Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Big changes in the Sargasso Sea

24.09.2014

Over one thousand miles wide and three thousand miles long, the Sargasso Sea occupies almost two thirds of the North Atlantic Ocean. Within the sea, circling ocean currents accumulate mats of Sargassum seaweed that shelter a surprising variety of fishes, snails, crabs, and other small animals.

A recent paper by MBARI researcher Crissy Huffard and others shows that in 2011 and 2012 this animal community was much less diverse than it was in the early 1970s, when the last detailed studies were completed in this region. 


Small rafts of Sargassum seaweed like this one are a common site in the Sargasso Sea. These rafts harbor a variety of small animals. Image: Debbie Nail Meyer © 2011 MBARI

This study was based on field research led by MBARI Senior Scientist Ken Smith, using the Lone Ranger, a 78-meter (255-foot) research vessel owned and operated by the Schmidt Ocean Institute. During three cruises in 2011 and 2012, Smith’s team steamed across the Sargasso Sea and used dip nets to collect samples of Sargassum seaweed (and its associated animals) at six different locations. They then classified and counted all the animals at each site.

The researchers chose their sampling and counting methods carefully so that they could compare their results with previous surveys that had been conducted in 1972 and 1973 in the same general part of the Sargasso Sea. Amazingly, the researchers could find no other studies between 1973 and 2011 during which scientists had systematically counted the Sargassum animal communities in this area. 

When the team analyzed the data from the recent cruises, they were surprised to find that animal communities in the Sargassum rafts were significantly less diverse than those observed in the 1970s. For example, 13 species of animals in several different groups (worms, nudibranchs, crustaceans, and sea spiders) were observed in the historical samples but were missing from the recent samples.

Unfortunately, the researchers did not have enough data to determine whether the differences they observed were the result of long-term shifts in ocean conditions in the Sargasso Sea or natural variations from place-to-place, month-to-month, or year-to-year. 

The authors note that ocean conditions were much cooler than normal during February 2011 and that there were large differences in animal communities observed just six months apart, in August 2011 and February 2012. So it is possible that this area routinely sees large natural variations in the types of animals present. As Huffard put it, “If this is a long-term decline [in biodiversity], then it is a very significant one. But we don’t know if this is part of the natural variability in this community.”

Previous studies indicate that much of the seaweed that ends up in the Sargasso Sea originates in the Gulf of Mexico and is carried into the central Atlantic by the Gulf Stream and other currents. This suggests that, in addition to local ocean conditions, large-scale variations in ocean currents and conditions in the Gulf of Mexico could affect the animals in Sargassum communities.

To tease out these confounding variables, Smith and Huffard are hoping to conduct a series of follow-up expeditions to the Sargasso Sea. They plan to focus on the northern part of the Sargasso Sea, near Bermuda, where more detailed historical data are available. They are presently working on a proposal for a grant that would allow them to analyze satellite imagery and collect field samples twice a year for three years. The proposed study would show how much year-to-year variability is normal for this region. 

At first glance, the animals that live in Sargassum rafts seem isolated from the rest of the world. But, like the seaweed they live in, these animal communities have many links to larger ocean food webs. For example, Sargassum animals provide essential food for sea birds, sea turtles, and bluefin tuna—all long-distance migrators. In fact, Sargassum rafts have been designated as “essential fish habitat” by the South Atlantic Fishery Management Council. 

The world’s oceans are changing, with water temperatures and ocean acidity on the rise and oxygen concentrations on the decline. In the Sargasso Sea, as in many other locations, detecting the biological effects of these long-term trends is a formidable challenge because animal communities can vary dramatically over short time periods. This study shows that animal communities in the Sargasso Sea are definitely changing. The next step is to find out why.

###

For additional information or images relating to this news release, please contact:

Kim Fulton-Bennett
831-775-1835, kfb@mbari.org

Original journal article:
C.L. Huffard, S. von Thun, A.D. Sherman, K. Sealey and K.L. Smith, Jr. (2014) Pelagic Sargassum community change over a 40-year period: temporal and spatial variability. Marine Biology, doi10.1007/s00227-014-2539-y.

Kim Fulton-Bennett | Eurek Alert!

Further reports about: Aquarium Atlantic Bay Aquarium Research MBARI Monterey Sargasso Sea animals long-term seaweed variations

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

MEMS chips get metatlenses

21.02.2018 | Physics and Astronomy

International team publishes roadmap to enhance radioresistance for space colonization

21.02.2018 | Physics and Astronomy

World's first solar fuels reactor for night passes test

21.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>