Land Loss and Human Impacts

Louisiana’s shrinking coastal zone is due to both natural causes such as rising sea levels and wave erosion, but human activity intensifies these evolutionary processes. Some of the most impactful land loss processes further increased by human activity include salt water intrusion, proliferation of invasive species, and subsidence.

Hurricanes and other storm events push salt water inland, increasing the salinity of wetlands to levels that damage local flora adapted to lower salinities, causing those plants to die, which in turn decreases their potential to reduce storm surge around human settlements. Dredged canals for oil and gas exploration provide easy pathways for salt water to move inland since these canals are often straight. [1] Healthy marshes decrease the distance that storm surges can infiltrate, so any man-made development that diminishes intermediate or salt marshes indirectly affects freshwater wetlands as well.

Invasive species are plants, animals, or other biota that are from other regions of the world that cause harm to our local native environment. One such invasive species with extensive ramifications for our coastal wetlands is the Coypu, or “nutria rat.” This large rodent devastates stands of native graminoids such as cordgrasses (Spartina spp) and bulrushes (Schoenoplectus spp). Coypu specifically target the base of stems and roots, digging for them in soft sediment platforms. [2] Lower root concentration in soils and active disturbance make for weakened substrates that are more susceptible to being washed away. Other invasive species have similar outcomes, but not necessarily by the same method. We have several invasive animals and plants in Louisiana, each introduced by humans either on purpose or accidentally, and each one has a destructive presence along our coast. CWPPRA actively works to counter the destruction of invasive species through research, engineering and reward-based mitigation, such as the Coastwide Nutria Control Program. [3]

Louisiana was built by the Mississippi River over the past several thousand years, depositing layer after layer of soft, uncompacted sediment. Naturally, that sediment will compact, causing the surface to sink. Developing human settlements might speed up this process due to increased weight. Some cities are sinking as fast as 12 millimeters per year. Combined with rising sea levels, these areas are getting 15 millimeters (.6 inches) closer to sea level each year. [4] Combining the natural subsidence rates with unnatural marsh degradation, flooding will continue to worsen in our towns and cities. The Coastwide Reference Monitoring System (CRMS) tracks subsidence as well as several other ecological conditions and CWPPRA project performance over 391 sites along the Louisiana Gulf Coast. [5] Human activity is an integral component of Louisiana’s coastal zone, and CWPPRA works with biologists, engineers, local governments, volunteers, and residents to study those adverse impacts and devise innovative methods to address and deter them.

 

Sources:

[1] http://web.mit.edu/12.000/www/m2010/finalwebsite/background/wetlands/wetlands-degradation.html

[2] http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Myocastor_coypus.htm

[3] https://www.nutria.com/site9.php

[4] https://www.nola.com/news/environment/article_fc2fc043-f0a3-55a5-b1a5-ce96dc712c3e.html

[5] https://www.lacoast.gov/crms/Home.aspx#

 

Featured Image from JennyCuervo [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)%5D

Cooking with Invasive Species

Louisiana is a great place to institute a culture of dining on invasive species because, in addition loving good food, we’ve got plenty of them.  In a state where hunting is common and nutria are rampant, the Coastwide Nutria Control Program (LA-03b, nutria.com) pays people to harvest nutria. There are many benefits to a program like this, including food, environmental protection, and partial income for indulging in a hobby for many sportsmen. On the science side, our nutria program maintains a database of regions where nutria are trapped or hunted that can aid in assessing their damage. [2] The tasty meat from nutria can also be used in cooking, so it doesn’t go to waste. The 2017 documentary “Rodents of Unusual Size” features coastal Louisiana natives, chefs, and others trying to limit the damage done by Louisiana’s nutria population. [3]

There are also plenty of recipes for feral hogs since they are the same species as domestic pigs, Sus scrofa, a staple in American cuisine. Feral hog meat can be substituted into any recipe that calls for domesticated pork, like a classic roast (pictured from Cook-off for the Coast 2019), however it’s important to make sure the hog was thoroughly inspected after harvest since they can carry parasites and diseases harmful to humans. Other invasives that have accessible recipes with a quick search on the web include apple snails (a delicacy in some parts of the world), water hyacinth, and multiple species of Asian carp.

Creative solutions to growing problems come in many forms. Harvesting invasive species as a food source is a multi-benefit solution in the fight against damage from invasives. While some scientists disagree with this method of invasive control, saying it has too little of an effect on invasive populations [1], putting invasive species on the dinner plate can help spread awareness of the issue and provide incentive for increased harvests. CWPPRA embraces new solutions to land loss in Louisiana, and we urge our readers to explore alternative food options that may help in our fight to #ProtectOurCoast. Who knows? You might find a new favorite food.

 

[1] https://www.theguardian.com/environment/world-on-a-plate/2015/feb/06/cooking-cant-solve-the-invasive-threat

[2] https://nutria.com/site24.php

[3] https://boingboing.net/2013/04/29/meat-from-a-20-kb-swamp-rat-t.html

Competitive Dominance Pt. II

Last week, Wetland Wednesday focused on dominant species in wetlands and conditions that contribute to competition. Last week we talked a lot about plants, but animals can be dominant in wetlands as well, for example the American Alligator (Alligator mississippiensis).

Alligators are one of the most recognizable predator species of swamp and marsh habitats, but they haven’t always been as numerous as they are now. Alligators were endangered as recently as 1987 due to human impacts, especially hunting. [1] Since their conservation proved so effective, they are no longer on the endangered species list, but instead are now “of least concern”. It is impressive to see such a strong recovery for an endangered species, and their recovery was successful for many reasons, including their lack of strong competitors. Very few animals compare in size or bite strength. As apex predators, they have essentially free reign over other species when they reach maturity, although there is some competition between individual alligators. Productivity in swamps and marshes is extremely high compared to other habitats, so there is plenty of food to go around, but they still compete with birds of prey and other large aquatic animals like alligator gar and alligator snapping turtles (those names probably aren’t coincidental…).

As we mentioned last week, dominant species are not always native. Invasive species like nutria, or coypu, often out-compete native muskrats for similar food sources and homes. Since nutria are larger than muskrats, fewer species can prey on them. [2] Invasive species like nutria can disrupt communities of native species to the point of local extinction in some cases, especially in island ecosystems. [3] Not all introduced species are invasive; some do not significantly impact their new homes. Invasive species are detrimental by definition. Nutria were originally introduced by humans, which means their dominance over native muskrats is a byproduct of human activity. Similarly, zebra mussels and apple snails were introduced by humans and out-compete native species in coastal Louisiana.

Many species face the threat of population decline due to human activity, whether directly or indirectly. In a way, nearly all species on the planet are in competition with humans for food, territory, etc. or compete against one another to survive amid human impacts like climate change. Humans have done a great job altering landscapes to become livable for us, but those landscapes aren’t always good for native species. This kind of disruption has consequences to our own safety, however. Degradation of coastal marshes in Louisiana has been a consequence of human activity, and the risk of lowered wetland protection from storms poses a threat to our settlements. Since we have invested so much in where we live, it is in our best interest to reverse some of the damage we have done to those areas. CWPPRA is dedicated to coastal restoration because it is a responsibility we owe to both the environments we have disrupted and our communities that have come to depend on these environments.

[1] http://www.endangered.org/animal/american-alligator/

[2] https://www.aphis.usda.gov/publications/wildlife_damage/content/printable_version/fs_nutria10.pdf

[3] http://www.pacificinvasivesinitiative.org/site/pii/files/resources/publications/other/turning_the_tide.pdf

Featured image from http://www.louisianaherps.com/american-alligator-alligato.html

Learning about Wetlands and Dining on Invasive Species

On November 18th, residents and visitors in St. Bernard Parish were treated to live music, cooking demonstrations, and the chance to sample wild boar recipes prepared by teams vying for bragging rights. Hosted by the Coastal Division of St. Bernard Parish, the first Cook-Off for the Coast was held at Docville Farm in Violet, Louisiana with proceeds benefiting the St. Bernard Wetlands Foundation. In addition to evaluating the food of the six competing teams, visitors watched local celebrity chefs prepare everything from gumbo to snapping turtle and talked with a range of coastal organizations about the importance of protecting southeast Louisiana’s coastal wetlands.

Sinead Borchert and Mirka Zapletal from the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) Outreach Office were in attendance with information about restoration projects in St. Bernard Parish, activity books, posters from the #ProtectOurCoast series, and recent issues of WaterMarks magazine. They also invited children and adults alike to match Louisiana wildlife with the correct wetland habitat. St. Bernard’s coast is vulnerable to storms, subsidence, erosion, and invasive species, putting wildlife habitat and coastal communities at risk. CWPPRA projects work to support Louisiana’s coastal wetlands and the people and wildlife that depend on these habitats.