SciSun: see Otter, Sea Grass   1 comment

Estuaries are one of the most important, and most complex, ecosystems on earth. Where rivers meet the sea – fresh water connects with salt water – estuaries are places of brackish water, or water that isn’t as salty as the ocean, yet still more salty than the fresh water of most rivers and lakes. This unique environment is vital to many species of fish and other aquatic and sea-life, creating a habitat where new-born animals can adjust to their world; and older animals can return to make new families.

Of course a wide-open expanse of water usually doesn’t make for a very appealing, or safe, area to live and it takes more than fish to make a community: Frogs and other amphibians; crabs and crayfish (we shall now be called ‘Langostino’!); clams, snails and other mollusks; and diverse types of plant life from grasses to lilies to Mangrove trees and shrubs all contribute to a healthy estuary; and when one of these elements gets out of control is where our hero enters the story. Or, enters the estuary.

In brackish areas off Monterey Bay, on the Pacific Ocean in north-central California, excess fertilizer from farming has been caught in the water system and carried into the estuaries where algae, happy to have the extra food, has flourished and spread so extensively it’s now blocking sunlight from other plants and severely damaging sea grasses, which are important living spaces for fish, mollusks, and other sea life. The story gets a little complicated here (and still, we haven’t seen the hero) – but basically, as the sea grass becomes stressed, it’s easier for algae, foreign material, and other unwanted parasites to attach themselves or coat seagrass leaves, further damaging and even killing the grass. However sea slugs (a generic name for many types of aquatic slugs and snails) eat this unwanted material from the grass leaves, helping the grass survive. As there’s more for the slugs to eat, naturally there’s more slugs, and this attracts crabs who are always looking for a good meal. As more crabs arrive and eat more slugs, the algae and other unwanted hangers-on continue to stress the grasses until ultimately the fish and other life that depends on thick, safe stands of grass suffer and the entire ecosystem could collapse (and we’re certain the crabs eat some of those fish, too. If you think sharks will eat anything, just be happy crabs aren’t 10 feet long).

So, finally, with much fanfare and maybe a parade, enters the hero – the California (Southern) Sea Otter (Enhydra lutris nereis)! who, more than anything else, likes to eat crab. And lots of it. In fact if a sea otter ever tried to go to the Saturday night all-you-can-eat crab-leg buffet, the manager probably wouldn’t let the otters come in because they’d eat so much. Well, have you ever seen any otters at the restaurant?

Some sea otters like a little salad with their dinner.  Others, not so much.

Some sea otters like a little salad with their dinner. Others, not so much.

So in a balanced and healthy estuary ecosystem, otters have their crab; slugs have their algae; seagrass has their sunlight; and fish have protection. Everyone’s happy. (probably not so much the crabs). Of course this is the way the environment functioned for thousands of years, until the otters came close to extinction in the 1800’s due to hunting. And farmers started extensive and excessive over-fertilizing about 70 years ago. And as recently as last year, any otters entering an ‘otter-free zone’ along parts of the California coast were immediately trapped and relocated in response to fishermen who said otters were eating all their catch of abalone and other shellfish. Obviously, some poor choices have been made, concerning the otter.

Scientists have only observed these otter-opportunites (otter-tunities?) within one specific area along Monterey Bay – and the algae and seagrass situation is affecting many more areas along the coast – but as more otters find their ways into more estuaries,inlets, and grassy marshes – and are allowed to live safely and undisturbed – they will help restore the natural balance between prey and predator; and grass and algae; and even fish and fisherman, benefiting everyone. Except maybe not so much the crabs.


Michonne Says: So there are ‘otters’ that eat ‘crabs’ that eat ‘slugs’ that eat ‘al-gee’ that keeps sun away from from the grass. Why don’t the ‘otters’ just eat the grass? That’s what marmots do and it’s a lot less confusing.

Posted September 8, 2013 by ECOVIA eco-adventure® in SciSun

Tagged with , , , , , ,

One response to “SciSun: see Otter, Sea Grass

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  1. I enjoyed this post very much and like the reference to an earlier post–from now we shall be called Langostino!

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