods are not fully understood but likely include; bait buckets, bilge water, live wells, water currents, and transportation by wildlife (8).

Due to the rapid spread, there have been few peer-reviewed management techniques for the clam (8). However, a physical barrier can be installed to stop the spread, the clams can be dredged for and removed, and molluscicides (a chemical that specifically kills mussels) can be used (7). The latter two options should only be limited in use as they can potentially harm native mussels.

Interactions with native mussels

Regarding interactions with other species, an emphasis should be placed on Unionidae, or the family of freshwater pearly mussels. Freshwater mussels are considered the most imperiled group of organisms in North America, with only a quarter of species having stable populations (20, 21, 22, 23, 24, 25, 26, 27).

Their declines are due to previous commercial harvesting, invasive species, sedimentation, declines in fish host species, urban development, disease, predation, poor water quality/eutrophication, dams resulting in habitat alterations, habitat destruction, and channelization (21, 28, 29, 30, 31).

Historically, native mussels dominated the streams and rivers of eastern North America (32). In addition, mussels are long-lived, with some species living up to 100 years (33). On average, many do not reproduce until age 7, which increases their susceptibility to threats contributing to their decline (34). Conversely, Asian clams typically live 3 to 4 years and reproduce early (35, 36).

Asian clams and mussels occupy the same physical space in rivers, streams, and lakes. They also are both filter feeders. It was initially thought that Asian clams did not impact native mussels (37). Although some early researchers (38) did state there were declines in native mussels due to new populations of Asian clams; these researchers were in the minority. In addition to differing habitat preferences, their ranges did not appear to overlap (39, 37, 40, 41).

Current research points to several ways Asian clams can negatively impact native mussels, including direct competition for food, displacing of juvenile mussels, and ingestion of mussel sperm. Additionally, Asian clams are prone to die-offs that produce excess ammonia, which can be fatal to native mussels (42, 43).

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Sources:

  1. Leff, L. G., Burch, J. L., & McArthur, J. V. (1990). Spatial distribution, seston removal, and potential competitive interactions of the bivalves Corbicula fluminea and Elliptio complanata, in a coastal plain stream. Freshwater Biology, 24(2), 409.
  2. Hornbach, D. J. (1992). Life history traits of a riverine population of the Asian clam Corbicula fluminea. American Midland, 248- Naturalist 257.
  3. Karatayev, A. Y., Padilla, D. K., Minchin, D., Boltovskoy, D., & Burlakova, L. E. (2007). Changes in global economies and trade: the potential spread of exotic freshwater bivalves. Biological Invasions, 9(2), 161-180.
  4. Lucy, F. E., & Graczyk, T. K. (2008). Revision of the distribution of Corbicula fluminea (Müller, 1744) in the Iberian Peninsula. Aquatic Invasions, 3, 355-358.
  5. Sousa, R., Antunes, C., & Guilhermino, L. E. D. P. S. (2008a). Ecology of the invasive Asian clam Corbicula fluminea (Müller, 1774) in aquatic ecosystems: an overview. In Annales de Limnologie-International Journal of Limnology. EDP Sciences, (Vol. 44, No. 2, pp. 85-94).
  6. Crespo, D., Dolbeth, M., Leston, S., Sousa, R., & Pardal, M. Â. (2015). Distribution of Corbicula fluminea (Müller, 1774) in the invaded range: a geographic approach with notes on species traits variability. Biological Invasions, 17(7), 2087-2101.
  7. https://www.adkwatershed.org/asian-clam
  8. https://nyis.info/invasive_species/asian-clam/
  9. Renard, E., Bachmann, V., Cariou, M. L., & Moreteau, J. C. (2000). Morphological and molecular differentiation of invasive freshwater species of the genus Corbicula (Bivalvia, Corbiculidea) suggest the presence of three taxa in French rivers. Molecular Ecology, 9(12), 2009-2016.
  10. Siripattrawan, S., Park, J. K., & Foighil, D. Ó. (2000). Two lineages of the introduced Asian freshwater clam Corbicula occur in North America. Journal of Molluscan Studies, 66(3), 423-429.
  11. McMahon, R. F. (2002). Evolutionary and physiological adaptations of aquatic invasive animals: r selection versus resistance. Canadian Journal of Fisheries and Aquatic Sciences, 59(7), 1235-1244.
  12. Phelps, H. L. (1994). The Asiatic clam (Corbicula fluminea) invasion and system-level ecological change in the Potomac River estuary near Washington, DC. Estuaries, 17(3), 614-621.
  13. Wittman, M., Reuter, J., Schladow, G., Hackley, S., Allen, B., Chandra, S., & Caires, A. (2008, December). University of California Davis, Reseach, Aquatic Invasive Species, Asian Clam pdf. (2008). Retrieved from University of California Davis: http://terc.ucdavis.edu/research/AsianClam2009.pdf
  14. Sousa, R., Nogueira, A. J., Gaspar, M. B., Antunes, C., & Guilhermino, L. (2008b). Growth and extremely high production of the non-indigenous invasive species Corbicula fluminea (Müller, 1774): possible implications for ecosystem functioning. Estuarine, Coastal and Shelf Science, 80(2), 289-295.
  15. Cherry, D. S., Scheller, J. L., Cooper, N. L., & Bidwell, J. R. (2005). Potential effects of Asian clam (Corbicula fluminea) die-offs on native freshwater mussels (Unionidae) I: water-column ammonia levels and ammonia toxicity. Journal of the North American Benthological Society, 24(2), 369-380.
  16. Gama, M., Crespo, D., Dolbeth, M., & Anastácio, P. M. (2017). Ensemble forecasting of Corbicula fluminea worldwide distribution: Projections of the impact of climate change. Aquatic Conservation: Marine and Freshwater Ecosystems, 27(3), 675-684.
  17. Sinclair, R.M. and Isom, G.B. 1963. Further Studies on the Introduced Asiatic Clam (Corbicula) in Tennessee. Tennessee Stream Pollution Control Board, Tennessee Department of Public Health. 1-75.
  18. Counts, C. L. (1981). Corbicula fluminea (Bivalvia: Corbiculidea) in. British Columbia. Nautilus, 95, 12-13.
  19. Gatlin, M. R., Shoup, D. E., & Long, J. M. (2013). Invasive zebra mussels (Driessena polymorpha) and Asian clams (Corbicula fluminea) survive gut passage of migratory fish species: implications for dispersal. Biological Invasions, 15(6), 1195-1200.
  20. Allan, J. D., & Flecker, A. S. (1993). Biodiversity conservation in running waters. BioScience, 43(1), 32-43.
  21. Bogan, A. E. (1993). Freshwater bivalve extinctions (Mollusca: Unionoida): a search for causes. American Zoologist, 33(6), 599-609.
  22. Lydeard, C., & Mayden, R. L. (1995). A diverse and endangered aquatic ecosystem of the southeast United States. Conservation Biology, 9(4), 800-805.
  23. Strayer, D. L., Downing, J. A., Haag, W. R., King, T. L., Layzer, J. B., Newton, T. J., & Nichols, J. S. (2004). Changing perspectives on pearly mussels, North America’s most imperiled animals. BioScience, 54(5), 429-439.
  24. Dudgeon, D., Arthington, A. H., Gessner, M. O., Kawabata, Z. I., Knowler, D. J., Lévêque, C., & Sullivan, C. A. (2006). Freshwater biodiversity: importance, threats, status and conservation challenges. Biological reviews, 81(2), 163-182.
  25. Bogan, A. E. (2008). Global diversity of freshwater mussels (Mollusca, Bivavle) in freshwater. Hydrobiologia, 595, 139-147.
  26. Ford, D. F. (2013). Ground-truthing Maxent in East Texas rivers. (Masters dissertation, The University of Texas at Tyler).
  27. Lopes‐Lima, M., Sousa, R., Geist, J., Aldridge, D. C., Araujo, R., Bergengren, J., & Zogaris, S. (2017). Conservation status of freshwater mussels in Europe: state of the art and future challenges. Biological Reviews, 92(1), 572-607.
  28. Williams, J. D., Warren Jr, M. L., Cummings, K. S., Harris, J. L., & Neves, R. J. (1993). Conservation status of freshwater mussels of the United States and Canada. Fisheries, 18(9), 6-22.
  29. Howells, R. G., Neck, R. W., & Murray, H. D. (1996). Freshwater mussels of Texas. University of Texas Press.
  30. Lydeard, C., Cowie, R. H., Ponder, W. F., Bogan, A. E., Bouchet, P., Clark, S. A., & Thompson, F. G. (2004). The global decline of nonmarine mollusks. BioScience, 54(4), 321-330.
  31. Allen, D. C., & Vaughn, C. C. (2010). Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance. Journal of the North American Benthological Society, 29(2), 383-394.
  32. Parmalee, P. W., & Bogan, A. E. (1998). Freshwater mussels of Tennessee. University of Tennessee Press.
  33. Anthony, J. L., Kesler, D. H., Downing, W. L., & Downing, J. A. (2001). Length‐specific growth rates in freshwater mussels (Bivalvia: Unionidae): extreme longevity or generalized growth cessation?. Freshwater Biology, 46(10), 1349-1359.
  34. Kacar, A. (2011). Some microbial characteristics of mussels (Mytilus galloprovincialis) in coastal city area. Environmental Science and Pollution Research, 18(8), 1384-1389.
  35. Prezant, R. S., & Chalermwat, K. (1984). Flotation of the bivalve Corbicula fluminea as a means of dispersal. Science, 225(4669), 1491-1493.
  36. McMahon, R. F., & Bogan, A. E. (2001). Bivalves. Ecology and Classification of North American Freshwater Invertebrates. 2nd ed. Edited by Thorp, JH, and AP Covich, Academic Press, New York.
  37. Kraemer, L. R. (1979). Corbicula (Bivalvia: Sphaeriacea) vs. indigenous mussels (Bivalvia: Unionacea) in US rivers: A hard case for interspecific competition?. American Zoologist, 19(4), 1085-1096.
  38. Gardner, J. A. (1976). The invasion of the Asiatic clam (Corbicula manilensis Philippi) in the Altamaha River, Georgia. Nautilus, 90 (3), 117-125.
  39. Sickel, J. B. (1973). A new record of Corbicula manilensis (Philippi) in the southern Atlantic slope region of Georgia. Nautilus, 87 (1), 11-12.
  40. Clarke, A. H. (1988). Aspects of corbiculid-unionid sympatry in the United States. Malacology Data Net, 2(3/4), 57-99.
  41. Belanger, S. E., Farris, J. L., Cherry, D. S., & Cairns Jr, J. (1990). Validation of Corbicula fluminea  growth reductions induced by copper in artificial streams and river systems. Canadian Journal of Fisheries and Aquatic Sciences, 47(5), 904-914.
  42. Scheller, J. L. (1997). The effect of dieoffs of Asian clams (Corbicula fluminea) on native freshwater mussels (Unionidae) (Doctoral dissertation, Virginia Tech).
  43. Ilarri, M. I., Antunes, C., Guilhermino, L., & Sousa, R. (2011). Massive mortality of the Asian clam Corbicula fluminea in a highly invaded area. Biological Invasions, 13(2), 277-280.

Map source: Mackie, G. L., & Brinsmead, J. K. (2017). A risk assessment of the golden mussel, Limnoperna fortunei (Dunker, 1857) for Ontario, Canada. Management of Biological Invasions, 8(3), 383.

Asian clam ID chart: https://adkinvasives.com/Invasive-Species/Detail/31

Using Conservation Techniques to Stop Poaching of Wildlife

The following was a term paper written for my conservation biology class in collaboration with Hallie Draegert

Abstract:

It is a well-known fact that the human population is increasing in size. The growth of one population, the humans, tends to impact other populations negativity. In this case, the concern is the impact it has on wildlife populations. As long as wildlife and human populations coexist problems will arise.  These problems can occur in response to tension between local human communities and the attempts of organizations working to conserve native populations of animals. Often these organizations seem to forget that the local’s livelihoods depend on exploiting the local animals. This has led to the creation of conservation models that do not work because they did not consider the local politics.

One of the most common crimes committed is poaching. Poaching has led directly to the extinction of many species and induces stress, on currently stable species. This could make future extinction of the population an issue that needs to be addressed. Since poaching is a serious problem for highly stressed species, it is critical to work to prevent the crime. There are many current techniques used to reduce and combat poaching. However, the issue has not been fully resolved. This is likely because only a single model is in use at a time in an area.

geograph-6097299-by-Mike-Pennington
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The rainforest is teeming with dynamic relationships!

There are many dynamic relationships in the rainforests of the world. Which is expected as they are home to up to 40 percent of known plant and animal species. Within the forest there are a widely variety of symbiotic relationships, which means there are interactions between two species. For some species the relationship is beneficial for both parties, this is call mutualism. For example the Brazil nut trees (Bertholletia excelsa) produces a nut that is an only be cracked by a few species, one of which is various agouti (Dasyprocta sp.) which is a small rat like animal. The tree benefits as it’s seeds are dispersed and the agouti receives a free meal.

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Description
English: A Central American Agouti (Dasyprocta punctata) in Panama experimenting with a western diet.
Source BirdPhotos.com
Author Tomfriedel

In some cases one species is unaffected and the other benefits, this is commensalism. A example of this would be a frog sheltering itself from a storm event under the leaves of a plant. The plant is un effected but the frog benefits. Lastly, parasitism is when one species is harmed and the other benefits. Bot flies are a common tropical parasite that lay their eggs on a mammal host. The eggs then hatch and the larva develop in the skin of the host animal.

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A frog in the rain in Belize. Image by Lauren Schramm

Competition is a symbiotic relationship in while two species use the same resources. Because it requires an energy investment both species are harmed, but the harm may be unequal. Many rainforest plants are animal pollinated or their seeds are dispersed by animals. Resource partitioning occurs when a resource is divided among species in some way like time or place. One way plants reduce their competition against each other is by targeting different animal groups. For example flowers pollinated by bats are often white making them easier to see at night, while flower pollinated by other animals are red, orange, and yellow. Bat pollinated flowers also contain a musky smells, while flower pollinated by moths, bees, and other insects have a strong fragrance. Plants also reduce competition by flowering and fruiting at different times. This is one reason there are always flowers and fruits available in the rainforest at any given time.

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Can remote sensing (drones) find harmful algae blooms?

A harmful aquatic algae bloom is when there is sudden a rapid growth of algae. In the past these were more commonly referred to as red tides. These populations of algae in term then produce extracellular compounds that can cause harm and even death to humans and wildlife and fish. Shellfish that are subjected to HABs cause humans to get sick. In rare cases people can even die. HABs most commonly occur in the oceans and large freshwater lakes, such as the Great Lakes.

Often HABs occurs due to nutrient runoff but it is important to understand these have been occurring for millions of years. There are fossilized HABs and fossils of whales found in a proximity and quality near the fossilized HABs that is is theorized the HABs resulted in the death of the whales. Climate change is increasing the frequency and intensity of HABs so it is clear we need to develop tools to predict and mitigate risks with HABs.

I looked at research into using remote sensing to predict algal blooms of Karenia brevis in coastal Florida. This algal is responsible for the most red-tides in Florida. It produces a neurotoxin that kills aquatic life and makes shellfish toxic to humans. Researchers used a geographic information system (GIS) to develop a machine learning method to detect harmful algal blooms (HABs).

Karenia brevis Images source: Florida fish and wildlife resources department
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What lives in the bottom of lakes and streams in Cobb County Georgia- benthic organisms!

Benthic organisms are remarkably diverse and vary with habitat. They include protozoa (like amoebas), sponges, cnidarians, flatworms, nematodes, isopods, crayfish, amphipods, mollusks, gastropods, leaches and aquatic worms, pelecypods, insects, and fish. Benthic species I have observed in my area (Cobb County, Georgia) include the Asian Clam (Corbicula fluminea), larval brook salamanders (Eurycea sp.), common sunfishes (Lepomis sp.), the Chattahoochee Crayfish (Cambarus howardi), caddisfly larva (Order Trichoptera), damselflies and dragonflies larval (Order Megaloptera), mayfly larva (Order Ephemeroptera), dragonflies and damselfly larval (Order Odonata), aquatic worms (phylum Annelida), Eastern Dobsonfly larval (Corydalus cornutus), water snakes (Nerodia sp.), longjaw minnow (Ericymba amplamala), river Cooter (Pseudemys concinna), true bugs (Order Hemiptera), true flies larval (Order Diptera), beetles (Order Coleoptera) and stonefly larval (Order Plecoptera). It is worth noting some of these species may only occupy the benthos for a period.

Image of a Brook Salamander. Brook salamanders are a genus, Eurycea, image by Lauren Schramm

Image of a Brook Salamander. Brook salamanders are a genus, Eurycea, image by Lauren Schramm

In some streams, Asian clams, an invasive aquatic species, can be one of the largest components of the benthic invertebrate community (Poff et al.,1993), however this is not the case in all streams in Cobb County. Black et al. (2003) evaluated benthic macroinvertebrate populations of two local streams: Sope Creek and Rottenwood Creek. In Sope Creek they found Ephemeroptera and Diptera to be the dominant orders. In Rottenwood Creek they found Trichoptera and Diptera to be the dominant orders.

An Asian Clam (Corbicula fluminea). Image by Lauren Schramm.

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Impacts of climate change on the Great Lakes

The Great Lakes contain 20 percent of the world’s freshwater (McBean 2008) and are already facing the impacts of anthropogenic climate change. The Greats Lakes have seen a 10 to 25 percent increase in precipitation from 1981 to 2010 (NOAA, 2019) due to increased evaporation. The amount of precipitation is predicted to increase by 12.5 percent by 2080 (Wang 2016). Increased rainfall has led to increased nutrients washed out of soils, as found in two studied watersheds (Wang 2018). In one watershed the amount of phosphorus washed out, due to soil erosion, could increase by 108 percent by 2099 (Ibid). These additional nutrients can result in nutrient loading and therefore algae booms and eutrophication in the Great Lakes.

One reason for the increased precipitation is the reduction in ice cover, which results in more evaporation. Ice cover has decreased by 71 percent on the Great Lakes from 1973 to 2010 (Collingsworth, 2017). Many commercially important fish species allow their eggs to overwinter below the ice, with reduced ice cover their eggs are more susceptible to wave action damage (Ibid). Models to predict how much ice coverage will be reduced vary widely but they all agree that the coverage will reduce by 2050. One initial benefit of reduced ice cover is that it will reduce the number of winter kills as there will be more circulation of oxygen.

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Water scarcity issues in Georgia/ Cobb County

Georgia experiences several droughts including one from 2005 to 2007 that made headlines as lake levels in Lake Lanier, which serves as a major water reservoir for Atlanta reached record lows. It was shown that this drought cost $2 billion dollars in loses, which included $87.6 million in recreation spending lost from visitors to lake Lanier as the lake levels were down 20.21 feet from full capacity. It was shown that this drought was caused by an increase in consumption rather than anthropogenic climate change. There have been other major droughts in 1954-1956, 1981, 1985- 1988, and 1998 – 2002, 2012 to 2013 and 2017. To lessen the effects of droughts in the future of Georgia, education, voting with our dollars as consumers, and a change in diet are key.

The county that I live in, Cobb County, has an excellent water stewardship program. They have a team of scientist that travel the county and regularly test the quality of streams and rivers. They also provide lots of programming with the public. They are home to the largest adopt-a-stream program in the country which is a great way to engage citizens in water quality issues. They often host workshops where you will make and take home a rain barrel. They also send out quarterly newsletters on water issues in the county and host stream clean ups in partnership with the Department of Natural Resources Rivers Alive program.

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Gaianism: an look at the mother earth worshipping religion

The Gaia theory was first introduced in 1979 by James Lovelock in his book Gaia a New Look at Life on Earth. The basic idea is that the earth is a self-regulating entity. While the theory was a scientific one, it launched a new pantheism religion known as Gaia worship or Gaianism, whose practitioners are known as Gaians. While Gaia worship is not new and Gaia is the oldest divine being who dates back to prehistoric times, the concepts of this religion are. For example, Gaianism is monotheistic while Gaia worshipers of the past were polytheists. Central to both the Gaia theory and the beliefs of Gaian is the concept that the earth is a self-aware being that is able to self-regulate. The relationship between the earth and Gaia is that of your body and you. The Gaians believe that this is their goddess. Many of the core concepts of this fringe pagan group stem from the Gaia theory or are directly linked to it. The three core concepts of Gaianism are honor the earth, reduce human impact on the earth, and be respectful of life in all forms and of the systems that support them.

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The religion tends to be much unorganized due to the nature of pagan religions. There is a very negative cultural associated with the word pagan, therefore, many pagans prefer not to state their religion. In addition, those who have not heard of the religion obviously will not follow it. Since it is not that popular not many people have heard of Gaianism. However, the most organized group of Gaianism developed from a Wicca coven in New York City. This group called themselves Gaia Group, but was created from Coven of Caerlleuad (Castle of the Moon) in August of 1983. This group saw that other Wicca groups were changing to have more future thinking outlook rather than trying to preserve the traditions of the past. The group saw this as holding them back due to the fact the negative views of Wicca are based mostly on their past practices. The group also saw the belief systems of the past as no longer relevant. In order to make the religion more universally accepted they replaced welsh traditions and gods with an ethic focused on Gaia. The group focuses on the ideals of repairing this world and the fact that we are members of a larger community. They took part in many protests and had a strong emphasis on community service. Unfortunately, the group disbanded in 1998.

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Dinosaurs and microfossils on the Blanco River- Texas

If you spend any amount of time in the town of Wimberly, Texas locals will be sure to mention the flood that happened in 2015. 13 people died and 350 homes were destroyed. However, there was a silver lining to the flood, a large number of fossils, including dinosaur footprints were discovered in the Blanco River. These footprints were discovered when the City of Blanco GIS manager was reviewing aerial photographs. From the photographs, we can clearly see the footprints of a four-legged dinosaur (or sauropod). Based on the distance between the front feet, foot size, time at which the tracks where made, and stride length it’s like that the tracks belong to Paluxysaurus Jonesi, or as anyone who has watched the land before time would call it, a longneck. It’s actually the state dinosaur of Texas. The footprints are located on federal owned land that you can only access with a ranger and I’m not sure if the public can visit. I was able to visit through the master naturalist program. Here is a link to other dinosaur footprint site in Texas you can visit though.

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These footprints were created by a baby little foot, captured by Lauren Schramm

There were a ton of other fossils the rangers pointed out to us as well. The most mind-blowing to me was a microfossil. At one point we were walking in some small gravel and the ranger told us to look down. Turns out we were actually walking on millions of microfossils of a former unicellular organism that lived in the ocean. The sheer number of them was astounding. The concept of microfossils is pretty crazy too. Researchers can actually find microfossils of plankton or pollen and learn a lot about what past environments where like.

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Microfossils! Captured by Lauren Schramm

 

Cave Ecosystems- zones and wildlife

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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