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Many amphibians depend on wetland ecosystems for reproduction and survival, and coastal wetlands are not the exception. Recent advances on climate change research predict a reduction in land cover of coastal wetlands due to sea-level rise in response to global warming. Although this scenario will contribute to further amphibian population declines worldwide the impacts of sea-level rise and its related salt water intrusion on anuran assemblages in coastal wetlands remain largely unknown. I documented patterns of abundance of the native Caribbean white-lipped frog (Leptodactylus albilabris) and the introduced marine toad (Bufo marinus) along an inland-to-coastal salinity gradient in Puerto Rico. In addition, I investigated the effects of increasing salinity on larval growth and survival to metamorphosis in L. albilabris and B. marinus in laboratory experiments. In the field, relative abundance of adults of L. albilabris decreased with increasing salinity, while B. marinus showed the opposite pattern. Laboratory experiments with L. albilabris and B. marinus revealed that percentage of larvae surviving to metamorphosis in both species was greatly reduced in 22-25% seawater (8 ppt), which is within salinity levels found in their natural distribution. In this salinity level, the native L. albilabris showed ∼100% metamorphosis failure while the introduced B. marinus showed ∼60% metamorphosis failure. The reduction in metamorphosis was due to high mortality in L. albilabris and was accompanied with morphological abnormalities in B. marinus. Tadpoles of only L. albilabris reared for four weeks showed significant weight loss at 8 ppt, but showed no difference in length. These results suggest that anuran tadpoles may be living near their physiological limit for salinity in the studied wetland. Conservation implications are profound, however, as salt water intrusion and urban encroaching inland may result in anuran population replacement, from native species to introduced species in this wetland.

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Coastal wetland plant communities are strongly structured by water depth and salinity. Rising sea level will cause changes in the hydro-period, surface water salinity and salt-water intrusion in coastal areas, which will reduce the distribution of forests in these areas. We studied the dynamics of a Pterocarpus officinalis stand in Puerto Rico over a 9-y period. We observed differences in plant growth, recruitment and mortality across a salinity gradient within a 1-ha plot. In areas of high salinity, recruitment, juvenile density and growth rates of juveniles and adults were lower. The detrimental effect of salinity was also observed in a growth experiment; seedlings in 5‰ and 10‰ salinity treatments had higher mortality, slower growth and less above- and below-ground biomass than control seedlings (0‰). In addition, an increase from 0 to 1‰ in salinity resulted in approximately 50% less nodulation in seedlings. Low recruitment in high salinity areas and lack of recruitment in adjacent grasslands will further reduce the distribution of this forest type. Although some ecosystems can respond to changing conditions by migration to more favourable areas, this is not the case with P. officinalis, and thus, restoration efforts are needed to re-establish this species where it occurred historically.

We describe adult morphology, advertisement call, and natural history diagnostic of a new species of Eleutherodactylus from a fresh water (palustrine) herbaceous wetland of northern coastal Puerto Rico. The new species is apparently the smallest Puerto Rican Eleutherodactylus and is morphologically most similar to E. gryllus, which inhabits high-elevation humid forests and cloud forests. Although both species have well-developed glands throughout the body, morphological ratios, body coloration, frequency of calls, call structure, and habitat association indicate that it is a well-differentiated species. The new species and E. gryllus may have diverged from an ancestral wetland-dwelling species.