Previously unsuspected dietary habits of Rimicaris hybisae

Previously unsuspected dietary habits of Rimicaris hybisae
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Transcript of Previously unsuspected dietary habits of Rimicaris hybisae

  • Emma Versteegh (382D), Cindy Van Dover (Duke Marine Lab), Max Coleman (382D)

    National Aeronautics and Space Administration

    Questions What causes the wide range of 13C values?

    Are 13C values related to dense and sparse assemblages? Do dense and sparse have different diets?

    Do dense and sparse differ in 15N and 34S values? How do 15N and 34S relate to diet?

    Hypothesis: Dense and sparse Rimicaris differ in diet: varying 13C values show real differences in food sources between individuals.

    Results

    Gut contents dense: bacteria Sparse: crustacea (5 out of 13)

    bacteria and crustacea (3 out of 13) bacteria only (5 out of 13)

    Sparse and dense R. hybisae have different 13C, 15N & 34S values Sparse / crustacea-eating: - Lower 13C values (-2.38 ) - Elevated 15N values (+0.34 ) - Lower 34S values (-2.22 )

    Carnivorous Lebbeus virentova 13C and 15N overlap with R. hybisae, differ from sparse in 34S only

    R. hybisae exoskeleton same 15N and 34S as guts, but different 13C Tail 13C and 34S reflect gut content, no enrichment

    Tail 15N enriched by +3.4 vs. gut Bacteria in gut: higher tail 13C and 34S Crustacea in gut: lower tail 34S

    Conclusions Dense and sparse R. hybisae use different food sources Dense R. hybisae eat / absorb episymbiotic bacteria only Sparse shrimp eat bacteria, crustacea, and possibly gastropods They might have different episymbiotic bacterial communities Diet switch possibly related to molting cycle

    Implications Contributes to understanding energy fluxes and elemental cycling for life at deep-sea hydrothermal vents. Ultimately helps solar system exploration mission planners determine how best to seek, identify, and characterize life that may (have) exist(ed) on Europa or other planetary bodies with sub-surface oceans.

    Rimicaris hybisae tail (sparse) R. hybisae tail (dense) Lebbeus virentova wholep R. hybisae gut (crustacea)p R. hybisae gut (bacteria & crustacea)r R. hybisae gut (bacteria) R. hybisae gill covers (dense)

    R. hybisae (crustacea) R. hybisae (bacteria & crustacea) R. hybisae (bacteria)

    Introduction Biological research at the worlds deepest hydrothermal vent fields:

    Earth analogs for environments on Europa Objectives: 1. Quantification of the efficiency of uptake of hydrothermal vent energy into

    biomass 2. Understanding of the C cycle at hydrothermal vent environments Supported by NASA ASTEP (Astrobiology Science and Technology for Exploring Planets)

    Life in the dark Photosynthesis: 6 CO2 + 12 H2O + sunlight C6H12O6 + 6 H2O + 6 O2 Chemosynthesis: 6 CO2 + 6 H2O + 3 H2S C6H12O6 + 3 H2SO4

    Would work on Europa too Quantify biomass expected? look on Earth How much new biomass/time? food web Hydrothermal vent fields at Mid-Cayman Rise (MCR) The worlds deepest, Piccard vent field, 4960 m, 398 C Von Damm vent field, 2309 m, off-axis, diffuse venting, 226 C

    Rimicaris hybisae - Dense and sparse Abundant at both known MCR vent fields Dense aggregations on active chimneys, or sparse peripherally High degree of spatial variability in population structure Feeds on chemosynthetic bacteria that are episymbiotic (gill cover, mouth parts)

    Von Damm food web

    Stable isotopes Stable isotopes of carbon, nitrogen and sulfur (13C, 15N, 34S values) can be used to disentangle food webs. You are what you eat: +1 (13C vs. VPDB) +3 (15N vs. AIR) +? (34S vs. VCDT) Large variations in R. hybisae tissue 13C values have been unexplained. Are 13C values not a good food web tracer in hydrothermal vent ecosystems?

    National Aeronautics and Space Administration

    Jet Propulsion Laboratory California Institute of Technology

    Pasadena, California www.nasa.gov

    Copyright 2014. All rights reserved.

    Jack Cook WH

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    Poster No. E-38

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