Introduction
For the past two centuries, the population of otters has been rapidly dwindling. This reduction can be attributed to the extensive hunting of otters through the Pacific maritime fur trade in the 18th and 19th centuries. Not only was hunting a significant factor in the otters’ fall, but other human factors posed hazards to the otters’ ecosystems. For instance, oil spills are a major cause of otter deaths due to their low numbers and location in a small area. The oil from these spills demolishes the insulating properties of the otters’ fur; therefore, many of the otters die of hypothermia as well as inhalation of the oils’ toxic fumes. Thankfully, sea otters gained protection under the Fur Seal Treaty of 1911 as well as the Marine Mammal Protection Act and the Endangered Species Act in the 1970s. As a protected species, otters have made a considerable comeback, especially in the Monterey area of California, and are making promising environmental changes to the Elkhorn Slough
The Importance of Otters
One of the many reasons there are so many government-implemented protections for otters is due to their essential role in the environment. In particular, otters are known as a keystone species, or a species that helps “define an entire ecosystem,” according to National Geographic. As top predators in their ecosystems, otters play a vital role in maintaining balance by controlling the population of marine animals like kelp, sea urchins, and crabs. The steady population of kelp is particularly crucial because it helps to reduce atmospheric carbon dioxide levels and other greenhouse gasses that contribute to global warming. The mere presence of otters in their habitats indicates a healthy ecosystem.
Decline of Elkhorn Slough
Not only was the otter population declining along the Pacific Coast, but the environment was also deteriorating in the Elkhorn Slough of Monterey, California. In the 1940s, the construction of a new harbor led to the erosion of the marshes due to the creation of new tidal energies. According to Brent Hughes, a marine ecologist from Sonoma State University, “There was sea level rise and an explosion of shore crabs.” The shore crabs in the surrounding area caused significant damage to the environment. These crabs burrow and consume the roots of the banks, which not only affects the animals living there but also makes the coastlines and housing more vulnerable to flooding from storm surges and higher sea levels. Fortunately, during this time, a small population of otters managed to survive near Big Sur.
Experiments on the Pacific Coast
Christine Angelini, a coastal ecologist from the University of Florida, eagerly accepted an invitation to travel to California and conduct experiments on the marshes regarding depopulating the crab population. Angelini and Hughes conducted a fascinating experiment to observe the impact of sea otters on the surrounding ecosystem. To better understand the ecosystem, scientists created two separate areas, one for otters and one without. They also put up experimental cages and fences that allowed crabs to come and go as they pleased but kept sea otters out. For three years, the scientists carefully observed and monitored these two areas without interfering. The goal of this experiment was to gain insight into the complex dynamics of the ecosystem and learn more about the role that sea otters play in maintaining balance.
Results
After Angelini and Hughes returned, their assumptions were confirmed. When otters were kept from accessing crab habitats, uncontrolled crab burrowing caused further erosion of the marshland coastline. However, in areas where both oysters and crabs coexisted, otters would consume the crabs, thus maintaining the balance of the crab population. Additionally, the decline in the crab population led to an increase in vegetation growth and a reversal of bank erosion, despite sea level rise and strong storm surges. In fact, “…by the study’s end, they were preventing 10 or so inches of salt marsh loss per year…” (Angelini and Hughes).
The presence of otters in a particular ecosystem has brought extraordinary balance, highlighting the significance of protecting these keystone species worldwide. The reintroduction of these vital creatures has contributed to the health and resilience of a system that is otherwise under a considerable amount of stress, as stated by Angelini.
1
0
Average Rating