Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AqTech > Topic 7 > Flashcards

Topic 7 Flashcards

1
Q

List the characteristics of fish eggs

A
  1. Egg shape
  2. Egg size
  3. Oil globules
  4. Chorion
  5. Yolk
  6. Perivitelline spacewidth
  7. Embryonic characters
  8. Miscellaneous characters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the miscellaneous characters of fish eggs

A
  1. Presence/absence of inner/secondary mbm
  2. Cleavage pattern
  3. Size & no. of micropyle
  4. Biochemical analysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Egg shape

A
  • Mostly spherical

- Anchovies: ellipsoidal, Gobby: flattened, Demersal species: irregular & large egg mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Egg size

A
  • Range in size from 0.5 - 26 mm

- Vary with type of breeding strategy –> viviparous: larger eggs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Oil globules

A
  • Presence/absence, no., size, colour, position & pigmentation
  • Usually 1 oil globule found posterior to yolk sac (in some species, oil globule can move during embryonic development)
  • Can have multiple oil globules –> eventually merge into single globule (as embryo develops)
  • identification of demersal eggs (mainly): colour of oil globule
  • Presence of melanistic pigment: deep yellow/brown
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Purpose of oil globules

A
  • serve to give hydrostatic lift in freshwater eggs

- note: marine eggs maintain buoyancy to a lower energy cost through egg hydration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Chorion

A
  • Highly adapted to the env. conditions under which embryo develops
  • Smoothness
  • Types of ornamentation: projections, threads, filaments, stalks –> aid in flotation (pelagic) or attachment (demersal)
  • Pelagic eggs –> thin chorions in relation to egg diameter; demersal eggs: thicker chorions
  • Colour (golden, pink tint)
  • Coating can be gelatinous or adhesive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Purpose of chorion

A
  • Attracts & activates spermatozoa for fertilisation
  • Prevent polyspermy upon fertilisation (hardening of chorion)
  • Protect developing embryo
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Yolk

A
  • Degree of yolk segmentation
  • Colour (opaqueness)
  • Pigmentation
  • Circulation pattern –> identify demersal eggs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Perivitelline spacewidth

A

Most have narrow to medium width perivitelline space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Embryonic characters

A
  • Embryonic pigment in late stages

- Pigment bands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Hippoglossoides dubius (Flathead Flounder)

A 
Egg diameter: 1.5 - 1.7mm
Oil globule: many 
Egg mbm: smooth
Property: Pelagic
Perivitelline space: wide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Eopsetta grigorjewi (Shotted Halibut)

A 
Egg diameter: 1.0 - 1.1
Oil globule: None
Egg mbm: smooth
Property: Pelagic
Perivitelline space: Narrow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pleuronichthys cornutus (Ridged-eye flounder)

A 
Egg diameter: 1.1 - 1.2
Oil globule: Single
Egg mbm: Sculptured
Property: Pelagic
Perivitelline space: Narrow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Pleuronectes yokohamae (Marbled flounder)

A 
Egg diameter: 0.8 - 0.9mm
Oil globule: None
Egg mbn: Smooth
Property: Demersal
Perivitelline space: narrow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pelagic vs Demersal eggs

A

Pelagic eggs: generally thin, homogeneous chorion; yolk is homogeneous, cleave relatively fast.
Demersal eggs: usually thick, more complex chorion which is more resistant to mechanical damage.

17
Q

How to determine which Zoea stage a mangrove crab is at?

A 
Identification of no. of setae on maxilipeds (modified mouth parts)
Zoea 1: 4 setae 
Zoea 2: 6 setae
Zoea 3: 8 setae
Zoea 4: 10 setae
Zoea 5: 12 setae
18
Q

If water quality poor (larval mangrove crab)

A

There is 6 stages of Zoea and in the event of poor water quality, the larval will enter Zoea 6. Zoea 6 has a different morphology

19
Q

Change in morphology: megalopod

A
  • Body flattened, retracted telson, legs start to grow to the side
  • May cannibalise one another so shelter & large SA required to ↓ mortality
20
Q

Mortality during first larval feeding (mangrove crab)

A
  • Unavailable food source/Inappropriate food source –> spawning earlier than usual
  • Newly developed digestive organs + absence of enzymes –> cannot digest
  • Size of live feed (not small enough)

Results in starvation & weakened individuals

21
Q

What happens if a larval crab misses the window period to become next stage?

A
  • Will die within the next few days
  • Lack of energy/nutrients –> cannot grow to the next stage
  • If remain at one stage for too long, energy required for advanced physiology will be even more & harder to catch up with the ontogenetic changes
22
Q

General timeline for feeding of larval/juvenile crab

A

Microalgae: 0 - ∼45 days
Rotifers: 0 - 9 days
Artemia: 7 - 21 days
Seafood paste: 18 - ∼ 45 days

23
Q

List the environmental factors affecting survival of juveniles

A
  1. Light availability
  2. Photoperiod
  3. Light intensity
  4. Aeration
  5. Dissolved oxygen
  6. Salinity
  7. Temperature
  8. Food availability
24
Q

Light availability (environmental factors affecting survival of juveniles)

A

2 protocols

  1. Lighted environment using rotifers as first feeding & adding microalgae
    - Microalgae exists as greenwater (contrast so can see better)
    - Concurrent rotifer culture within
  2. “French Technique”
    - Rear post larvae in dark env during first few days after hatching
    - Feed with live feed as 1st food
25
Q

Photoperiod (environmental factors affecting survival of juveniles)

A
  • Inverse r/s w water temp –> post-larvae reared at low water temp require longer photoperiod
  • Low temp retard growth due to ↓ed metabolism –> need to extend predatory feeding to ↑ larval growth
  • 10 - 15 mins of twilight –> prevent stress arising from abrupt switch in light intensity
26
Q

Light intensity (environmental factors affecting survival of juveniles)

A
  • Differ among species

- Initate predatory behaviour in some fishs (e.g. gilthead seabream)

27
Q

Aeration (environmental factors affecting survival of juveniles)

A
  • Creates water circulation to suspend post-larve & live feed
  • Mix tank water
  • Avoid strong aeration during first feeding & development of swim bladder –> result in gas-bubble dz
28
Q

Dissolved oxygen (environmental factors affecting survival of juveniles)

A
  • provided during water change/aeration
  • maintain 80% saturation (may affect physiology if below)
  • Addition of microalage –> maintain DO; photosynthesis in light but DO may drop at night time
  • Water change at night –> remove catabolites & maintain optimal DO
  • Alternative: injection of pure liquid oxygen
29
Q

Salinity (environmental factors affecting survival of juveniles)

A
  • Change in salinity –> affect metabolism
  • Ability to tolerate & overcome salinity differences –> maintain homeostasis
  • Osmoregulation –> energetically costly process –> not enough energy to grow
30
Q

Temperature (environmental factors affecting survival of juveniles)

A
  • ↑ed temp influences rate of metabolism
  • Enhanced growth rate in ↑ing temp
  • Detrimental effects beyond 40°C –> pejus temp reached: max temp at which max rate of physiological process is observed
31
Q

Food availability (environmental factors affecting survival of juveniles)

A
  • Maintain high prey density –> stimulate predatory actions + initiate first feeding
  • Improve survival possibilities
  • Response differ among species (active predators vs less active predators)
  • Take into account species’ feeding behaviour, food ingestion & assimilation
32
Q

Husbandry for mangrove crab

A
  • Water current required –> zoea are planktonic larvae & need to be kept suspended
  • Twitching zoea –> may be dying OR undergoing metamorphosis
  • Good water quality: 22ppt, Disinfected seawater,, aeration, 50% water change
  • Provide shelter to ↓ predatory stress
33
Q

Problems in hatchery: crab

A
  1. Loss of berried eggs on female during incubation (unknown reasons)
  2. Infestation of endoparasites (biosecurity breach) –> reduced health of female crab & quality of larvae
  3. Death amidst molting
34
Q

Sources of risk: Feed

A
  • ↑ in dz occurrence globally –> human activities & climate change
  • Pathogens jump hosts/host shift
  • Tpt accelerated global movement of species (air tpt)
  • brings pathogens & previously unexposed host populations tgt

E.g. By-catch or fish used for fish feed harbour pathogen

  • (if frozen) virus contained in thawed water & body fluids of the fish –> released during thawing (if thrown directly in)
  • Free virus released in env through live fish & seabird faeces (bird eat sick fish + bird travel long dist –> spread further)
  • Virus contained in the tissues of fish consumed by other fish
35
Q

Source of risk: infected wild stock

A
  • ↑ stocking density –> infections likely to occur
  • Pathogen infect wild indivs (interaction, open aquaculture system)
  • Infected wild indivs caught & brought back to hatchery/used as feed
  • Intrduction of pathogens into hatchery
36
Q

Source of risk: Malfunction of systems within facility

A
  • UV lights not working –> no chemical filtration

AqTech (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions