2. Questions - Eno River

Original Questions:
  1. Water Snakes What niche do water snakes have in the Eno River ecosystem, and how would their absence affect this ecosystem?
  2. Snail Distributions What factors determine the size/ species distribution of snails on the Eno?
  3. Water Quality and Fish What is the necessary water quality for the species of fish in the Eno River to survive? 
  4. Plants and Chub Will removing streamside vegetation affect the survivorship of juvenile creek chub (Semotilus atromaculatus)? 
  5. Snail Size How is snail size related to presence in stream microhabitats?
  6. Spider Webs What environmental factors influence web site selection of water spiders? 
  7. Reconnection In intermittent rivers, specifically the Eno, which separate certain living species from others and offer differing nutrients and conditions, what is the result immediately upon reconjoining these ponds with the main body of water? What adaptive traits have species in the Eno developed to accommodate its dynamic environment? 
  8. Amphibians How would the extinction of amphibians affect ecosystem interactions?
Modified Versions and Example Approaches:
  1. Water Snakes - What role do water snakes have in the Eno River food chain?
    1. Experimental approach: compare prey abundance in snake enclosures vs. exclosures (but be aware of cage artifacts)
    2. Observational approach: compare prey abundance in rivers or river reaches with & without snakes (but be aware of differences between sites besides snake abundance)
  2. Snail Distributions - How does algae quantity determine the size species distribution of snails on the Eno River?
    1. Experimental approach: Put 10, 20, 40, 80 snails on similar substrates and see how they change the availability of algae over time
    2. Observational approach: Measure the amount of food (algae) on rocks where there are small versus large snails (but remember that the relationship could go either way: where there are lots of snails, there's very little algae because they eat it all, or where there is lots of algae, there are lots of snails)
  3. Water Quality and Fish - In what conditions (pH, salinity, oxygen, and nitrate) do we find sculpin in the Eno River?
    1. Experimental: Grow fish in the lab in tanks with varying water quality
    2. Observational: Look at records of fish species present before and after changes in water quality (or look at records for many rivers across the region in a similar way)
  4. Plants and Chub - How will removing streamside vegetation affect the abundance of juvenile creek chub (Semotilus atromaculatus)?
    1. Experimental: Before-After-Control-Impact (BACI) design: count fish before and after vegetation removal in one reach and also in a control reach with no vegetation removal
    2. Observational: Exercise left to the reader =)
  5. Snail Size - Do crayfish eat snails, and are they size-selective?
    1. Experimental: Put crayfish in containers with snails of different sizes and observe changes in snail abundance
    2. Observational: Observe crayfish - were are they located?
  6. Spider Webs - How does the distance from the bank affect the abundance of spider webs and prey insects?
    1. Experimental: Exercise left to the reader
    2. Observational: Measure sunlight, elevation, distance from bank, vegetation type, insect traffic
  7. Reconnection - Are there species that only live in intermittent ponds and are not found in the main river channel?
    1. Experimental: Nah...
    2. Observational: Look at species changes before and after reconnection. Is fish size different in disconnected and reconnected ponds?
  8. Amphibians - How would the removal of Fowler's toads and Eastern American toads affect the species composition of algae in Eno River ephemeral ponds?
    1. EXperimental: Put toad larvae in tanks with known algal composition, and keep other similar tanks without larvae as controls. Look at changes in algal composition (# of species or relative abundance of each species) over time.
    2. Observational: Find rivers where toads are present and nearby rivers where toads used to exist but have been eliminated by Chytrid fungi (Australia, maybe, for some Australian toad species?). Compare algal composition in the paired rivers/watersheds.
Potential Research Challenges:
  1. Cage artifacts - cages might include/exclude ecologically important but ignored factors
  2. Multicausality - there are multiple ways to get the same results (regression relationships, etc.)
  3. In observational studies, locations that differ in the factor of interest may also differ in other relevant factors