Taking Care of Our Bivalves

Clams

Posted by Anna Potorski

Growing up, I spent the majority of my summers in Rhode Island because two of my dad’s favorite things are fishing and clamming. My dad is a pretty cool guy and although I know he loves me, I’ve come to terms with the fact that he loves fishing and clamming more. From May to October the only conversations we have revolve around how many clams he caught and how large the fish were. However, his interest extends further than just what he can catch, but also how the ocean works. For us, the air we breathe is incredibly important to our health. Similarly, the water which clams live in is crucial to their health.

Clams live in what is called an estuary. An estuary is a partially enclosed body of water which may connect to the ocean or have rivers or streams running from it to a larger body of water. Because of this, pollution to this body of water may cause severe problems for the clams. The pollutants fester in the water which the clams live in. There are four factors which directly affect a clam and may be changed due to pollutants.

First off, the temperature of the water must maintain between forty-eight degrees and eighty-eight degrees Fahrenheit. The idea temperature is sixty-eight degrees. Temperatures too high or temperatures too low may cause growth to stop.

Secondly, the salt content of the water is also crucial to health of a clam. The average salinity of the ocean is thirty-five parts per million. The estuaries in which clams grow generally have a lower salinity, ranging between twenty and thirty parts per million. This salinity is the ideal salinity to promote clam growth.

In addition to temperature and salt content is turbidity. Turbidity is the term used to describe how clear the water is. Clams are filter feeders meaning they filter water through and strain out the nutrients in the water. Too much sediment in the water may damage the clams ability to filter properly.

Lastly, there must be a proper nutrients source, as with any organism. Clams eat phytoplankton which, as their name suggests, grow through photosynthesis. The nutrients in the water is also concerning. When water is too nutrient, algae will compete with phytoplankton and usually outgrow the plankton. Clams can still eat the algae but, if the algae grows too uncontrollably the clams may not be able to keep up. Too much algae in the water can choke out other forms of aquatic life.

Maintaining the health of the water is crucial for clam survival. It is so easy to see clams as a tasty deep-fried food. However, it is important to recognize their impact on their ecosystem. As previously mentioned before, clams help control the algae population. A population of algae which is too abundant chokes out the life of other aquatic organisms because it can decrease the level of oxygen. 

As filter feeders, clams are promoting a stronger penetration of sunlight which aids in the growth of vegetation in the water. Clams also remove carbon dioxide from the water by incorporating the carbon into their shells.

A clam filters fifty gallons of water a day. That is a ton of water for such a small organism. However, when we pollute the water, the nutrients, salinity, turbidity, and temperature are affected. In turn, the health of the clam is compromised. A clam can survive for a few days by closing its valves. However, a few days is not enough time to repair a whole body of water.

As time goes on, the acidity of the ocean is changing. The pH levels have lowered and this is particularly dangerous for bivalves. Carbonate ions are the building blocks for the clam’s shell. The growing acidity of the ocean has resulted in weaker shells. On the West Coast, the Netarts Bay in Oregon featured a loss in oyster larvae population. The oyster larvae could no longer form shells due to the lowered pH levels on the water.

The distribution of clams may also be affected by the rising sea levels. As the sea levels rise, the patterns of tides change as well. Clams favor sand or mud flats, found in estuaries. These flats are directly affected by the tides of the ocean as they are connected. Scientists are not entirely sure how the sea level rise may affect these estuaries. Should the sand and mud flats maintain elevation relative to the tidal levels, the clams will remain production and growth in a happy manner. However, this is not what scientists are hypothesizing. For the levels of flats to water must maintain the proper ration dependent on sediments. The faster the sea levels rise, the less likely these estuaries are able to retain the correct ratios and the more likely it is that clam populations, along with other shell fish, will become less productive.

Efforts to protect clams are made. For instance, to allow clams to grow and reproduce, the times in which you may catch clams for your own pleasure is limited. However, this is not enough. We must make more conscious efforts to protect our water. It is not just a clam, it is a stepping stone for so many other organisms in the ocean to survive, reproduce, and grow.

Resources:

http://www.partnershipforcoastalwatersheds.org/how-the-local-effects-of-climate-change-could-affect-clams-and-native-oysters/

http://www.cooswatershed.org/Publications/clams%20and%20water%20quality.pdf