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A dynamic foundation to pond ecology.
We propose to characterize nitrogen and phosphorus cycling within
a series of marine and hypersaline pond environments. Three phenomena
will be explored: a) as salinity rises, ponds switch from nitrate-dominated
to ammonium-dominated nitrogen economies. When coupled to man-made
elevations in nitrogen input, this may result in an extreme bottleneck
in nitrogen cycling. This has dramatic implications regarding
the consequences of dumping in hypersaline habitats. We plan to
explore the sources of inorganic nutrients within these inland
ponds, and assess the ammonium/ nitrate stoichiometry during a
pond's trajectory towards hypersalination. b) Sea-bird rookeries
within fringing mangrove communities may provide ponds with a
nutrient subsidy creating steep environmental gradients. Sponges
living in symbiotic association with the mangrove prop-roots may
be creating short-circuit nutrient recycling as they harvest phytoplankton
nourished by these nutrients, and share resources with the prop-root
tissues with which they are intimately associated. We hope to
test this hypothesis through isotope analysis, and measurement
of various biotic indicators. c) Invertebrate communities growing
epizoitically on the fringing mangrove habitats, may also be serving
as a source of nitrogen and shaping environmental gradients. As
ponds become prohibitively hypersaline, the mangrove prop-roots
lose their epizoite community and cease to contribute in this
way. We plan to characterize nitrogen gradients in marine and
hypersaline mangrove habitats, and correlate this with invertebrate
"tissue loads".
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