Ecology & Zoology

North American marine turtles are at risk if global warming occurs at predicted levels, according to scientists from the University of Exeter. An increase in temperatures of just one degree Celsius could completely eliminate the birth of male turtles from some beaches. A rise of three degrees Celsius would lead to extreme levels of infant mortality and declines in nesting beaches across the USA.


Marine turtle. Credit: Copyright Lucy Hawkes, MTRG

At least to female swordfish.

Scientists from the Universities of Exeter and Glasgow today reveal how some females become sexually mature more quickly if they see attractive males.

The researchers studied a captive population of green swordtail fish, a species native to Central America and popular in tropical aquariums. The green swordtail is named after the striking sword-like growth, which males develop on their tail-fin, so they appear larger and more attractive to females.


Male green swordtail fish. Credit: Copyright Craig Walling, University of Exeter

At a 9 am press conference at the American Association for the Advancement of Science Annual Meeting (AAAS) on February 18th, an international team of leading fisheries economists, biologists, and ecologists will call for the abolition of government fuel subsidies that keep deep-sea fishing vessels moving to deeper waters.

"Industrial fisheries are now going thousands of miles, thousands of feet deep and catching things that live hundreds of years in the process - in the least protected place on Earth," says Elliott Norse of the Marine Conservation Biology Institute.

In international waters beyond the 200 nautical mile Exclusive Economic Zones (EEZs) of coastal countries, many of the fisheries are virtually unregulated.

Industrial agriculture faces painful challenges: the end of cheap energy, depleted water resources, impaired ecosystem services, and unstable climates. Scientists searching for alternatives to the highly specialized, energy intensive industrial system might profitably look to the biological synergies inherent in multi-species systems, according to an article in the March-April 2007 issue of Agronomy Journal. The paper's author, Fred Kirschenmann, Distinguished Fellow for Leopold Center for Sustainable Agriculture, Iowa State University, states that industrial agriculture assumes:

 

Plants have an immune system that resists infection, yet 10% of the world's agricultural production is lost annually to diseases caused by bacteria, fungi, and viruses. Understanding how disease resistance works may help combat this scourge.

In a new study published online this week in the open-access journal PLoS Biology, Tessa Burch-Smith, Savithramma Dinesh-Kumar, and colleagues show how one aspect of the plant immune system is defined by the gene-for-gene hypothesis: a plant Resistance (R) gene encodes a protein that specifically recognizes and protects against one pathogen or strain of a pathogen carrying a corresponding Avirulence (Avr) gene.

In tobacco and its relatives, the N resistance protein confers resistance to infection by the Tobacco mosaic virus (TMV).

The simultaneous effect of habitat fragmentation, overexploitation, and climate warming could accelerate the decline of populations and substantially increase their risk of extinction, a study published in the Proceedings of the Royal Society B has warned.


The viability of many marine and terrestrial species could be impaired due to interacting human activities that cause the loss of species' habitats, overexploitation of their populations and warming of their environments. Credit: Top left: John Veron from Corals of the World. Top right: Wolcott Henry/Marine Photobank, Bottom left: Steve Spring/Marine Photobank, Bottom right: NASA-GSFC/Marine Photobank

Sometimes it is better to follow the advice of others rather than your own mind even though you seem to have things under control. Not only humans but also fish follow this doctrine as shown by ecologists Jörgen Johnsson and Fredrik Sundström of Göteborg University, Sweden, in the journal Ethology.

They allowed European minnows to learn the correct route through a maze to obtain food in the presence or absence of a predatory brown trout. Then a naïve minnow joined the group on later trials either in the presence or absence of the trout.

A male fish can size up potential rivals, and even rank them from strongest to weakest, simply by watching how they perform in territorial fights with other males, according to a new study by Stanford University scientists. The researchers say their discovery provides the first direct evidence that fish, like people, can use logical reasoning to figure out their place in the pecking order.

The study, published in the Jan. 25 edition of the journal Nature, is based on a unique experiment with cichlids (SIK-lids), small territorial fish from Africa. "In their natural habitat, male cichlids are constantly trying to ascend socially by beating each other up," said study co-author Russell D. Fernald, professor of biological sciences at Stanford.

Despite the icy cold and darkness, beneath the frozen surface of the sea in Antarctica thrives a rich and complex array of plants and animals. But what will happen to all those creatures if global warming reduces the ice-cover, as is predicted for coming decades?

UNSW marine ecologists Dr Emma Johnston and Graeme Clark have been working with the Australian Antarctic Division to survey marine communities along the striking coast of Wilkes Land, east Antarctica.


The stark beauty of Antarctica's ice hides a wealth of marine life. Copyright Graeme Clark UNSW.