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Marine Lifecycles > Smoltification > Flashcards

Smoltification Flashcards

1
Q

Define Anadromicity

A

when an organism migrates up river (from the sea) to spawn

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2
Q

What is the parr-smolt transformation governed by?

A

Endogenous Rhythm and Exogenous cues

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3
Q

What is the parr-smolt transformation?

A

A process where salmon change from a freshwater fish into a seawater fish by changing their physiology, biology, behaviour and biochemistry

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4
Q

What do environmental cues do (in references to p/s)

A

environmental cues cause a biological cascade which causes the endocrine system to influence biological functions.

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5
Q

What are the two environmental cues that trigger the p/s transformation?

A
  1. Photoperiod

2. Temperature

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6
Q

When is the decision to smolt made?

A

In conditions where the photoperiod is decreasing

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7
Q

When is the p/s transformation complete?

A

When the photoperiod starts to increase

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8
Q

What is meant by the term photoperiod?

A

The amount of light available

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9
Q

How does temperature influence the p/s transformation?

A

A higher temp increases the growth rate (within reason - if too high enzymes denature and the fish dies)

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10
Q

Atlantic salmon come up stream to hatch - where they hatch depends on …….?

A

Temperature and Latitude

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11
Q

How long does it take for the eggs to hatch once they have been laid? And what months of the year?

A

70-160 days, from march through june

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12
Q

What is the name for the salmon (once hatched) and just had its first feed?

A

Alevins

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13
Q

They become … over time (before migration but in FW)

A

Parr

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14
Q

Whan do they begin the p/s transformation?

A

in their 2nd year

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15
Q

What is the name for the salmon when they migrate out to SW?

A

Smolt

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16
Q

How long do they stay in SW as smolts for?

A

3 - 5 years

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17
Q

What happens after 3-5 years?

A

They migrate back to FW to spawn

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18
Q

When do the salmonids become sexually mature?

A

During the migration from saltwater back to freshwater

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19
Q

What environmental cue induces the transformation?

A

The photoperiod

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20
Q

What does temperature do (with regards to the transformation)?

A

It is the modulator so it increases or decreases the acceleration of inhibition

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21
Q

What is meant by the ‘Peak of Smoltification’?

A

When the organism can move into saltwater without any problems

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22
Q

What is meant by ‘The Smolt Window’?

A

The time period when the organism is susceptible to increased light (Feb/Mar)

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23
Q

What does the smelt window depend on?

A

Population and Location

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24
Q

The fish need to …….. … …………. …… to …………. to environmental cues

A

Need to be a certain size to respond

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25
Q

When is the size window?

A

Around August

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26
Q

What happens if the parr is too small at the time of the size window?

A

They will wait another year

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27
Q

What do fish farmers use to farm salmon?

A

They use photoperiod controlled smoltification

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28
Q

What does this controlled photoperiod smoltification cause?

A

out of season smoltification

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29
Q

What happens in the hatcheries?

A

They expose the newly hatched fish to 24hour sunlight and excess food for growth

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30
Q

How much is the growth rate increased compared to the wild in fish farming?

A

double the growth rate

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31
Q

By increasing the growth rate in fish farming what happens?

A

it means the fish smelt early on

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32
Q

Phototreatment is initiated to simulate winter- how long is this simulation and what are the hours of light vs dark?

A

6 weeks - 18 hours of dark and then 6 hours of light

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33
Q

Phototreatment is initiated to simulate spring- how long is this simulation and what are the hours of light vs dark?

A

6 weeks - 6 hours or dark and 18hoursof light

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34
Q

When does the winter period start and finish?

A

Sept - Oct

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35
Q

When does the spring period start and finish?

A

Oct - Nov

36
Q

What happens at the end of November (in fish farming)?

A

The salmon are now smolts and can be transferred into SW

37
Q

How does the transformation begin (with reference to endocrine)

A

Endocrine system senses environmental cues and changes start

38
Q

What do receptors trigger in the endocrine system?

A

Receptors trigger T3 and T4 thyroid hormones, Cortisol, growth hormone, ICF-1 all to increase and trigger prolactin to decrease

39
Q

What is the main endocrine tissue and where is it located?

A

The pituitary gland is located just outside the blood-brain barrier

40
Q

What is the main endocrine tissue controlled by?

A

The hypothalamus

41
Q

The hypothalamus connects with nerves and releases into…?

A

the posterior pituitary

42
Q

What happens in the posterior pituitary?

A

signalling molecules are secreted into the bloodstream; Neuroendocrine secretion of hormones via the posterior pituitary via hypothalamus

43
Q

What type of secretion occurs in the posterior pituitary?

A

neuroendocrine secretion

44
Q

What type of secretion occurs in the anterior pituitary?

A

Hormone secretion

45
Q

What happens in the anterior pituitary

A

controlled release of inhabitation of the hormones into the blood stream

46
Q

What do endocrine tissues in the pituitary release?

A

growth hormone, thyroid hormone, corticotropin, gonadotropin, prolactin

47
Q

What is GHRH

A

Growth hormone releasing hormone

48
Q

What is TRH

A

Thyroid releasing hormone

49
Q

What is CRH

A

Corticotropin releasing hormone

50
Q

What is GRH

A

gonadotropin releasing hormone

51
Q

What is GHIH

A

Growth hormone inhibiting hormone

52
Q

What is PIH

A

Prolactin inhibiting hormone

53
Q

What does the hypo-pituitary GH (IGF-1) affect?

A

Growth and SW tolerance

54
Q

What does the hep-pituitary interrenal axes affect?

A

SW tolerance by stimulating physiological changes

55
Q

What does the hypo-pituitary thyroid do?

A

The hypothalamus contains TRH which is released and stimulates the anterior pituitary to release TSH (thyroid stimulating hormone)

56
Q

What does TSH do?

A

stimulates the production of T3 and T4

57
Q

What is T3 used for?

A

The metabolism

58
Q

What is T4 used for?

A

Growth

59
Q

What chemical do T3 and T4 depend on?

A

Iodine

60
Q

What does NIS stand for?

A

Na+ Iodine symporter

61
Q

What does NIS do?

A

Transport Iodine into the epithelial cells (lining the colloid) where it is oxidised (from -ve to +ve Iodine) and moved into the colloid

62
Q

Where is the +ve iodine stored?

A

In the colloid located in the thyroid globulin (T4) until needed

63
Q

What happens when thyroid hormones are needed?

A

Iodine is arranges into T3 or T4 and secreted into the blood

64
Q

Which of the thyroid hormones is secreted the most?

A

T4

65
Q

T3 has a …… ……. to receptors on target tissues and thus higher ………..

A

higher affinity

biological activity

66
Q

When T4 circulates in the blood stream, what happens in the cells?

A

It is de-ionized to T3 which is more biologically active

67
Q

How is thyroglobulin synthesised and what does it contain?

A

thyroglobulin is synthesises by thyroid epithelial cells and contains tyrosines

68
Q

How is Iodine transported into the lumen of the follicle?

A

by NIS

69
Q

What does thyroid peroxide do?

A

Thyroid peroxide catalyses the iodination of tyrosines on thyroglobulin and also catalyses the synthesis of thyroxine or triodothryonine from two iodotryosines

70
Q

What does cathepsin beta do?

A

Hydrolyses thyroglobulin into thyroxine and triiodothyronine that enters the blood

71
Q

Where is T4 produced?

A

In follicles

72
Q

T3 and T4 bind to the same receptors, true or false?

A

True

73
Q

What happens to T4 once it is in the peripheral tissues?

A

it is converted to T3

74
Q

What changes in behaviour do salmonids have when p/s transformation occurs?

A

They go from aggressive to schooling behaviour, and begin to rise from the gravel

75
Q

when p/s transformation occurs why does their swim bladder increase?

A

They will be swimming more and need it for bouyancy

76
Q

What changes in appearance do salmonids have when p/s transformation occurs?

A

they become silver and change shape to become slim and thin, losing their parr markings

77
Q

When the p/s transformation occurs there is a change in rheotaxis; what does this mean

A

This means that they start to seek out light and rise towards it.

78
Q

What changes in growth do salmonids have when p/s transformation occurs?

A

Increased growth
faster length growth
lower condition factor

79
Q

What is the equation for the condition factor?

A

weight/lenght

80
Q

How do the parr increase their SW tolerance to become a smolt

A

Decrease # FW chloride cells

Increase # SW chloride cells

81
Q

How do the parr decrease the number of FW chloride cells/increase the number of SW chloride cells?

A

Use NKA isoform alpha 1A to decrease FW

Use NKA isoform alpha 1B to increase SW

82
Q

Explain how the intestinal cell changes in the p/s transformation

A
  • Na+K+ATPase creates Na+ gradient
  • Na+ gradient drives the NKCC citrons to absorb K and 2Cl-
  • Cl- goes out via chloride channels
  • intestinal water uptake increases
  • Na+K+ATPase increases intestinal permeability as salt water drinking begins
83
Q

Why as a smolts is there decreased urinary production?

A

they are now hypo osmotic to their environment and so lose water so less urine production

84
Q

Intestinal absorption of water occurs mainly through the ……… route but the ………. route is also possible

A

paracellular

transcellular

85
Q

What do aquaporins do?

A

they increase the permeability across the phospholipid bilayer (essentially water channels)

Marine Lifecycles (3 decks)

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