Red tide (Karenia brevis), which has been in bloom along the Gulf Coast since October 2017, has plagued the west coast of Florida for centuries; however, the severity and duration of the most recent 2017/2018 bloom which has killed marine life along 150 miles of Florida's coast, spotlights the need for solutions to this recurring problem.
Image credit Florida Fish and Wildlife Conservation Commission
Bivalve shellfish are natural filters of water. Historical populations of native hard clams within SW Florida estuaries were legendary, referred to as "the largest bed of hard clams in the United States". ( Schroeder 1924) . SW Florida’s seemingly inexhaustible wild clam beds supported 2 canneries for 40+ years. It took about 50 years of relentless dredging to wipe out these clam beds. Restoring large densities of these algae consuming shellfish will provide the filter to decrease nutrient concentrations in our estuaries.
The ABC plan utilizes an existing workforce who has the knowledge, skills, and tools to restore long depleted native clam resources---our local clam farmers. Our local farmers cannot harvest during red tide events, evaporating jobs, eliminating cash flow thus placing their farms in economic peril. The plan proposes to put this local industry to work by setting aside sufficient qualified acreage to be restored by establishing permanent clam beds protected from both commercial and recreational harvest. Through the husbandry of experienced farmers, these clam beds will mature and become self-recruiting, leading to an increase in native populations over time.
Video credit Cutthroat Clams
Clams are extremely efficient filter feeders; a single clam will filter 5 gallons of seawater per day.
Clams have the ability to absorb pollutants, bacteria, and viruses in polluted waters; High densities of native clams can reduce harmful algae through consumption of Karennia Brevis, the algae producing Florida red tide.
See the power of clam filtration by watching a short filtration video by the University of Florida IFAS.
Filter feeders promote clearer water allowing deeper penetration of sunlight, boosting sea grass growth.
Filter feeding clams remove algae from the water column and transfer the nutrients to the benthic environment (bottom).
These nutrients can promote sea grass growth and be used as support for a variety of organisms that live in the sediment (e.g., brittle stars and worms).
Clams remove nitrogen from the water by filter feeding. The Nitrogen is incorporated into their shells and meat. Clams also stimulate bacteria that are capable of changing nitrogen in the water to harmless nitrogen gas, effectively making it unusable for algae.
Clam beds aid in coastal reinforcement and counteract erosion by creating beds extending as much as 12 inches into the bottom. In a dense mature clam bed, clams will be close to one another, like bricks in a road. Clam beds support a higher diversity of marine life than sand flats, providing food and refuge.
Clams extract carbon from seawater to make their shells. An average clam contains 3 grams of carbon in their shell providing a source of carbon sequestration. Clams extract phosphorus from the seawater and store up to 1% of their meat weight in phosphorus.
Video credit University of Florida/IFAS
...over multiple years. This skilled workforce of local clam farmers (small family farms) utilizing proven farming techniques in cooperation with our scientific advisors, is an efficient method to stabilize working waterfronts, enhance water quality, maximize sustainability of local fisheries, and benefit local economies.
Among the broader economic implications of red tide for the State, the southwest Florida shellfish aquaculture industry loses hundreds of thousands to millions of dollars almost every year due to red tide (Adams, et al. 2016). Tourist and wild fisheries lose similar millions in lost revenues
The Southwest Florida clam farmers firmly believe that restoration of native clam (M. campechiensis) populations in Charlotte Harbor will lead to cleaner water, greater biodiversity, and protection of our local economy by providing the first line of defense for our estuary.
The ABC plan is informed by a suite of scientific advisors and will utilize cooperative partnerships with the goal of enhancing new research, advancing existing science, and will maximize efforts that address research needs as identified by the advisors.