Dispersal and migration Flashcards
Dispersal
Movement away from birth population to another location or population
Active or passive
Migration
active, cyclic mass movement of individuals among areas at predictable times
What are 3 different marine invertebrates dispersal types?
1) Direct release
2) Lecithotropich larvae
3) Planktotrophic larvae
What do lecithotrophic larvae feed on?
Yolk
What do planktotrophic larvae feed on?
Plankton: algae, bacteria, zooplankton
How do marine bony fishes disperse?
Disperse eggs and sperm
Which dispersal type has larger eggs?
Direct release > lecithotrophic > planktotrophic
Which dispersal type has the largest number of eggs?
Planktotrophic > lecithotropich > direct release
What is the size range of microscale?
cm to m
What is the size range of mesoscale?
m to km
What is the size range of macroscale?
100’s to 1000’s km
What do larvae do when settling?
1) use light cues to mantain depth
2) Use chemical and biological cues to choose final settling site
3) Settle on adults of the same species and avoid certain areas thanks to chemical cues
Some pre-settling problems of larvae:
1) Predation in plankton
2) Starvation
3) Loss to inappropriate habitat
Some post-settling problems;
1) Metamorphosis energy cost
2) Predation
3) Crowding increases mortality
Connectivity
Degree of interchange
Where does most larval exchange take place?
Along the coasts
Where is highest predation rate and what defense mechanisms do larvae have?
Estuaries, movable spines
What type of larvae is most dispersed?
Planktonic
Why do species disperse?
1) Habitat loss does not lead to extinction
2) Less chance of inbreeding
3) Spread over habitats
4) Food availability when phytoplankton bloom
5) Avoid overcrowding
How and why do planktonic organisms migrate vertically?
How: night at surface, day in depth, common in coastal or very deep waters
Why: Avoid predation and to save energy in cooler water
How is migration organised?
1) Spawning area -> dispersal -> 2) Nursery area -> Recruitment -> 3) Adult stock, feeding area -> spawning/feeding -> spawning area -> migration -> adult stock
Natal homing
Return or stay in birthplace
