Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Invasive sea squirt alive and well on Georges Bank

22.11.2004


Image DSCF1526. Tunicate colony of a species of the genus Didemnum encrusting and cementing a pebble gravel seabed and crowding a dark orange anemone (lower part of photo). Note the relatively few holes in the mat where the gray background is visible. Northern Georges Bank (41 deg 54.429 min N lat, 67 deg 27.146 min W lon). Water depth 59 m (194 ft). November 2004. Width of specimen shown is 9 inches. Collectors: Page Valentine, Jeremy Collie, and Robert Reid. Photo credit: Dann Blackwood, U.S. Geological Survey.


Image DSCF1537. Underside of tunicate mat in image DSCF1526 showing pebble gravel cemented by colonial tunicates (pale yellow color). Note the relatively few holes in the mat where the gray background is visible. Northern Georges Bank (41 deg 54.429 min N lat, 67 deg 27.146 min W lon). Water depth 59 m (194 ft). November 2004. Width of specimen shown is 5.6 inches. Collectors: Page Valentine, Jeremy Collie, and Robert Reid. Photo credit: Dann Blackwood, U.S. Geological Survey.


The invasive sea squirt that federal and university researchers discovered on Georges Bank a year ago is flourishing in U.S. waters near the U.S.-Canada boundary, a joint research team announced today following a research cruise that concluded last week.

Scientists from the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), and the University of Rhode Island estimate that mats made of thousands of individual squirts infest a 40 square mile area of seabed that is highly productive for fish and sea scallops. In large parts of the affected area, the sea squirts cover 50 percent or more of the seabed. The Georges Bank infestation is unique, the only known occurrence of this magnitude in a major offshore fishing ground.

Sea squirts are tunicates, a type of sea life with a primitive spinal cord and a firm, flexible outer covering called a "tunic," from which the name derives. A filter-feeding species of the genus Didemnum, they form dense mats, made of thousands of individuals, by attaching to firm substrates such as gravel, sea scallops, mussels, docks and other structures, and even seaweed. Tunicates can overgrow sea scallops and mussels, and they may affect other species of clams and worms that live in the seabed below the tunicate colony. An "invasive species" is one that is not native to an ecosystem, and that may harm that ecosystem if introduced.



In the fall of 2003, the same research team first spotted this infestation over roughly 6 square miles of ocean bottom during a scientific cruise to study habitats on Georges Bank. This year, the team surveyed a larger area with tunicate coverage.

The scientists observed mats over at least 40 square miles of the gravel substrate on the northern edge of Georges Bank. Video and photo transects using the USGS seabed observation and sampling system (SEABOSS) documented the distribution of the tunicate colonies in water depths of 42 to 65 meters (138 to 213 feet). The cruise was conducted aboard the NOAA Ship Delaware II.

Scientists will analyze data they collected on the cruise to determine if the tunicate invasion has the potential to alter seabed communities that sustain commercial fish species. Tunicate fragments were also found in the stomachs of haddock and winter flounder collected in the area, but did not appear to be digested. Samples of the tunicate will be evaluated to determine its nutritional value to predators, and to confirm the species through DNA analysis.

The tunicate can spread by reproducing either sexually or asexually by budding. The free-swimming tadpoles produced by sexual reproduction live only a few days, during which time they can be spread by tidal and storm currents to form new colonies. By contrast, fragments of colonies are long-lived. Controlled experiments in Cape Cod waters by USGS and Woods Hole Oceanographic Institution scientists have shown that small pieces removed from Didemnum colonies increase dramatically by budding in a matter of weeks. Thus, fragmentation of tunicate mats could promote the spread of the species.

The Didemnum species occurs along the coasts of the Netherlands and France. In the U.S., it has been documented in coastal New England from Connecticut to northern Maine, along the California coast, and in October of this year, it was first reported in Puget Sound off Edmonds, Washington. The same species (or a close relative) is present at several localities in New Zealand. Officials in Edmonds and in New Zealand have used chemical applications and physical removal in attempts to eradicate the relatively small infestations there.

The species thrives in marine environments that lie within its preferred temperature range (28 to 75 degrees F) and that have firm substrates and plentiful food, conditions that are widespread off the coasts of New England and Atlantic Canada. It could change gravel habitats that lie along the northern edge of Georges Bank, and immobile sand habitats characteristic of southerly Bank. Didemnum cannot survive on habitats of moving sand, and therefore much of the shallow Bank crest is not threatened. It is not yet known to occur on mud habitats that are typical of the deep basins of the Gulf of Maine.

Ellen Mecray | EurekAlert!
Further information:
http://www.usgs.gov

More articles from Earth Sciences:

nachricht Live from the ocean research vessel Atlantis
13.12.2018 | National Science Foundation

nachricht NSF-supported scientists present new research results on Earth's critical zone
13.12.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>