A new (probably fossil) species of Thyasirid Clam from the Beaufort Sea.

Thyasirid Clams are known from across the world’s oceans from the intertidal zone to the ocean deeps. Many species are associated with cold seeps and hot vents where food chains are based upon chemotrophic Bacteria and Achaeans (micro-organisms that generate energy by processing chemicals in the water or sediment without photosynthesis), and are probably themselves symbiotic hosts to such chemotrophs.

In a paper published in the journal ZooKeys on 10 December 2014, PaulValentich-Scott of the Santa Barbara Museum of Natural History and CharlesPowell, Thomas Lorenson and Brian Edwards of the United States Geological Survey describe a new species of Thyasirid Clam from the Canning Seafloor Mound in the Beaufort Sea off the north coast of Alaska.

The new species is named Wallerconcha sarae, where ‘Wallerconcha’ honours Thomas Waller of the Smithsonian Institution, for his work on living and fossil Bivalves (‘Wallerconcha’ literally translates as ‘Waller’s shell’, though this is not explained in the text) and ‘sarae’ honours Sara Powell, the daughter of Charles Powell.

Wallerconcha sarae, length = 23.9 mm, height = 21.3 mm, width = 16.7 mm. (A) Exterior of right valve. (B) Exterior of left valve. (C) Dorsal view of both valves. (D) Close up of periostracum of right valve. (E) Interior of left valve. (F) Interior of right valve. (G) Close up of hinge of left valve (H) Close up of hinge of right valve. Valentich-Scott et al. (2014).

The species is described from five shells, plus some additional fragmentary material, collected in two sediment cores from the Canning Seafloor Mound, ranging from 12.8 mm to 23.9 mm in length. No soft tissue was preserved with the shells, so their biology is unclear, but Canning Seafloor Mound is considered to be a cold seep environment (i.e. an environment in which hydrocarbons are seeping from buried sediments into the water column, providing a distinct chemical environment favourable to chemotrophic Bacteria and Achaeans) and the living Wallerconcha sarae is likely to have either hosted collonies of such micro-organisms symbiotically or have fed on free living ones.

The location of the Canning Seafloor Mound off the coast of northern Alaska. Valentich-Scott et al. (2014).

The shells were collected from between 2 cm and 4.65 m below the surface. Valentich-Scott et al. estimate that the sedimentation rate at the Canning Seafloor Mound to be about 50 cm per thousand years, which would make the shells less than 10 300 years old, with the youngest being quite recent. However this does not take into account the sediment compaction rate. The oldest shell was found at a level that also contained the plankticforaminiferan Neogloboquadrina pachyderma, which is considered to have been extinct for 1.8 million years, suggesting that this specimen is at least that old, while a partial shell of the Gastropod Neptunea was found at a depth of 2.31 m, also associated with a shell of Wallerconcha sarae. This Snail is known from the earliest Miocene to the Holocene in the North Pacific, and from the late Pliocene to the Holocene of the Arctic Ocean and North Atlantic, being thought to have originated in the Pacific and entered thr other areas after the opening of the Bering Strait in the latest Miocene or early Pliocene, giving a maximum age to these sediments at around the Miocene/Pliocene boundary.

Shaded seafloor bathymetry showing shape and approximate dimension of the Canning Seafloor Mound. The core sites are shown as red dots. Valentich-Scott et al. (2014).

See also…

A new species of Thyasiroid Clam from British Columbia.

Thyasiroid Clams are a group of Veneroid Bivalves found in deep waters around the world. They are not well understood as a group, as most species are known only from their shells, which allows for only a limited understanding of their soft tissue anatomy and lifestyle.

A new species of Giant Clam.

Giant Clams of the genus Tridacna are large Bivalve Molluscs in the Cockle Family (Cardiidae). They are extremely distinctive, both for their large size and their bright colouration, which is caused by symbiotic algae that live within the flesh of their mantles. Giant Clams...

Predation of Freshwater Mussels in the Early Cretaceous of Spain.

Unionoid Bivalves (Freshwater Mussels) appeared before the beginning of the Triassic, and became the dominant freshwater invertebrates in...

Follow Sciency Thoughts on Facebook.

Oil rig runs aground on Sitkalidak Island on New Years Day.

On 21 December 2012 the Shell Oil Exploration Rig Kulluk left the port of Dutch Harbor on Unalaska Island, Alaska, with the intention of reaching the port of Seattle, in Washington State. It did this despite extremely poor weather conditions, apparently to avoid paying a tax bill that would be incurred if the rig remained in Alaska on 1 January, attempting to make the voyage in winds described as 'near-hurricane force'. On 28 December the rig ran into trouble, when one of the vessels towing it, the Edison Chouest Offshore operated Anchor Handling Tug Supply Vessel Aiviq, suffered an engine failure. This lead to a loss of control of the Kulluk, which dragged the two attached vessels, the Aiviq and the Alert 16 km towards the rocks of Kodiak Island over the following four days, before a cable connecting the Aiviq to the Kulluk snapped and the struggle was abandoned to avoid the loss of the towing vessels. The vessel eventually ran aground on 500 m deep rocks of Sitkalidak Island.

The Kulluk on rocks of Kodiak Island. AP.

The United States Coast Guard has formed a unified incident command with companies involved in the salvage operation, including experts brought in from Dutch company Smit Salvage. A total of 630 people and twenty-one vessels, are said to be involved.

The Kulluk is in the Arctic as part of a Shell plan to drill for oil in the Beaufort and Chukchi Seas, a project which has provoked considerable controversy with environmental groups concerned that the rigs will not be able to operate safely in Arctic waters, and which has bee dogged by problems from the outset. In February 2012 protestors from Greenpeace occupied the Nobel Drilling vessel Nobel Discoverer, which will be forming the other part of the two-drilling rig operation. In December 2012 the Nobel Discoverer was again detained, this time by the US Coast Guard for safety reasons. A third vessel, the Arctic Challenger failed to meet seaworthiness requirements for some months. 

This new disaster has renewed calls for the US Department of the Interior to rescind Shells permits to drill in the Arctic. The event will also cost the company severely in financial terms, as it will be forced to reimburse all costs incurred by the recovery operation, as well as the original tax bill, estimated at US$6-7 million, since the vessel never made it out of Alaskan waters. 

Shell has issued no statement other than to confirm that there was no loss of life in the incident, that the rig was not leaking any oil, and that it will cooperate fully with the US Coast Guard.

See also Amnesty International reports on the 2012 Bodo Oil Spill, Greenpeace activists occupy drilling ship in New Zealand, Oil spill off the coast of Nigeria, The UN reports on oil pollution in Ogoniland, Nigeria and Drilling for oil on the Ningaloo Reef.

Follow Sciency Thoughts on Facebook.