Foraging ecology. Road map. Amphibians that feed under water 2/23/2012. Part II. Roberto Brenes. I. Adaptations of amphibians to foraging on water

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1 Foraging ecology Part II Roberto Brenes University of Tennessee Center for Wildlife Health Department of Forestry, Wildlife and Fisheries Road map I. Adaptations of amphibians to foraging on water i. Caecilians ii. Caudata iii. Anura II. Foraging ecology of tadpoles Amphibians that feed under water Several amphibian families have adapted to aquatic life Mostly opportunistic Both active hunters or sit and wait 1

2 Genus Thyphlonectes Active hunters Poor vision Smell and tact Opportunistic Generalists Caecilians Typhlonectes compressicauda diet (Verdade, 2) Several families adapted to aquatic life Salamandridae Cryptobranchidae Sirenidae Amphiumidae Proteidae Hyobranchial apparatus Support and move gills Expand and contract the buccal cavity during feeding Amphiuma Caudata Video 2

3 Use suction to capture the prey Just with buccal expansion Rapid strike Manipulate prey with teeth Diet Fish Aquatic invertebrates Worms Crustaceans Aquatic salamanders respond to odor, movement or touch; terrestrial ones respond to movement Caudata Diet of Hynobius retardatus larvae Kohmatsu and Yukihiro (21) Salamanders prey on other salamanders Can be cannibals Scavengers Predators 3

4 Salamander larvae Same as adults: opportunistic predators Aquatic invertebrates Tadpoles Other salamanders Aquatic Frogs Predators Sit and wait Use camouflage or hiding places Xenopus Video Xenopus borealis diet (Bwong and Measey, 21) 4

5 Most have: Keratinized jaw Rows of labial teeth Papillae Food transport by buccal pumping Food particles catch by branchial filaments and branchial mucus Tadpoles Adults and tadpoles have different Diets Carnivorous Insectivorous Little selection Herbivores Scarpers Filters Grazers Carnivores Oophagous Classical stream ecosystem Cummins

6 Multiple functional roles of tadpoles McDiarmid and Altig 1999 Classical ecosystem with tadpoles Cummins 1974 Tadpoles mouth structures are specialized for their diet Filters: feed on small particles on surface Grazers: feed on biofilm or algae Tadpoles 6

7 Stream grazers: feed from algae in fast moving streams Oophagus: feed eggs Detritivorous: Fine particles from substrate Tadpoles Carnivores: Feed on animals Cannibals: Feed on their own species Open swimmers: Feed floating particles Gatherer: Feed particles from the bottom Tadpoles Tadpole declines 35 Year 1 Year 2 3 uals/m 2 Individu

8 Loss of Biomass (47%) Average Biomass s AFDM/m 2 y 14 Before * p= After 1 8 P= * p= Colostethus Hyla Centrolenidae Rana Total Loss of production (72%) p mg AFDM/m 2 y Before mg After * p=.3 P= mg Colostethus Hyla Centrolenidae Rana Total How might energy flow change? Sun light Leaf litter Egg masses Metamorphosis Forest Stream Neonates Prey Primary producers Primary consumers Secondary consumers Algae Diatoms Macro-invertebrates Tadpoles Macro-invertebrates Fish 8

9 How are other groups affected? Sun light Leaf litter Egg masses Metamorphosis Forest Stream Neonates Prey Primary producers Primary consumers Secondary consumers Algae Diatoms Macro-invertebrates Tadpoles Macro-invertebrates Fish Algae Bloom Tadp oles/m2 C Guabal Pools Tadpole Algae hyll a mgm-2 Chloroph 5 2 Connelly et al. in press What is going to happened in the Forest 9

10 Reduction in amphibians as prey 1% C. Montgomery 8% Percent of Capture 6% 4% Amphibians consumed Dipsas sp Imantodes cenchoa Leptodeira septentrionalis Sibon annulatus Sibon longifrenis Oxybelis brevirostris 2% % April - May June - July August - September October - November Montgomery et al. in press Trophic cascades caused by ranavirus Decline in number of individuals resulted in an increased in the abundance of the zooplankton community Zooplankton (ind/ml) R 2 =.78 Y= X Survival (%) Control 2 Zooplankton (ind/ml) R 2 =.81 Y= X Wood frog Survival (%) 1

11 Trophic cascades caused by ranavirus Decline in number of individuals resulted in an increased in the biofilm layer of the pools Average biofilm AFDM (mg) R 2 =.84 Y=.2+.21X.2 Control survival (%) Average biofilm AFDM (mg) R 2 =.85 Y= X. Wood frog Survival (%) Trophic cascades caused by ranavirus Decline in number of individuals resulted in an increased of phytoplankton Average Chlorophyll (mg/ml) R 2 =.269 Y= X Control Survival (%) 1.6 Average Chlorophyll (mg/ml) R 2 =.58 Y= X Wood Frog Survival (%) Summary Aquatic amphibians are mostly predators Opportunistic Non selective Salamander larvae and caecilians can be active hunters Aquatic anurans are ambush predators Tadpoles have mouth parts adapted to the niche they inhabit Tadpoles are an important part of the ecosystem 11

12 Questions What is the function of the hyobranchial apparatus in caecilians and aquatic salamanders What is/are the major difference/s on foraging strategies between aquatic anuras, Caecilians, and aquatic salamanders What is/are the major difference/s on foraging strategies between adult anurans and its larvae What is the ecological role of tadpoles. What happened if they are removed? 12