Earthbytes

USGS: Tiny Grazers Play Key Role in Marine Ecosystem Health

Tiny sea creatures no bigger than a thumbtack are being credited for playing a key role in helping provide healthy habitats for many kinds of seafood...

Gammarus mucronatus, an amphipod grazer that can promote healthy eelgrass beds. Copyrighted photo courtesy of Matthew Whalen/UC Davis. (High resolution image)

According to a recently published study by the Virginia Institute of Marine Science and U.S. Geological Survey, tiny crustaceans like Gammarus mucronatus (see photo above) play a critical role to protect seagrasses from overgrowth by algae. By eating algae on seagrass, these small animals keep ocean environments healthy for native and economically important species.

“Inconspicuous creatures often play big roles in supporting productive ecosystems,” said the study'd lead author, Matt Whalen. “Think of how vital honeybees are for pollinating tree crops or what our soils would look like if we did not have earthworms. In seagrass systems, tiny grazers promote healthy seagrasses by ensuring algae is quickly consumed rather than overgrowing the seagrass. And by providing additional refuge from predators, fleshy seaweeds that drift in and out of seagrass beds can maintain larger grazer populations and enhance their positive impact on seagrass.”  

 USGS scientist Jim Grace, a study coauthor, says that seagrass habitats are also beneficial to people.

“Not only do these areas serve as nurseries for commercially important fish and shellfish, such as blue crabs, red drum, and some Pacific rockfish, but they also help clean our water and buffer our coastal communities by providing shoreline protection from storms,” Grace said. “These tiny animals, by going about their daily business of grazing, are integral to keeping healthy seagrass beds healthy.”

Comparison of algae fouling on eelgrass with and without grazers. Copyrighted photo courtesy of Matthew Whalen/UC Davis. Copyrighted photo courtesy of Matthew Whalen/UC Davis. (High resolution image)

Without these algae grazers, say the authors, algae could accumulate in a thick enough layer to block sunlight and prevent the seagrasses from photosynthesizing, which would kill them.  The decline of seagrass in some areas is partly the result of excess nutrients in water that stimulates excessive algal growth on seagrasses. 

J. Emmett Duffy of the Virginia Institute of Marine Science, another coauathor of the study, says that coastal managers have been concerned for years about excess fertilizer and sediment loads that hurt seagrasses. Duffy sees study results as convincing field evidence that tiny animals that graze on algae can be just as important as good water quality to prevent algal blooms and keep seagrass beds healthy.

The study, “Temporal shifts in top-down versus bottom-up control of epiphytic algae in a seagrass ecosystem,” was published in the recent issue of Ecology, a journal by the Ecological Society of America.

Read more about seagrass:

Related articles

Kaipara is 'last harbour standing'

Tohoku coast faces man-made perils in wake of tsunami

Need to Read: Wales' secret underwater habitats captured by new video project

DamCam: Lowhead Dam Removal on the Harpeth River to Start This Week

via www.harpethriver.org

From the US Fish and Wildlife Service: the City of Franklin and the Tennessee Department of Environment and Conservation will begin demolition of the City’s Harpeth River Lowhead Dam on Wednesday, July 25, at 11:00p.m.

The project will take out the only barrier on the Harpeth River, a lowhead dam, and improve fish habitat and water quality. The project will also improve public access and enhance recreational opportunities on the Harpeth for fishing and paddling.

Earlier this year the National Fish Habitat Partnership named this project
in their “2012 Ten Waters to Watch list.”  The Department of Interior also
named this project as a model of America’s Great Outdoors River Initiative
to conserve and restore key rivers across the nation, expand outdoor
recreational opportunities and support jobs in local communities.

The total cost of the project is $870,000, with $350,000 in federal grants
to the Harpeth River Watershed Association from collaborative funding
programs of the U.S. Fish and Wildlife Service, Southeast Aquatic Resources Partnership, and the National Fish Habitat Partnership for projects to improve fish habitat.The project is expected to be complete in fall of 2012. The Harpeth River Watershed Association is installing a Dam Cam thatwill tape the entire demolition process.To see the Dam Cam go www.harpethriver.org/damcam. This will enable the public to view this project while the area is off limits as a construction site. Water
recreation and canoe/kayak launch is temporarily prohibited during
construction.

 

Glad somebody has a use for all of that dog hair...

While photographing a nesting phoebe, I saw this tufted titmouse collecting hair and fuzz from my dogs' blanket on the porch:

 

 

White-Nose Bat Deaths: Fungus Behind Mysterious Deaths In U.S. And Canada Came From Europe

New info on WNS:

Experts had suspected that an invasive species was to blame for the die-off from "white nose syndrome." Now there's direct evidence the culprit was not native to North America.

The fungal illness has not caused widespread deaths among European bats unlike in the U.S. and Canada. In North America more than 5.7 million bats have died since 2006 when white nose syndrome was first detected in a cave in upstate New York. The disease does not pose a threat to humans, but people can carry fungal spores.

It's unclear exactly how the fungus crossed the Atlantic, but one possibility is that it was accidentally introduced by tourists. Spores are known to stick to people's clothes, boots and caving gear.

Read the rest of the story at www.huffingtonpost.ca

PLoS ONE: Elevated Mortality among Birds in Chernobyl as Judged from Skewed Age and Sex Ratios

ABSTRACT

Background

Radiation has negative effects on survival of animals including humans, although the generality of this claim is poorly documented under low-dose field conditions. Because females may suffer disproportionately from the effects of radiation on survival due to differences in sex roles during reproduction, radiation-induced mortality may result in male-skewed adult sex ratios.

Methodology/Principal Finding

We estimated the effects of low-dose radiation on adult survival rates in birds by determining age ratios of adults captured in mist nets during the breeding season in relation to background radiation levels around Chernobyl and in nearby uncontaminated control areas. Age ratios were skewed towards yearlings, especially in the most contaminated areas, implying that adult survival rates were reduced in contaminated areas, and that populations in such areas could only be maintained through immigration from nearby uncontaminated areas. Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. In addition, males sang disproportionately commonly in the most contaminated areas where the sex ratio was male skewed presumably because males had difficulty finding and acquiring mates when females were rare. The results were not caused by permanent emigration by females from the most contaminated areas because none of the recaptured birds had changed breeding site, and the proportion of individuals with morphological abnormalities did not differ significantly between the sexes for areas with normal and higher levels of contamination.

Conclusions/Significance

These findings are consistent with the hypothesis that the adult survival rate of female birds is particularly susceptible to the effects of low-dose radiation, resulting in male skewed sex ratios at high levels of radiation. Such skewed age ratios towards yearlings in contaminated areas are consistent with the hypothesis that an area exceeding 30,000 km² in Chernobyl’s surroundings constitutes an ecological trap that causes dramatic excess mortality.

via www.plosone.org

More Damning Evidence Points to Pesticide as Cause of Mass Bee Deaths | Common Dreams

Continuing saga of the bees...interesting article:

Bayer-produced imidacloprid harmful to bees even at very low levels

- Common Dreams staff

A new study published in Naturwissenschaften - The Science of Nature by a leading bee expert provides damning evidence that a widely used pesticide, even at low levels, is harmful to bees.

The pesticide that the study (pdf) looked at was imidacloprid, one of the most widely used pesticides worldwide. It is neonicotinoid insecticide produced by Bayer CropScience.

via www.commondreams.org

New Deep-Sea Hydrothermal Vent Communities Found in the Southern Ocean - PLoS Biology

Interesting (open access) study of organisms found in hydrothermal vent areas of the Southern Ocean...important discovery relative to biodiversity of species in this underexplored region of Earth's oceans.

Authors Summary:

Deep-sea hydrothermal vents are mainly associated with seafloor spreading at mid-ocean ridges and in basins near volcanic island arcs. They host animals found nowhere else that derive their energy not from the sun but from bacterial oxidation of chemicals in the vent fluids, particularly hydrogen sulphide. Hydrothermal vents and their communities of organisms have become important models for understanding the origins and limits of life as well as evolution of island-like communities in the deep ocean. We describe the fauna associated with high-temperature hydrothermal vents on the East Scotia Ridge, Southern Ocean, to our knowledge the first to be discovered in Antarctic waters. These communities are dominated by a new species of yeti crab, stalked barnacles, limpets and snails, sea anemones, and a predatory seven-armed starfish. Animals commonly found in hydrothermal vents of the Pacific, Atlantic, and Indian Oceans, including giant Riftia tubeworms, annelid worms, vent mussels, vent crabs, and vent shrimps, were not present at the Southern Ocean vents. These discoveries suggest that the environmental conditions of the Southern Ocean may act as a barrier to some vent animals and that the East Scotia Ridge communities form a new biogeographic province with a unique species composition and structure.

via www.plosbiology.org

Dr. Douglas Fields: Science cuts through the hysteria for answers to worldwide increase in fatal shark attacks

A great article today by neurobiologist Douglas Fields (at Huffington Post) explores growing numbers of shark attacks in the world's waters...I enjoyed his analysis, which includes interesting pieces of shark's natural history:

Is there a scientific explanation for these alarming data and the spike in recent fatal shark attacks?

Yes, both experts agree. The steady increase in shark attacks is easily explained by the increase in human population and growing popularity of water related sports and recreational activities. "The increase in shark attacks is largely a function of human demographics and growth. The number we get in any given year is purely a function of how many people went into the water," says Burgess.

There are, however, some new patterns emerging from Burgess' data on shark attacks. "There has been an increase this year [in shark attacks] in a number of areas where we have not traditionally had such attacks, undoubtedly by white sharks, most notably the three series of attacks in Russia in areas of cold water most of the time," he says. This, he explains is due to warming of waters, possibly associated with global warming, that are allowing sharks to expand their range farther north and south into waters that they normally do not go, and also because warmer water induces more people entering the sea.

via www.huffingtonpost.com

At the end of the article, George Burgess, shark researcher and curator of the International Shark Attack File at the Florida Museum of Natural History has some good advice for us terrestrial humans:

"When we enter the sea, we need to understand that we are visiting a foreign environment," Burgess observes. "We are terrestrial animals. Our evolution occurred on land. We don't have gills. We can't swim very well, and as such every time we enter the sea it is a wilderness experience for us...."

 

Is Blinky a Nuke Mutant?

See the story with this photo at gizmodo.com

One of the articles making rounds in the No Nukes community today is this story about a wolf fish with three eyes caught near a nuclear power plant in the Cordoba province of Argentina.

The nuclear power station (Central Nuclear Embalse) on the southern shore of Embalse Rio Tercero near Embalse, Cordoba, Argentina [Source: Google Earth, image date 3/13/11, eye altitude 9,461 feet]

Central Nuclear Embalse is one of two nuclear power stations in operation in Argentina. Embalse is a Pressurized Heavy Water Reactor fueled by natural uranium and using heavy water for cooling. Embalse also produces cobalt-60, a radioisotope used in medicine and industry.

Embalse made news in August of 2011 when contracts were signed between the Argentine government, state-run utility Nucleoelectrica Argentina and Candu Energy to overhaul and expand the plant.

And the fish? Hoplias marabaricus -- the wolf fish -- ranges from Central America down through Argentina and usually lives near the edges of black and white water streams or pools, or on flooded forest floors. Young wolf fish sometimes become stranded in these flood pools and have to wait for the next floods to move back into stream channels.

In Brazil, researchers have studied this species as a potential stock fish for artisanal fishermen who have been dislocated from traditional river fishing areas by construction of dams for hydroelectric power generation. The wolf fish is also a species known to aquarists and sport fishermen.

Wolf Fish (Hoplias malabaricus) [Photo credit: Cláudio D. Timm]

Impacts to fish and wildlife living near nuclear plants or exposed to radionuclides is not a new area of concern. The Fukushima disaster last spring inspired a new round of articles on exposure of marine life, and consequences of  legacy nuclear waste disposal on salmon near the Hanford facility in Washington have been studied. The damage to wildlife from water intake systems at nuclear plants led the Environmental Protection Agency to propose new rules this year to reduce the number of fish killed by these cooling systems.

Finding scientific information on "fish mutations near nuclear plants" was a bad search parameter on Google today, unless you wanted to read more about Blinky and the 3-eyed fish of of Embalse.

I found the original article about this catch to be interesting, in case you want to read about it in Spanish: El pez de tres ojos de los Simpson era argentino.

Amazing things you can find in the goldenrod

Goldenrod seems to be peaking here in the holler. I spent some time poking around in it yesterday when I went down the lane with my dogs and cats. Here's what I found (besides the goldenrod):

Goldenrod soldier beetle (Chauliognathus pensylvanicus), 9/13/11 [Photo credit:Cathie Bird]

Red wasp (Polistes carolina), 13 September 2011 [Photo credit: Cathie Bird]

Locust borer (Megacyllene robiniae), 13 September 2011 [Photo credit: Cathie Bird]