Navigation Links
VIMS study: Propeller turbulence may affect marine food webs
Date:4/19/2011

A new study by researchers at the Virginia Institute of Marine Science shows that turbulence from boat propellers can and does kill large numbers of copepodstiny crustaceans that are an important part of marine food webs.

The studyby VIMS graduate student Samantha Bickel, VIMS professor Kam Tang, and Hampton University undergraduate Joseph Malloy Hammondappears in the March issue of the Journal of Experimental Marine Biology and Ecology.

The researchers don't expect their findings to lead to any new "No Wake" signs in local waterways; their interest instead is to better understand how significant levels of propeller-induced mortality among copepods might affect local food webs in Chesapeake Bay and other highly trafficked waterways.

"Non-predatory mortality such as this is rarely considered in the literature," says Bickel, "but it could be important for properly understanding zooplankton ecology and food-web dynamics in coastal and estuarine waters, particularly during summer months when recreational boating increases."

Zooplankton are small drifting animals that consume algae and other microscopic floating plants. Copepodsshrimp-like crustaceans about the size of a rice graintypically make up a major part of the zooplankton community and serve an important role by moving energy up the marine food chainfrom microscopic plants that are too small for most fish to eat up to larger game-fish and, ultimately, humans.

"If turbulence from boat propellers is killing off large numbers of copepods," says Bickel, "it could be reducing the supply of food energy available to fish, and reducing zooplankton grazing of algal blooms." "It's like cutting down the number of zebras in a herd," she adds. "That would affect not only the zebras, but also the grass they eat and the lions that eat them."

This type of shift could potentially have a noticeable impact on marine food webs and water quality. "If a large portion of copepods are being killed, and if they sink down to the bottom, you could have additional high-quality organic material available for bottom-dwelling organisms to eat," says Bickel. "If the amount is high enough, microbial decomposition could even perhaps contribute to development of localized low-oxygen 'dead zones.'"

The researchers caution that there are untold millions of zooplankton in the world's aquatic systems, so that when viewed at a global scale, the portion of copepods killed by boat-generated turbulence is probably minimal.

"The importance of turbulence as a source of mortality among copepods would be of much greater importance at a local scale," says Bickel, "including highly trafficked areas near harbors and marinas, and within closed freshwater systems such as lakes."

The research team studied propeller-induced mortality both in the field and laboratory. During the spring of 2010, they sampled copepods at three sites near the mouth of the Hampton River, a tributary of Chesapeake Bay. One site was a marina with numerous boats but minimal turbulence due to an imposed speed limit. The second was in a high-traffic area of a nearby navigational channel, where fast-moving boats generated considerable turbulence in their wakes. The third site was a tranquil shoreline opposite from the marina, with few boats and little or no boat-generated turbulence.

They compared the percentage of live and dead copepods collected from these sites using a dye that is only taken up by living copepods. The results of their comparison showed a much higher fraction of dead copepods in the channel (34%) than in the marina (5.9% dead) or along the shoreline (5.3%).

A field experiment in the York River near the VIMS campus confirmed the results of the Hampton River study. Here, they sampled copepods from within the wakes of passing boats, and again found a link between turbulence and mortality: the percentage of copepod carcasses increased from 7.7% outside the wakes to 14.3% inside the wakes.

The researchers were careful in both cases to minimize turbulence from their own vessel, using a rowboat for the Hampton River study and maintaining an idle during sampling in the York.

The team's final experiment took place in the laboratory, where they exposed copepods to turbulence from a small motor calibrated to mimic the effects of different boat propellers. Their results again confirmed their earlier findings, with a clear link between mortality and increasing levels of turbulent energy.

Their experiments also show that natural turbulence from tides, currents, and waves is unlikely to stress or kill copepods other than perhaps during an extreme storm event such as a hurricane or nor'easter.


'/>"/>

Contact: David Malmquist
davem@vims.edu
804-684-7011
Virginia Institute of Marine Science
Source:Eurekalert  

Related biology news :

1. Study: Algae could replace 17 percent of US oil imports
2. Study: Emissions trading doesnt cause pollution hot spots
3. Nature study: Jefferson researchers unravel proteins elusive role in embryo and disease development
4. Study: Tiger numbers could triple if large-scale landscapes are protected
5. IU study: Humans critical ability to throw long distances aided by an illusion
6. UC Davis study: Wild salmon decline was not caused by sea lice from farm salmon
7. Study: Personal contacts at work help people better understand organ donation
8. Study: Osteoporosis drug reduces bone loss, tumor size in oral cancer
9. Study: mechanism that controls cell movement linked to tumors becoming more aggressive
10. Illinois study: Ginseng just got better -- not as bitter
11. Study: Ecological effects of biodiversity loss underestimated
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
VIMS study: Propeller turbulence may affect marine food webs
(Date:2/7/2017)... Feb. 7, 2017 Zimmer Biomet Holdings, Inc. ... healthcare, will present at the LEERINK Partners 6th Annual ... Hotel on Wednesday, February 15, 2017 at 10 a.m. ... the presentation can be accessed at http://wsw.com/webcast/leerink28/zbh .  ... conference via Zimmer Biomet,s Investor Relations website at ...
(Date:2/2/2017)... 2, 2017   TapImmune, Inc. (NASDAQ: ... specializing in the development of innovative peptide and ... cancer and metastatic disease, announced today it has ... of a second clinical lot of TPIV 200, ... alpha. The manufactured vaccine product will be used ...
(Date:1/30/2017)... --  Invitae Corporation (NYSE: NVTA ), ... announced that it will report its fourth quarter and ... Monday, February 13, 2017, and Invitae,s management team will ... Eastern / 1:45 p.m. Pacific. During ... results, guidance, and recent developments and will spend the ...
Breaking Biology News(10 mins):
(Date:2/23/2017)... and NEW YORK , Feb. ... Lumeon , a leading digital health company, and ... provider of telemedicine and remote patient monitoring, announce ... telemedicine reimbursements.  DN Telehealth maximizes ... in real-time, extending consultations beyond a physical clinical ...
(Date:2/23/2017)... ... 2017 , ... BellBrook Labs is formalizing a significant expansion ... biochemical analyses critical for Lead Discovery. The company’s Lead Discovery Services will ... inhibitor potency and selectivity, mechanism of action, and inhibitor residence times on drug ...
(Date:2/23/2017)... , Feb. 23, 2017  MIODx announced today ... two key immunotherapy technologies from the University of ... a method to monitor a patient for response ... and CTLA-4.  The second license extends the technology ... is likely to have an immune-related adverse event ...
(Date:2/23/2017)... , Feb. 23, 2017  Seattle,s upscale Capitol Hill ... a strange place for a head lice treatment salon to ... between a Tuscan restaurant and a French bistro on E ... perfect. "We aren,t just any old lice clinic, we pride ... feel comfortable, and release some of the stigma associated with ...
Breaking Biology Technology: