How Can Clams Promote Seagrass Health? An Astonishing Victory

How Can Clams Promote Seagrass Health? An Astonishing Victory

October 26, 2022

Seagrass beds, a very important marine ecosystem, are becoming increasingly threatened by climate change and human impacts. In fact, around 20% of our seagrass beds have been lost globally. Scientists all around the world are researching ways to make seagrass beds more resilient to these detrimental effects. Some scientists are jumping to clams as a potential solution to save our seagrasses. Let’s dive into how and why!

What even is seagrass?

Seagrasses are marine flowering plants. Seagrass beds (an ecosystem formed from seagrasses) are ranked as one of the most environmentally valued ecosystems for their biodiversity, carbon storage, and nutrient cycling. This makes these ecosystems especially important for conservationists. Seagrasses can be affected by poor fishing practices and improper boating practices that scrape the ocean floor. Additionally, climate change is causing a raise in sea level, temperature, and severe weather events further affecting seagrass beds. On another note, large scale seagrass deaths are often due to an accumulation of toxic sulfide in the ocean’s sediment which is where the benefit of clams comes into play.

So how can clams help seagrass?

Clams are cool little critters who filter out small particles in the ocean with their little siphons. As they clean the water, they increase its transparency, allowing more sunlight to shine through. Thus, seagrasses get more sunlight, allowing them to photosynthesize more food!

Watch this video to see how clams filter water.

How clams filter water- helping seagrasses photosynthesize!

Lucinid clams – chemosynthetic mollusks

Lucinid clams live in the roots of seagrass, helping to keep the ground sediment healthy. These clams have chemosynthetic (the ability to convert molecules into organic matter) bacteria in their gills that oxidize sulfides, making it non-toxic. When seagrass is stressed it can lose its ability to detoxify sulfide which most likely results in mortality. With the presence of lucinid clam’s chemosynthetic bacteria detoxifying the excess sulfide, it gives seagrass a better chance of survival. In a 2012 study, Van der Heide of the University of Groningen in the Netherlands and his team sampled seagrass beds, digging 20 cm deep into the sediment to see what organisms lived there. They found that when there was a high number of bivalves(aquatic mollusks with a hinged shell- oysters, clams, etc.) present then there was also a higher presence of seagrass suggesting that these clams promote the presence of seagrass!

So why is that cool? Well because seagrass populations are in decline and very prone to sulfide toxicity, clams can protect our seagrass beds from this toxicity with their chemosynthetic bacteria!

So overall clams are pretty cool. Clams can purify the water increasing clarity and sunlight exposure while also cleaning up any toxic sulfide. Yay!

Clam reintroduction for seagrass- Sarasota Bay Watch

Releasing clams into the bay to help filter water for our seagrasses!

Sorting clams to introduce in Sarasota's Bay to help with seagrass establishment ! — Sorting clams before releasing them with Sarasota Bay Watch! (Featuring me on the left and Martha Robinson on the right)

But is this a one-fix-all solution?

Some people worry about the effects of adding too many clams in an area and what effect it might have on other animal populations. How might adding so much of one type of clam affect other types of clams? Adding too many of one animal may cause an offset balance to another organism, and scientists are always trying to be aware of this.

Another question being asking is why are clams not repopulating themselves? What is causing the decrease in the clam’s populations for humans to have to step in and help them? Is there a predator of the clams that is killing them off? Is there not enough food for them? Looking at the issue one step further may help to restore the clam populations to a balanced level so human interaction is not needed.

Like so many environmental issues occurring today, there usually isn’t a one-solution-fixes-all scenario. But with multiple solutions and tragedies to fighting environmental problems, there can be huge change.

A call for action- Save our seagrass

Overall, research has shown that the mutualism between clams and seagrass is promising for the reestablishment and health of seagrass beds. However, it is not the only solution, its a start. More research needs to be done on the potential harmful effects of adding too many of a particular clam in certain areas and establishing a number of clams that is ideal for seagrass establishment.

You can do your part to help seagrass beds by reducing the chemical input into our waters (either for your own home or by supporting healthy companies), support sustainable fishing practices, and support organizations who do research on ways to help our ocean ecosystems be more resiliant. Furthermore, you can learn safe boating practices if you boat in the ocean to keep the sediment healthy.