Month: February 2013

by Morgan Kelly, Office of Communications

Ecologists have evidence that some endangered primates and large cats faced with relentless human encroachment will seek sanctuary in the sultry thickets of mangrove and peat swamp forests. These harsh coastal biomes are characterized by thick vegetation — particularly clusters of salt-loving mangrove trees — and poor soil in the form of highly acidic peat, which is the waterlogged remains of partially decomposed leaves and wood. As such, swamp forests are among the few areas in many African and Asian countries that humans are relatively less interested in exploiting (though that is changing).

Yet conservationists have been slow to consider these tropical hideaways when keeping tabs on the distribution of threatened animals such as Sumatran orangutans and Javan leopards, according to a recent Princeton University study in the journal Folia Primatologica. To draw attention to peat and mangrove swamps as current — and possibly future — wildlife refuges, Katarzyna Nowak, a former postdoctoral researcher of ecology and evolutionary biology at Princeton, compiled a list of 60 primates and 20 felids (the large-cat family that includes tigers and leopards) known to divide their time between their natural forest habitats and some 47 swamp forests in Africa and Asia.

Because swamp forests often lack food sources, fresh water and easy mobility, few mammals are exclusive to these areas, Nowak reported. Consequently, conservation groups have not intensely monitored the animals’ swamp use.

But the presence of endangered cats and primates in swamp forests might be seriously overlooked, Nowak found. About 55 percent of Old World monkeys — primates such as baboons and macaques that are native to Africa and Asia — take to the swamps either regularly, seasonally or as needed. In 2008, the Wildlife Conservation Society reported that the inaccessible Lake Télé swamp forest in the Republic of the Congo was home to 125,000 lowland gorillas — more than were thought to exist in the wild. Among big cats, the Bengal tiger, for instance, holds its sole ground in Bangladesh in the Sundarbans, the world’s largest mangrove forest.

Life in the swamps can still be harsh for some animals. Species such as the crab-eating macaque and fishing cat can adapt somewhat readily to a life of swimming and foraging for crustaceans. Meanwhile, Zanzibar’s red colobus monkey — driven to coastal mangroves by deforestation — can struggle to find the freshwater it needs, as Nowak reported in the American Journal of Primatology in 2008. Such a trend could result in local extinction of the red colobus nonetheless, she said.

Nowak concludes that swamp forests beg further exploration as places where endangered species such as lowland gorillas and flat-headed cats have preserved their numbers — and where humans could potentially preserve them into the future.

Read the abstract.

Citation: Nowak, Katarzyna. 2013. Mangrove and Peat Swamp Forests: Refuge Habitats for Primates and Felids. Folia Primatologica. Vol. 83, no. 3-6, pp. 361-76.

By John Greenwald, Princeton Plasma Physics Laboratory

Corkscrew-shaped instabilities called “snakes” have long been a common feature of the hot, electrically charged plasma gas that fuels fusion reactions, which could provide a future source of clean and abundant energy for generating electricity. Such snakes trap impurities released from the plasma-facing walls of experimental fusion vessels called tokamaks, and these impurities radiate away copious amounts of energy, cooling the plasma to temperatures below those required to create fusion reactions. Understanding the formation and survival of snakes can thus be essential to eliminating the problem so that fusion can take place.

New experimental data reported today in Physical Review Letters sheds light on how snakes form and survive in fusion plasmas. The paper, whose lead author is Luis Delgado-Aparicio of the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL), cites recent experiments on the Alcator C-Mod tokamak at the Massachusetts Institute of Technology Plasma Science and Fusion Center (MIT-PSFC). The findings compiled by a multidisciplinary team show that the formation of snakes cannot be explained, as previously thought, by plasma pressure alone. Instead, the formation reflects complex interactions among phenomena that include the separately evolving plasma density and temperature conditions that produce the plasma pressure. This separate evolution of density and temperature also enables the snakes to survive periodic relaxations of plasma pressure known as sawtooth instabilities.

Read the abstract.

Citation:
Delgado-Aparicio, Luis; Linda Sugiyama, MIT; Robert Granetz, MIT; David Gates, PPPL; John Rice, MIT; Matthew Reinke, MIT; Manfred Bitter, PPPL; Eric Fredrickson, PPPL; Chi Gao, MIT; Martin Greenwald, MIT; Kenneth Hill, PPPL; Amanda Hubbard, MIT; Jerry Hughes, MIT; Earl Marmar, MIT; Novimir Pablant, PPPL; Yuri Podpaly, MIT; Steven Scott, PPPL; Randy Wilson, PPPL; Steve Wolfe, MIT; and Steve Wukitch, MIT. 2013. Formation and stability of impurity “snakes” in tokamak plasmas. Physical Review Letters 110, 065006.

This work was performed under U.S. DOE contracts including DE-FC02-99ER54512 and others at MIT and DE-AC02-09CH11466 at PPPL. Computational support was provided by the National Energy Research Scientific Computing Center under DE-AC02-05CH11231.