Carnivorous Swamp Beast Discovered In Madagascar 157
crudmonkey writes "Researchers have identified a previously unknown species of carnivore lurking in one of the world's most endangered lakes. Durrell's vontsira, named in honor of the late conservationist and writer Gerald Durrell, was first photographed swimming in Madagascar's Lake Alaotra in 2004. Subsequent surveys confirmed the mongoose-like creature was indeed a new species. Durrell's vontsira is the first new carnivorous mammal discovered in Madagascar in 24 years. Little is known about the species, which is roughly the size of a cat."
Which is it? Or is it both? (Score:3, Interesting)
Durrell's vontsira is the first new carnivorous mammal discovered in Madagascar in 24 years.
Elsewhere in the article, twice, is this:
The first new carnivorous mammal to be discovered for 24 years
Was the last carnivorous mammal that was discovered, discovered 24 years ago in Madagascar? I don't know about anyone else, but I would infer from the qualifier "in Madagascar" that a carnivorous mammal was discovered less than 24 years ago somewhere else in the world.
We are so quick to label it a 'beast' (Score:4, Interesting)
Re:and then... (Score:1, Interesting)
You seem to think that a lake is as simple as a impermeable bathtub or a bowl with a fixed volume of water. It isn't. Water has a constant volume, but we aren't dealing with a constant volume. It's a dynamically flowing system. And the basin in which the water sits isn't fixed either.
Infilling of lakes by sediment happens all the time, and, yes, it does result in shallowing of the lake and its eventual conversion into dry (or at least swampy) land. Lakes rarely deepen. Vegetation and sediment usually fills them up unless some process is regularly cleaning that material out (e.g., river erosion), dissolving the bedrock (e.g., in limestone areas) or the lake bottom is subsiding for some reason (e.g., tectonics or sediment compaction).
Lakes are at a given level because of an equilibrium between inflow and outflow. Inflows can be from direct precipitation, from water on the surface of the land (i.e. runoff) or can be subsurface (i.e. groundwater). Outflows can also be over the surface or into the groundwater, plus evaporation. Independent of the water inflow and outflow, the equilibrium level is often strongly determined by the terrain and the effect it has on those inflow/outflow rates. For example, if the lake level overtops a natural barrier, then the outflow increases greatly and the lake doesn't get significantly higher no matter how much extra water flows in. Think of it like a natural dam with a reservoir behind it. In this circumstance, if "extra dirt" fills to the level of the top of the dam, then guess what? No more lake. All you have is mud-filled plain and maybe a river flowing over it. Change the shape of the terrain (e.g., by dumping sediment on it) and even with the same amount of water passing through the system and no change in climate you can make a lake disappear entirely. The water flow is still there, but it may be largely in the groundwater, not forming a pool on the surface.
In areas where vegetation is stripped away another effect comes into play. Not only will you deliver more sediment into the lake due to increased erosion, but you also change the timing and rates at which water flows over the terrain and into the groundwater. Vegetation acts as a kind of buffer, so that when heavy rains fall, it tends to soak up the water like a sponge and impede its flow. This has three important effects: 1) it increases the amount of infiltration of surface water into the groundwater, 2) it slows down the surface flow and prolongs it, and 3) it decreases the peak amount of surface flow. This means that if you strip away the vegetation more of the water fill flow quickly down the slopes into the lake basin, overtop the natural barriers, and keep on going down the drainage system. Raging river floods will become more common. Whereas if the plants are there, the water will be released more slowly into the lake and there is more groundwater, replenishing the lake in between the rainstorms. This difference in flow amounts and timing can mean the difference between the lake drying out completely between rainfalls and merely being lower, even with the rainfall pattern being exactly the same as it was before.
All other things kept the same, stripping away vegetation around a lake will often have profound effects. It's one of the reasons that it is standard practice in environmentally responsible parts of the world to leave a significant buffer of forest around lakes to try to minimize the effect of human activities.