At first glance, the vast salt marshes in the Gulf of Mexico seem like a monocultural tesselation of seagrass and water. But take a closer look and you will be amazed at the microcosm of life that exists in its diversity of microhabitats. The expansive flats of marsh grass are teeming with life, concealed in their verdent blades are a menagerie of birds, fish, and invertebrates. When we motor up to a site, my eyes have to adjust from staring at a blanket of marsh grass, to carefully examining the activity in the marsh. If you are patient, and keep a watchful eye, the grass will come to life. Seaside sparows and red-winged blackbirds bustling among the blades, tiny crabs scuttling in and out of mudholes, snails noisily munching on blades of grass, minnows darting around stems. And once you really start to pay attention you notice the gator slides, bird nests, and all the abiotic features that the animals create in their marshland paradise.
The eggs of an oyster drill (a predatory snail) inhabiting an oyster shell
I'm back on oil-spill detail in the Gulf of Mexico, this time working in the sweltering salt marshes of southern Louisiana. As part of a marsh-assessment team, our task is to collect vegetative data as well as soil and plant tissue samples to assess the extent of oil damage to the marsh grass beds.
One of our sample sites
This work was started last spring just after the spill happened (a year ago now!) and we are re-sampling the study plots that were initially erected to account for changes in vegetative structure. Already we have seen signs of erosion. As oil contamination killed the marsh grass, the beds have eroded back. At some sites, residual oil can still be seen in the grass beds and in the wrack line of dead vegetation.
At this point, our findings are only empirical; the samples we collect are sent off to a lab for physical and chemical analyses. I am hopeful that the data we are collecting will be a critical tool in elucidating the details of how the oil spill has impacted the marshes, and the native flora and fauna of the Gulf of Mexico.