Indirect effects fascinate ecologists because they can link the population dynamics of species that do not directly interact, as in the classic example of predatory fish affecting phytoplankton abundance by consuming specific sizes of zooplankton (Brooks and Dodson 1965).
Why are otter populations decreasing?
Senior environmental scientist Mike Harris of the California Department of Fish and Wildlife said the study showed high mortality rates are likely the biggest contributor to the population decline — and the No. 1 cause of death was great white shark bites.
Why are otters considered sentinel species?
Sea otters are an apex predator of the nearshore ecosystem. The species is considered a keystone species because of their critical importance to the health and stability of the nearshore marine ecosystem. They are also considered a sentinel species because their health reflects that of California’s coastal oceans.
Why are otters important to their ecosystem?
Otters also have a pivotal role in river ecosystems. They are predators, meaning they help control the populations of food species they prey upon. This affects the ecosystem as a whole, and as a result, their presence is a signal that the ecosystem is healthy.
Why are otters keystone species?
Sea otters are a “keystone species” which means that they can exert top-down pressure via predation on sea urchins, which are grazers upon kelp. As urchin density decreases from sea otter predation, so does the grazing pressure on kelp and as a result kelp forests flourish in the presence of sea otters.
Why did the sea otter population decrease?
Pollution is only the most recent threat to sea otters posed by humans. They were hunted to near-extinction by the early 20th century before an international ban on hunting, conservation efforts, and reintroduction programs allowed sea otters to rebound. Learn more about sea otters at NWF’s Ranger Rick.
Why do biologists use indicators?
This tolerance affords them sensitivity to indicate environmental change, yet endurance to withstand some variability and reflect the general biotic response. Bioindicators include biological processes, species, or communities and are used to assess the quality of the environment and how it changes over time.
Why do otters like to play with rocks?
Study says they may be expressing excitement for dinner. A study from researchers in the United Kingdom found otters may juggle rocks in anticipation of eating, but also as a brain teaser to keep their minds sharp.
Why do otters need clarity?
What is the relationship between water clarity and otter survival? __Clearer water is better for otters because since they eat urchins, the clearer water helps them find food easier.
Why do otters show babies?
Although sea otters are very protective for their babies, but they also tend to use their babies as a defensive mechanism. A sea otter tends to show its baby to a predator so that the predator might feel compassion for them.
Why do river otters play with rocks?
Stones as anvils While all sub-species of otters use the forelimbs to rip open urchins, the Californian otters were observed to have used rocks as a surface to pound urchins and crabs, as well as mussels (observed most frequently).
Why do sea otters need water?
They can survive on land, however, water is necessary for their existence. Some otter species will come on land to travel, eat, or groom their fur. Yet, otters to a large degree depend on the water, so living on land only is not possible.
Why do we need indicator species?
Indicator species are a useful management tool, and can help us delineate an ecoregion, indicate the status of an environmental condition, find a disease outbreak, or monitor pollution or climate change. In one sense, they can be used as an “early warning system” by biologists and conservation managers.
Why does ecological succession not follow a predictable path?
Succession does not follow a predictable path because there are many unique variables, such as weather and available nutrients.
Why is there an inverse relationship between otters and sea urchins?
Sea Urchin In this predator-prey relationship, where the urchin is the prey and main source of food for the sea otter, sea urchins play a large role in the population growth for the otter (Costa, 2011). If there was a decrease in sea urchin population, this would consequently have an adverse effect on the sea otter.
Why are otters endangered?
Giant otters, endangered top predators which live in Amazon river ecosystems, were nearly wiped out because of demand for their fur. Following the banning of fur trade, giant otter numbers have recovered across South America. However, there are several emerging threats to this sensitive species.
Are otters nearsighted?
Their eyes are adapted for underwater vision, leaving them nearsighted when out of water. On land, otters rely on their sense of smell, hearing and touch to get around.
Can i hunt on my own land without a license in kentucky?
Do I need a license to hunt my own land? If you are a Kentucky resident hunting on your own property, then neither you, your spouse nor your dependent children need a license or statewide deer permit to harvest a deer.
Can an otter survive in the desert?
Habitat of the Otter It is much easier to list the habitats that river otters don’t live in than to list the areas they do. The only types of ecosystems in which otters cannot be found are deserts, mountains, and polar regions. Basically, they can be found anywhere they have easy access to both land and water.
Can sea otters see in colour?
Even though sea otters don’t have highly acute vision to resolve fine detail, they can likely ascertain danger based on contrast due to brightness or color differences (yes, sea otters can see color , similar to a red-green colorblind human!.