Lecture2_LifeCycles

Question 1

What are the Ecological Advantages of pelagic Larvae?

Answer 1

Decrease food competition
exploit plankton food sources
enable dispersal and colonization
escape benthic predators

Question 2

What factors influence population variability in marine species?

Answer 2

Life history strategies
demographic characteristics
recruitment variability
environmental influences
exploitation effects
external factors such as pollution

Question 3

What are the types of larval development Strategies

Answer 3

Direct Development
Planktonic Larvae
Lecithorophic Larvae

Question 4

What characterizes direct development in marine larvae? What is an example of one?

Answer 4

Minimal/No pelagic phase
larvae resemble adults
low dispersal potential
Ex. Cephalopods

Question 5

What are the main features of planktootrophic larvae? What is an example of one?

Answer 5

Feed during pelagic phase
longer dispersal distances
most common larval type
ex. Benthic inverts such as Rock Lobsters

Question 6

What are the main features of Lecithotrophic larvae? What is an example of one?

Answer 6

Gets nutrition from yolk sac
doesn’t feed in water column
short pelagic stage
ex. many fish species

Question 7

How long is the Tropical Rock Lobster’s larval phase? Why does that influence the fishery?

Answer 7

Very long larval phase, 9-11 months.

Larvae are mopped up and counted then released, those become market ready in 3 years providing accurate future biomass estimates

Question 8

What are the three main developmental stages in larval fish?

Answer 8

1. Embryonic: development stars in a protective membrane (egg/embryo) after fertilization
2. Larval: marked by significant growth/development. Highest mortality here
3. Juvenile: Metamorphosis occurs. Fish resembles adult fish. Often migrating from planktonic to benthic/reef

Question 9

What occurs during fish metamorphosis?

Answer 9

Adult structural and behavioural changes

development of caudal fin rays

transition from pelagic to demersal environments

Question 10

What environmental factors critically affect larval development?

Answer 10

1. Temperature: affects growth rate
2. Food availability
3. Habitat quality

Question 11

what does Pelagic Larval Duration (PDL) influence?

Answer 11

important implications for recruitment, distribution and connectivity

Question 12

What is the SAAB Hypothesis?

Answer 12

Larvae use sensory navigation including odor, sound, visual, and geomagnetic cues to locate estuarine habitats

Question 13

According to SAAB what are the two main navigation strategies in marine larvae?

Answer 13

Infortaxis: offshore searching

Rheotaxis: directional swimming towards estuarine cues

Question 14

What is the difference between semelparous and iteroparous reproduction?

Answer 14

Semelparous involves single reproduction while iteroparous involves multiple reproductions in a life time

Question 15

What are the pros/cons of Dispersal vs Retention larval strategies in reef fish?

Answer 15

Dispersal refers to the movement of larvae across large distances, typically driven by ocean currents. It increases genetic diversity and colonization potential, but risks higher predation and unfavourable environments

Retention involves larvae staying relatively close to their spawning site. This increases survival by guaranteeing suitable conditions with less predation, but decreases genetic diversity and colonization potential

Question 16

What does the “Lottery Hypothesis” state recruitment depends on

Answer 16

1. Adequate supply of larvae (large spatial scale process)
2. Adequate habitat (small spatial scale process)

Question 17

What is a life history strategy?

Answer 17

a set of traits resulting from natural selection

Any characteristic that affects the survival and reproduction of an animal is by definition, a part of the life history pattern of a species

Question 18

What characterizes r-selected species?

Answer 18

Rapid reproduction
many offspring with lower survival rates
short life cycles

Question 19

What characterizes K-selected species?

Answer 19

Fewer offspring with high survival rates
parental care
slower growth

Question 20

What are r-selected species environments associated with?

Answer 20

Unpredictable/fluctuating

Resources are abundant but there is competition or environmental unpredictability.

ie exploiting temporary resources

Question 21

What are k-selected species environments associated with?

Answer 21

K-selected species thrive in stable environments/predicatable with limited resources and
intense competition.

Question 22

What are the three typical population growth phases?

Answer 22

1. Logarithmic/exponential growth phase with many resources. Density Independent
2. Transitional or declining growth phase
3. Stationary Phase: Population reaches carrying capacity, limited resources and intense competition. Density dependent

Question 23

What is carrying capacity (k)?

Answer 23

Refers to the maximum population size an environment can sustain.

Question 24

What are the main density-dependent population regulation mechanisms?

Answer 24

Growth plasticity
reproduction adaptation
size-selective predation
cannibalism
territoriality
stress responses
disease management

Question 25

What are density dependent mechanisms?

Answer 25

population regulation through changes in birth and death rates