SeaWeb - Science: Did You Know?

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A large leatherback sea turtle swims with a school of fish off the coast of Brazil.
Credit: Projeto Tamar Brazil/Marine Photobank

Leatherback sea turtles dive the deepest of all turtle species, with the deepest dive recorded to reach 3/4 of a mile, or 1.2 km, which is a little more than the deepest recorded dive of a sperm whale.

Source: Sea Turtle Conservancy

Jellyfish Blooms

Jellyfish, which are actually zooplankton not fish, consist of 98% water, and have existed in the ocean for more than 650 million years. In lieu of a brain or a heart, jellyfish rely on sensitive nerve endings at the base of their tentacles to orient themselves with their surroundings and defend themselves.

Jellyfish are carnivorous creatures and feast on algae and a smaller type of plankton known as zooplankton. When feasting, jellyfish consume food in through the orifice, which serves as both the mouth and the anus of the animal. From there the food goes to the gastrovascular cavity, which also serves as gulley, stomach, and intestine, before cycling back through the orifice and out of the body.

Jellyfish populations have boomed in recent years, but still little is known about what affects this.

Source: National Ocean Service, NOAA

Reef Threats: Disease

Times are tough for coral. Experts estimate that 10 percent of the world’s coral reefs are beyond repair and a further 60 percent will perish by 2050 from both natural and man-made causes. But by limiting coral’s intake of carbon dioxide and working to stop pollutants from entering the ocean, the process of saving the coral reefs can begin.

As humans continue to generate excess carbon dioxide by burning fossil fuels and to pollute water sources, coral reefs become more vulnerable and therefore more susceptible to diseases. Coral diseases are instigated through the invasion of bacteria and fungi as well as by chemical and physical changes in the water. Some of the major types of coral diseases are “black-band,” “white-band,” and “yellow blotch.”

For the most part, these diseases are exactly what they sound like. Black-band disease, for instance, causes a black crescent-shaped band on the coral, which eventually surrounds the coral, eating away at its tissue. White-band, likewise, leaves white scar-like marks on the coral and yellow blotch leaves yellow patches on the coral which soon kill the tissue and become infested with algae, slowly killing the coral.

Once a coral reef is damaged or infected by a disease, the entire coral ecosystem—the animals that feed off or live in it— are affected as well. Therefore, it is vital that measures be taken to prevent infection before it occurs.

Two thousand delegates from around the world, including six SeaWeb staff members, are in Cairns, Australia to attend the 12^th International Coral Reef Symposium from July 9 - 13.

Source: Hazards to Coral Reefs, NOAA

Hey, Who Turned Off the Lights?

Estimates show that a 4-foot sea level rise will result in the flooding of 287 energy facilities in the lower 48 states of the United States. More than half of these facilities are in Louisiana. Florida, California, New York, Texas and New Jersey will face flooding in 10 to 30 plants each.

Climate change has raised sea level by about 8 inches since 1880. Depending on how anthropogenic greenhouse gas emissions are regulated now, it is estimated that waters will rise somewhere between 20 to 80 more inches (1.6 to 6.7 feet) this century.

Pooling data from USGS, NOAA and FEMA, a study by Climate Central makes mid-range projections of 1 to 8 inches rise by 2030.

U.S. map with pins indicating plants below the 4-inch elevation

Pink dots represent electric facilities less than 4 ft above local high tide; green dots represent natural gas; black dots represents oil/gas; yellow dots represent facilities that do not fall in the previous categories.

Source: Strauss, B. and Ziemlinski, R. Sea Level Rise Threats to Energy Infrastructure. Climate Central. For more information, visit: sealevel.climatecentral.org.

Celebrating Biodiversity

Tuesday May 22 is International Day for Biological Diversity. The Convention on Biological Diversity is highlighting marine biodiversity as the theme of the year.

There are innumerable reasons why diversity of life on Earth is important, but not least among them is that the loss of biodiversity reduces genetic diversity in crops and livestock and decreases the availability of wild biological resources, both of which are problematic for global food security.

Some of the biggest threats to marine biodiversity are invasive species, such as the prevalence of lionfish in Atlantic waters, and habitat loss by human development projects.

Source: Convention on Biological Diversity, Society for Conservation Biology

Banning Fish Discards

Fishermen using industrial fishing methods in the EU are discarding between half and 66 percent of the fish they catch in order to bring back a haul concentrated with fish that fetch the highest price.

As a result of European vessels catching more fish than can be safely replenished, 82 percent of Mediterranean stocks and 63 percent of Atlantic stocks are being overfished. Exhausting fish stocks threatens the marine ecosystem.

Policymakers reviewing the EU Common Fisheries Policy (CFP) were moved by public pressure via social media in support of a discard ban, according to The Guardian. Chef Hugh Fearnley-Whittingstall, who stars in a TV show about cooking with locally produced ingredients, is leading the ongoing fight to stop the practice of throwing back edible fish, usually dead, from industrial catches.

In mid-March, Spain orchestrated opposition to a ban of the discard practice. Spain has the EU's biggest fleet and receives more of the EU's fishing subsidies than any other member state. But perhaps Fearnley-Whittingstall can continue to rally the public for a CFP with a discard ban?

The vote on the final proposal is scheduled for July, and the reformed CFP will go into effect in 2013, according to the European Commission's Directorate-General for Maritime Affairs and Fisheries website.

Learn more about the discards ban >>

Source: European Commission's Directorate-General for Maritime Affairs and Fisheries

Earth Day’s Origins

The Unocal Corporation oil spill in 1969 spewed more than 3 million gallons of crude oil into California’s Santa Barbara Channel before it was plugged. The eruption occurred from drilling-induced cracks in the sea floor. This oil spill inspired Senator Gaylord Nelson (D-Wis.) to found Earth Day on April 22, 1970.

“I don’t like to call it a disaster,” because there has been no loss of human life. “I am amazed at the publicity for the loss of a few birds,” Fred L. Hartley, CEO of Unocal Corporation from 1964 to 1988.

The public disagreed with Hartley. Twenty million Americans took to the streets, parks, and auditoriums to demonstrate for a healthy, sustainable environment in massive rallies across the United States in 1969.

During the next few years there was more environmental legislation than at any time in U.S. history, including laws that protected sensitive coastal areas and endangered species.

The Earth Day movement has grown exponentially over the last several decades, with more than 180 countries organizing annual events. While Earth Day was founded to draw attention to a healthy environment, its roots are firmly planted in the ocean. Accounting for both earth and ocean when planning for a healthy, thriving environment will ensure a sustainable future for generations to come.

Source: Darren Hardy, University California-Santa Barbara

Diving Deep

To study the deep-sea, biologists typically plunge specialized research vessels off of a “mother ship” on the surface of the ocean. The most famous deep diving submersible in the U.S. is the Alvin, which was commissioned in 1964 and can descend four kilometers.

Since then, the U.S., France, Russia and Japan have all designed vessels capable of descending two or three additional kilometers. Such descents are equivalent to going the length of 54 football fields underwater. These vessels can access all the deep oceans except the trenches.

It’s pretty exciting then, when the Mariana Trench—with a maximum depth of 35,576 feet, or 6.7 miles, or 10.8 kilometers…more than 98 football fields—is within reach!

Remembering a Tragedy

March 11, 2012 marked one year since a 9.0 magnitude earthquake hit northeastern Japan, followed by a tsunami with 10-foot-high waves that destroyed much of the area and infrastructure, including an active nuclear power plant.

Radioactive contamination at levels above regulatory limits were found in the marine environment directly around the Fukushima Daiichi nuclear power plant following the earthquake and tsunami that released large amounts of radiation into the Pacific ocean.

The large volume of water in the Pacific Ocean is expected to quickly disperse and dilute any radioactive materials to extremely low levels. However, scientists will continue to monitor the progress and development of radiation exposure.

Source: World Health Organization. Impacts on seafood safety of the nuclear accident in Japan

Groups of clownfish adhere to a very strict hierarchy with a single dominant female, one breeding male, and a few non-breeding males.

The female is the largest, with the breeding male being the second largest. If the dominant female is removed, usually by death, then the dominant male changes sex to become female and the other males move up the chain. This makes clownfish Protandrous hermaphrodites.

Angels of Love

French Angelfish are believed to choose a mate and remain together for life. Although the pair typically spends most of their time together, they will circle each other, in a process known as carouseling, after being separated for a period of time. Their spawning ritual tends to be very simple because of the strong bond they have with each other at all times.

Invasive kelp has arrived in San Francisco Bay!

Wakame (Undaria pinnatifida), a non-native kelp species from Japan, has infiltrated the San Francisco Bay. If left unchecked, this quick-growing kelp can damage ship hulls, nets, fishing gear, ropes and other equipment while competing with native kelp species for light, food and space. Scientists believe wakame first arrived in Southern California in 2000 and has since been making its up way up the coast. Like other invasive species, it can be unintentionally transported around the world in ballast water or on the hulls of boats. Local government, non-profit and volunteer groups are working to try and eradicate the aggressive species, removing the kelp from boats, slips, docks and piers.

Turtle Tears?

Sea turtles have salt excretion glands behind their eyes, which makes it appear as though they are crying. These glands give sea turtles the ability to ingest saltwater without getting dehydrated.

You can spot the difference between seals and sea lions in four easy steps

Though they share many traits, seals and sea lions belong to two distinct families. Seals belong to the family Phocidae considered “true seals” while sea lions are classified under the family Otariidae, or “eared seals.” While you might find either of these Pinnipeds off the coast of Northern California, a trained observer can look for these four characteristics to distinguish between the two marine mammals:

Ears: Sea lions have visible external ear flaps whereas seals have small ear holes known as pinnae.
Front flipper: Sea lions have long, mostly hairless flippers with short nails whereas seals have short, fur-covered flippers with long claws.
Hind Flippers: Sea lions have flexible hind flippers that can be rotated forward to “walk” on land whereas seals have a single hind flipper that points backward to “worm” or “galluph” forward on land.
Whiskers: Sea lion whiskers are smooth whereas most seal whiskers are crimped or beaded.

Christmas tree worms use their bright feathery plumes for respiration and to gather food

These aptly named tube dwelling creatures live in tropical waters around the world anchored to corals. The cautious critters quickly retreat into their burrow when disturbed, slowly reemerging to extend their colorful plumes soon after. The polychaete worms use their distinctive filamentous fans to filter oxygen and tiny food particles and plankton from the water column.

All of the reefs surrounding Guadeloupe are threatened by human activities.

The World Resource Institute’s Reefs at Risk analysis classified almost every reef within the 400 km² area surrounding the islands as threatened by overfishing. The report estimated that eighty five percent of the reefs in the surrounding waters are threatened by coastal development while roughly twenty five percent of reefs are threatened by marine-based pollution. Additional anthropogenic threats include agricultural pollution, urban pollution and sediment runoff from deforestation.

Source: Reefs at Risk in the Caribbean >>

Seagrasses

Seagrasses occupy only 0.1% of the seafloor, yet are responsible for 12% of the organic carbon buried in the ocean, which helps reduce greenhouse gases.

The estimated coverage of seagrasses globally is between 300,000 and 600,000 square kilometres (186,000 square miles and 372,000 square miles).

A hectare of seagrass absorbs 1.2 kilograms of nutrients per year, equivalent to the treated effluent from 200 people.

Over a billion people live within 50 km of a seagrass meadow. Millions of people obtain their protein from animals that live in seagrasses.

More information about seagrasses >>