These clams play an important role in their ecosystems. As filter feeders they improve water quality for the plants and animals with whom they share an environment by cleaning out any floating particles and phytoplankton. Mercenaria mercenaria are known for burrowing, especially when threatened by predators. They prefer to do so in coarse substrates but will settle in any kind of sand, mud, and shell debris. They may migrate if the environment is unsuitable for their needs, but once settled will repopulate routinely after harvesting as a productive and fruitful crop. Besides the role they play in their own ecosystems, hard-shell clams are also extremely important to economics, especially in coastal cities, as they are “harvested both recreationally and commercially and are the most valuable commercially harvested clam in the United States”. Their populations and health are economically integral.Most of these clams are used as crops, causing their notable lifespans to be about four to eight years when they reach “the peak of their commercial marketability”. Shell thickness specifically is affected by a variety of factors. These include temperature, age, seasonal differences, food availability, crowding, and population density. Left to their own devices, however, these clams may live for quite a long time, only to cease their growing after about fifteen years. The reason for this experiment is to determine how the clams’ shell thickness is mutually dependent on whether or not their habitats are considered protected. This experiment will be conducted by using a comparison between the clams from Roger Williams University and those from Fort Wetherill. The null hypothesis states that unprotected or protected waters have no effect on the clams’ thickness, whereas the alternate hypothesis posits that unprotected waters have smaller clam shells in comparison to protected waters.
In order to test these hypotheses, twenty clam shells were collected as random samples. Half were from Roger Williams University, the region with more unprotected waters, and the other half were from Fort Wetherill, the region considered to have a larger amount of protected waters. The shell thickness was calculated to the nearest tenth of a millimeter using calipers. Furthermore, the clams were measured from top to bottom, perpendicular to the clam’s opening. The size in millimeters was recorded by hand to prevent any lost data from technological malfunctions.
After the statistical test was performed, the data showed that Roger Williams University hosts hard clams (mercenaria mercenaria) with thicker shells than those at Fort Wetherill. The former possessed an average thickness of 21 millimeters while the latter averaged out at 10.7 millimeters. Both sets of samples fell within a range of ten, removing any outliers from the equation. This means that clams from Roger Williams University possess nearly twice the shell thickness of those from Fort Wetherill.
This information shows that clams in unprotected waters develop thicker shells than those in protected waters, proving the alternate hypothesis incorrect. The explanation for this is likely that there are hazards associated with the unprotected waters, so the clams grew thicker shells to protect themselves. Another theory is that avid fishing, legal or illegal, can cause clams to grow thicker shells to protect themselves from the misplaced hooks and bait hitting them. This could have a number of negative consequences. For instance, clam size is relevant to their economic value, as smaller and larger clams each hold a place in the market for different types of food. Thicker shells mean larger clams and a decrease in availability of the smaller clams, potentially affecting the resident economy. Additionally, the clams’ nutrients being focused toward growing their shells may inhibit other necessary activities such as migration, filtration, and sexual activity.
If this experiment were to be repeated, improvements could be made in the samples; they should be gathered from areas that are entirely protected or unprotected to maintain the integrity of the project. Additionally, at least two hundred samples should be collected and measured, as only using twenty decreases the validity of the findings as they are too few to be representative of the whole local population. Isolating, to the best of the researchers’ ability, the independent variable would also be important. Even though it cannot be completely separated in a natural environment like the ones being used, measuring and recording the additional outside variables such as temperature, salinity, and water turbulence could help identify a more accurate measurement, as “daily environmental variability has a strong influence on the conditions and results at the study site”. Also, these outcomes will still only apply to the local area in which the experiment took place, as clams from one section of the world cannot speak for the rest of the population and their specific situations. These adjustments would make the experiment much more effective for reaching a true conclusion on whether or not clamshell thickness is higher or lower in protected waters in contrast to unprotected waters, which was the overall purpose of this research.