Not One, But Two Kinds Of Males Found In Invasive Round Goby Fish

SOURCE

ScienceDaily (June 18, 2009) — Scientists have found the existence of two types of males of a fiercely invasive fish spreading through the Great Lakes, which may provide answers as to how they rapidly reproduce.

The research, published in the Journal of Great Lakes Research, looks at the aggressive round goby, a bottom-dwelling fish which infested the Great Lakes watersheds around 1990. Presently, they are working their way inland through rivers and canal systems and can lead to the decline of native species through competition and predation.
Researchers at McMaster University discovered evidence that in addition to round goby males which guard the nest from predators and look after their offspring, there exists what scientists call "sneaker" males – little males that look like females and sneak into the nests of the larger males.
"The existence of these two kinds of males will help scientists understand how round gobies reproduce, how quickly their populations grow, and track how these populations change over the course of invasion," says Julie Marentette, lead author and a Ph.D. student in the department of Psychology, Neuroscience & Behaviour at McMaster University. "This has the potential to have a significant impact on how researchers tackle what has become a very difficult problem in the Great Lakes."
Because males expend lots of energy or eat less while guarding their nests, and attracting females while providing care can be difficult, males in some species have found a sneakier way to mate, Marentette explains. Instead of courting females and protecting the young, some males will parasitize the courtship –and sometimes the parenting duties –of conventional males. They do this by sneaking into the nests of big males or pretending to be females.
"Prior to our findings, only one type of male reproductive behaviour would have been incorporated into projections and modeling analyses of the population dynamics of round goby invasive capacities", says Sigal Balshine, associate professor in the department of Psychology, Neuroscience & Behaviour and academic advisor on the study. "Our results will shed light on how populations of this invasive species are likely to grow and spread through time and space."
The McMaster scientists compared the physical, hormonal and sperm traits of hundreds of males, and found that the nest-guarding, parental males were big, black and had wide heads. The small female-like sneaker males were tiny, mottled brown and had narrow heads. Both types of males produced sperm, but sneakers produced more sperm than the parental males, and had bigger testes. By contrast, parental males have bigger glands used to produce pheromones that attract females.
Funding for the research was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Fund for Innovation, the Ministry of Research and Innovation and the Department of Fisheries and Oceans (DFO).
Adapted from materials provided by McMaster University.

Polar Bear And Walrus Populations In Trouble, Stock Assessment Report Suggests

SOURCE

ScienceDaily (June 19, 2009) — The U.S. Fish and Wildlife Service has released reports documenting the status of polar bears and Pacific walrus in Alaska. The reports confirm that polar bears in Alaska are declining and that Pacific walrus are under threat. Both species are imperiled due to the loss of their sea-ice habitat due to global warming, oil and gas development, and unsustainable harvest.

“Polar bears and walrus are under severe threat, and unless we act rapidly to reduce greenhouse pollution and protect their habitat from oil development, we stand to lose both of these icons of the Arctic,” said Brendan Cumming, oceans program director at the Center for Biological Diversity.
The reports, issued pursuant to the Marine Mammal Protection Act, summarize information on population abundance and trends of polar bears and walrus, threats to the species, and include calculations of human-caused mortality and whether that mortality is sustainable.
There are two polar bear populations in Alaska: a Southern Beaufort Sea stock, which is shared with Canada, and a Chukchi/Bering Sea stock which is shared with Russia. The Pacific walrus occurs in the Bering and Chukchi seas and is shared with Russia.
For the Southern Beaufort Sea polar bear stock, the Fish and Wildlife Service estimated a minimum population of 1,397 bears and an annual human-caused mortality of 54 animals, well above the calculated sustainable rate of 22 animals per year. The stock assessment states that “the Southern Beaufort Sea population is now declining.”
For the Chukchi/Bering Sea polar bear stock, the Service estimated a minimum population of 2,000 bears and an annual human-caused mortality of 37 animals from Alaska and between 150-250 bears killed per year in Russia. The calculated sustainable rate of harvest is 30 animals per year. The stock assessment states that “the population is believed to be declining” and is “reduced based on harvest levels that were demonstrated to be unsustainable.”
For the Pacific walrus, the Service estimated a minimum population of 15,164 animals and an annual human-caused mortality of between 4,963 and 5,460 animals. The calculated sustainable rate of harvest is 607 animals per year.
Of the three population estimates, only the estimate for the well-studied Beaufort Sea polar bears is considered reliable. The Chukchi/Bering Sea polar bear population is based on incomplete data and could be an overestimate, while the walrus estimate is an underestimate as it only represents surveys in about half of the walrus habitat and does not account for walrus not counted because they were in the water rather than hauled out on ice.
“These reports publicly confirm what scientists have known for several years: Polar bear and walrus populations in Alaska are in trouble,” added Cummings. “And even if the population numbers are not precise, we know that without their sea-ice habitat they are likely doomed.”
The Marine Mammal Protection Act requires that the secretary of the interior and the secretary of commerce prepare stock assessments for marine mammals. The assessments are meant to be used as the basis for management decisions such as permitting the killing or harassment of the animals from commercial fisheries, oil and gas exploration, boating and shipping, and military exercises.
To ensure that decision-makers have the most accurate information, stock assessments are supposed to be revised every year for endangered marine mammals and every three years for other species. While the National Marine Fisheries Service – the agency responsible for whales, dolphins, and seals – has largely complied with this requirement, the Fish and Wildlife Service, responsible for polar bears, walrus, sea otters, and manatees, had completely ignored it.
In 2007 the Center sued the Wildlife Service and obtained a court order requiring the release of updated reports. Stock assessments for the Florida manatee were released last week, while sea otter reports were issued last year.
The polar bear is currently listed as threatened under the Endangered Species Act as a result of a petition and litigation by the Center for Biological Diversity. The Fish and Wildlife Service is under court order to make a finding on the Center’s petition to protect the Pacific walrus under the Endangered Species Act by September 10, 2009.
A copy of the stock assessments released June 18 can be found at http://alaska.fws.gov/fisheries/mmm/reports.htm
Adapted from materials provided by Center for Biological Diversity.

Basking Sharks: Disappearing Act Of World's Second Largest Fish Explained

SOURCE

ScienceDaily (May 14, 2009) — Researchers have discovered where basking sharks – the world's second largest fish – hide out for half of every year, according to a report published online on May 7th in Current Biology. The discovery revises scientists' understanding of the iconic species and highlights just how little we still know about even the largest of marine animals, the researchers said.

"While commonly sighted in surface waters during summer and autumn months, the disappearance of basking sharks during winter has been a great source of debate ever since an article in 1954 suggested that they hibernate on the ocean floor during this time," said Gregory Skomal of Massachusetts Marine Fisheries. "Some 50 years later, we have helped to solve the mystery while completely re-defining the known distribution of this species."
Using new satellite-based tagging technology and a novel geolocation technique, the researchers found that basking sharks make ocean-scale migrations through tropical waters of the Atlantic Ocean during the winter, traveling at depths of 200 to 1,000 meters. Their data show that the sharks sometimes stay at those depths for weeks or even months at a time. "In doing so, they have completely avoided detection by humans for millennia," Skomal said, emphasizing that as one of the very largest of marine animals, the sharks grow to over 10 meters and weigh as much as seven metric tons.
Skomal said they were "absolutely surprised" when they first received a signal from the tagged sharks coming from the tropical waters of the western Atlantic, in the vicinity of the Caribbean and Bahamas. After all, basking sharks were always believed to be cool-water sharks, restricted to temperate regions.
Several factors had made basking sharks a challenge to study. On top of the fact that they disappear for long periods of time, they also feed exclusively on plankton. That means they can't readily be captured with traditional rod-and-reel methods. And even when the sharks are found closer to the ocean surface, they spend their time in the cool-temperature, plankton-rich waters that limit underwater visibility and make diving difficult.
The findings could have important implications for the conservation of basking sharks, which have shown some signs of dramatic decline in the last half century and are listed as threatened by the International Union for Conservation of Nature.
"Coupled with recent genetic data, our finding indicates that the Atlantic population – and perhaps the world population – are connected and may constitute a single population," Skomal said. "Hence, the global population of basking sharks may be even smaller than previously thought." Efforts to boost basking sharks' numbers will therefore need to be coordinated at a global scale.
The authors include Gregory B. Skomal, Massachusetts Division of Marine Fisheries, Oak Bluffs, MA; Stephen I. Zeeman, University of New England, Biddeford, ME; John H. Chisholm, Massachusetts Division of Marine Fisheries, New Bedford, MA; Erin L. Summers, Maine Department of Marine Resources, Boothbay Harbor, ME; Harvey J. Walsh, Woods Hole Oceanographic Institution, Woods Hole, MA; Kelton W. McMahon, Woods Hole Oceanographic Institution, Woods Hole, MA; and Simon R. Thorrold, Woods Hole Oceanographic Institution, Woods Hole, MA.
Journal reference:
Gregory B. Skomal, Stephen I. Zeeman, John H. Chisholm, Erin L. Summers, Harvey J. Walsh, Kelton W. McMahon, and Simon R. Thorrold. Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean. Current Biology, 2009; DOI: 10.1016/j.cub.2009.04.019
Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Biologists Close In On Mystery Of Sea Turtles' 'Lost Years'

Source:

http://www.sciencedaily.com/releases/2007/09/070928203128.htm

Science Daily — Biologists have found a major clue in a 50-year-old mystery about what happens to green sea turtles after they crawl out of their sandy nests and vanish into the surf, only to reappear several years later relatively close to shore.

In a paper set to appear Wednesday in the online edition of the journal Biology Letters, three University of Florida sea turtle scientists say they found the clue by analyzing chemical elements ingrained in the turtles’ shells.
Their conclusion: The turtles spend their first three to five “lost years” in the open ocean, feeding on jellyfish and other creatures as carnivores. Only after this period do they move closer to shore and switch to a vegetarian diet of sea grass – the period in their lives when they have long been observed and studied.
“This has been a really intriguing and embarrassing problem for sea turtle biologists, because so many green turtle hatchlings enter the ocean, and we haven’t known where they go,” said Karen Bjorndal, a professor of zoology and director of UF’s Archie Carr Center for Sea Turtle Research. “Now, while I can’t go to a map and point at the spot, at least we know their habitats and diets, and that will guide us where to look.”
The discovery is important not only because it’s a first, but also because it may aid in conservation of the turtles -- which, like all sea turtles, are classified as endangered. “You can’t protect something,” said Bjorndal, “if you don’t know where it is.”
The paper’s lead author is Kimberly Reich, a UF doctoral student in zoology who did the work as part of her dissertation research. The other authors are Bjorndal and Alan Bolten, a faculty member in zoology and associate director of the sea turtle center.
Famed sea turtle biologist Archie Carr first discussed the mystery of the green sea turtles’ “lost years” in his 1952 book, “The Handbook of Turtles.” Half-dollar sized hatchlings trundle off subtropical and tropical beaches worldwide, then vanish, only to reappear, dinner-plate-sized, over continental shelves in depths of less than 650 feet. Only a tiny number of green turtles between the half-dollar and plate-sizes have ever been spotted.
To solve the problem, Reich, Bjorndal and Bolten turned not to scouring the ocean but rather to a technique that over the past two decades has become increasingly important in questions related to ecological origin: stable isotope analysis.
The higher an animal on the food chain, the more heavy isotopes it accumulates. As a result, the technique, which measures the ratios of heavy to light isotopes, can distinguish samples from herbivorous versus carnivorous creatures and where on the food chain they lie.
The researchers captured 44 turtles off a long-term study site near Great Inagua in the Bahamas. The sample included 28 that had been tagged in previous years, indicating they were residents of the site, and 16 untagged turtles assumed to have recently arrived.
They cut off tiny pieces near the center of the turtles’ shells in a harmless process that Bjorndal likened to trimming one’s fingernails. The biologists used a mass spectrometer, a machine that separates isotopes according to charge and mass, to analyze the oldest, or earliest-grown, portions of the shell sample versus the newest portions.
The analysis revealed that with the new arrivals to the site, the ratio of light to heavy nitrogen isotopes in the older versus new shell samples was “significantly different,” as the paper said. The ratios were very similar to ratios observed in oceanic-stage loggerhead turtles known to be carnivorous. For these reasons, among others, the researchers concluded the turtles spend their first three to five years in the open ocean.
Green turtles nest on subtropical and tropical beaches worldwide. That suggests the young turtles are widely distributed in the oceans during their oceanic stage, but Bjorndal said further study is required to confirm that.
Green turtles are the ocean’s largest hard-shelled turtle, with only soft-shelled leatherbacks eclipsing their size. They were heavily exploited for food by native peoples and then by explorers and colonists who prized the animals for remaining alive and fresh for months on ships. Although they were among the first animals listed under the Endangered Species Act in 1973, they and their eggs continue to be hunted in much of their range today.
Said Bjorndal, “Anything that helps us discover geographically where they are is going to stand us in good stead to be able to protect them.”
Note: This story has been adapted from material provided by University of Florida.

Fausto Intilla

www.oloscience.com

Corals Added To IUCN Red List Of Threatened Species For First Time

Source:

http://www.sciencedaily.com/releases/2007/09/070912094029.htm

Science Daily — For the first time in history, the IUCN Red List of Threatened Species includes ocean corals in its annual report of wildlife going extinct.

A comprehensive study of marine life sponsored by Conservation International (CI) and implemented jointly with the IUCN (World Conservation Union) used data from the Galapagos-based Charles Darwin Research Station and other regional institutions to conclude that three species of corals unique to the Galapagos Islands could soon disappear forever.
The 2007 IUCN Red List designates two of the corals -- Floreana coral (Tubastraea floreana) and Wellington's solitary coral (Rhizopsammia wellingtoni) -- as Critically Endangered, while a third -- Polycyathus isabela -- is listed as Vulnerable. The Red List also includes 74 Galapagos seaweeds, or macro-algae, with 10 of them receiving the most threatened status of Critically Endangered. Prior to 2007, only one algae species had been included on the Red List.
"There is a common misconception that marine species are not as vulnerable to extinction as land-based species," said Roger McManus, CI's vice president for marine programs. "However, we increasingly realize that marine biodiversity is also faced with serious environmental threat, and that there is an urgent need to determine the worldwide extent of these pressures to guide marine conservation practice."
The Galapagos marine research was conducted by the Global Marine Species Assessment (GMSA), a joint initiative of IUCN and CI launched in 2005 with the support of dozens of experts and research institutions. The GMSA is studying a large portion of Earth's marine species to determine the threat of extinction.
"These Galapagos corals and algae are the first of many marine species that will be added to the Red List due to our findings," said GMSA Director Kent Carpenter of Old Dominion University in Virginia. "What is significant is that climate change and over-fishing -- two of the biggest threats to marine life -- are the likely causes in these cases."
Scientists blame climate change for more frequent and increasingly severe El Niño events that have caused dramatic rises in water temperatures and reduced nutrient availability around the Galapagos Islands in the Eastern Tropical Pacific Ocean, off South America. The warmer water harms corals and algae, both of which constitute the structural foundation of unique and diverse marine ecosystems.
Corals build reefs that are habitat for fish and other marine life, and also are a major attraction for divers in the Galapagos, where tourism makes a significant contribution to the local and national economy.
The recovery of algae species following strong El Niño events is harmed by over-fishing of the natural predators of sea urchins, which feed on the algae. Mushrooming urchin populations scour rocks clean of algae, depleting a major food source for other species such as the Galapagos marine iguana.
"Marine ecosystems are vulnerable to threats at all scales -- globally through climate change, regionally from El Niño events, and locally when over-fishing removes key ecosystem building blocks," said Jane Smart, head of the IUCN Species Program. "We need more effective solutions to manage marine resources in a more sustainable way in light of these increasing threats."
Other coral and algae species lacked sufficient information to determine their IUCN Red List status, so they received the designation of Data Deficient. Researchers believe many of these species are likely to be listed as threatened with extinction when more detailed information becomes available.
The GMSA is the first strategic global review of the conservation status of marine species, including every marine vertebrate species and selected invertebrates and plants. Funded predominantly by CI, the five-year GMSA initiative is engaging experts from around the world to compile and analyze all existing information on the status of approximately 20,000 marine species to determine their risk of extinction according to the IUCN Red List Categories and Criteria. The resulting analysis will identify marine "hotspots" of high conservation priority in order to focus protection efforts on their habitats and species.
Note: This story has been adapted from a news release issued by Conservation International.

Fausto Intilla

www.oloscience.com

PCBs May Threaten Killer Whale Populations For 30-60 Years

Source:

http://www.sciencedaily.com/releases/2007/09/070910094122.htm

Science Daily — Orcas or killer whales may continue to suffer the effects of contamination with polychlorinated biphenyls (PCBs) for the next 30 -- 60 years, despite 1970s-era regulations that have reduced overall PCB concentrations in the environment, researchers in Canada report. The study calls for better standards to protect these rare marine mammals.

In the study, Brendan Hickie and Peter S. Ross and colleagues point out that orcas face a daunting array of threats to survival, including ship traffic, reduced abundance of prey and environmental contamination. Orcas, which reach a length exceeding 25 feet and weights of 4-5 tons, already are the most PCB-contaminated creatures on Earth. Scientists are trying to determine how current declines in PCBs in the environment may affect orcas throughout an exceptionally long life expectancy, which ranges up to 90 years for females and 50 years for males.
The new study used mathematical models and measurements of PCBs in salmon (orcas' favorite food) and ocean floor cores to recreate a PCB exposure history to estimate PCB concentrations in killer whales over time. It concluded that the "threatened" northern population of 230 animals will likely face health risks until at least 2030, while the endangered southern population of 85 orcas may face such risks until at least 2063. PCBs make whales more vulnerable to infectious disease, impair reproduction, and impede normal growth and development, the researchers say.
"The findings provide conservationists, regulators, and managers with benchmarks against which the effectiveness of mitigative steps can be measured and tissue residue guidelines can be evaluated," the study reported. "The results of our study on PCBs may paint an ominous picture for risks associated with emerging chemicals, as the concentrations of structurally-related PBDEs are doubling every 4 years in marine mammals," researchers added.
"Killer Whales (Orcinus orca) Face Protracted Health Risks Associated with Lifetime Exposure to PCBs" Environmental Science & Technology, September 15, 2007
Note: This story has been adapted from a news release issued by American Chemical Society.

Fausto Intilla

www.oloscience.com

Humpback Whales Recorded Clicking And Buzzing While Feeding For First Time

Source:

http://www.sciencedaily.com/releases/2007/09/070901084549.htm

Science Daily — For the first time, researchers have recorded “megapclicks” — a series of clicks and buzzes from humpback whales apparently associated with nighttime feeding behaviors — in and around NOAA’s Stellwagen Bank National Marine Sanctuary.

As detailed in the most recent issue of the Royal Society journal Biology Letters, this study offers the first documentation that baleen whales produce this type of sound, normally associated with toothed whales and echolocation.
“We’ve known that humpback whales exhibit a variety of foraging behaviors and vocalizations, but these animals as well as other baleen whales were not known to produce broadband clicks in association with feeding,” said David Wiley, sanctuary research coordinator and leader of the research team. “However, recent work with special acoustic tags has made us reexamine our previous assumptions, with this expansion of the acoustic repertoire of humpback whales.”
The research team from the Hawaii Institute of Marine Biology, Woods Hole Oceanographic Institution, University of New Hampshire, and NOAA’s National Marine Sanctuary Program used multi-sensor acoustic tags attached with suction cups to study whale behavior. The data provided a record of the whales’ underwater movements, including heading, pitch, roll, and sounds made and heard. During the tagging studies, broadband clicks were recorded exclusively during nighttime hours. Sharp body rolls also occurred at the end of click bouts containing buzzes, suggesting feeding episodes.
Alison Stimpert of the Hawaii Institute of Marine Biology, the lead author on the paper, labeled the sounds “megapclicks” based on their form and the scientific name for humpback whales (Megaptera novaeangliae). This acoustically active species has been known to produce complex “songs” on their breeding grounds, but knowledge of sound production on northern feeding grounds has been limited.
The researchers report that the similarity of the megapclicks to sounds made by toothed whales suggests echolocation-assisted feeding behaviors, especially where buzzes at the end of a series of clicks appear to be associated with attempts to capture prey. The sounds may also be used to detect the sea floor or other large targets. Another possibility for the megapclicks could be to attract prey, such as herding schools of fish or chasing animals out of the sediments. But the research team notes that a lack of knowledge about baleen whale hearing and sound production prevents any definitive answers at this time about the function of the megapclicks.
Additional humpback whale tagging studies completed earlier this summer in the Stellwagen Bank sanctuary may provide further insights into sound production in northern feeding grounds.
The report appeared in the Aug. 8, 2007 on-line issue of Biology Letters. Funding for the project was provided by NOAA’s National Marine Sanctuary Program and the University of Hawaii Sea Grant College Program. Research was conducted under National Marine Fisheries Service permit no. 981-1707-00.
Recordings of clicking and buzzing whales can be found here. http://stellwagen.noaa.gov/pgallery/sounds.html
Note: This story has been adapted from a news release issued by National Oceanic & Atmospheric Administration.

Fausto Intilla

www.oloscience.com