Three yearsinsight into zooplankton life in a semi-enclosed Arctic … · 2017-02-06 · Three yearsinsight into zooplankton life in a semi-enclosed Arctic Fjord, Billefjorden, Svalbard

Three years insight into zooplankton life in a semi-enclosedArctic Fjord, Billefjorden, Svalbard.

Seasonal population dynamics, annual calendar of reproduction and development.

Katarzyna Dmoch1, Janne E. Søreide2, Katarzyna Blachowiak-Samolyk1, Emilia Trudnowska1

and Malin Daase3

1

2

Main objective

To identify annual and seasonal mesozooplankton patterns

important knowledgeto differenciate between

natural variability vs. larger climate driven changes

Station BAB 78°39.7 N, 16°43Outer sill 80 m Outer basin ~230 mInner sill 45 m Inner basin ~190 m

Billefjorden – time series station BABStudy area

Physical charactersics

*Billefjorden – a sill fjord with local cold water formation and seasonal ice cover

an Arctic Oasis in the otherwise Atlantic influencedIsfjorden system.

-1.5 oC

spring bloom in May

Study area

Physical and biological samplingMay 2011 to Sept. 2013 (~monthly)

Hydrography: Continuous mooring data, CTD casts

Algal biomass: Fluoroscens 19 m depth mooring and fluorometer attached to CTDChlorophyll a measurements from filtered water and sea ice cores

Zooplankton: WP2 closing net/Multiple Plankton Sampler (MPS) midi (Hydro Bios)Both nets: 0.25 m2 opening and mesh size 200 µmStandard sample depths: 0-20m; 20-50m; 50-100m, 100-180m (bottom)

July Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun July

Mesozooplankton charactersitics - composition, relativeabundance and frequency of occurrence

Relatively stable composition, highly dominated

Taxon % Share Frequency % No of taxons accounting for share in abundance

Microcalanus spp. 28,1 100 Pseudocalanus spp. 18,1 100 Calanus glacialis 16,9 100 Oithona similis 16,6 100 80% 4Bivalvia veliger 5,7 71 Cirripedia 3,9 67 Limacina helicina 2,9 86 92% 7Copepoda nauplii 2,8 90 Calanus finmarchicus 1,8 100 Metridia longa 1,0 100 Triconia borealis 0,5 100 98% 10Acartia longiremis 0,3 100 Aetideidae juv 0,2 100 Echinodermata larvae 0,2 52 Oithona atlantica 0,2 86 Calanus hyperboreus 0,2 100 Fritillaria borealis 0,1 43 Sagitta elegans 0,1 100 Polychaeta larvae 0,1 67 Oikopleura spp. 0,1 76

Cumulated share in abundance

49 taxa identified

Mesozooplankton charactersitics - composition, relativeabundance and frequency of occurrence

Relatively stable composition, highly dominated

Taxon % Share Frequency % No of taxons accounting for share in abundance

Microcalanus spp. 28,1 100 Pseudocalanus spp. 18,1 100 Calanus glacialis 16,9 100 Oithona similis 16,6 100 80% 4Bivalvia veliger 5,7 71 Cirripedia 3,9 67 Limacina helicina 2,9 86 92% 7Copepoda nauplii 2,8 90 Calanus finmarchicus 1,8 100 Metridia longa 1,0 100 Triconia borealis 0,5 100 98% 10Acartia longiremis 0,3 100 Aetideidae juv 0,2 100 Echinodermata larvae 0,2 52 Oithona atlantica 0,2 86 Calanus hyperboreus 0,2 100 Fritillaria borealis 0,1 43 Sagitta elegans 0,1 100 Polychaeta larvae 0,1 67 Oikopleura spp. 0,1 76

Cumulated share in abundance

GROUPS % Share OccurrenceSmall copepods 16 - 94% constant Large copepods 1 - 41%PredatorsMeroplankton - 68% temporalMucus filtrators - 22%

• Total abundance [ind. m-2]

GROUPS % Share OccurrenceSmall copepods 16 - 94% constant Large copepods 1 - 41%PredatorsMeroplankton - 68% temporalMucus filtrators - 22%

2011 2012 2013

0

100000

200000

300000

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M J J A D J J A S O N D J F M A A M J J S

Copepoda npl Predators Large Copepods Small Copepods Mucus Filtrators Meroplankton the rest

Mesozooplankton charactersitics - total abundance

Small copepods: important year-roundLarge copeods: important in summer and autumnMeroplankton: highly abundant in spring-summerMucus filtrators: numerous in autumn

Mesozooplankton charactersitics - total abundanceRelatively low variability in total abundance:min. 168 673 – max. 533 139 ind. m-2 (3 times difference only)

2011 2012 2013

0

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Mesozooplankton charactersitics - total abundanceRelatively low variability in total abundance:min. 168 673 – max. 533 139 ind. m-2 (3 times difference only)

2011 2012 2013

0

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200000

300000

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500000



In comparison: Mesozooplankton in Kongsfjorden in 1998-99 with 100um varied by one order of magnitude (Lischka and Hagen 2016)

Vertical distribution of total zooplankton [ind. m3]

Autumn/Winter at depth

Spring-Summer surface



16 360 ind. m-3

3 417 ind. m-3

3 144 ind. m-3

5 671 ind. m-3

Surface and deep strata - the largest seasonal variation in zooplankton abundanceThe average densities attained between 20--100m were the most alike:

1 404 - 1 315 ind. m-3

Maximum

Main contributors to surface-subsurface abundances temporarily important

• surface-subsurface

• subsurface

• surface -intermediate

Meroplankton in May-July Weighted Mean Depth (WMD+-SD)Mucus filtering noncrustaceans in the autumn

Mucus filtrators

Meroplankton

Maximum

2 953 ind. m3

14 140 ind. m3

160 ind. m3

1 973 ind. m3

Main contributors to surface-subsurface abundances temporarily important

• surface-subsurface

• surface -intermediate

Meroplankton in May-July Weighted Mean Depth (WMD+-SD)Mucus filtering noncrustaceans in the autumn

Mucus filtrators

Meroplankton

Maximum

2 953 ind. m3

14 140 ind. m3

160 ind. m3

1 973 ind. m3

Main contributors to deep and intermediate depths:omnivorous copepods

Deep living omnivorous calanoidsYear-round mean and maximum densities in deepest layer Maximum

3 527 ind. m3

190 ind. m3

• very high abundance• high in winter

• low abundance• year-round

WMD - weighted mean depth of species occurrence• bubbles – ind. m-2 in relative scale, • SD bars – spread of distribution

Triconia borelis• low abundance• around 100m• stable

Oithonia similis• high abundance• signs of migration• late summer ascent• winter deeper but in

intermediate layer

67 ind. m3

3 142 ind. m3

Maximum

Contributors to intermediate depths:ominvorous cyclopoids


Omnivorous cyclopoids

Main contributors to seasonal vertical zooplankton patterns

Pseudocalanus spp.: peak in surface in July, descent in AugustCalanus spp.: peak in surface in May-June, descend in July-August

2 747 ind. m3

4 656 ind. m3

Maximum


• high abundance• spring ascent• autumn descent

Annual repeatable patterns – seasonal developmentPseudocalanus spp.

herbivore/omnivore

consistent:• peaks in the autumn• main overwintering stages

CIII-IV• main reproduction in

May or May/June

0

50000

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Pseudocalanus spp. AM P. ac. AF P. min. AF CV CIV CIII CII CI

Annual repeatable patterns – seasonal developmentPseudocalanus spp.SL herbivore/omnivore



May or May/June

0

50000

100000

150000

200000

250000



buthigh interannual variability in abundance

Annual repeatable patterns – seasonal developmentPseudocalanus spp.

herbivore/omnivore



May or May/June

0

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Reproduction:• CI peaks in July -- main reproduction in May or beginning of June (2013)• start -- in 2011-2012 – at the leatest in April

-- in 2013 – in June/estimated as 45 days before CI occurrence at 0°C (Corkett and McLaren 1978)/

butsome differences in timing of reproduction onset

0

50000

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150000

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0

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Pseudocalanus spp. AM P. min. AF P. ac. AF

Annual repeatable patterns – seasonal development

Mirrored in females of 2 species:

• P. minutus present y-round• P. acuspes in May – June• P. minutus - a decline in 2013

and low recruitment in 2013

connected with 2 species occurrence:

0

50000

100000

150000

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250000



0

5000

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Pseudocalanus spp. AM P. min. AF P. ac. AF


Mirrored in females of 2 species:

• P. minutus present y-round• P. acuspes in May – June• P. minutus - a decline in 2013

A possible explanation of high interannual variability of abundance?

and low recruitment in 2013

connected with 2 species occurrence:


0

50000

100000

150000


Pseudocalanus spp. AM P. ac. AF P. min. AF CV CIV CIII CII CI0

60000

120000

180000


Calanus spp. AM AF CV CIV CIII CII CI

Winter declines of populations :• in May Pseudocalanus maintained only 2% while Calanus 3,4%

of previous autumn maximum

Mortality - another reason of high interannual variability of abundance?


0

50000

100000

150000


Pseudocalanus spp. AM P. ac. AF P. min. AF CV CIV CIII CII CI0

60000

120000

180000


Calanus spp. AM AF CV CIV CIII CII CI

0

500

1000

1500 Parasagitta elegans =>20m =>10m =>5mm <5mm

0

400

800


Hydrozoa Ctenophora

Predationpressure

Timing of reproduction

ABUNDANCE SCALE+++ very high ++ intermediate + very low

Peaks and presence of first developmental stages of taxa – a proxy for reproduction

Occurrence of first developmental stages of taxa:• nauplii, CI copepodites, larvae, chaetognaths <5mm



Occurrence of first developmental stages of taxa:• nauplii, CI copepodite, larvae, chaetognaths <5mm

Large herbivorous copepods - reproduction the most restricted in time



Large omnivorous copepods - reproduction prolonged or year-round – also npl presentalso a Pseudocalanus



Carnivorous: • Parasagitta – main reproduction in July, prolonged untill autumn• Ctenophores – in winter and June

Calendar of seasonal versus interannual variabilityof population development of taxa

A syntesis of 3y taxa occurrence based on abundances normalized for each taxon and year separatelyby the year’s mean and standard deviation /source data in SD units/

Calendar views the time when enlarged or diminished populations of taxa can be expected

- elevated

- around mean

- lowered

Abundance:

LC – large copepods, SC – small copepods


Expected and unexpected patternspulsed occurrence and consistent patterns• meroplankton – May, June, July• mucus filtrators – August, September

- elevated

- around mean

- lowered

Abundance:


- elevated

- around mean

- lowered

Abundance: Expected and unexpected patterns

• C. finmarchicus and C. hyperboreus – in June, July• mucus filtrators – in August, September


- elevated

- around mean

- lowered

Expected and unexpected patternsa wide time window of enlarged population occurrence in the autumnand minima in May/June• C. glacialis (but possibly some confuse of CI-II stages)• Pseudocalanus spp. and Acartia longiremis• some small omnivorous cyclopoids


- elevated

- around mean

- lowered

Expected and unexpected patternsa similar time window of enlarged population occurrence• M. longa and Triconia borealis in the autumn• together with Microcalanus spp. in March-April

SummaryBillefjorden: an Arctic system driven by local processes

• Abundant community with stable composition• Low variability in total abundance seasonally and annually• Herbivorous - the highest seasonal and annual variability• Omnivorous and carnivorous species more year-round consistent

• Consistent predominant patterns in seasonal vertical distributionI. Herbivorous copepods: trong seasonal vertical migration II. Omnivorous cyclopoid copepods: upper 100 m/intermediate depthsIII. Omnivorous calanoid copepods: below 100 m

• Timing of reproduction: Herbivores: strong and narrow time windowOmnivores-carnivors: wide time window or year-round

ADDITIONALLYA summary table of species seasonal development which can serve as a proxybefore planning the cruises or experiments

Documents

Three yearsinsight into zooplankton life in a semi-enclosed Arctic … · 2017-02-06 · Three yearsinsight into zooplankton life in a semi-enclosed Arctic Fjord, Billefjorden, Svalbard