Monday, February 6, 2012

Lake Levels Return to Normal...Giant Salvinia Lies in Wait

The drought and its impacts on Caddo Lake are still fresh on the minds of those who have ties to the lake. Recent rains have brought the lake back up to about normal but they have also set the stage for an active giant salvinia growing season. 

Going into the winter, the hope was that extremely low water levels combined with a cold winter like we have had the past two years would kill off much of the remaining giant salvinia. Our luck with favorable weather for killing giant salvinia has yet to materialize. No one is complaining at all about the rain, but the warm temperatures have allowed giant salvinia to not only survive the winter, but to begin growing already. 

The rain has been much appreciated and it is good to see the lake back to normal at the moment. The inflows to the lake have dispersed giant salvinia far and wide across the lake though. A boat ride on the upper Texas portion of the lake this past Saturday confirmed just this. As you can see in the photo below, there is plenty of giant salvinia hanging around out there already. One of the other things observed on the lake were small pieces of salvinia floating around all over the lake...on the boat roads, off the beaten path, in the marinas...basically everywhere.

Much of the giant salvinia is also actively growing. The picture below illustrates just this. The upper part of the plant appears to be burned from light freeze damage while the lower part of the plant is actively growing. The four lobes of the plant visible at the bottom of the picture are referred to as "terminal buds" and are the actively growing portion of the plant.

Terminal buds are the plant that salvinia weevils prefer to feed on and lay eggs in. From a perspective of sustaining weevil populations on the lake, it is good to see this growth; however, actively growing salvinia this early in the year is not so good.

The picture below further illustrates the active salvinia growth seen on the lake. The smaller leaves laying flat on the water's surface are primary salvinia that has recently begun to grow. While extensive mats of salvinia are not yet present, it likely won't take long for these mats to start forming.

It is only early February though, so a good killing freeze is not totally out of the question. If a hard freeze like those seen in 2010 or 2011 comes along, the salvinia will likely take a hit.

For now though, giant salvinia on Caddo Lake is alive and well. It is simply biding its time until spring truly arrives.

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