LDWF meeting to talk about Big Lake Oysters

[Duck Butter]

Originally Posted by MathGeek

I've read most of the published literature on hypoxia in the Gulf of Mexico, and cited a lot of it in papers I've co-authored.

The suggestion in the above discussion that the hypoxia in the near shore waters off of Cameron Parish may be attributable to nutrient loading from the Calcasieu estuary or negatively correlated with its oyster stocks has not appeared in the published papers which have focused primarily on the role of the Mississippi River and secondarily on the role of mobile muds from the larger rivers and existing sediments.

But all the existing evidence supports the plausibility of inverse correlations between oyster reefs in Calcasieu and algae blooms and hypoxia in the adjacent Gulf waters:

1. Oyster reefs reduce the effects of nutrient loading, effectively reducing N, P, and C levels in the water before it exits the estuary.
2. Oyster reefs reduce turbidity in the estuary, allowing sunlight to penetrate deeper supporting more photosynthesis and a greater food web within the estuary.
3. Oysters remove tremendous amounts of phytoplankton from the water, thus reducing the quantity of algae that reaches nearshore Gulf waters and decomposes on the bottom.
4. Oyster reefs reduce erosion by several mechanisms, thus reducing the carbon in existing sediments from reaching near shore waters from erosion and tidal action.
5. Oyster reefs grow and maintain tremendous biomass in the estuary itself, increasing the average trophic level of carbon that enters the system via photosynthesis. Carbon that reaches higher trophic levels is not decomposing in bottom waters during the summer months where risks of hypoxia are the greatest.

No one is denying the benefits of oysters, they are extremely important as you have pointed out. But oysters are not a magic bullet, nor do they decrease hypoxia to a noticable extent. They will shut down in hypoxic conditions. They can't just uproot and move away from the conditions, so they shut down, therefore no more filtration.

And not everything is published material, some is just common sense. Rivers are what brings in the nutrients, why would the Calcasieu River and the waters that drain into it not be full of nutrients like every other river in the lower US?


oysters and hypoxia
http://scholarcommons.usf.edu/msc_facpub/160/

Actual oyster filtration potential must be lower than many advocates of oyster restoration assume, and replenishing the bay with oysters is not the means of controlling blooms and hypoxia.


http://www.int-res.com/articles/meps...1/m341p299.pdf
[SIZE=1][SIZE=1]Recently published models, which allow for spatial and temporal matching of oyster and
phytoplankton populations in mainstream Chesapeake Bay, support the conclusion of Pomeroy et al.(2006; Mar Ecol Prog Ser 325:301–309) that oysters cannot, and could not, control the spring blooms that are the ultimate cause of summer hypoxia.
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