Chapter 17
Diurnal vertical migration
? Diurnal vertical migration is a very
common phenomenon,
? A few examples
Changes in the abundance of the copepod Calanus finmarchicus in
the surface,between 06:00 and 14:00 h during 6 weeks from 21st
June to 11th August,1991,off Californian coast
§ 17.1 Characteristics diurnal vertical
migration of zooplankton
? samples of night plankton at the
surface are notably different from
those taken during the day,not
only in their faunistic composition
but also quantitatively.
? The number of ind,colleted in the
surface layers become ten times
higher between 16:00 and 20:00pm.
? The only possible explanation of
these variations is vertical
migration,representing a rhythm of
24h.
Diurnal vertical distribution of the copepod C,finmarchicus
females in Loch Fyne,Clyde Sea,Scotland
? Distribution as a function
of the time and maximum
depth sampled where the
copepod Gaussia
princeps is found,solid
line,regression curve:
z=zo+a cos wt
= 487-230 cos wt.
? Vertical distribution of the
copepod C,finmarchicus
from the 14th to 16th July,
1933 in Georgia Bank
? Top,females
? Medium,Copepodid V
? Bottom,Females on 17th
and 18th July 1933
Distance of DVM in some
planktonic crustacea
Groups species Distance of DVM (m)
Cladocera Daphnia longispina 0.6
Copepods
Diaptomus shoshome
Calanus finmarchicus
Pleuromamma robusta
Metridia pacifica
8.8
About 100
>600
400-500
Mysis Boreomysis microps
Eucopia unguiculata
400
400
Hyporiid Vibia propinqua 400
Euphausiid Nematoscelis megalops
Thysanopoda acutifrons
200
600
Pattern of the migration
? Chusing (1951) analysed all the work on crustacea and
considered that it is possible to arrange their patterns of
migration in the following general scheme:
1,Rising in the evening from the,day depth” towards the
surface
2,Departure from the surface at about midnight or before it
3,Rising to the surface just before dawn
4,Rapid sinking at dawn to the,day depth”
5,Remaining during the day at a,day depth” more or less
variable
§ 17.2 Causes of diurnal migration
1,Light intensity is of primary importance.
? The observations on DVM at high latitudes where
during part of the year there is no alternation
between days and nights gives a kind of,natural”
experiment,
? Calanus and other principal species of the
zooplankton remain in the superficial layer of water
without migration
? this also appears again in winter with the return of the
change of day to night,During the winter night
calanus stays in the depths at a constant level,
Hypothesis of
phototaxis
2,rather large variations around the optimal light
intensity,This species is called,eurylume”
species.
The zooplankton seem to stay at an optimal light
intensity and show a negative phototaxis above certain
levels and positive one below that level.
Hypothesis of
Optimal
light intensity
3,Animals must rise to surface in a certain
time avoiding of sinking to bottom due to
gravity
Rising is active,and sinking is passive,Migration
is a kind of diurnal alternation of periods of
activity and inactivity,
geotaxis
4,Feeding and avoiding fed
? Zooplankton rises upper layer for Phytoplankton at
dark night,
? Zooplankton sinks to bottom where the light is dim
for avoiding fed at daytime.Hypothesis
of food
In summary of the DVM reasons
? Light is without any boubt the fundamental factor,
? Temperature is an important accessory factor
? Pressure and gravity are auxilliary factors which may
probably not e neglected.
? Avoiding fed and active feeding.
? Biological behavior,for example,the existence of an
internal biological rhythm,must also be considered
Diurnal vertical migration
? Diurnal vertical migration is a very
common phenomenon,
? A few examples
Changes in the abundance of the copepod Calanus finmarchicus in
the surface,between 06:00 and 14:00 h during 6 weeks from 21st
June to 11th August,1991,off Californian coast
§ 17.1 Characteristics diurnal vertical
migration of zooplankton
? samples of night plankton at the
surface are notably different from
those taken during the day,not
only in their faunistic composition
but also quantitatively.
? The number of ind,colleted in the
surface layers become ten times
higher between 16:00 and 20:00pm.
? The only possible explanation of
these variations is vertical
migration,representing a rhythm of
24h.
Diurnal vertical distribution of the copepod C,finmarchicus
females in Loch Fyne,Clyde Sea,Scotland
? Distribution as a function
of the time and maximum
depth sampled where the
copepod Gaussia
princeps is found,solid
line,regression curve:
z=zo+a cos wt
= 487-230 cos wt.
? Vertical distribution of the
copepod C,finmarchicus
from the 14th to 16th July,
1933 in Georgia Bank
? Top,females
? Medium,Copepodid V
? Bottom,Females on 17th
and 18th July 1933
Distance of DVM in some
planktonic crustacea
Groups species Distance of DVM (m)
Cladocera Daphnia longispina 0.6
Copepods
Diaptomus shoshome
Calanus finmarchicus
Pleuromamma robusta
Metridia pacifica
8.8
About 100
>600
400-500
Mysis Boreomysis microps
Eucopia unguiculata
400
400
Hyporiid Vibia propinqua 400
Euphausiid Nematoscelis megalops
Thysanopoda acutifrons
200
600
Pattern of the migration
? Chusing (1951) analysed all the work on crustacea and
considered that it is possible to arrange their patterns of
migration in the following general scheme:
1,Rising in the evening from the,day depth” towards the
surface
2,Departure from the surface at about midnight or before it
3,Rising to the surface just before dawn
4,Rapid sinking at dawn to the,day depth”
5,Remaining during the day at a,day depth” more or less
variable
§ 17.2 Causes of diurnal migration
1,Light intensity is of primary importance.
? The observations on DVM at high latitudes where
during part of the year there is no alternation
between days and nights gives a kind of,natural”
experiment,
? Calanus and other principal species of the
zooplankton remain in the superficial layer of water
without migration
? this also appears again in winter with the return of the
change of day to night,During the winter night
calanus stays in the depths at a constant level,
Hypothesis of
phototaxis
2,rather large variations around the optimal light
intensity,This species is called,eurylume”
species.
The zooplankton seem to stay at an optimal light
intensity and show a negative phototaxis above certain
levels and positive one below that level.
Hypothesis of
Optimal
light intensity
3,Animals must rise to surface in a certain
time avoiding of sinking to bottom due to
gravity
Rising is active,and sinking is passive,Migration
is a kind of diurnal alternation of periods of
activity and inactivity,
geotaxis
4,Feeding and avoiding fed
? Zooplankton rises upper layer for Phytoplankton at
dark night,
? Zooplankton sinks to bottom where the light is dim
for avoiding fed at daytime.Hypothesis
of food
In summary of the DVM reasons
? Light is without any boubt the fundamental factor,
? Temperature is an important accessory factor
? Pressure and gravity are auxilliary factors which may
probably not e neglected.
? Avoiding fed and active feeding.
? Biological behavior,for example,the existence of an
internal biological rhythm,must also be considered
