Scubaism

Since it was discovered in May by a pair of spearfishermen 5 miles (8 kilometers) off Trinidad’s eastern shore, a mud volcano has attracted hordes of sightseers who trek to a bluff to watch waves crash over its summit, which measures 160 feet (49 meters) across. If it does become an island, don’t plan on ever spending your holiday on it: It would be a muddy, wave-lashed piece of ground that could slip back underneath the sea at any moment.

Graham Scott, 37, was spearfishing in May in a favored spot with a friend when he discovered the mud volcano, then only 5 feet (1.5 meters) high. “It was strange,” Scott recalled in a telephone interview. “The mud was soft. Soft like clay.” Since then, it has ballooned to a height of some 40 feet (12 meters), reaching to just below the ocean’s surface, with a base 490 feet (149 meters) across.

On shore, there is disquiet. “It may grow, and grow, and grow until some day it blows up,” said Jude Neckles, who can see the site from the front porch of his house in Mayaro. Scientists say that’s unlikely.

Mud volcanoes are not normal volcanoes, which erupt lava and superheated gases from deep within the earth, said Roderick Stewart, a seismologist at the University of the West Indies in Trinidad. Rather, they are created when natural gases, often methane, escape pressurized areas from shallower levels in the crust. “There is little heat and energy behind it,” Stewart said in a telephone interview. “There’s no lava. There’s no magma.”

Disaster officials insist the new mud volcano poses no threat to people on land. Mud volcanoes are a common phenomenon on and around the twin-island nation of Trinidad and Tobago — the world’s fifth-largest exporter of liquefied natural gas.

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For the second time in a decade, the California Department of Fish and Game plans to poison Lake Davis to rid the lake of unwanted northern pike fish.

In the early 1990s, someone illegally planted northern pike in the Plumas County lake, a fish so voracious, it eats almost all other fish. If it swam downstream, officials warned it could threaten and perhaps wipe out native fisheries in the delta.

Sometime after Labor Day, an army of fish and game workers will descend on Lake Davis. First they’ll treat streams, then the lake itself. Fish and Game will then spray CFT Legumine, a rotenone-based organic chemical. Within hours after the application, fish should start dying.

Ten years ago, residents of the nearby city of Portola, which at that time got its drinking water from Lake Davis, staged massive protests when Fish and Game went in with plans to poison the lake. On the day of the poisoning, concerned residents, even the mayor, chained themselves to buoys in the lake. Chemicals were pumped in, fish died and Portola lost its water source. Three years later, pike reappeared.

While most Portolans are accepting the poisoning as a necessary evil to eradicate the pike, just in the past several weeks some opposition has begun to form. “We really don’t know the total effect but we see diseases like autism, Down syndrome, cancer, breast cancer in women going way up,” said Dan Wilson, organizer of the newly formed Save Lake Davis Committee.

Wilson says there has been an unusually high rate of autism and cancer among students at C. Roy Carmichael Elementary School in Portola where he teaches. However, Dr. Hank Foley of The Plumas County Public Health Agency told News 10 there is no statistical evidence to support that claim and no evidence to indicate even a casual connection between the poisoning a decade ago and illnesses or birth defects that have occurred since then.

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The Mississippi Sound and Mobile Bay are full of sharks this year, according to scientists who conduct surveys in area waters.Scientists say shark numbers appear particularly robust since Hurricane Katrina, and they speculate that the increase is partly because of limited fishing after the storms of 2004 and 2005 and increased salinity in bays and inshore waters because of a two-year drought. The drought has increased salinity in Mobile Bay, Mississippi Sound and into the Mobile-Tensaw Delta, expanding the range of all saltwater creatures.

The biologists say 95 percent of the sharks they encounter are smaller species that pose no threat to man. Fishermen in the Delta have reported catching a number of sharks this summer, including in areas as far north as Gravine Island, several miles northeast of downtown Mobile.

“I’m certainly not surprised to hear that sharks are being caught above Interstate 10,” said Eric Hoffmayer, a shark scientist with the Gulf Coast Research Laboratory in Ocean Springs. Hoffmayer began surveying local shark populations in 1998 and has tagged about 1,000 sharks in the last four years, working mostly inshore of the barrier islands. About 70 percent of the sharks are juveniles, less than 3 feet long.

“Since Katrina, we’ve had major increases in shark populations in the nearshore areas,” he said. “The Mississippi Sound is a really good nursery area. Whether there is a lot of protection from predators or a lot of food, I don’t know, but there are a lot of sharks around.”

The dominant species inshore are blacktips, Atlantic sharpnose, finetooth and bull sharks. The sharpnose and finetooth are small species, topping out at less than 5 feet. Blacktips may reach 6 feet and about 100 pounds, but are not considered a threat to people. The portly bull shark, implicated in most Gulf Coast shark attacks, can get up to about 6 feet but weigh as much as 600 pounds.

Juvenile bull sharks, known for their ability to tolerate freshwater, are common in bayous and other brackish areas. “They are 2 to 3 feet when they are born, so they would be the top predator in freshwater. There are not many things that are going to eat a 3-foot bull shark,” Hoffmayer said. “Are they up there eating all freshwater fish? We just don’t know.”

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Lower than usual sightings of common dolphins have been reported by the Sea Trust, which surveys their numbers in the Irish Sea. Their findings have been echoed by similar surveys in the English Channel. Dolphin sightings were also down in the Bay of Biscay, said a spokesman for Marinelife which surveys the area along with the English Channel.

Marinelife’s research director, Dr Tom Brereton, said the decline in dolphin numbers could be because of a change in environmental conditions. “The changes highlight how we need to act quickly, to address major issues such as climate change and over-fishing,” he said.

The Sea Trust, which is the marine branch of the Wildlife Trust of South and West Wales, have been surveying cetaceans - dolphins, whales, and porpoises - in the Irish Sea aboard the Stena Europe ferry between Fishguard and Rosslare for the last four years.

Cliff Benson, chair of the Sea Trust, said that in previous years sightings of Risso’s dolphins have begun in April and continued to October. “It may just be a blip or it could be the first signs of a major collapse in our cetacean populations,” said Mr Benson. “We really need to find out which it is and quickly.”

In 2005, Sea Trust volunteers filmed a “superpod” of common dolphins which was estimated to consist of more than 1500 dolphins off the Pembrokeshire coast. But Mr Benson said pod sizes and the number of sightings had been “way down” on previous years.

“It would not be so disturbing if we did not know that this apparent decline is being experienced in neighbouring seas,” he said. “When Marinelife told me that they were experiencing a similar drop in sightings in the English Channel and the Bay of Biscay I was really shocked.”

Adrian Shepherd from Marinelife said in June and July, numbers of the three main dolphin species - common, striped and bottlenose - were down by 80% on the previous year in the English Channel and the Bay of Biscay.

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The invasive Australian jellyfish, Phyllorhiza punctata, first reported in great quantities in the Gulf of Mexico in 2000, has made a vigorous reappearance this summer in waters from southwestern Louisiana to Morehead City, North Carolina. Beachgoers and boaters are encouraged to report their sightings of these exotic jellies to the Dauphin Island Sea Lab’s jellyfish website, Dockwatch.

Since 2000, Phyllorhiza sightings have occurred in the Gulf as far west as Galveston Bay, Texas, but only in a handful of numbers. This year, not only are their numbers higher, but their range has extended up to the Mid-Atlantic states. “Reports from the Panhandle of Florida and North Carolina indicate they’re pretty concentrated elsewhere,” states Dauphin Island Sea Lab Senior Marine Scientist Dr. Monty Graham.

Ranging in size from a softball to a basketball, the Australian jellyfish present little to no danger in terms of their sting. A preponderance of jellies, however, could pose a threat to the commercial fishing and shrimping industry as they foul up trawling nets and consume eggs and larvae of important fishery species.

“We just started getting reports of Phyllorhiza appearing on the east coast of Florida and as far up as North Carolina this year. We don’t think that jellies from the Gulf are pouring up the coast, necessarily, but the appearances and concentrations of these animals in both places may be related,” says Dr. Graham.

“Phyllorhiza are prolific feeders; they can compete with commercially important fish for food, and they also eat the larvae of these fish. In their native waters, they tend to be fist-sized; here in the Gulf, they can be a big as dinner plates.”

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Abalone divers have come under fire for being partly to blame for the spread of a deadly virus which has stripped the industry of tens of millions of dollars.

Diseased molluscs have been found along a two-hundred kilometre stretch of Victoria’s coastline. Reefs have been closed and farms stripped of stock. And there is no sign the epidemic is under control.

The herpes-like virus, called ganglio-neuritis was first detected at a Portland abalone farm early last year. Since then its wreaked havoc on Australia’s $75-million exotic and farmed abalone industry.

Dr. Peter Appleford, of Fisheries Australia says it is a nasty virus. “It has a short infection time and a high mortality rate, so once the animals get it, they die,” he said. Hundreds of thousands of abalone farmed at sites where the virus has been detected were destroyed. Breeders say the government was doing too little too late.

But today the authorities hit back, blaming divers. Dr Appleford says divers must not dive in more than one place without thoroughly washing every single piece of their clothing and equipment, otherwise the deadly disease will continue to destroy the abalone industry.

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Sightings by marine scientists of dolphins in the north Atlantic’s Bay of Biscay have dropped off by 80 percent compared to the same period in 2006, a wildlife conservation group said Wednesday.

The alarming drop in numbers of the Bay’s three most common species of dolphin — the striped, bottlenose and common — can be attributed to one or both of two causes, Clive Martin, senior wildlife officer for the Biscay Dolphin Research Programme, told AFP.

“We know for a fact that by-catch is killing thousands of dolphins every year,” he said, referring to commercial fishing operations in the bay, which is formed by the northern coast of Spain and the eastern French seaboard up to the tip of Brittany.

Martin singled out French “pair trawlers” that sweep the ocean with huge nets twice the size of a football pitch strung out between them as being especially lethal to the marine mammals. “Dolphins are sometimes trapped hundreds at a time, and are asphyxiated” when they cannot come up for air, he said. Most dolphins typically replenish their lungs with fresh air every five minutes or so, he explained.

The second — and probably more important — reason that dolphins have disappeared is that there is simply very little left for them to eat. “Anchovy fishing in the Bay of Biscay has progressively failed, and this year there is a complete ban by Spain, France and the United Kingdom on the fishing of anchovies,” a principal food source for dolphins, Clive said.

He speculated that the roving sea mammals — which swim in pods numbering in the dozens for bottlenose dolphins, and sometimes in the thousands for the common dolphin — had moved west toward the mid-Atlantic looking for food. A sharp decrease in the presence of many seabirds that also feed on fish — such as auks, shearwaters and gannets — lends support to this explanation.

The Bay of Biscay Research Programme has been systematically recording dolphin sightings along the same route from Bilbao, Spain to Portsmouth, England for 13 years. Compared to the comparable period in 2004 and 2005, dolphin sightings in 2007 have decreased by 50 percent, he said.

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A school of several hundred hammerhead sharks was spotted from between 200 meters and 500 meters from the beach in Koga, Fukuoka Prefecture, on Aug. 1. A witness reported seeing the sharks, saying, “There were loads of sharks with hammerlike heads.” Three days later, two 3.5-meter hammerhead sharks were sighted by holidaymakers at Usami beach in Ito, Shizuoka Prefecture.

Aqua World Ibaraki Prefecture Oarai Aquarium said five to six smooth hammerhead sharks captured near beaches have been brought to the facility each week this month, although the same number is usually caught in nets in one year. There are nine types of hammerhead shark. Those spotted in waters near the Japanese archipelago are mainly smooth or scalloped hammerheads.

According to Kazuhiro Nakaya, a professor of marine life at the Graduate School of Fisheries Sciences at Hokkaido University, hammerheads usually head north, swimming with the warm ocean current around this time of year. Every summer, many hammerheads are sighted several kilometers offshore in Tottori, Fukuoka and other prefectures. Last August, a school of about 60 hammerheads was spotted off Shimonoseki, Yamaguchi Prefecture. “It’s quite natural for hammerhead sharks to be sighted off Izu and the Kyushu region,” Nakaya said.

Following the latest sighting of hammerheads close to beaches, some people speculated the sharks strayed close to shore because they were chasing short-tail stingrays, pointing out that the sharks were seen swimming along a school of that fish. But other experts noted that since the sharks seen in Koga were hammerhead pups about one meter long, it is unlikely that they would be preying on stingrays.

It seems that what happened this year was that the sharks were spotted near the shore because a warm ocean current was flowing relatively close to the coast.

Yojiro Shiba, chief shark keeper at Oarai aquarium, said it is not unusual for about 100 to 200 baby scalloped hammerheads to form a school.

Do they pose a risk to humans? “Hammerhead sharks are basically timid, and it’s extremely rare for them to attack humans,” Shiba said. Unlike great white sharks, the hammerhead has a small jaw, and even that of an adult hammerhead is only 30 centimeters wide. The immature sharks seen in Koga had jaws only 10 centimeters wide.

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Tidechaser has a great article on the marine life of Malaysia’s Tioman island. He went walking on the coast at low tide and took photos of what he found — crabs, pufferfish, nudibranches, flatworms, marine spiders,  acropora, hard coral and sea stars. You won’t need to put on your scuba gear to see all this!

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Rick Macpherson summarises what happens to a coral reef when a hurricance hits it:

With Flossie bearing down on Hawaii, I’ve been asked by more than a few people today what impacts, if any, hurricanes can have on coral reefs. Since coral reefs are the bedrock of Hawaii’s tourism, the fear that severe hurricanes can have a catastrophic effect on the state’s economy is very real. So what do we know?

Much of what we know about hurricane impacts to reefs comes from studies in the Caribbean where severe storms have been slamming well monitored reef communities for decades. Studies show that the base coral frame is fairly resistant and immovable. But strong storm surge and wave energy can certainly damage or destroy branching corals or even smaller boulder coral colonies.

Reef life such as soft corals, sponges, and any other encrusting organisms that live attached to the base coral frame can break away and be pulverized in the churning wave surge. Some of the fragmented life (sponges and corals) might survive, reattach, and continue growing in a new location if it is not buried or transported to a location where living conditions are inhospitable.

Another threat to reefs from hurricanes can be smothering from sediment suspended in wave surge or, more commonly, muddy runoff from land as a result of torrential storm downpour. Along Australia’s Great Barrier Reef, sediment laden flood waters can completely block sunlight to some shallow reefs allowing only 1% of light to reach corals at depths of 10 m. Large scale flooding can carry land-based pollutants such as insecticides, fertilizers, and herbicides out to the reef. Fresh water can kill corals at shallow depths where mixing is low.

Despite these seemingly formidable assaults from hurricanes, coral reef ecosystems have recovered from severe storms for millions of years. Coral reefs are characterized as disturbance communities. While subject to frequent changes, disturbance communities tend to promote biodiversity by either selecting for species that can capitalize on rapid fluctuations or by promoting competition (and speciation) through specialization to exploit microhabitats and niches.

While hurricanes can be catastrophic for reefs, recent studies also show that hurricanes may actually have beneficial outcomes in some scenarios. Evidence is building that the cooling effect hurricanes have on sea temperatures may actually help corals recover from the bleaching caused by warming oceans. It is a controversial debate at the moment, but if the frequency of hurricanes increases with global warming, then the negative effects that are expected for coral bleaching [due to ocean warming] could be mitigated by the cooling that the hurricanes bring about.

But keep in mind that such a hypothesis only considers relief from reef threats caused by elevated sea surface temperatures. Hurricanes offer no quick fix to threats coming from unsustainable uses of coral reefs (coastal development, commercial or destructive fishing, coral mining, etc.) So while a storm-prone world might help mix (and cool) a warming sea, a slew of other stressors are waiting in the wings to further punish already over-stressed and sensitive coral reef systems.

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