topic 12

Question 1

how does aphotic orgaisms survive

Answer 1

relies on food produced in the surface-dead organisms-photic is opposite

Question 2

nutrient availability in aphotic and photic zones

Answer 2

low phosphate levels-not soluble
runoff into photic zone+upwellibg

Question 3

freshwater productivity

Answer 3

total productivity is higher but limited by small total area

Question 4

demersal fishing -2 types

Answer 4

demersal long lining-line oif baited hookks
demersal trawling-

Question 5

pelgoic fishing types

Answer 5

trawling-tuna is example
drift nets-long net that trap fish
purse seining-net around shoal of fishboat goes around shoal and pulled tight underneath-trapping fish
long lines

Question 6

environemental impacts of fishing

Answer 6

k selected specie decline-reach sexual maturity at older age-orange roughy-20 years
overfishing could remove breeding populations

Question 7

issues with byctachfor each type of fishing

Answer 7

Immature fish aare too small to sell
Catch quota may already have been reached-so thrown away
Drift net bycatch-non selective-shark
Pelagic long line-albatross-k selected
Pelagic trawling-trap predators in nets
Demersal-high chance of mixed species
shrimp bycatch-small netting lagrer fish unable to escape

Question 8

habitat damage

Answer 8

dynamite fishing-stuns fish-used in coral reefs
food chain impacts
se\bed damage-demersal trawling
sea grass beds-trawling may cause disturbance -increased sedimentation-harder for new plants to colonis-important for fishing nursery

Question 9

how to reduce environmental impacts((

Answer 9

catch quotas
fishing euipment and design-
-mesh size
TEDS-escape panels for turtles
dolphin pingers
hook shape-curved tip hooks-tuna instead of albatross
night fishing-no birds
biodegradbel-redues ghost fishing

Question 10

restricted fishing methods

Answer 10

ban drift nets
bans on demersal trawling
NTZs-no take zones
closed seasons-allowing fish to grow to a large size

Question 11

p.t 2 restricted fishing methods

Answer 11

maximum catchable size
protevted individuals-female lobsters carrying eggs
captove breeding and release-

Question 12

popultain dynamiccs

Answer 12

breeding rates-carrying cap[acity
asult mortality rate
adult population
overfishing
MSY

Question 13

russell formula

Answer 13

s2=s1+(aA+G)-(C+M)
biomass at end
biomass-beg. year
yong fish added-biomass
biomass added by growth
caught by fishing
lost through mortalilt

Question 14

why is collecting data difficult

Answer 14

uneven spread of fish population
they are mobile
need a large sample size to be proportional to the total area

Question 15

data from fishing catches

Answer 15

mean fish size-reducing fish size may show that adult pop. is dclining

Question 16

data from research what it shows

Answer 16

shows the likelihood of a sudden collapse
colllecting data on planktonic fish eggs-nummber of fish likely to be recruited -allows to aniticpate th elowering of the MSY

Question 17

Factors affecting aquaculture specie selection

Answer 17

local conditions
market demand
disease res.
rapid growth rate
good apperance
gender control-hormonally when young-rainbow trout-better flavour female-still produce milt but only produces female offspring

Question 18

control of pests and disease

Answer 18

cirulating currents-less contact between fish- less pathogens
low stock density+pesticides
wrasse to kill lice

Question 19

competition and predation

Answer 19

fencing+netting-
liscence to cull seald

Question 20

control of abaiot ic factors

Answer 20

temperature-
dissolved 02-removal of faecal matter
day length-longer day lengths-de;ays maturation-larger-salmon
water flow-reduces collisions-less pathogens

Question 21

control of limiting factors in salmon aquaculture-

Answer 21

salmon need high 02-water sprays
using antibiotics reduces pathogens
food chain is controlled–low value pellets-sand eels

Question 22

polyculture

Answer 22

reaerinf species together increasing productivity

Question 23

example of a polyculture

Answer 23

IMTA
fed aquaculture-large
inorganic extractive aquaculture-absorb of inorganic nutrient seaweed
organic extractive aquaculture -species that catch food items such as plankton

Question 24

aquaponics

Answer 24

hydroponics+aquaculture
lettuce+tilapia

Question 25

increasing trophic efficeincy

Answer 25

herbivourous fish-tilapia
carnvorous more demand-low efficiency low basal metabolic rate

Question 26

FCR

Answer 26

food conversion rate

Question 27

environmental impacts of aqauculture and how to reduce

Answer 27

Habitat loss-mangroves-careful site selection
Antibiotic resistance -lower stock densities
Wild gene pool impacts-fish escape and breed with local pop.-brighter colour less likely to survive-put eggs under high pressure creating triploid fish-sterile-also bigger
organic waste-faecal matter surplus-deoxygenation-freshwater aquaculture systems have effluent treatment plants
food supply impacts-overfishing of wild pop.-sandeels-use more plant based products -herbivorous plants

Question 28

aircraft body design how it can be made to reduce noise

Answer 28

high bypass ratio engines-
2 cowlings allows airflow
smooths the follow of the air and reduces the noise