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WATER COLUMN DATA AND SPECTRAL IRRADIANCE MODEL
Citation:
Cifuentes, L. A., P M. Eldridge, J Kaldy, AND R. Maffione. WATER COLUMN DATA AND SPECTRAL IRRADIANCE MODEL. Chapter IV, Dunton (ed.), Effects of Dredge Deposits on Seagrasses: An Integrative Model for Laguna Madre. U.S. Army Corps of Engineers, Galveston, TX, I:IV-1-54, (2003).
Description:
Water samples collected monthly, for 18 months, from six sites in the Laguna Madre were analyzed to identify and quantify phytopigments using High Performance Liquid Chromatography (HPLC). In addition, water column pigment and nutrient data were acquired at 12 stations in Upper (ULM) and Lower Laguna Madre (LLM) during the summer 1996 cruise. The spatial and temporal scale of sampling provide a unique perspective on the dynamics of phytoplankton communities within the Laguna Madre. Phytopigment identification from field samples was consistent with the known pigment complex for Aureoumbra lagunensis, Texas brown tide. Pigment identification and pigment ratios indicate that the dominant phytoplankter at most sites was brown tide; however, other groups were also present. Extreme pigment ratios in Lower Laguna during September 1997 may be the result of a red tide bloom or a wind event suspending benthic diatoms. Additionally, this data set documents the decline of brown tide in the Upper Laguna. Nutrient data collected along a transect through the Laguna indicates that Baffin Bay and Arroyo Colorado may be sources of anthropogenic nutrients. Pigments were identified and quantified for the major seagrass species in Laguna Madre. Pigment ratios for the seagrasses were substantially higher than published values, because HPLC is more sensitive than traditional methods.
Inherent optical properties (IOPs) of Laguna Madre waters were studied in August 1997. Preliminary measurements of absorption and backscattering coefficients were performed along with analyses of total suspended solids (TSS) and pigment concentrations in both upper and lower Laguna Madre. Strong relationships were observed between IOPs and TSS, which can ultimately be used to compute spectral irradiance in the water with the radiative transfer numerial model called Hydrolight. Finally, we describe a simple spectral irradiance productivity model that can use data provided by Hydrolight to estimat