Intertidal foundation species support ecological communities and protect anthropologically valuable inland resources during storm events. The persistence of intertidal foundation species and their concomitant communities with global change will largely depend upon their ability to adapt to altered environmental conditions such that they can both re-colonize hurricane and anthropogenically disturbed sites, and migrate inland and to the north. Rhizophora mangle is a foundation species that occurs in the intertidal zone along the subtropical and tropical shorelines of Florida and produces propagules that can float and thus recruit over long distances. We are conducting a common garden experiment using Rhizophora to test three hypotheses. First, are wide ranging foundation species such as Rhizophora, adapted to local habitats or do they have high phenotypic plasticity such that propagules from all populations are equally capable of adapting to any site within their species’ range? Second, do half sibling cohorts of Rhizophora from the east and west coasts of Florida show the same variation in responses to biotic and physical environments? Third, do salt marsh foundation species that co-occur in the same habitat inhibit or facilitate the recruitment of Rhizophora?
Results/Conclusions We compared growth in height and productivity (as leaf production) between east and west coast populations and among cohorts. We found that height varied with coast (ANOVA P = <0.0001), insect predation (P = <0.0001) and coast x predation (P = 0.0032). Productivity varied with coast (ANOVA P = <0.0214), maternal family (P = <0.0214), insect predation (P = <0.0001) and predation x coast (P = <0.0214), Predation was inversely proportional to the rank of vegetation density (ANOVA P=0.0067). Of four marsh species tested, one species, Distichlis spicata was the most effective in reducing the influence of the parasite (ANOVA P=0.0445). Thirty-three percent of the seedlings were preyed upon and predation resulted in mortality for 50% of these seedlings. For seedlings that survived predation, plant height at 2 years was reduced by 20% and canopy volume by 50%. Cohorts from the east coast were less likely to be preyed upon and therefore may have been adapted to the most common insect predator (Cydia desotanum).
