IngentaConnect Effects of increased salinity on tadpoles of two anurans from a C...

Abstract:

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.

Keywords: ANURAN METAMORPHOSIS; CANE TOAD; COASTAL WETLANDS; SALINITY RESPONSE; SALINIZATION; SEA-LEVEL RISE; TADPOLE DEVELOPMENT; WHITE-LIPPED FROG

Document Type: Research article

DOI: 10.1163/156853808783431451

Affiliations: 1: Department of Biology, University of Puerto Rico-Río Piedras Campus, P.O. Box 23360, San Juan, Puerto Rico, 00931-3360;, Email: neftalirios@yahoo.com

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Effects of increased salinity on tadpoles of two anurans from a Caribbean coastal wetland in relation to their natural abundance