1 / 7

Killer whales and sea otters

Killer whales and sea otters. Daily caloric requirements:. Male killer whale: 308,000 Kcal/day or 5-7 sea otters. Killer whale and seal otter energetics. Female killer whale: 187,000 Kcal/day or 3-5 sea otters. Account for 40,000 sea otters lost over 6 years?.

victoria
Download Presentation

Killer whales and sea otters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Killer whales and sea otters • Daily caloric requirements: • Male killer whale: 308,000 Kcal/day or 5-7 sea otters • Killer whale and seal otter energetics • Female killer whale: 187,000 Kcal/day or 3-5 sea otters • Account for 40,000 sea otters lost over 6 years? • 5 sea otters per day per whale x 365 days x 6 years = 10,950 sea otters! • 10,950 sea otters eaten x 4 whales would account for 40,000 sea otter losses Where have all the sea otters gone?

  2. Killer whales and sea otters • Sea otters usually not main component of killer whale diet -- why the change? • Some fish populations have declined in recent decades • Shortage of certain fish caused substantial declines in harbor seals and sea lions • Shortage of seals and sea lions resulted in killer whales preying on smaller sea otters Where have all the sea otters gone?

  3. Sea otters important part of coastal community; loss of sea otters results in many indirect effects Killer whales and sea otters • Why should we care about sea otter declines? Where have all the sea otters gone?

  4. Indirect effects on communities • Predation (or parasitism) can reduce competition, preventing competitive exclusion • Predators typically feed on several types of prey • Prey selected based on its relative abundance • Superior competitors can reach high relative abundance, but predation can control such populations • Example: removal of starfish (Pisaster) in rocky intertidal results in competitive exclusion by mussels Where have all the sea otters gone?

  5. Indirect effects on communities • Predation (or parasitism) can result in many indirect effects on other species • Example: ant-rodent interactions • Both ants and rodents eat seeds in Chihuahuan Desert • Removal of rodents caused initial increase in ant populations, but then a decrease Where have all the sea otters gone?

  6. Indirect effects on communities • Keystonespecies = species that have strong effect on the composition of the community • Removal of keystone species causes a decrease in species richness • Example: sea otters eat sea urchins which are superior competitors; if sea urchin populations increase, kelp reduced and species richness drops Where have all the sea otters gone?

  7. Indirect effects on communities • Kelp ‘forest’ Where have all the sea otters gone?

More Related