LETTER TO THE EDITOR: It takes a whole lotta clams to clean up an estuary

June 26, 2021
By Marcy Shortuse

BY MARCY SHORTUSE – Barry Hurt of Little Gasparilla Island has been studying the effects of red tide on our waters and economic system for several years, and he thinks he has come up with a plan to make a difference. “A Billion Clams,” or “Project ABC,” has been at the forefront of Hurt’s focus for quite some time and believes it could mean the difference between sustainability and catastrophic failure for our local waters.

Why clams? Hurt, who has been coming to Little Gasparilla Island since 1985 and living there full time since 2004, has been farming clams through a lease on Sandfly Key since 2001. Most of the clamming leases near Gasparilla Island are on Sandfly Key, but there is one in Bull Bay. None of these leases have been farmable since December of 2020, due to red tide.

According to Hurt, bivalve shellfish are natural filters of water, and in the early part of the 1900s Southwest Florida waters contained some of the largest beds of hard clams in the United States. Hurt said it took about 50 years to wipe those clam beds almost completely out of existence, because of over-farming and dredging.

“Restoring large densities of these algae consuming shellfish will provide the filter to decrease nutrient concentrations in our estuaries,” he said.

Filter feeding clams remove algae from the water column and transfer the nutrients to the benthic environment (the lowest level of the underwater ecosystem). These nutrients can promote sea grass growth, which also serves another valuable purpose. Our area’s sea grass is gone by more than 75 percent … but sea grass is needed by many creatures to stay alive, including manatees. Transferring that algae down to the bottom of the floor of the water also feeds the organisms that live there, which further balances the ecosystem.

Clams are extremely efficient filter feeders; a single clam will filter five gallons of seawater per day. Clams play an important role in the cycling of nutrients, including nitrogen (N). Clams do not absorb nitrogen directly from their environment, rather they feed on naturally-occurring phytoplankton, which use dissolved inorganic nitrogen, available in the water, to grow. Clams also stimulate the growth of bacteria that changes the nitrogen in the water, making it a very inhospitable place for the algae that is harmful.

Hurt said 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 Karenia Brevis, the algae producing Florida red tide.

Mercenaria mercenaria, the northern quahog.

According to Hurt’s website, clamrestoration.com, 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,” Hurt said. “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.”

There are two types of clams that play an important role to clam farmers in our ecosystem – Mercenaria campechiensi, which is our almost non-existent native clam, the southern quahog, and Mercenaria mercenaria, the northern quahog that is artificially farmed here.

Hurt said if you were to find one of the rare native clams that may still exist in our waters, they can be 40 to 60 years old. The northern quahogs that are farmed here can only last potentially two summers in our warmer water.

“We need to provide some sort of stream of income for those farmers, as well as doing all the work in the bay that needs to be done,” Hurt said. “We need to hire the clam farmers who know how to make clam sets. They’re not easy to make. We need them to do the husbandry work for three years, until the beds can sustain themselves; they are non-harvestable for that time. Our native clam is a very hardy clam, a thicker walled clam, and it holds up to the hot water a lot better. The commercial clam that the guys grow is a northern clam, and it is easier to shuck but it doesn’t hold up in the heat as well. Typically, you don’t want to let them stay in water one summer, but if they go into the second summer in that hot water we lose a lot of clams. What we’re talking about is having clam farmers revitalizing industry, growing the northern clams on their leases, but through the red tide closures they can work the native clam beds.

“Our farming community is in bad shape. Between hurricanes, red tide and COVID. Those guys can’t make a living. We need to restore what was overfished.”

If you are interested in getting involved with the ABC Project, go to clamrestoration.com for more information.

This article will run in full-length in a future Gasparilla Island Magazine issue.