Guest lectures Flashcards
(117 cards)
Ashley Tripp-Atlantic Cod of Newfoundland: How are crayfish studies carried out?
Put into different little chambers to determine how the crayfish are affected by different levels of CO2 in the water
Ashley Tripp-Atlantic Cod of Newfoundland: Why are crayfishs’ levels of CO2 measured?
- to see how different levels of CO2 affect their stress levels in the water
- changes in regulation of their gills
- correlates with climate change
Ashley Tripp-Atlantic Cod of Newfoundland: What happened to the cod’s population in 1990? What has this affected?
- collapse of population, still have not recovered
- when cod population declines, seal’s population increases
Ashley Tripp-Atlantic Cod of Newfoundland: Since 75% of the cod’s diet is capelin, what would be assumed? What is the reality?
- their population should increase when cod went very low, but that’s not what happened
- part of a very complex food web
- only ones in the middle of the food chain = “Wasp Waist” is the Capelin
- There will always be another predator to eat them
Ashley Tripp-Atlantic Cod of Newfoundland: What is the life history of the capelin?
- Egg, larvae, metamorphosis, juvenile, adult
- Mortality (most) happens when they are younger
- as they get older, their life expectancy increases
- More larvae=more adults that will survive (correlated)
- BUT, more eggs does not mean more larvae!!!
- Year class strength determined by 2 weeks post-hatch
- Short lived fish=only a few year classes
- High natural fluctuations in population size (+ or - 40 percent)
- **Spawning Habitat quality is what is dependent on whether their will be high survivorship or not
Ashley Tripp-Atlantic Cod of Newfoundland: More larvae means more ______, but more eggs does not mean more _________ for capelin.
adults
larvae
Ashley Tripp-Atlantic Cod of Newfoundland: What is the capein’s high survivorship or mortality dependent on?
spawning habitat quality
Ashley Tripp-Atlantic Cod of Newfoundland: How do capelin spawn?
- males release sperm in the water
- females release eggs and stick to sediment
Ashley Tripp-Atlantic Cod of Newfoundland: How are capelin’s spawning habitats chosen?
- suitable sediment
- temperature (2-12 degrees)
Ashley Tripp-Atlantic Cod of Newfoundland: Where do capelin usually reside and where do they go to spawn?
- stay in the beach then move into deeper waters during the summer to spawn
- females don’t throw all their eggs into one spawning site, they have multiple
Ashley Tripp-Atlantic Cod of Newfoundland: How do capelin eggs develop?
- delayed development depending on the temperature
- high temperatures=hatch earlier
- colder temperatures=delayed hatching
Ashley Tripp-Atlantic Cod of Newfoundland: What are larval tows used to figure out?
- Larval densities
- Larval prey densities (zooplankton)
- Predator densities
Ashley Tripp-Atlantic Cod of Newfoundland: What are beach cores used for?
- Egg densities
- Developmental stage
- Environmental conditions
Ashley Tripp-Atlantic Cod of Newfoundland: What is impacting capelin populations?
- Predators
- Spawning habitat qualities
- Temperature
- Prey
- Fisheries
Ashley Tripp-Atlantic Cod of Newfoundland: As body size of larvae increases, what happens to mortality?
- bigger is better
- larval mortality decreases as body size increases
Ashley Tripp-Atlantic Cod of Newfoundland: What does a later spawning time mean for the offspring of capelin?
- Less time to gain critical mass for the overwintering
- Longer time spent in the egg developing = decreased survival
Ashley Tripp-Atlantic Cod of Newfoundland: How does climate change affect capelin populations?
-there may no longer be any beach spawning due to being too hot for the eggs
Ashley Tripp-Atlantic Cod of Newfoundland: When higher trophic level fish becomes less abundant, we tend to do what?
we fish down the food chain
Ashley Tripp-Atlantic Cod of Newfoundland: What percentage of the biomass of the spawning stock should only be fished?
only 10% of biomass
Ashley Tripp-Atlantic Cod of Newfoundland: How can fish be aged?
using the otolith, a fish’s ear bone
Ashley Tripp-Atlantic Cod of Newfoundland: What does the larval otolith provide information about?
- age of the fish (counting rings in the bone)
- proxy for environmental conditions
- chemical signatures
Ashley Tripp-Atlantic Cod of Newfoundland: What does the adult otolith provide information about?
- microchem using laser ablation (production of individuals to the spawning stock biomass, the degree of exchange of individuals among geographically separated regions)
- can find important levels of concentrations of different elements/molecules
Ashley Tripp-Atlantic Cod of Newfoundland: How are whales identified?
- by unique markings on their tails (take pictures)
- whales are tagged on just before the dorsal fin
Ashley Tripp-Atlantic Cod of Newfoundland: Tagging whales allows us to collect what kind of information?
- record sound
- see what they are seeing
- see their food
- see their interactions
- see where they are in the water column
- gauge reaction to the tag