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ECOL111 - Population Biology Questions with Answers
(100% Correct Answers)
13. Ecosystem services by cockles Answer: - Filtering out particulate
water/ bacteria through in/excurrent channels using siphons and
mucus from glands
- Fossils have 20-30 year record of sea ice conditions
- Food for birds, fish, marine mammals
- Sediment stabilisation through pseudofaeces deposit and
bioturbation
- Shell material isotope analysis used to show water conditions/
productivity
- Increase benthic production and benthic-pelagic coupling
13. Case studies of cockles Answer: - NY Harbour lost bivalves from
petroleum and fire in hudson river
- Dutch Wadden Sea decline in subtidal beds of cockles causing
collapse of eider duck population and loss of filtering
© 2025 All rights reserved
,2
- Gulf of California reduced flow in Colorado River lead to bivalve
decline causing benthic productivity to decline
13. Causes of cockle decline Answer: - Nutrient pollution
- Diatom blooms and eutrophication (anoxic conditions)
- Fires/ Petroleum
- Recruitment failure/ high mortality rates
- Interspecific competition with more tolerant species Macoma balthica
13. Case Study of Fiordland (Doubtful Sound) Bivalve interactions
Answer: - Manapouri power station aided widespread decline of inner
fjord bivalves (none left in system, some in outer areas)
- Tunnel boring cause population isolation in fjords based on estuarine
circulation
- Prey based shifts in Jasus Edwardsii rock lobster due to lack of
bivalve prey
13. Management of bivalves Answer: Based on biomass growth rather
than ecological importance or role are ecosystem service provider
© 2025 All rights reserved
, 3
14. Population Answer: A group of organisms that have connectivity
across time and space
14. Difference between Open and Closed populations Answer: Closed
populations are when the members of the population are fixed (no
emi-/immigration) and are thus easier to predict population increase
and changes using predictive models.
Open populations are dynamic (not fixed) and immigration is random
and from unknown sources.
14. Example of Open Population Answer: Spiny Rock Lobsters (jasus
edwardsii) - highly migratory, planktonic stage with moults lasts to 18
months and can travel 100,000kms with recruitment and settlement
location related to oceanographic conditions.
14. Example of closed population Answer: Kakapo originally ranged
through mainland NZ before decline from fragmented populations
(first indicator), changes in native tree masting and introduced
mammalian predators confined them to Codfish and a few other
protected islands.
© 2025 All rights reserved
ECOL111 - Population Biology Questions with Answers
(100% Correct Answers)
13. Ecosystem services by cockles Answer: - Filtering out particulate
water/ bacteria through in/excurrent channels using siphons and
mucus from glands
- Fossils have 20-30 year record of sea ice conditions
- Food for birds, fish, marine mammals
- Sediment stabilisation through pseudofaeces deposit and
bioturbation
- Shell material isotope analysis used to show water conditions/
productivity
- Increase benthic production and benthic-pelagic coupling
13. Case studies of cockles Answer: - NY Harbour lost bivalves from
petroleum and fire in hudson river
- Dutch Wadden Sea decline in subtidal beds of cockles causing
collapse of eider duck population and loss of filtering
© 2025 All rights reserved
,2
- Gulf of California reduced flow in Colorado River lead to bivalve
decline causing benthic productivity to decline
13. Causes of cockle decline Answer: - Nutrient pollution
- Diatom blooms and eutrophication (anoxic conditions)
- Fires/ Petroleum
- Recruitment failure/ high mortality rates
- Interspecific competition with more tolerant species Macoma balthica
13. Case Study of Fiordland (Doubtful Sound) Bivalve interactions
Answer: - Manapouri power station aided widespread decline of inner
fjord bivalves (none left in system, some in outer areas)
- Tunnel boring cause population isolation in fjords based on estuarine
circulation
- Prey based shifts in Jasus Edwardsii rock lobster due to lack of
bivalve prey
13. Management of bivalves Answer: Based on biomass growth rather
than ecological importance or role are ecosystem service provider
© 2025 All rights reserved
, 3
14. Population Answer: A group of organisms that have connectivity
across time and space
14. Difference between Open and Closed populations Answer: Closed
populations are when the members of the population are fixed (no
emi-/immigration) and are thus easier to predict population increase
and changes using predictive models.
Open populations are dynamic (not fixed) and immigration is random
and from unknown sources.
14. Example of Open Population Answer: Spiny Rock Lobsters (jasus
edwardsii) - highly migratory, planktonic stage with moults lasts to 18
months and can travel 100,000kms with recruitment and settlement
location related to oceanographic conditions.
14. Example of closed population Answer: Kakapo originally ranged
through mainland NZ before decline from fragmented populations
(first indicator), changes in native tree masting and introduced
mammalian predators confined them to Codfish and a few other
protected islands.
© 2025 All rights reserved
