 Algae bloom in the ocean.
What's Wrong With Our Oceans?
In many places along the coastline, sea life is significantly deteriorating. Some scientists call it “evolution in reverse” to explain the primitive bacteria, plankton, and 500 million-year-old jellyfish that now thrive in place of marine mammals and big fish in some areas.
The Dead Zones
Ancient seas contained little or no oxygen and did not support the sea life familiar to us now. It was a time when bacteria and jellyfish ruled the oceans. Now scientists at NASA's Goddard Earth Sciences Data and Information Center say we may be returning to those conditions once again. There are over 150 dead zones in the earth’s oceans, one right here off the Los Angeles County coastline. What has happened?
We are overdosing the ocean with the nutrients that algae and bacteria love: nitrogen, carbon, iron and phosphorous.These compounds keep our lawns green, make our crops grow and fuel our modern society. However, few coastal wetlands remain to filter out those nutrients (native plants soak up the excess nutrients and thrive). These nutrients cause excessive algal blooms. But the algae-eating shellfish and sardines have been over-harvested, leaving an over-growth of blooms.
Marine algae, or phytoplankton, occur naturally and are the first link in the ocean’s food chain. In ideal conditions, algae, protozoans and bacteria keep each other in check. When the equilibrium is upset, certain types of algae overwhelm their competitors. Here's what happens:
- Urban runoff containing fertilizers (nutrients) and other pollutants flow into the ocean.
- The warm freshwater runoff rolls on top of a denser colder layer of saltwater. The two don’t mix, inhibiting the flow of oxygen downward.
- The excess nutrients feed blooms of algae, which turn coastal waters soupy green.
- As the algae dies, dead cells sink to the sea floor where they’re broken down by oxygen-sucking bacteria, consuming most of the oxygen in the water. The cycle repeats, producing more algae.
- Without enough oxygen, fish, corals, snails, sea stars, crabs and other shellfish suffocate. The sea life dies.
- Algae, worms, jellyfish and bacteria thrive.
Death by Plastic
Take a walk along any beach, and you’re bound to find bits of garbage. Sift through the sand, and up come bottle tops, foam pellets and shredded plastic bags.
That trash isn’t only from littering on the beach. Most of the plastic garbage in oceans originates from city streets. Rain washes it into creeks and storm drains, depositing it in the ocean. Sometimes it washes back onto the beach, but most of it swirls in the ocean. For every square mile of ocean surface, there are nearly 50,000 pieces of garbage, mostly plastic. Some of it has been in the sea for 50 years—and it won’t decompose anytime soon. In fact, there is now an island of trash twice the size of Texas—called the Pacific Garbage Patch—floating between California and Hawaii, according to the National Oceanic and Atmospheric Administration (NOAA).(1)
The results are devastating. Land birds on remote islands, 1,000 miles from civilization, now die with plastic debris in their stomachs. The total number is overwhelming. More than 1 million sea birds and 100,000 mammals (sea lions, whales and dolphins) die worldwide each year from eating plastic, according to a study by the US Marine Mammal Commission.(2)
Toxic Algae
Off the shore of California, sea lion mothers, famous for their unusually strong maternal instinct, are attacking their pups and killing them.
Why? Algae can turn toxic. Sea lions, sea birds, dolphins and other mammals eat sardines and anchovies that contain algae (Pseudo-nitzschia). This alga thrives on all the nutrients it’s being fed, multiplies rapidly, and produces a product known as domoic acid. The acid doesn’t cause much damage to the small fish that eat the algae. However, when those small fish are consumed by marine mammals, the acid damages brain cells, causes seizures, impairs navigation and memory, and alters behavior. This is caused by a neurotoxin and usually results in death.
Domoic acid has been identified in very high levels at the mouths of both the Los Angeles and San Gabriel Rivers.
Learn More
www.latimes.com
scripps.ucsd.edu
marinedebris.noaa.gov
http://www.longbeachcomber.com/
1 Carey Morishige, Pacific Islands Outreach Coordinator, the National Oceanic and Atmospheric Administration's Marine Debris Program.
2 Acevedo-Whitehouse, K., F. M. D. Gulland, D. Greig, and W. Amos. 2003. Disease susceptibility in California sea lions. Nature 422:35. Bossart, G. D. 2006. Marine mammals as sentinel species for oceans and human health. Oceanography 19:44 – 47.
Conrad, P. A. 2007.
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