Conflict,controversy, and compromise: The Concho water snake (Nerodia harteri paucimaculata) versus the Stacy Dam and Reservoir

The Colorado River Municipal Water District (CRMWD) of Big Spring, Texas, planned to construct the Stacy Reservoir and Dam on the Colorado River near Paint Rock, Texas, yet needed a Section 404 permit from the US Army Corps of Engineers pursuant to the Clean Water Act. In 1986 the Concho water snake (Nerodia harteri paucimaculata) was listed as threatened under the Endangered Species Act (ESA). Much of its remaining range included the stretch of the Colorado River that would be flooded by the proposed dam. After initially rejecting CRMWD proposals for mitigation, and informing the Corps of Engineers that it would issue a jeopardy opinion regarding the 404 permit pursuant to Section 7 of the ESA, the US Fish and Wildlife Service reversed its stand. The final biological opinion stated that reasonable and prudent alternatives previously rejected as unfeasible would remove the threat of jeopardy. This paper concludes that experimental management techniques proposed by FWS to allow dam construction do not adequately ensure survival of the Concho water snake and an alternative water source should have been found.     

Implications of dispersal and life history strategies for the persistence of Linyphiid spider populations

Linyphiid spiders have evolved the ability to disperse long distances by a process known as ballooning. It has been hypothesized that ballooning may allow populations to persist in the highly disturbed agricultural areas that the spiders prefer. In this study, I develop a stochastic population model to explore how the propensity for this type of long distance dispersal influences long term population persistence in a heterogeneous landscape where catastrophic mortality events are common. Analysis of this model indicates that although some dispersal does indeed decrease the probability of extinction of the population, the frequency of dispersal is only important in certain extremes. Instead, both the mean population birth and death rates, and the landscape composition, are much more important in determining the probability of extinction than the dispersal process. Thus, in order to develop effective conservation strategies for these spiders, better understanding of life history processes should be prioritized over an understanding of dispersal strategies.     

A preliminary report on effect of pulsed magnetic fields on fresh water fish (Labeo rohita) chromosomes

Marine-life scientists around the world are already carrying out investigative trials to obtain higher yields under in-captive breeding conditions, on both edible varieties and ornamental fishes with optimal inputs. However, for such trials to succeed there is a need for genetic improvement. The idea that fish production can be enhanced by genetic manipulation is gaining acceptance, as there is a strong possibility that qualitative improvement of economically important traits can be achieved by identifying and utilizing more effective genotypes. In the present communication a tentative plan for genetic manipulation of fresh water fish using controlled, pulsed magnetic fields, is being discussed. Chromosome preparations of Labeo rohita were made using Colchicine-Methanol-Acetic acid air drying technique, using tissue from gills. The fish were exposed to Pulsed Magnetic Field (PMF)with intensity 0.2 Gauss, pulsing at 50 Hz frequency (sine wave) for 6 hours / day for a total period of 30 days inside specially designed magnetic field enclosures. The karyological investigations revealed no distinct difference between "test" and "control" groups.     

Effects of predators on sea urchin density and habitat use in a southern California kelp forest

Grazing sea urchins can reduce kelp abundance and therefore strongly affect kelp forest community structure. Despite the ecological importance of sea urchins, direct field studies on the role that urchin predators play in shaping urchin populations are rare for southern California. We conducted surveys and manipulative experiments within kelp forests near San Diego, CA, (32–51′28″N, 117–16′00″W) from 2006 to 2009 to determine whether predators such as sheephead (Semicossyphus pulcher) and spiny lobsters (Panulirus interruptus) may be linked to purple urchin (Strongylocentrotus purpuratus) and red urchin (Strongylocentrotus franciscanus) distribution and habitat use, as well as purple urchin density-dependent mortality. Purple urchins were less dense and more cryptic inside a local marine protected area (MPA) that contained high predator abundance than in nearby heavily fished areas, whereas red urchins rarely were found outside the MPA. Urchin proportional mortality was inversely density dependent during the day when sheephead were active, despite fish aggregations in plots of high urchin density, but was density independent during the night when lobsters were active. Urchin mortality was reduced under understory algal cover during the day, but not during the night. Examining whether urchin mortality from predation is density dependent and how habitat complexity influences this relationship is imperative because behavioral changes and increases in urchin populations can have vast ecological and economic consequences in kelp forest communities.     

The uses and implications of avian vocalizations for conservation planning

There is a growing recognition that animal behavior can affect wildlife conservation, but there have been few direct studies of animal behavior in conservation programs. However, a great deal of existing behavioral research can be applied in the context of conservation. Research on avian vocalizations provides an excellent example. The conspicuous nature of the vocal behavior of birds makes it a useful tool for monitoring populations and measuring biodiversity, but the importance of vocalizations in conservation goes beyond monitoring. Geographic song variants with population-specific signatures, or dialects, can affect territory formation and mate choice. Dialects are influenced by cultural evolution and natural selection and changes can accumulate even during the timescale of conservation interventions, such as translocations, reintroductions, and ex situ breeding. Information from existing research into avian vocalizations can be used to improve conservation planning and increase the success of interventions. Vocalizations can confer a number of benefits for conservation practitioners through monitoring, providing baseline data on populations and individuals. However, the influence of cultural variation on territory formation, mate choice, and gene flow should be taken into account because cultural differences could create obstacles for conservation programs that bring birds from multiple populations together and so reduce the success of interventions.