Friday, May 9, 2008

Coecles Harbor Natural Meadow Redux

Following up on our first dive of the year in January at Coecles I decided it was just about time to check the status of this interesting meadow we had observed 3 months ago. We are very interested in this site for a couple reasons. First, the Town of Shelter Island may be interested in funding restoration work in town waters and this may be the only candidate site (actually an unvegetated area across the Harbor would be the focus if we were to undertake any work). As part of this, we need to find out the relative contribution of seeds vs. lateral shoot recruitment in meadow maintenance. If seeds are the primary means of meadow maintenance then it would not be a good idea to collect seeds from this site.

Second, and more importantly, we are VERY interested in learning more about the ecology of muddy bottom protected sites like this. Based on recent historic losses, these sites are becoming very rare and if we are to preserve what is left and possibly return grass to other similar areas, we must first understand how these systems function. The more we can learn about how these meadows survive under multiple stressors such as high temps, fine sediments, low light and high bioturbation, the closer we can come to re-establishing grass in other similar areas in the region.

On April 30th we anchored at the same site where we had first observed all of the seedlings in January, luckily this time it was much warmer! Once in the water I was surprised to see the number and size of the reproductive shoots floating above the canopy. On closer inspection the flowers proved to be very large and even the vegetative shoots were taller and had wider blades than I had expected. Even more interesting was the fact that there were many more seedlings than there were adult shoots; even more than I had observed previously. Apparently this meadow really does rely on seedling recruitment for maintenance. It almost appeared to be a case of forced annual expression although it is difficult to say this for sure. We have seen similar things in Noyack Creek and Bullhead Bay.

In some areas there were no adult shoots to be found, only seedlings. In these areas it was a little difficult to distinguish adult shoots form seedlings, but excavating (and replanting!) a few individuals and comparing leaf width with nearby adult shoots made this possible. Seedlings were so dense is some areas it appeared that they were almost chocking each other out. This close proximity appears to also have assisted the spread of wasting disease from neighbor to neighbor as evidenced by the large numbers of infected leaves in these dense patches.

Other interesting observations included the huge number of stickleback nests observed (photo at right), mostly on the taller reproductive shoots. In the past I have seen these nests on natural grass in Noyack Creek and on our plantings in Sag Harbor Cove, but never in the numbers we found in Coecles. It really was amazing. Since it was so long since I had seen a nest I wasn't sure what they were at first and actually poked a little inside one just to see if it had eggs...oops it did! (see above and left) Usually, we see the males (?) guarding the nest, but I didn't. Steve said he did.

Some other points of interest included a couple false angel wing siphons coming up out of the bottom and numerous mantis shrimp burrows (see top photo) that looked like miniature volcanoes. As far as snails, there wasn't an overabundance of mud snails or mud snail eggs, but they did seem to be concentrated in certain areas resulting in lots of eggs on some plants.

I look forward to getting back to Coecles as the season progresses, but I don't look forward to what will likely be a bad case of swimmers itch next time...


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