Recently, we went to see the movie “Where the Crawdads Sing” and it points to a world that, with growing human encroachment, and the realization those places that are getting harder to find. It also points to among other things, the prejudice and quick to judge attributes of the human race, when we don’t understand someone different from us. It makes for a nice love story, but emphasizes the beauty and the resilience of nature, if left alone. I believe most true biologists (naturalists) aspire and dream of the life Kya experienced in “the marsh.”
“Where the Crawdads Sing” directed by Olivia Newman from a screenplay by Lucy Alibar, the film is an adaptation of Delia Owens’ best-selling 2018 novel of the same name. The film stars Daisy Edgar-Jones as Kya, a woman who lives a simple life in a North Carolina marsh who is accused of killing her ex-boyfriend Chase Andrews.
Kya, listened to her mother who often encouraged her to explore the marsh. Her mother would say: "Go as far as you can–way out yonder where the crawdads sing." Kya’s boyfriend would reiterate and explain that those places are "far in the bush where critters are wild, still behaving like critters.”
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First off, crayfish or better yet, crawdads don’t sing. They are decopods, that occasionally venture from subsurface aquatic environments completely submerged and burrow into the mud for over-wintering and complete part of their life cycle. For the most part any singing would be hard to hear, although acoustic detectors have come a long way in animal surveys the last 10 years.
Crayfish are freshwater crustaceans resembling small lobsters (to which they are related). In some places, they are also known as crawfish, crawdads, freshwater lobsters craydids, crawdaddies, mountain lobsters, rock lobsters, mudbugs, baybugs or yabbies. They breathe through feather-like gills. Some species are found in brooks and streams, where fresh water is running, while others thrive in swamps, ditches, and paddy fields. These critters use hemolymph, not hemoglobin as their primary respiratory pigment. Some of the excitement I had in the good ole days.
In graduate school I conducted a variety toxicity tests on a southern species of “crawdad” Procambarus clarkii, or the red swamp crayfish and investigated pathways for acute and/or chronic toxicity. Most crayfish cannot tolerate polluted water, although some species, such as Procambarus clarkii, are hardier. The toxicity tests were called 96 hour LC 50 tests. In short, these tests determined lethal concentrations of a contaminant that would kill 50% of the organisms tested in 96-hour period.
In Texas at that time, these crawdads could be found in several sites still relatively unpolluted back in the 1980s and provided great test organisms for determining metabolic pathways for uptake of various forms of nitrogen and ammonia toxicity. Extensive Interstate and road construction, urban sprawl and parking lot construction have altered or eliminated many of the sites I surveyed in the San Marcos area several decades ago. Come to find out crayfish are very sensitive to nitrite, nitrate and all the nitrogen family compounds prevalent in our local streams and waters.
Crayfish, once common in Nebraska Streams, are getting fewer and fewer. Despite their importance ecologically, crayfish populations are declining worldwide, with 48% of North American crayfish species considered threatened according to research by Taylor et al. 2007 and Richman et al. 2015.
Low head dams are one of many threats to crayfishes that can disturb habitat, alter flow regimes, and impede migration, however, sedimentation, loss of aquatic plants, pesticide runoff and riparian development and disturbance are other culprits.
I want to be positive in a time where many are not, because there is so much greed, corruption and bad news in the world today. Remote places are getting few and far between. There are fewer and fewer and wilder-less (wilderness) places that one can see wild things, on even a small scale. Improved management of these ecosystems will be critical in the coming years.
Oceans, estuaries and brackish marshes are biologically so productive, they are always worth talking about, when we think about biodiversity. I had to leave you with some advice from the Ocean by Mr. Ilan Shamir;
Be shore of yourself
Come out of your shell
Take time to relax and coast
Avoid pier pressure
Sea life’s beauty
Don’t get tide down
Have a great rest of the summer.
Michael P. Gutzmer, PhD is principal and owner of New Century Environmental LLC and provides environmental consulting services in the Great Plains. NCE works with water, wetlands, habitat development threatened and endangered species and pollution problems. Please email me at email@example.com.