Thursday, October 21, 2010

HUNTING FOR HYDRILLA

After spending several days on house repairs and yard maintenance during resettlement in New Iberia, the urge for a change of scenery overcame us, and my botanist friend Vickie decided to drag me along on a search for a plant that grows in nearby St. Martin Parish. She has included a write-up about this plant in her book WHY WATER PLANTS DON'T DROWN, which Susan Elliott of Pinyon Publishing is now illustrating. After lunch, we boarded the Honda and set out for Lake Martin where she had collected specimens of this plant during her career as a professor of botany at the University of Louisiana in Lafayette. I’ve written about Lake Martin in other blogs, but the subject of hydrilla plants has never come up.

The drive through the lowlands in St. Martin Parish in the October sunshine was pleasant, and when we arrived at the lake, we found several trucks parked near the boat landing where fishermen, truant from work, had put in their aluminum Joe boats and pirogues earlier in the day. One returning fisherman, reloading his boat in the 86 degree weather waved me over to see his catch of eight small bass, big enough for a mess, but not large enough to brag about. “I’m staying up here on the dock,” I told him, “because I know how many ‘gators populate this lake.”

“You’re right,” he answered, casting an eye at Vickie standing too close to the edge of the lake, twisting a plant around a stick. “I just ran over one a few minutes ago.”

“It’s a wonder it didn’t turn your boat over,” I said, and he shook his head.

“Lucky, I guess,” he answered. He looked quizzically at me standing there on the dock with the sun turning my white hair even whiter, dressed in pedal pushers and a t-shirt, and asked, “You from around here? “ The question was more like “What are you doing out here?” but I wasn’t offended. I did look out of place.

“For about 45 years,” I told him. He looked relieved that I wasn’t a “come here,” and showed me how his trailer tires had become entangled in “some kind of seaweed” as he pulled it out of the water and onto the boat ramp. At the time I didn’t know that it was hydrilla, the plant for which Vickie had been searching.

Hydrilla is an aggressive water weed that invades water systems and drives away all native and introduced aquatic plants. It survives under lower light conditions than any other species and grows beneath other plants, making it able to live at greater depths. Because it can use low light, it starts photosynthesizing earlier in the day than other plants and captures most of the carbon dioxide that enters the water during the night. The plant is 93-95% water so it can make large volumes of biomass using very few resources. In the summer, it grows rapidly, doubling its biomass. Then it branches as it approaches the water surface and fills the water column up to 20 feet deep, shading out other plants. In California, hydrilla infested an irrigation canal so densely that the water backed up over the banks and ran down a hillside. Hydrilla mats can damage dams and power plants, and interferes with boating and fishing. It can also decrease fishing stocks. In the case of the fisherman to whom I talked, his truck tires spun on the water plants washed up on the boat ramp. Only with the help of another fisherman did he get his boat out.

Among the sights I saw: a mosquito as large as a small dragonfly that landed on the rearview mirror of the Honda; a yellow/gold willow tree glistening in the sunlight, a grove of lotus, and muddy water surfaces covered with duckweed and mats of large yellow flowers called burr marigolds.

As we followed the dusty road to the end of the lake, we saw a long Joe boat filled with eight people who had been cruising on a swamp tour – they’d probably been looking for ‘gators, one of which Vickie spied (and I urged her on) as we sped away with a plastic bag filled with hydrilla specimens.

We got lost on the way home. As a school bus passed, we saw “St. Martin Parish” painted on its yellow side. “Hay la bas,” I hollered, “we’re near St. Martinville. “ And suddenly we emerged in St. Martinville, no thanks to the old Louisiana map I had unearthed that had a hole smack center in the area we were traveling. That’s the way we usually travel – lost – but we find serendipity along the way.

And the hydrilla? It was still green and perky when we reached home; however, I am advising Vickie not to throw it in the coulee behind our house or the drainage ditch will be overcome by this plant, which looks like an ominous caterpillar that lured us outdoors today. Right now, it‘s drifting in a small white cereal bowl in the kitchen. Did I say that it captures most of the carbon dioxide during the night? And what about our oxygen?
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