Under ideal circumstances, we can do a lot of good. But when circumstances handicap or restrict our potential—in ways we cannot circumvent—we just do the best that we can.
That principle is true for humans as well as in the water-filtering services of the humble bivalves we call oysters—according to recent research involving the University of Maryland.1,2
Dr. Matthew Gray, an ecologist at the University of Maryland Center for Environmental Science, studied the water-filtering abilities of oysters. He showed how real-world conditions can handicap the ability of oysters to improve water quality, compared to oysters in idealized experimental conditions.1,2
Living in and below the tidal zone in coastal shores, oysters must be flexible to survive.
In other words, as they eat, oysters filter the waters that they live in. If those waters contain ideal conditions—such as temperature, salinity, dissolved oxygen levels, etc.—then the oysters can filter lots of water, every day.
However, if oysters live in less-than-ideal conditions, then they filter less water, and so add less improvement to their habitat.1 This is shown by quantitatively comparing experimental results from laboratory tests to observational data of what oysters do in the wild.
ICR has previously reported on bivalve-produced benefits of water quality improvement—removing picoplanktonic algae biomass from coastal waters of the Chesapeake Bay—to prevent “dead zones.”
The habitat heroes, who provide clean-up services to estuarial coast-waters, are oysters and mussels.
Laboratory experiments can facilitate interesting investigations, and may even yield informative data, but how much of those artificial scenarios are representative of real-world activities? With shellfish like oysters and mussels, as with other animals, field studies allow for data observed in the wild that is much more relevant (and realistic) for understanding how such creatures really live.4
But even heroes need a little help from friends—or from environmental conditions. That’s why oysters—if they are living in not-so-optimal conditions—don’t “clean up” estuarial waters as efficiently as they could if their living conditions were qualitatively improved.
But what about bivalves feeding in normal (natural) conditions? What about oysters that live in real bay-water? The water temperature makes a difference on how actively oysters filter-feed.
Also, what about the water’s saltiness? If the oyster-bed is subjected to a drop in salinity the oysters lose their appetite for filter-feeding.1 Likewise, what about water turbidity—clarity versus cloudiness?
Also, the amount and type of available food makes a difference. Some algae are delicious and nutritious, yet other algae are undesirable or even harmful. Even oysters have taste sensitivities!
Furthermore, a relaxed oyster will filter-feed more than a frightened oyster. So, if predatory crabs are lurking nearby, oysters will defend themselves as bivalves do, by “clamming up” (closing their shells together), which necessarily interrupts an opportunity to filter-feed.1 Better to eat less plankton than to be eaten by a carnivorous crustacean!
Meanwhile, there is a lesson for us humans: notice that oysters nevertheless filter-feed at a less-than-optimal level—which is better than nothing! So they do contribute some improvement to water quality in their estuarial waters, even when doing so in less-than-ideal habitat conditions.1,3
Of course, ideal circumstances usually exist only in imaginations. Yet the lack of ideal circumstances is never an excuse to avoid doing what is feasible with whatever is available.5
May God give us wisdom and courage, to use whatever resources we now have, for that which is truly good.
Stage image: Oysters filter-feeding in the Chesapeake Bay.
Stage image credit: Dave Harp. Copyright © 2020. Adapted for use in accordance with federal copyright (fair use doctrine) law. Usage by ICR does not imply endorsement of copyright holders.
References
1. Wheeler, T. B. Pumped-up performance: Oysters’ filtering feat overstated. Fisheries News. Posted on BayJournal.com May 20, 2020, accessed June 2, 2020.
2. Quoting from Wang, L., J. Song, et al. 2020. Adaptive Feeding in the American Oyster Crassostrea virginica: Complex Impacts of Pulsatile Flow during Pseudofecal Ejection Events. Limnology and Oceanography. doi: 10.1002/lno.11433. See also Gray, M. W., P. zu Ermgassen, et al. 2019. Spatially Explicit Estimates of In Situ Filtration by Native Oysters to Augment Ecosystem Services during Restoration. Estuaries and Coasts. 42: 792-805.
3. Quoting Johnson, J. J. S. 2019. Termite Skyscrapers Hidden in Plain View. Acts & Facts. 48(4): 21. See also Gedan, K. B., L. Kellogg, and D. L. Breitburg, 2014. Accounting for Multiple Foundation Species in Oyster Reef Restoration Benefits. Restoration Ecology. 22 (4): 517-524; Pipkin, W. 2018. Freshwater Bivalves Flexing their Muscles as Water Filterers. Chesapeake Bay Journal. 28(7): 1.
4. Johnson, J. J. S. 2015. Crayfish, Caribou, and Scientific Evidence in the Wild. Acts & Facts. 44(6): 20.
5. Consider the example of the Old Testament champion named Shamgar, whose example is a true lesson about doing—with God’s grace—whatever we can, with whatever we have. Not having ideal weaponry Shamgar nonetheless used what he had, a farm tool (ox-goad), to accomplish a great military feat for God and God’s people. (Compare Judges 3:31 with 1 Samuel 13:19-22.) God blessed Shamgar’s resourcefulness and courage—by giving Shamgar (and his people) a providential deliverance.
*Dr. Johnson is Associate Professor of Apologetics and Chief Academic Officer at the Institute for Creation Research.
