autumn vertical distribution of zooplankton in the eastern ... - IMBER

AUTUMN VERTICAL DISTRIBUTION OF ZOOPLANKTON IN THE EASTERN
TROPICAL MEXICAN PACIFIC IN RELATION TO OXYGEN, FOOD
AVAILABITY AND HYDROGRAPHY
Jaime Färber Lorda, Emilio Beier, Ignacio Romero,
Victor Godinez, Cesar Almeda, Jose Martín Hernandez 1, Ana Franco 1 Aramis Olivos 2.
0 División de Oceanología, CICESE, Ensenada, México
1 Universidad Autónoma de Baja California. Instituto de Investigaciones Oceanológicas, Ensenada, México
2 Universidad de Colima, Manzanillo, México

Outline
• Why study the Eastern Tropical Mexican Pacific
• Introduction and former work in the area.
• The Habitat Compression hypothesis.
• The PROCOMEX XI Cruise. November 2009.
• Results
• Conclusions
IMBIZO, Crete, Farber Lorda et al.

Why Study the Eastern Tropical Pacific
The eastern tropical Pacific is an unique and huge area, in which some
uncommon characteristics challenge the validity of some recognized
principles in oceanography. Some of them:
- Relatively high productivity, high stratification and low circulation, which
produces a pronounced Oxygen Minimum Layer (OML).
- In this thick low oxygen layer (Over 1000 m in some areas), we do not
have the presence of sulphide, like in other low oxygen areas (i.e. Black
Sea).
-Typical levels for most of the hypoxic areas are

Circulation in the Eastern tropical Pacific (Kessler, 2006)
IMBIZO, Crete, Farber Lorda et al.

Fernandez-Álamo and Färber Lorda, 2006
Oxygen minimum depth in the eastern tropical Pacific. The higher zooplankton
volumes coincide, in most cases, with the shallower oxygen minimum depth.
IMBIZO, Crete, Farber Lorda et al.

Farber Lorda et al, 2009

Godinez et al. Unpublished

Support for the Habitat
Compression
Hypothesis
The treshold is 1 ml l
Färber Lorda and Fiedler, Unpublished
IMBIZO, Crete, Farber Lorda et al.

Fernandez Alamo and Färber Lorda, 2006
Historical data of zooplankton volume (mainly
EASTROPAC data) shows greater volumes around
the Costa Rica Dome, off Peru, and extend to the
equatorial area, where the equatorial undercurrent
transports cooler, oxygenated and nutrient rich
waters from the east, with a deeper OML. N=2405

IMBIZO, Crete, Farber Lorda et al.
Farber Lorda et al (2004b )and Farber Lorda
(2004c) found not significant differences
between day and Stations for zooplankton
Biomass.

Historical data of Day and Night zooplankton volumes in
ETPac. In certain areas differences between night and
day are not so obvious.
Considering former evidence by Färber Lorda et al.
(2004b) and Färber Lorda et al (2004c), who found no
significant differences between day and night
zooplankton biomasses, and trying to show a no
Night/Day difference in the ETPac area; the Night/Day
ratio was obtained for 1 degree areas.
Fernandez Alamo and Färber Lorda, 2006
IMBIZO, Crete, Farber Lorda et al.

• There is a good
coincidence between
areas with shallow low
oxygen and small N/D
ratios.
• A significant difference
between night and day
was not found, probably
related to the great
variability of the data.
From: Fernandez Alamo and Färber Lorda, 2006
Hypothesis: The shallow thermocline and/or low oxygen confine the animals,
not adapted to low oxygen, to stay above the OML, restraining their vertical
distribution to shallow waters and concentrating zooplankton above the OML, or
the thermocline, this is my Habitat Contraction Hypothesis (Summer ASLO,
Victoria, 2006), even if someone elses gave it that name.
IMBIZO, Crete, Farber Lorda et al.

GCW
SCC
WMC
IMBIZO, Crete, Farber Lorda et al.

PROCOMEX Cruise, November, 2009
Study area of the
PROCOMEX XI Cruise,
November 2009.
IMBIZO, Crete, Farber Lorda et al.

E
El Puma Research Vessel
IMBIZO, Crete, Farber Lorda et al.

• During the cruise we were at the end of a moderate El Niño year.
Considering this we migth expect warmer temperatures and a deeper
thermocline and Oxygen Minimum (OM)
IMBIZO, Crete, Farber Lorda et al.

Sampling
• CTD casts, Temperatrure, Salinity, Florescence, Oxygen.
• Nutrients: Nitrate+nitrite, Ammonium, Phosphate, Silicates.
• Filtrations for Particulate matter: seston, protein, carbohydrates,
lipids, pigments.
• MOCNESS tows: 0-500 m.
• Bongo tows 200-0 m.
• PCO2 , Omega aragonite, Omega Calcite, pH, DIC.
• Microzooplankton grazing.
IMBIZO, Crete, Farber Lorda et al.

• Färber Lorda et al., 2009
IMBIZO, Crete, Farber Lorda et al.

• B transect the gyres bring low salinity water to the extremes of the
transect.
IMBIZO, Crete, Farber Lorda et al.

The two chlorophyll maxima are not well defined due to the presence of the
California Current waters and the gyres present in the area. The oxygen minimum
is deeper.
IMBIZO, Crete, Farber Lorda et al.

• More stratified waters were present in the southern transect
IMBIZO, Crete, Farber Lorda et al.

• The more stratified D transect shows the presence of 2 chlorophyll
maxima, at around 50 and 120 m.
IMBIZO, Crete, Farber Lorda et al.

1 60 14 0 12 0 100 8 0 60 40 20 0
PROCOMEX NOV 2002
0
50
100
Depth (db)
150
O2(µmol/kg)
200
IMBIZO, Crete, Farber Lorda et al.

Results
MOCNESS samples clearly show the drastic reduction of zooplankton bellow
100 m.
IMBIZO, Crete, Farber Lorda et al.

MOCNESS D03 18:00
50-0 m
Taxa
Piscis eggs
Piscis larvae
Echinodermata larvae
Cirripedia larvae
Cephalopoda larvae
Doliolids Salps
Appendicularia
Chaetognata
Siphonophora
Medusae
Heteropoda
Gasteropoda
Polychaeta
Stomatopoda larvae
Brachyura
Crustacea
Mysidacea
Carida
Euphausiacea
Isopoda
Amphipoda
Ostracoda
Cladocera
Foram Radiolaria
Copepoda
0 2 4 6 8 10 12 14 16
Ln Abundance 100 m -3
IMBIZO, Crete, Farber Lorda et al.

Taxa
Piscis eggs
Piscis larvae
Echinodermata larvae
Cirripedia larvae
Cephalopoda larvae
Doliolids Salps
Appendicularia
Chaetognata
Siphonophora
Medusae
Heteropoda
Gasteropoda
Polychaeta
Stomatopoda larvae
Brachyura
Crustacea
Mysidacea
Carida
Euphausiacea
Isopoda
Amphipoda
Ostracoda
Cladocera
Foram Radiolaria
Copepoda
MOCNESS D03 18:00 Day
50-0 m
0 2 4 6 8 10 12 14 16
Ln Abundance 100 m -3
50-100 m
0 2 4 6 8 10 12
Ln Abundance 100 m -3
100-150 m
150-200m
0 1 2 3 4 5 6
0 1 2 3 4 5 6
Ln Abundance 100 m -3 Ln Abundance 100 m -3
Abundances:
Copepod
50-0m 2’339,943
50-100m 30145
100-150 m 76
Foraminifera and
Radiolaria
50-0 m 10086
50-100m 3289
100-150m 33
Ostracoda
50-0m 32165
50-100 2569
100-150m 16
Chaetognata
50-0m 2091
50-100m 371
100-150m 3
IMBIZO, Crete, Farber Lorda et al.
Euphausiacea
50-0 330
500-100 261
100-150 230
150-200 67
Appendicularia
50-0 330
50-100 0
100-150 0
This hundreth times reduction of
copepods is related to the oxygen
minimum (0.1 ml/l), present in this
transect, at around 120 m. OM was
deeper because of the moderate
2009 El Niño. However Copepods
and Foraminifera and radiolaria
abundances rise moderately again at
the 300-400 and 400-500 m layers.
Euphausiids mantained their low
abundance dow to 150 m.

MOCNESS Station D03
Station D03 18:00
27/11/2009
MOCNESS
0
Zooplankton Volume (ml 100 -3 )
0 20 40 60 80 100 120
O [ml/l]
0 1 2 3 4 5 2 γ 21 22 23 24 25 26 27 28 θ [kg/m3 ]
0
-100
200
-200
400
Depth
-300
P [db]
600
-400
800
-500
-600
1000
1200
O 2
Flu
Θ S γ θ
Θ [°C]
4 6 8 10 12 14 16 18 20 22 24 26 28 30
IMBIZO, Crete, Farber Lorda et al.
34 34.2 34.4 34.6 34.8 35 S [ups]
Flu [μg/l]
−1 0 1 2 3

MOCNESS Night
Station D03 04:00
0-50m
50-100m
100-150m
150-200m
Taxa
Piscis eggs
Piscis larvae
Echinodermata larvae
Cirripedia larvae
Cephalopoda larvae
Doliolids Salps
Appendicularia
Chaetognata
Siphonophora
Medusae
Heteropoda
Gasteropoda
Polychaeta
Stomatopoda larvae
Brachyura
Crustacea
Mysidacea
Carida
Euphausiacea
Isopoda
Amphipoda
Ostracoda
Cladocera
Foram Radiolaria
Copepoda
0 2 4 6 8 10 12 14
0 2 4 6 8 10 12
0 1 2 3 4 5 6 7
0 1 2 3 4 5
Ln Abundance 100 m -3
Ln Abundance 100 m -3
Ln Abundance 100 m -3
Ln Abundance 100 m -3
Copepod
50-0 146260
50-100 88736
100-150 133
Foraminifera and Radiolaria
50-0 1574 300-400 533
50-100 1484 400-500 1240
100-150 318
150-200 80
200-300 684
Ostracoda
50-0 65620
50-100 67
100-150 50
Chaetognata
50-50 1544
50-100 652
100-150 7
Euphausiacea
50-0 477
50-100 247
100-150 1
Appedicularia
50-0 606
50-100 67
100-150 0
IMBIZO, Crete, Farber Lorda et al.

Station D03 04:00
28711/2009
MOCNESS
0
Zooplankton Volume (ml 100 m -3 )
0 20 40 60 80 100 120 140
-100
-200
Depth
-300
-400
-500
-600
IMBIZO, Crete, Farber Lorda et al.

MOCNESS
Station D03 01:30
Piscis eggs
Piscis larvae
Echinodermata larvae
Cirripedia larvae
Cephalopoda larvae
Doliolids Salps
Appendicularia
Chaetognata
Siphonophora
Medusae
Heteropoda
Gasteropoda
Polychaeta
Stomatopoda larvae
Brachyura
Crustacea
Mysidacea
Carida
Euphausiacea
Isopoda
Amphipoda
Ostracoda
Cladocera
Foram Radiolaria
Copepoda
0-50 m
0 2 4 6 8 10 12 14
Ln Abundance 100 m -3
Abundances
Copepods
0-50 265151 200-300 173
50-100 83751 300-400 2401
100-150 1825 400-500 3688
150-200 456
Foraminifera, Radiolaria
0-50 29770
50-100 8807
100-150 1105
150-200 261
50-100 m
0 2 4 6 8 10 12
Ln Abundance 100 m -3
100-150 m
0 1 2 3 4 5 6
Ln Abundance 100 m -3
Ostracoda Euphausiacea
0-50 60466 0-50 579
50-100 3755 50-100 369
100-150 159 100-150 7
150-200 86 150-200 1
Chaetognata Appendicularia
0-50 9788 0-50 9266
50-100 738 50-100 686
100-150 5 100-150 5
150-200 m
0 1 2 3 4 5 6
Ln Abundance 100 m -3

Station D03 01:30
MOCNESS
29/11/2009
0
Zooplankton Volume (ml 100 m -3 )
0 20 40 60 80 100 120 140 160
-100
-200
Depth
-300
-400
-500
-600
IMBIZO, Crete, Farber Lorda et al.

0
-100
Station D03 11:30
MOCNESS
29/11/2009
Zooplankton Volume (ml 100 m -3 )
0 20 40 60 80 100
Station D03
-200
Depth (m)
-300
-400
-500
-600
Depth (m)
Low pH follow the biovolumes profiles of
Zooplankton from the MOCNESS net
Samples (M. Hernandez and A. Franco)
D3
IMBIZO, Crete, Farber Lorda et al.
pH in situ

0
-100
Station D03 11:30
MOCNESS
29/11/2009
Zooplankton Volume (ml 100 m -3 )
0 20 40 60 80 100
-200
Depth (m)
-300
-400
-500
Depth (m)
-600
There is a coincidence of low
zooplankton biovolumes with low
Omega Aragonite values. We can
suppose that the synergic effect of
low oxygen with corrosive water,
Will further restrain vertical migration of
Zooplankton (M. Hernandez and A.
Franco).
IMBIZO, Crete, Farber Lorda et al.
Omega Aragonite
D3

Deep (m)
800
1000
1200
Nitrate + Nitrite (μΜ)
Ammonium (μΜ)
0 5 10 15 20 25 2 3 4 5 6
0
0
200
200
400
400
600
600
Deep (m)
1400
1600
1800
2000
1400
1600
1800
2000
Phosphate (μΜ)
Silicate (μΜ)
0 1 2 3 4 0 10 20 30 40 50 60 70
0
0
800
1000
1200
The two chlorophyll maxima
Coincide with the two
ammonia peaks in the profile
for the 48 hours D03 station
(A. Olivos).
However, for ammonia, a
strong variability was found
during the 48 hours sampling
station
200
400
600
200
400
600
Deep (m)
800
1000
1200
Deep (m)
800
1000
1200
1400
1600
1800
2000
1400
1600
1800
2000
27/ 11/ 2009
28/ 11/ 2009
IMBIZO, Crete, Farber Lorda et al.

Trophic conditions
Particulate Organic
matter(Protein+
carbohydrates+ lipids
=POM) reflect, for both
transects, the circulation
and hydrographic
structure, with higher
values at the rim of the
gyres present in the area.
IMBIZO, Crete, Farber Lorda et al.

IMBIZO, Crete, Farber Lorda et al.

IMBIZO, Crete, Farber Lorda et al.

Conclusions
• Oxygen profiles show a deeper than usual Oxygen minimum during
November 2009, due to el Nino conditions.
• Two chlorophyll maxima were found, being more stratified the
southern D transect, for this transect, the second peak follows the
0.1 ml l oxygen layer.
• Zooplankton vertical distribution shows a dramatic reduction in its
abundances and volumes at the oxygen minimum layer.
• The Omega Aragonite and pH profiles follows the same trend as
zooplankton volumes for the MOCNESS tows
• Ammonia profiles coincide with the two chlorophyll maxima at
station D03, but their values varied during the 48 hours period.
IMBIZO, Crete, Farber Lorda et al.

Conclusions
• Along transect profiles of Particulate organic matter (protein+
cabohydrates+lipids) showed better trophic conditions at the rim of
a persistent gyre in the area.
• Our findings were determined by the El Nino conditions, we can not
assume that those are the “normal” conditions.
• A quite variable vertical distribution was found, but the general
pattern seem to be the dramatic reduction of zooplankton in the
OMZ.
• However the presence of copepods at deeper waters, with a small
increase of certain groups, leave the question of the adaptations to
low oxygen open.
• Our results support the Habitat Contraction Hypothesis.
Zooplankton is concentrated in the first 100m.
IMBIZO, Crete, Farber Lorda et al.

PROCOMEX XI participants
IMBIZO, Crete, Farber Lorda et al.

Phkaristo! Thank you! Gracias
IMBIZO, Crete, Farber Lorda et al.