Hydrology and water quality have been identified as important drivers of periphyton mat production in the Everglades, where increases in water depth and mat phosphorus levels result in an anomalous decline in mat biomass. This study was conducted to determine whether these patterns are unique to the Everglades or are in fact symptomatic of tropical karstic wetland systems throughout the northern Caribbean region.  Periphyton mat samples and water quality data were collected at sites throughout shallow, marl-based wetlands in Belize, Mexico and Jamaica. These data were then compared to a larger dataset collected from comparable sites within the Everglades National Park.

Results/Conclusions:

Total biovolume, biovolume, dry weight, ash-free dry weight and chlorophyll a biomass all declined in relation to water depth, and while the negative relationships were all significant for the Everglades (p<0.0001), only biovolume and chlorophyll a biomass showed a significant trend for Caribbean sites (p=0.037 and p=0.023). The relationship between chlorophyll a concentration and water depth differed between Everglades and Caribbean sites, with the former showing a significant positive relationship (R²=0.35, p<0.0001) and the latter showing a significant negative relationship (R²=0.34, p<0.001).  This discrepancy may arguably be the result of the small sample size from the Caribbean, as well as the inclusion of an anomalous sampling event from Belize. Percent organic content showed a positive relationship with water depth for both Everglades (R²=0.23, p<0.0001) and Caribbean sites (R²=0.35, p<0.001). Principle Component Analysis also showed that at Everglades and Caribbean sites, periphyton mats with higher total phosphorus levels tended to have lower biomass, higher organic content and were found at deeper sites, while mats with lower total phosphorus levels tended to have higher biomass, lower organic content and were found at shallower sites.
The results of this study showed the distinct relationships between (i) water depth and mat organic content and (ii) periphyton mat total phosphorus levels and biomass in Everglades marshes.  By testing for these relationships at a number of similar karstic wetland habitats in Belize, Mexico and Jamaica, this study also strongly corroborates the patterns observed in the Everglades.  This has effectively shown that water depth and, to a greater extent, periphyton total phosphorus content, are both correlated with periphyton biomass in tropical karstic wetland systems, suggesting that they are drivers for periphyton dynamics in these systems.