Mangrove forests are being removed or degraded at an alarming rate, even though they play a vital role in the sustainability of tropical coastal communities. Many of these forests are identified as degraded based on observable changes in their leaves (e.g., density, size, color, etc.). Of these, color can be considered one of the most important indicators of degradation because changes in the spectral response may be indicative of changes in the leaf pigment content. In this investigation, hyperspectral laboratory techniques were applied to examine potential relationships between the mangrove leaf spectral response and three leaf pigments: chlorophyll a, chlorophyll b, and total carotenoid content. Using an ASD spectroradiometer, the spectral reflectance of leaf samples were collected from poor condition, dwarf and healthy black (Avicennia germinans) and from healthy and poor condition red (Rhizophora mangle) mangroves located in a degraded mangrove system of the Mexican Pacific. A subset of 150 representational leaves was then used for pigment content analysis. The results indicate significant relationships between the spectral response and the levels of chlorophyll a, b, and total carotenoid content contained in the leaves. In particular, wavebands at the red edge position were shown to be the best predictors of the pigment contents. The results also indicate that vegetation indices do not necessarily improve the ability to predict these constituents. Finally, the red edge position was found to be significantly different between the healthy and poor condition mangroves (P = 0), with the healthy mangroves having longer wavelengths associated with the red edge position.
The Great Islands zone, in the Gulf of California, presents high phytoplankton concentration as a result of the high
Turbulent Kinetic Energy (TKE). In this work we looked for dynamics zones based on Empirical Orthogonal Function
analysis (EOF). The input data were Sea Surface Temperature (SST) and Chlorophyll-a concentration (Chla) from daily
MODIS-AQUA at 1 Km from 2003 to 2006. Time series were generated to define the average conditions for summer
and winter spring tides. Results showed that in general and during summer-spring tides, higher Chla concentrations are
localized in the west coast, with a displacement to the south. These high Chla were associated with tidal mixing. Zero
EOF values in summer showed the boundary between low SST and high Chla. During winter-spring tides there were
more spatial variability than during summer time. Zero EOF value in winter time showed low SST and Chla in the west
coast due to stronger mixing conditions that stay longer. Results of this work emphasize that a dynamic regionalization
can be used in high TKE areas and it helps to define zones with a similar response based on the input parameters chosen.
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