Sea Otters Keystone Species

The study conducted by Weisle, Nagaswami, and Peterson is displayed about river otters and how they are different in structure from other marine mammals. River otters must depend on their thick layer of hair for survival. River otters are semi-aquatic mammals, which are considered to have denser fur than any other mammals. It’s thick, sleek coat, which keeps it dry and warm, is made up of two types of hair. The longer outer hairs are water repellent as known as guard hairs, and the other is underhair. The guard hairs could provide some protection for the more delicate underhairs. The three authors of this article, “River otter hair structure facilitates interlocking to impede penetration of water and allow,” addresses a question upon why the

The subspecies was also listed as a highest priority “Species of Special Concern” by the State of California (USFWS, 1998). There are many factors that play into why the Point Arena mountain beaver is classified as endangered. In addition to their low reproductive rate, according to USFWS (1998), the vulnerability of the mountain beaver results from two reasons: 1) few populations with extremely limited distribution; and 2) the number of individual populations are low. Habitat loss and fragmentation is another concern for the Point Arena mountain beaver, any disaster, natural or manmade, has the potential to impact the subspecies (USFWS, 1998). These threats include, elimination or degradation from land development, livestock grazing, transportation and utility corridors, invasion of alien plant species, and timber harvest (USFWS, 1998). Additional threats to the subspecies include, predation by feral animals and household pets, poisoning, human caused disturbances, clumped and fragmented distribution, vulnerability to localized catastrophic events, like fires, storms, landslides, flooding, prolonged drought, and/or disease, and most notably genetic isolation and drift (USFWS,

The lecture explained how the population of sea otters declined, due to the environmental pollution. First, the oil rigs along the Alaskan coat serve as an indication to pollution. This directly refutes the reading passage which states that predation was most likely the reason, since the bodies of the dead sea otters didn't wash on the shores.Secondly, the passage mention that the water samples that were extracted from the sea revealed the presence of chemicals. Again, this contradicts with the lecture which claims that the whales which the otters consume were not available anymore. Which had forced the sea otters to change their diet to include small sea animals. Thirdly, the lecture mentions that the decrease in sea otters population was

Cetacean bycatch in fishing industries has been a highly debated topic for decades and is still considered an ongoing problem(NOAA 8). However, when it is looked at in comparison, the problem of bycatch has already been solved as much as is possible while still allowing fishing industries to fish at all. Cetaceans are defined as marine mammals. Bycatch is defined as any marine life that is caught and returned to the sea, whether it is dead or alive(Brooke 2). Therefore, many marine animals that are considered bycatch are not harmed in any way. Including these animals, the national bycatch ratio is still low(Brooke 3). Many actions have already been taken since this has become an issue that has reduced bycatch

The impact of toxoplasmosis has resulted in the endangerment of the California sea otter and the extinction of alala, the Hawaiian crow. With only 1300 Hawaiian monk seals in existence, toxoplasmosis can potentially lead to their extinction. The extinction of the Hawaiian monk seal can produce devastating effects on the species that rely on the Hawaiian monk seal for food, such as the Tiger shark and Galapagos shark (NOAA, 2016). Meanwhile, the fish, crustacean, and cephalopod population may increase due to the reduction in predators. Therefore, the extinction of a species can disrupt Hawaii’s sensitive

The area of research that I have selected is the effects of overfishing in the Sea Otter ecosystem off the coast of California. The effects caused by the fishing pressure on the ecosystem will have different outcomes, depending on the strength and the types of relationships of the organisms present. (4) Red Abalone populations have declined drastically, to the point of the abalone fishery collapse. Several factors have led up to the collapse including Withering Syndrome, where the organism loses the ability to attach itself to rocks, making it more susceptible to predation, or the organism can eventually wither and starve to death. Sea Urchins and Red Abalone are a part of the same ecosystem, and are competitors of each other.(5) Both organisms graze on macroalgae and are a primary food source for Sea Otters. Sea Otters occurred from the North Pacific Rim down to Baja California, Mexico, but now only occur in small isolated patches (9) It is understood that Sea Otter presence can characterize community structure, where they can control and determine the size of Sea Urchin and Red Abalone populations. In the absence of Sea Otters, “Urchin Barrens” are created from the overgrazing of macroalgae by Sea Urchin. In these areas the ecosystem have changed dramatically, due to the overfishing, or in this case the over hunting, of Sea Otters causing a trophic cascade.(7)In some areas, Sea Otters have been reintroduced, in other areas they were never removed, and in others they

Harassment is any activity that decreases a manatee’s fitness, most commonly recognized by a change in behavior.1 Many previous studies have provided extensive evidence of harassment, and unanimously support a positive correlation between the number of people and increased manatee activity as well as the use of protected areas, making a sound argument for the need for increased regulation and prohibited activities in the springs.4, 5 However, there is a predominant research gap in providing compelling data that human interactions have a deleterious impact on the fitness of manatees.1

The population decline in monk seals is due to several different factors with the biggest reason due to the low pup and juvenile survival rates (Curtice et al, 2011). At the Kure Atoll on the Northwestern Hawaiian Islands, 32 pups were observed in 1964 and 30 pups were observed in 1965. Of these pups born, all but one died or disappeared within 60 days after birth. This was also seen in the 1970’s at Green Island and Kure Atoll, where a mean population of 17 and 14 seals, respectively, was counted on these beaches, with a birth total of 10 showing a population decline of 70% (Gilmartin et al, 2011). The juvenile survival rate is still seen today with one in five monk seals surviving to the reproductive age, with one year old seals having the highest mortality rates (Norris et al, 2011).

Loggerhead eggs and hatchlings are a large food source for a variety of terrestrial animals, nearshore predatory fish, and seabirds, providing substantial amounts of energy and nutrients for these species (Wilson et al. 2010). A five or ten year period of loggerhead turtle declines may cause sublethal effects such as decreased growth rates or reproductive output for these predator species and a fifty year period of loggerhead turtle decline may potentially have more severe impacts such as significant declines for local populations that rely on eggs and hatchlings as a food source.

HOW HAS HUMAN ACTIVITY IMPACTED THE DECLINE IN POPULATION OF THE MACQUARIE ISLAND ELEPHANT SEAL?

Firstly, the author states that pollution sources such as oil rigs near Alaskan beaches is killing the sea otters. Also, a research held on water samples in the area showed that it contains high levels of chemicals that may indirectly kill the otters. This view is objected by the lecturer. He proposes that Orcas use the animals as source of food, that is why there are no signs of dead otters on shores of Alaska, which would however be

The presence or absence of sea otters influences marine ecology at the community-level. Studies have shown that kelp forests enhance the underwater environment, providing a suitable habitat for fishes. The declining kelp beds in California in the mid 1900’s propelled the Kelp Habitat Improvement Project, whereby attempts were made to eliminate sea urchins that are

In this article “saving the sea otters is just part of her normal day at work” by Kitson Jazynka My Opinion was that I think a lot of the sea mammals are dying because the bacteria in the water. First of all,”Otters in Alaska have been dying at a higher than normal rate over the past 10 years.”This quote

The presence or absence of sea otters influences marine ecology at the community-level. Studies have shown that kelp forests enhance the underwater environment, providing a suitable habitat for fishes. The declining kelp beds in California in the mid 1900’s propelled the Kelp Habitat Improvement Project, whereby attempts were made to eliminate sea urchins that are primary predators of kelps. Studies showed that the elimination of sea otters during the 1800s from the Californian waters might be responsible for the dwindling numbers of kelp forests. Further studies have also shown that the population density of sea otters affects seaweed biodiversity as well. In a study conducted in Alaska on three different bays, the Torch Bay, Deer Harbor and the Surge Bay, it was found that the presence of sea otters led to a decrease in the population of sea urchins, which led to an increase in the population of seaweeds. In addition, it was also found that annual kelps predominated the areas where sea otters were present, and perennial kelps predominated in areas that had lesser sea otter populations (qtd. in “Interaction with kelps & sea otters”).

Cetacean bycatch is an ongoing problem in the oceans of the world. Cetaceans are defined as whales, dolphins and porpoises(CBRC 1). Bycatch is “marine mammals that are “captured” but discarded”(Read 2). This happens when fishing industries are fishing for a certain type of marine animal and other marine animals are caught accidentally along with the intended catch. Many times, this leads to the death of the animal that was not meant to be caught, and the animal is tossed back into the ocean. This happens with all kinds of marine life, and it has caused the depletion of many different species. However, this is specifically bad for cetaceans, such as dolphins and whales, because they have such a long lifespan(Brown 2). They also take a very long time to mature(Brown 2). These factors make catching these animals very detrimental to the species as a whole because it takes longer for them to reach an age where they can reproduce(Brown 2). The population of many cetaceans have decreased exponentially. When there is someone watching the nets that cetaceans are accidentally caught in, many times they can be saved. However, there are only select few types of fishing methods that do this, and they are not of the prevalent fishing methods that produce cetacean bycatch. This is a problem because there is a connection between most living animals. If a certain part of the connection is eliminated, it will all fall apart. For example, the relationship between