Navigation Links
Jellyfish dominate fish in over-harvested Namibian waters

By sampling sea life in a heavily fished region off the coast of Namibia, researchers have found that jellyfish have actually overtaken fish in terms of the biomass they contribute to this ocean region. The findings represent a careful quantitative analysis of what's been called a "jellyfish explosion" after intense fishing in the area in the last few decades. The findings are reported by Andrew Brierley, of the University of St. Andrews, and his colleagues in the July 12th issue of the journal Current Biology.

An increasing abundance of jellyfish off Namibia had been noted for some time, but an analysis of this trend's effect on the ecosystem has been hampered by a lack of hard data on jellyfish abundance. The authors note that prior to their work, less formal observations had pointed to a striking change over time--for example, jellyfish are now so numerous in the region that they significantly interfere with fishing operations and industrial water-uptake systems. In addition, large jellyfish species such as Chrysaora hysoscella and Aequorea forskalea have become more commonly reported.

In their new work, the researchers sampled waters all along the Namibian shelf, between the borders of Angola and South Africa, in an area known as the northern Benguela. In the past, this region has offered abundant fish stocks, thanks largely to its being served by cool, nutrient-rich upwellings occuring along the continental shelf. The fish stocks, including sardines and anchovies, have been heavily exploited since the 1970s and have been strongly depleted in the process. Because fish and jellyfish essentially compete for similar nutrient resources, a dramatic decline in fish populations could theoretically contribute to a substantial shift in the abundance of jellyfish.

The researchers' findings indicate that jellyfish now account for significantly more biomass in the northern Benguela waters than do fish. Based on the data they obtained--by using sc ientific echosounders and trawl nets to sample jellyfish and fish in an area of over 30,000 nautical miles--the researchers estimate the total biomass of jellyfish in the region to be 12.2 million metric tons (mostly contributed by the large A. forskalea species), whereas the biomass of fish accounts for only 3.6 million metric tons.

In their report, the authors point out that jellyfish biomass has risen in numerous locations worldwide, possibly as a consequence of fishing. Climactic changes could also contribute to jellyfish population shifts.

The authors also note that jellyfish have few predators and that jellyfish abundance has significant potential consequences for oceanic ecosystems--such consequences include slowed or attenuated fish-stock recovery and alterations in the nature of carbon cycling.


'"/>

Source:Cell Press


Related biology news :

1. Survey finds silver contamination in North Pacific waters
2. Detecting microalgae in coastal waters
3. How fish species suffer as a result of warmer waters
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:5/23/2017)... GENOA, Italy , May 23, 2017  Hunova, the first robotic ... and trunk, has been officially launched in Genoa, Italy ... Europe and the USA . The ... launched on the market by the IIT spin-off Movendo Technology thanks to ... view the Multimedia News Release, please click: ...
(Date:4/19/2017)... New York , April 19, 2017 ... competitive, as its vendor landscape is marked by the ... the market is however held by five major players ... Safran. Together these companies accounted for nearly 61% of ... of the leading companies in the global military biometrics ...
(Date:4/11/2017)... , April 11, 2017 Crossmatch®, a ... authentication solutions, today announced that it has been ... Research Projects Activity (IARPA) to develop next-generation Presentation ... "Innovation has been a driving force ... program will allow us to innovate and develop ...
Breaking Biology News(10 mins):
(Date:8/15/2017)... CA (PRWEB) , ... August 15, 2017 , ... ... pioneering graphene biosensors that accelerate pharmaceutical and biotherapeutics development, announces the launch of ... number of steps needed to gain kinetic binding data for a wide range ...
(Date:8/15/2017)... ... August 15, 2017 , ... The Conference Forum ... 360° (IO360°) programming through a series of upcoming panels and events. The partnership culminates ... at The Roosevelt Hotel in New York City. , “With our experience in producing ...
(Date:8/14/2017)... ... August 14, 2017 , ... Opal ... using USB or PCI Express, announced the release of SYZYGY™, a new open ... satisfy the need for a compact, low cost, low pin-count, high-performance connectivity solution ...
(Date:8/11/2017)... ... August 11, 2017 , ... Algenist continues to disrupt ... unlocking collagen like never before. , Collagen is the key structural element skin ... with Liquid Collagen™, which include: , First to market ...
Breaking Biology Technology: