Dispersal and migration

Question 1

Dispersal

Answer 1

Movement away from birth population to another location or population
Active or passive

Question 2

Migration

Answer 2

active, cyclic mass movement of individuals among areas at predictable times

Question 3

What are 3 different marine invertebrates dispersal types?

Answer 3

1) Direct release
2) Lecithotropich larvae
3) Planktotrophic larvae

Question 4

What do lecithotrophic larvae feed on?

Answer 4

Yolk

Question 5

What do planktotrophic larvae feed on?

Answer 5

Plankton: algae, bacteria, zooplankton

Question 6

How do marine bony fishes disperse?

Answer 6

Disperse eggs and sperm

Question 7

Which dispersal type has larger eggs?

Answer 7

Direct release > lecithotrophic > planktotrophic

Question 8

Which dispersal type has the largest number of eggs?

Answer 8

Planktotrophic > lecithotropich > direct release

Question 9

What is the size range of microscale?

Answer 9

cm to m

Question 10

What is the size range of mesoscale?

Answer 10

m to km

Question 11

What is the size range of macroscale?

Answer 11

100’s to 1000’s km

Question 12

What do larvae do when settling?

Answer 12

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

Question 13

Some pre-settling problems of larvae:

Answer 13

1) Predation in plankton
2) Starvation
3) Loss to inappropriate habitat

Question 14

Some post-settling problems;

Answer 14

1) Metamorphosis energy cost
2) Predation
3) Crowding increases mortality

Question 15

Connectivity

Answer 15

Degree of interchange

Question 16

Where does most larval exchange take place?

Answer 16

Along the coasts

Question 17

Where is highest predation rate and what defense mechanisms do larvae have?

Answer 17

Estuaries, movable spines

Question 18

What type of larvae is most dispersed?

Answer 18

Planktonic

Question 19

Why do species disperse?

Answer 19

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

Question 20

How and why do planktonic organisms migrate vertically?

Answer 20

How: night at surface, day in depth, common in coastal or very deep waters
Why: Avoid predation and to save energy in cooler water

Question 21

How is migration organised?

Answer 21

1) Spawning area -> dispersal -> 2) Nursery area -> Recruitment -> 3) Adult stock, feeding area -> spawning/feeding -> spawning area -> migration -> adult stock

Question 22

Natal homing

Answer 22

Return or stay in birthplace