went to a talk today

now before i start, i cannot promise that i will be posting every day, but since this is new to my and i have nothing better to do at this moment i will try to get at least somehting up here once a day (not that anyone other than tait reads this thing)...

So today I went to a "brownbag lunch talk" similar to the brainwash lectures that southampton used to have (bc im assuming anyone who reads my blog probably knows me)... and it was by
Jim Fourqurean an expert in seagrasses. He talked about nutrient limitations in certain areas around South Florida, around the Florida Keys, Florida Bay, Fort Jefferson and the Gulf. In Florida Bay, which basically sits between the everglades and the keys, there is alot of nitrogen and little phosphorous, making much of Florida Bay P limited. Conversely, sites oceanside of the Keys had higher P, making those sites N limited. (This makes sense, as terriginous sediments closer to land are usually nitrogen rich and phosphorous pour, where as carbonate sediments, occuring more offshore, tend to be the opposite.)

Anyway, his team conducts surveys of the bottom, made maps of bottom cover by the 5 different seagrass species (which is very exciting, for those of use in the more temperate climates we have only 1 species, Zostera marina, although you can count Ruppia I guess bc it is brackish). And it is pretty interesting to look at these maps. Thalassia is the dominant but in certain habitats, like some of the deep water sites, Halophila dominates, and in areas of higher nutrient availability Halodule or Syringodium dominates. He also noticed that in fertilization experiments where there was plenty of Thalassia, that the nutrient availabilty was such that Syringodium and Halodule abandoned their root structure, growing their rhyzomes out of the sediment, up and over the Thalassia canopy. I have actually observed this and it is quite amazing. This is possible, of course due to seagrasses ability to intake nutrients both through the sediments at the rhyzome and from the water column through the blades. He also noticed algal responses in these experiments... but these are not what I want to talk about...

The most interesting work from the talk is one a post-doc of his is doing, Anna Armitage
The cool thing they are looking at is not just the flora response to the added nutrients, but the faunal response as well. This is very interesting work, particularly bc the two sites they chose are very different. One site had very little growth and was nutrient limited. Another site was dense with grass and was not nutrient limited. Through their nutrient addition to the nutrient limited site, they found not only an increase in flora, that is more grass and algal growth, but an increase in animal density. But it wasn't just animal density that changed, but the community as well. Caridean shrimp, and amphipods, both epiphyte grazers, composed a much larger percentage of the community that before the nutrient additions. Sea cucumbers also were in higher abundance, being detrital feeders. Numbers of fish also increases, but this could be for multiple reasons, the increased food (epiphytes, crustaceans) or the increased structure. The intersting site was the second one. There was no significant floral response, and yet the animal densities saw a larger increase and similar community shifts. This raises questions, as to what the animals are responding to, is it a higher nutritional value of the plants, or are there so many animals that they are consuming the epiphytes and microalgae so fast that there are no observed changed in the flora? This creates problems as to how productivity should be addressed, because in this case, biomass is not showing any significant changes in vegetation and yet the animals are showing that something is indeed happening. Whatever is going on, it is something that I am sure will be investigated again, many times, to figure out exactly what it is that the fauna are responding to...

hope that didnt bore anyone too much, i linked to Jim's site, and I am not sure if he has this kind of work up there yet as they are just putting all the data together now....