Titanic: Expedition captures images and hi-def video

December 04, 2016

St. John’s (Bernd F. Laeschke – August 2010): During an expedition to the wreck of the Titanic, stunning 3-D images have been captured for the first time. Scientists and archaeologists aboard the research vessel The Jean Charcot produced the most detailed ever map of the wreck site. The RMS Titanic, Inc., the company that was awarded ownership rights to the wreckage as salvor-in-possession in 1994, organized the new expedition that is co-led by the Woods Hole Oceanographic Institution (WHOI).

A YouTube video-clip titled “Expedition Titanic: ROV Recovery” is available here.

RMS Titanic was the largest passenger steamship in the world when she set off on her maiden voyage from Southampton, England to New York City on 10 April 1912. The Olympic-class passenger liner, owned by the White Star Line, struck an iceberg at 11:40 pm on April 14, 1912 about 400 miles (644 kilometers) south of the Grand Banks of Newfoundland, and sank at 2:20 am the following morning. In one of the deadliest peacetime maritime disasters, 1,517 people drowned, and only 706 survived. The 882 feet (269 meter) vessel did have a displacement of 52,310 tons. With a height of 175 feet (53 meter), the Titanic featured 9 decks and 840 staterooms. Fully loaded, it could carry 2,687 passengers and a crew of 860.

Chris Davino, President of RMS Titanic, Inc., outlines the goals of the current Titanic expedition in this YouTube video here. The expedition was able to probe the wreck and the large debris field surrounding it with a pair of robots that captured thousands of photographs and hours of high definition video. Scientists aim to complete a full inventory of the ships remains and artifacts that are partially buried under almost a century of sediment.

Some of the most stunning images of the Titanic wreck are seen in this video, placed on YouTube by Premier Expeditions.

Hermit crabs congregate to find a larger snail shell

December 04, 2016

Berkeley (Bernd F. Laeschke – October 2012): Terrestrial hermit crabs congregate to kick another crab out of its shell and move into a larger home, research from a University of California, Berkeley finds. The decapod crustaceans (Coenobita compressus) usually live inside a discarded snail shell and forages for plants and carrion along the Pacific coast from Mexico to Peru. All hermit crabs appropriate abandoned snail shells for their homes, but the dozen or so species of land-based hermit crabs are the only ones that hollow out and remodel their shells, sometimes doubling the internal volume. This provides more room to grow, more room for eggs and a lighter home to lug around as they forage.

But empty snail shells are rare on land, so the best hope of moving to a new home is to kick others out of their remodeled shells, said Mark Laidre, a UC Berkeley Miller Post-Doctoral Fellow. When three or more terrestrial hermit crabs congregate, they quickly attract dozens of others eager to trade up. They typically form a conga line, smallest to largest, each holding onto the crab in front of it, and, once a hapless crab is wrenched from its shell, simultaneously move into larger shells.

“The one that gets yanked out of its shell is often left with the smallest shell, which it can’t really protect itself with,” said Laidre, who is in the Department of Integrative Biology. “Then it’s liable to be eaten by anything. For hermit crabs, it’s really their sociality that drives predation.”

The crabs’ unusual behavior is a rare example of how evolving to take advantage of a specialized niche - in this case, land versus ocean - led to an unexpected byproduct: socialization in a typically solitary animal.

“No matter how exactly the hermit tenants modify their shelters, they exemplify an important, if obvious, evolutionary truth: living things have been altering and remodeling their surroundings throughout the history of life,” wrote UC Davis evolutionary biologist Geerat J. Vermeij in a commentary in the journal Current Biology that first published the research. “Organisms are not just passive pawns subjected to the selective whims of enemies and allies, but active participants in creating and modifying their internal as well as their external conditions of life,” Vermeij concluded.

Laidre conducted his studies on the Pacific shore of Costa Rica, where the hermit crab Coenobita compressus can be found by the millions along tropical beaches. He tethered individual crabs, the largest about three inches long, to a post and monitored the free-for-all that typically appeared within 10-15 minutes.

Most of the 800 or so species of hermit crab live in the ocean where empty snail shells are common because of the prevalence of predators like shell-crushing crabs with wrench-like pincers, snail-eating puffer fish and stomatopods, which have the fastest and most destructive punch of any predator. On land, however, the only shells available come from marine snails tossed ashore by waves. Their rarity and the fact that few land predators can break open these shells to get at the hermit crab may have led the crabs to remodel the shells to make them lighter and more spacious.

The importance of remodeled shells became evident after an experiment in which Laidre pulled crabs from their homes and instead offered them newly vacated snail shells. None survived. Apparently, he said, only the smallest hermit crabs take advantage of new shells, since only the small hermit crabs can fit inside the unremodeled shells. Even if a crab can fit inside the shell, it still must expend time and energy to hollow it out, and this is something hermit crabs of all sizes would prefer to avoid if possible.

Pearse Resurgence: Cave divers discover three new species

December 04, 2016

New Zealand (Bernd F. Laeschke – June 2012): Cave divers discovered several new species - a transparent amphipod, a worm, and a small snail -in the Pearse Resurgence, a system in the remote Motueka Valley on the South island of New Zealand near Nelson. Pearse Resurgence is connected to the Nettlebed Cave, a deep, extensive cave system in the Mount Arthur Range. It was thought to be the deepest cave system in the southern hemisphere until divers pushed deeper in the nearby Ellis Basin cave system during an expedition in April 2010.

"It's not easy to get inside the caves, and we want to know about the very specific life in them," says Dr. Graham Fenwick, a scientist at New Zealand’s National Institute of Water and Atmospheric Research (NIWA). "It's important to do an inventory of life in New Zealand, and in this case, it's a pretty special type of environment, and we don't have many limestone karst systems that are readily explored."

Worldwide, these aquifer studies are yielding rich troves of biodiversity. The importance of the stygofauna is twofold - they contribute to the health of the aquifer by bio-filtration and in turn they may represent an important marker of the health of the water.

The bio-survey in the Pearse Resurgence was performed using two techniques. Firstly, any invertebrates observed free swimming in the cave were captured by hand using a tube with a bulb on the end. The second technique involved the deployment of baited fauna traps in the cave at depths from 16 to 377 feet (5 to 115 meters) below the surface. Small plastic jars baited with a small shrimp were filled with nylon gauze and secured in various places in the cave, in crevices and amongst sediments.

One species of amphipod crustacean new to science dominated the stygofauna collected from the Pearse Resurgence. This species is completely colorless. "It is 6-8mm long, the divers could see it crawling over rocks, it really is a beautiful animal. It belongs to the poorly known genus Paraleptamphopus, one of two genera within the New Zealand endemic Family Paraleptamphopidae," says Fenwick.

Originally described from Canterbury's deep alluvial aquifers, this family is represented by species inhabiting groundwater and marginally subterranean habitats throughout New Zealand. Within the Pearse Resurgence, this amphipod was found most commonly within the main shaft, where the expedition's divers stalked it on rock faces or caught it in small traps baited with shrimp.

It appears to live on the water-worn rock surfaces from within 6.56 feet (2 meters) of the surface of the main shaft's air bell, to depths of more than 131 feet (40 meters) where they were taken amongst gravel and finer sediments.

The two other stygofaunal invertebrates discovered in the system were a minute gastropod snail (about 0.06 inches or 1.5 millimeter in diameter) and an oligochaete worm (about 0.31 inches or 8 millimeter long). Both were taken from rare deposits of fine sandy sediments within the main shaft at depths from 49 to 112 feet (15-34 meters). "All these new finds are endemic to this area," says Fenwick.

Tahiti: Corals hold evidence of ancient mega flood

December 04, 2016

French Polynesia (Bernd F. Laeschke – March 2012): Coral around Tahiti, the largest island in the Windward group of French Polynesia, has linked the collapse of massive ice sheets 14,600 years ago to a dramatic and rapid rise in global sea-levels of around 46 feet (14 meters). Previous research could not accurately date the sea-level rise but now an Aix-Marseille University-led team has confirmed that the event occurred 14,650-14,310 years ago.

“It is vital that we look into Earth’s geological past to understand rare but high impact events, such as the collapse of giant ice sheets that occurred 14,600 years ago,” said Dr Alex Thomas of Oxford University’s Department of Earth Sciences. “Our work gives a window onto an extreme event in which deglaciation coincided with a dramatic and rapid rise in global sea levels - an ancient ‘mega flood’. Sea level rose more than ten times more quickly than it is rising now! This is an excellent test bed for climate models: if they can reproduce this extraordinary event, it will improve confidence that they can also predict future change accurately.”

During the Bølling warming, a warm interstadial period at the end of the last glacial period, high latitudes of the Northern hemisphere warmed as much as 15 degrees Celsius over several hundred years. The team was able to use dating evidence from Tahitian corals to constrain the sea level rise to within a period of 350 years, although the actual rise may well have occurred much more quickly and would have been distributed unevenly around the world’s shorelines.

“The Tahitian coral is important because samples, thousands of years old, can be dated to within plus or minus 30 years,” Thomas said. “Because Tahiti is an ocean island, far away from major ice sheets, sea-level evidence from its coral reefs gives us close to the ‘magic’ average of sea levels across the globe; it is also subsiding into the ocean at a steady pace that we can easily adjust for.”

The research is part of a large international consortium, the Integrated Ocean Drilling Program (IODP), and the coral samples were obtained by drilling down to the sea floor from a ship positioned off the coast of Tahiti. What exactly caused the Bølling warming is a matter of intense debate: a leading theory is that the ocean’s circulation changed so that more heat was transported into Northern latitudes.

The new sea-level evidence suggests that a considerable portion of the water causing the sea-level rise at this time must have come from melting of the ice sheets in Antarctica, which sent a ‘pulse’ of freshwater around the globe. However, whether the freshwater pulse helped to warm the climate or was a result of an already warming world remains unclear.

The Marine Biosecurity Porthole

December 04, 2016

Auckland (Bernd F. Laeschke – Juli 2011): "The Marine Biosecurity Porthole" is a website that publishes previously unseen records of pests that threaten New Zealand's marine environment. Examples of species featured include the Styela clava, a stalked sea squirt, the Mediterranean fan worm Sabella spallanzanii and the Pyura stolonifera sea squirt - all of which are non-native marine organisms, the Ministry of Agriculture and Forestry (MAF) and the National Institute for Water and Atmospheric Research (NIWA) said.

The website includes data from marine surveillance programs and NIWA's Marine Invasive Taxonomic Service that can be accessed by researchers and members of the public interested in protecting the marine environment.

"This portal will enable those people to find the most current information on what has been recorded in our waters and where those pest species have been detected,” said Simon McDonald, MAF's Manager of Marine Surveillance. "Since 2001, NIWA and other research providers have completed 43 baseline surveys of ports and marinas throughout New Zealand where vessels enter from overseas as part of MAF's marine surveillance program. These surveys provided information about both indigenous and non-indigenous species present in those locations. In addition, NIWA surveys high-risk locations twice-yearly for key unwanted pests. Now this information is collated in one easy-to-access location."

NIWA’s Aquatic Biosecurity Program Leader Graeme Inglis says the portal features a web-mapping application that allows users to view sites surveyed around New Zealand and distribution records for individual species. A metadata catalog allows users to search for and download information and specialized reports. "It also gives access to information on significant marine pests and a metadata catalog allowing search and download of information and reports. We're very excited that this important information is now so accessible to those who need it. We see this as an on-going project that will incorporate new data and information as it becomes available."

The Marine Biosecurity Porthole website can be accessed at http://www.marinebiosecurity.org.nz/.