Lecture 17 Flashcards
What is ranging behaviour?
Where they go to forage
What is foraging itself?
What they do when they get there e.g. who do the animals actually catch their prey. Depend on the species
What are the issues of foraging in the sea?
. Navigating in a featureless environment
. Spatial distribution of prey (not evenly distributed)
. Environmental factors e.g. tide, ocean currents (could be faster than they can swim- to have to contend with this or poss utilise)
. Prey disturbed vertically as well as horizontally
. Prey are not normally visible from the surface
. Physiological limitations (related to the fact that they are diving- have to hold their breath- limit to how long they can stay submerged for)
Why is oceanography important?
Determines the location of the food:
- sides of primary production (plants)
. Winter vs summer (changes in productivity and sunlight levels) (south vs north)
. Depth in water column (deeper=less likely to have primary produces)
. Stratification
- nutrients
. N, Si, Ph, Fe
- where food gets aggregated or concentrated
. Prey isn’t homogenous
. Prey is patchy
. Need to locate optimal prey patches (if predator- come back to the same place/ remember)
What is the oceans surface circulation major current dominated by?
. Gyres
. Wind patterns e.g. build up, could use this if you were a bird
Give some oceanographic features
. Coastal upwelling . Bathymetry . Fronts . Eddies (Impact whether the nutrients are coming up to the herbivores)
What are coastal upwellings driven by?
Wind
What is the oceanographic feature bathymetry? (What is it caused by, where)
Upwelling caused by currents and bottom structure- changes in the underlying topography of the marine landscape
. Galapagos
. Seamounts
. Continental shelf edge
What is the oceanographic feature fronts? Explain
Temperature salinity discontinuously
Is different bodies of water coming together
If you have a low and high salinity water coming together the low salinity will sit on top because it is less dense
What is the oceanographic feature eddies? (What are they and what are they a result of)
. Result from circulation patterns
. Warm and cold core rings and jets
Where do upwellings tend to be? What are they linked to?
Coastal regions
Linked to tidal features and wind
What do gyres transport?
Nutrients to shallow waters- primary production here and brings lots of animals (predictable)
What does sea surface temperature link to?
The availability of resources for the primary producers
more in cold water then warm
How often do El Niño events take place?
Every 5-10 years
What is La Niña closes to?
Normal surface temperature and currents (cold water extends from South America to the Pacific- opposite in El Niño. Impacts cold formation)
Give an example of species that’s breeding season fails in El Niño years
Seals and birds
What is a time-depth recorder used for?
Records pressure- at the surface the pressure in 1atmosphere less than when animals dive down. So if you can monitor that change in pressure then you can monitor how deep the animals are going (usually have a gps)
As shown by time-depth recorders how does sea surface temperature affect seal behaviour? Give an example of a year when this happened
When they had a warm water anomaly in 2005 seals changed where they went and at what time and how deep they dived- went further out
What does oceanographic features affect?
(. Work at different scales
. Wide variety of oceanographic features)
. Linked to productivity
. Ultimately linked to food- drive the food chain
What is the new idea for how we can sample the water column at great depths?
Using animals such as elephant seals and attaching devices to them (movements of higher predators in the Pacific Ocean)
Define the diving behaviour diving
Period of submersion- 3 components:
. Descent
. Bottom time = foraging time (some sea floor, some not)
. Ascent
Define the diving behaviour surface
Time spent at surface between dives (maybe the breath or rest- elephant seals rest under water) (missed foraging time)
Define the diving behaviour dive cycle
Dive plus surface
Define the diving behaviour dive bout
A group of dives (before taking a break) (recovering/ preparing for a dive)
