Microorganisms Help Wetlands

Seeing microorganisms and cellular structures brought about a new era of scientific discovery, from understanding infectious agents to recognizing sub-cellular structures in living tissues. Microscopy allows us to observe the smallest parts of our natural world invisible to the human eye. Different types of microscopes and other analyzing tools have allowed ecologists and environmental scientists to assess the health of wetlands in coastal Louisiana. From geologists to botanists, sedimentologists to ecologists, microorganisms are a vital ally in the fight against wetland loss in coastal Louisiana.

Microorganisms like phytoplankton (microscopic plants) can be great indicators of aquatic and wetland habitat health because they are easily affected by changes and easy to observe under a microscope. Studies across the Gulf Coast sample phytoplankton and zooplankton (microscopic animals) to keep tabs on large-scale changes in water quality. For example, algal blooms, which are huge growths of phytoplankton, often lead to the death of important fisheries species. These blooms also indicate poor water quality and contribute to the worsening of hypoxia.

Soil microbes can give information on marsh platform health. In response to stressful situations, these microbes can change their cell walls’ chemical makeup to reduce physiological damage. By identifying both the stressed and non-stressed types of molecules, soils can be assessed quickly. Healthy soils are important in keeping nutrients cycling, which is crucial in keeping wetland plants alive and growing.  Without a stable microbiome supporting plant growth, marsh platforms degrade and can no longer sustain life or provide any ecosystem services.

Microscopic organisms also play a huge role in coastal Louisiana’s wetlands because they are crucial in regulating marsh platforms, feeding our fisheries, and producing a huge portion of atmospheric oxygen for all terrestrial life on the planet. Coastal scientists study these tiny indicator species to quantify the health of wetland ecosystems. For example, fisheries rely on trophic interactions (food web/food chain) that include phytoplankton as the primary producers. Since seafood is such a profitable industry in Louisiana, we have a great appreciation for microbes. Louisiana’s crucial shrimp harvest and signature oysters rely directly on plankton, and larger sport fish rely on eating other things that eat plankton.

Although tiny, microorganisms play an important role in Louisiana’s coastal wetlands. As complex a system as our coast is, it’s easy to see direct impacts that a weak microbial community may have on certain pieces of the full ecosystem. We urge our scientists, engineers, and legislators to be conscious of each problem our coastal zone faces and the tricky side effects that may come with them. When restoring our coast, we must look at the big picture as well as the key parts involved in our coastal wetland system!

 

Sources:

https://www.epa.gov/national-aquatic-resource-surveys/indicators-zooplankton

https://link.springer.com/article/10.1007/s100400050013

https://www.researchgate.net/profile/Colin_Jackson11/publication/225750153_Effects_of_Salinity_and_Nutrients_on_Microbial_Assemblages_in_Louisiana_Wetland_Sediments/links/587e38e408ae4445c06fac52/Effects-of-Salinity-and-Nutrients-on-Microbial-Assemblages-in-Louisiana-Wetland-Sediments.pdf

Featured image of a Haptophyte from https://johandecelle.wordpress.com/2014/10/02/a-novel-diversity-of-haptophytes-unveiled-by-metabarcoding/

Plankton

We talk a lot about the health of marine life in terms of fish, oysters, crabs, and other large organisms that we can observe with the naked eye, but we often look past the microorganisms that, in some cases, can be better indicators of water quality, productivity, and overall ecosystem health. [1] The microorganisms in question often fall under the umbrella term of “plankton”. Directly translated from Greek, the root word “planktos” means wandering and describes how these organisms move through ecosystems. There are many varieties of plankton, including producers (phytoplankton) and predators (zooplankton).

One key characteristic that all plankton share is that they do not move very far on their own; they rely on currents and other movement in the water column for most of their migration. While some planktonic organisms can move with a flagellum (tail made of proteins), most of the movement for all plankton comes from external forces. [2] Currents and mixing often occur in the pelagic (uppermost open water) layer because of wind, temperature variation, and a variety of other factors. Phytoplankton thrive in the shallower layers of the pelagic zone where abundant sunlight and gas exchange are available. Higher concentrations of carbon dioxide at the surface allow phytoplankton to photosynthesize, removing carbon dioxide from the atmosphere and giving off the oxygen we breathe. Phytoplankton produce about half of the oxygen in our atmosphere by some estimates, which makes them just as important as our rainforests and other terrestrial ecosystems. [3]

Plankton do not all fit into one taxonomic group; there are plankton from each kingdom. [4] Our coastal waters contain species from each, including microcrustaceans like copepods, bacteria like blue-green algae (cyanobacteria), and juvenile life stages of larger animals like oysters and fish. Jellyfish in their most recognizable form, the medusa, are technically plankton, too: they have no locomotion so they just drift. As easy, plentiful prey, plankton often form the base of marine food webs. Unfortunately, having too many phytoplankton is a very real, very dangerous issue in coastal Louisiana where excess nutrients coming down our waterways provide lots of food for phytoplankton. An overgrowth of phytoplankton can cause an algal bloom [5] and associated hypoxic or dead zone. See our post ‘Stress pt. II: Flooding and Hypoxia’ for more information on how too many producers can decrease the amount of oxygen.

CWPPRA projects help to decrease the area of the Gulf of Mexico dead zone by restoring wetlands. The more wetlands we have in our Mississippi river watershed, the more filtration of excess nutrients we have. Filtration is a major benefit of wetlands and can prevent phytoplankton from accessing these excess nutrients. Hopefully one day nutrient filtration and other pollution reducing practices will allow the gulf to return to its former glory.

 

[1] https://academic.oup.com/plankt/article/36/3/621/1503238

[2] http://www.biologyreference.com/Ph-Po/Plankton.html

[3] https://news.nationalgeographic.com/news/2004/06/source-of-half-earth-s-oxygen-gets-little-credit/

[4] http://www.seafriends.org.nz/enviro/plankton/class.htm

[5] https://www.epa.gov/nutrientpollution/effects-dead-zones-and-harmful-algal-blooms

Featured image from http://blueplanetsociety.org/2016/04/studying-phytoplankton-with-citizen/