Endangered Species

Vanishing wetlands pose a threat to species who reside in these unique habitats for all or part of their life cycle. Population decline can be caused by a variety of threats, including invasive species competition, habitat loss, and overharvesting or over-predation. There are species who rely heavily on constant or predictable conditions in specific parts of the year such as seasonal rainfall, temperature cycles, and sometimes other species who migrate for part of the year. Populations subjected to too much stress for an extended period often experience population decline as well. In some cases, those species become threatened, endangered, or even extinct.

CWPPRA and U.S. Fish and Wildlife Service will celebrate and observe Endangered Species Day on May 17th, 2019, to celebrate and highlight the species and habitat protection efforts throughout the coast. Louisiana is home to 11 endangered species, including three species of bivalve mollusks, three species of sea turtle, two species of birds, two plants, and one fish. Of these, every single one is reliant on wetlands. All three bivalves (fat pocketbook, pink mucket, and tan riffleshell) are freshwater filter feeders who live in flowing water. They clean pollutants from the water before it reaches our coastline, improving water quality for our coastal residents. Sea turtles are among the most popular sea creatures and they rely on our coast for their nesting grounds. Leatherback (largest, deepest-diving, and most migratory), hawksbill (thickest scutes/shells), and Kemp’s ridley (smallest and rarest) feed on different creatures, but they seem to all agree on jellyfish. The two bird species on the list are the interior least tern and the red-cockaded woodpecker. Terns are fishing birds that enjoy the banks of the Mississippi River, whereas the woodpeckers utilize the upland hardwood forest ecosystems of northern Louisiana. The two plants are American chaffseed and Louisiana quillwort. Chaffseed is a semiparasite that relies on fire to proliferate in longleaf pine forests. Louisiana quillwort is a semiaquatic graminoid (grass-like plant that spends some time underwater). The lone fish species, the Pallid Sturgeon, is a ray-finned, bottom-feeding, freshwater fish that can live up to a century. They like the turbid waters of the Mississippi River and its distributaries.

Clearly, these 11 native species have adapted to Louisiana’s dynamic landscape and they each fill a different niche within their respective habitats, so a one-size-fits-all solution does not exist for their preservation. CWPPRA funds projects that help maintain or restore vital habitat for these species and the other species they rely on for food. If a species goes locally extinct, it can have a ripple effect that throws off pre-established balances throughout the ecosystem. Coastal protection has an extensive impact, protecting areas further upstream as well, so CWPPRA indirectly eases pressure on the inland species. Endangered species are one of many reasons our coast deserves to be restored and protected.

For more information about these species and other threatened and endangered species, visit the US Fish and Wildlife Service’s website: https://www.fws.gov/endangered/.

The featured image is from https://www.nature.org/en-us/explore/animals-we-protect/leatherback-sea-turtle/

Competitive Dominance

Ecosystems around the world are in a constant state of competition as inhabitants impact each other, whether directly or indirectly. The theory of competition deals with interactions between populations within a defined range or habitat. [1] Individuals with more beneficial adaptations are more “fit” and will often out-compete others for resources like food, territory, or sunlight. Today, we will look at how one species can become dominant over its competitors in wetlands and what conditions might disrupt or completely tear down dominant species.

Some of our readers may immediately think of monoculture farming as a sort of dominance, and they would be correct. Although it is through artificial selection, crop species present some trait that Homo sapiens deems worthy of cultivating. For example, huge swaths of land in the United States have been clear-cut to make room for corn farms, cattle ranches, or even sugar cane farms. Maybe not to the same degree as artificial selection, natural selection can also produce habitats with dominant plants and animals. Coastal Louisiana’s wetlands are great examples of this. From Cypress swamps to Spartina marshes, wetlands are home to some hardy species who have adapted to harsh and variable conditions.

Wetlands go through cycles of drought and flood conditions, which can prove fatal for many species. [2] Wetland plants have adapted to survive the cycles and even exploit them. Cypress trees are a useful example because they don’t necessarily need flooded conditions to grow, they just need space and a little bit of protection when they are young. [3] Instead of becoming competitive on dry land with the thousands of other obligate dry land trees, cypress ancestors developed the ability to survive in water where few other plants competed. More information about their adaptations can be found in our second post about flood stress tolerance. In the salt marshes along our coast, smooth cordgrass (Spartina alterniflora) and other graminoids (grass-like species) dominate with their salt tolerance and fast reproduction. More about how cordgrass and black mangroves dominate other coastal species can be found in our first post about salt stress tolerance.

Within a species’ endemic (native) habitat, populations are limited by food availability, competition, and predation. However, species can move to non-native habitats that have plenty of food, less fit competitors, or little to no predation, in which case that species can become problematic. Invasive species are detrimental by definition and coastal Louisiana has several examples, which can be found in our invasive species article. Unfortunately, many invasive species move to new habitats with the help of humans, sometimes by accident and sometimes on purpose.

If you want to learn more about how human impact and other factors can change dominance structures, be on the lookout for Dominance pt. 2 next Wednesday!

[1] https://www.nature.com/scitable/knowledge/library/species-interactions-and-competition-102131429

[2] https://www.worldwildlife.org/habitats/wetlands

[3] https://www.arborday.org/trees/treeguide/treedetail.cfm?itemID=787

Featured Image from https://www.flickr.com/photos/9428166@N03/2686432231