Guide of SEA PREDATORS

IFDN: The Atlantic Salmon
The fast water brings them food and makes it difficult for predators to see them in the froth.
Smolts abandon their territories, form schools and swim near the water’s surface, drifting downstream with the current as they move out to sea.
In the river they will feed on insects, but at sea they begin to feed on zooplankton (microscopic organisms on drifting plants) and small fish..
Adult salmon are fish that swim in the open sea, cruising at depths of less than 30 m.
Adult salmon are eaten in turn by seals, sharks, and perhaps killer whales..
While in the ocean, salmon are sometimes infected with small crablike parasites called sea lice.
The sea lice feed on the salmon’s skin and the skin’s mucous cover.
The little holes the sea lice chew in the skin can let bacteria and virus infect the salmon.
If salmon have a lot of sea lice, the lice can kill them.


SEA PREDATORS

Science Now
When their primary predators disappear, sea urchins can turn entire kelp forests into underwater deserts.
Endowed with five bony teeth and a slew of prickly spikes, purple sea urchins have the unusual ability to gradually burrow into a rock, creating a customized shelter from predators like sea stars and sea otters.
When predators are prevalent, the urchins are confined to these holes, so they feed by waiting for passing pieces of algae to collide with them.
However, when a primary predator like the California sea otter suffers from severe population declines, sea urchins gain more freedom to roam the ocean floor.
Without otters to balance out the ecosystem, California's famous kelp forests get hit with a double dose of pressure from purple sea urchins - first because the urchins can graze more freely, and then because their population numbers soar.
By scraping away at a rock with their teeth and spikes, purple sea urchins can eventually hollow out a hole in which to hide from predators, like this sea star.
Sea otters keep California's kelp forests healthy by snacking on sea urchins, which can clear-cut entire underwater forests if their predators disappear.

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info: SEA PREDATORS


Photo by www.smugmug.com

Graduate School of NOCS - Graduate School of NOC PhD Project Description
They are subject to intensive exploitation and management in sub-Arctic seas.
Lithodids are mostly of deep-sea living, and these representatives remain scarcely known, but first indications suggest that SO king crab biology can be rather different from that of northern hemisphere congeners, which might be due to their evolutionary history (Thatje 2005).
Understanding the ecology and physiology of early life history adaptations in deep-sea king will not only help to better understand their role within high-latitudinal and deep-sea ecosystems, but help to evaluate the use and risks of king crab fisheries, particularly in waters around the island of South Georgia.
Methodology Studies on early life histories will be carried out under controlled lab conditions both at NOC and at sea.
This includes the set-up and maintenance of aquaria systems under variable working conditions (at NOC, at sea, South).
Nothing is known about deep-sea lithodid life histories, which holds especially true for the genus Neolithodes.
This project is associated with NOCS research in Ocean Biogeogemistry & Ecosystems svth@noc.soton.ac.uk .

Benefits



Finding the role of Antarctic toothfish in the Ross Sea ecosystem - NIWA Science
Antarctic toothfish (top right) and its main prey in the Ross Sea.
Visitors to the white continent have long been spurred by the twin passions of profit and science; in the 19th and 20th centuries, sealing and whaling had huge impacts on the Antarctic and Ross Sea ecosystems.
Until recently, the Ross Sea was one of the last productive continental shelf and slope areas in the world not targeted by commercial fishing, apart from some exploratory fishing by the Soviet trawler fleet during the 1970s.
Over the last few years, however, the Ross Sea has become a long-line fishing ground for Antarctic toothfish (Dissostichus mawsoni) ..
Maintaining this balance in the Ross Sea is difficult, and requires a better understanding of the ecosystem effects of fishing there..
Research at NIWA aims to use available information to understand the potential effects on the Ross Sea ecosystem of fishing Antarctic toothfish.
In collaboration with international colleagues, we have been pulling together pieces of the Ross Sea ecosystem puzzle from diverse sources of information.
We’re developing a trophic model for the Ross Sea to determine the role of the Antarctic toothfish in this ecosystem.

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