LTER meeting February 2013

LTER-MC meeting 15 Feb 2013

Thesis: Long-term variability of plankton phenology in a Mediterranean time series (LTER-MC) Phenology in plankton Main results from methods applied Patterns observed to date Final analysis

Acartia clausi

Emiliania huxleyi

Minidiscus comicus Chaetoceros socialis

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Part I species selection • community structure analysis • Initial selection 46 species

Part II results • Significant changes in phenology • Relationships with temperature

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Zooplankton n=111 categories 1. Calanoid juveniles ( juv of Clausocalanus

spp.+P.parvus) 2. Penilia avirostris 3. (bulk) appendicularia 4. Acartia clausi 5. Paracalanus parvus (only adults)

Phytoplankton n=344 categories 1. (bulk undetermined ) Undetermined phytoflagellates <10m size 2. (genus level) Chaetoceros spp. 3. Chaetoceros tenuissimus 4. Skeletonema pseudocostatum 5. Leptocylindrus danicus

Plankton community structure RAD curves

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LTER-MC meeting 15 Feb 2013 4

Plankton community structure Frequency distribution curves

Phytoplankton 168 categories occur with a frequency of <1% This class is discarded from consideration since the data is too sparse

Zooplankton Only 14 out of categories <1% frequency


Initial selection n=46 species, genus level and groups


Significant changes in phenology: phytoplankton


Chaetoceros socialis Spring colonial diatom with peak in April - April peak increased in second part of

time series - Start and middle phases of phenology

are significantly later - End of phenology did not have a

significant change - Timing of peak was significantly later

Significant changes in phenology


Dinobryon faculiferum Spring flagellate with peak abundance in March continuing through August - Decrease in late summer abundance

after 1995 - The start of season phenophase was

significantly later after 1995 - The duration was significantly shorter

after 1995



Heterocapsa niei Spring dinoflagellate with a peak in May - Start and middle of season are significantly later - Duration is longer in part II of t.s. - Timing is earlier after 1995



Skeletonema pseudocostatum Spring diatom with a peak in July (part I) which has shifted to May in Part II - Timing is later in part I of time series - Timing is earlier in part Ii of t.s. But not

significant



Minidiscus comicus Summer diatom with a peak in September (part I) and August (part II - Timing after 1995 is significantly

earlier in all phenophases



Chaetoceros tenuissimus Bimodal diatom with a primary peak in spring and secondary in autumn Peak in May (part I) shifted to June in part II - Start of season significantly later

after 1995 (this phenophase corresponds to the later mean seasonal abundance cycle)

- Timing [1:6] later in part I - Timing [7:12} earlier after 1995



Skeletonema menzelii Bimodal diatom with summer peak in August and autumn peak in October - The end was significantly earlier after

1995 - The timing was also significantly

earlier after 1995



Significant changes in phenology: zooplankton


Significant changes in phenology: phytoplankton


Significant changes in phenology • Most species did not change phenology over long term ! • Four phytoplankton species that occur during the spring season changed

• The start of season and timing was later • Phenology of D.faculiferum restricted, H.niei enlarged (duration)

• Spring and autumn zooplankton species showed significant change • A.clausi, C.typicus, O.similis, C.paululus had earlier phenology

• Summer zooplankton had a stable phenology over the long term

• P.parvus, Evadne+Pseudoevadne, P.avirostris

• Changes observed in bulk assemblages could be attributed to species level changes in phenology of target species


Relationships with temperature phytoplankton

Species that had significant changes in phenology also had significant relationships with temperature anomalies within each season


Relationships with temperature zooplankton


Significant relationships with temperatures • spring phytoplankton and zooplankton species had strong relationships

with temperature • The timing of bimodal species was later when warmer

• S.menzelii, S.pseudocostatum

• Spring zooplankton species phenology was earlier when temperature anomalies were higher • A.clausi,C.typicus, O.similis, C.paululus (as for ∆ phenology) • End of season phenology and seasonal temperature

• 2 species within the zooplankton genera Oithona and Clausocalanus had significant relationships with temperature anomalies in different seasons




Final analysis


Final analysis Community assembly


Final analysis - Consideration of more than 46 species - Expand to all taxa > 1% frequency of occurrence - Correlation with other environmental parameters

- Salinity - Heat flux - Light - Chl a - nutrients

LTER meeting February 2013

Science

Transcript of LTER meeting February 2013