February 2013 meeting update for LTER research. Heather A. Wright Stazione Zoologica Anton Dohrn Naples, Italy

1. 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
1

2. LTER-MC meeting 15 Feb 2013
Part I species selection
• community structure analysis
• Initial selection 46 species
Part II results
• Significant changes in phenology
• Relationships with temperature
2

3. LTER-MC meeting 15 Feb 2013
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
<10m size
2. (genus level) Chaetoceros spp.
3. Chaetoceros tenuissimus
4. Skeletonema pseudocostatum
5. Leptocylindrus danicus
Plankton community structure
RAD curves
3

4. 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

5. LTER-MC meeting 15 Feb 2013 5
Initial selection
n=46 species, genus level and groups

6. LTER-MC meeting 15 Feb 2013 6
Part I species selection
• community structure analysis
• Initial selection 46 species
Part II results
• Significant changes in phenology
• Relationships with temperature

7. LTER-MC meeting 15 Feb 2013 7
Significant changes in phenology: phytoplankton

8. LTER-MC meeting 15 Feb 2013 8
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

9. LTER-MC meeting 15 Feb 2013 9
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
Significant changes in phenology

10. LTER-MC meeting 15 Feb 2013 10
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
Significant changes in phenology

11. LTER-MC meeting 15 Feb 2013 11
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
Significant changes in phenology

12. LTER-MC meeting 15 Feb 2013 12
Minidiscus comicus
Summer diatom with a peak in
September (part I) and August (part II
- Timing after 1995 is significantly
earlier in all phenophases
Significant changes in phenology

13. LTER-MC meeting 15 Feb 2013 13
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
Significant changes in phenology

14. LTER-MC meeting 15 Feb 2013 14
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

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Significant changes in phenology: zooplankton

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Significant changes in phenology: phytoplankton

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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

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

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Relationships with temperature
phytoplankton

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Relationships with temperature
phytoplankton

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Relationships with temperature
zooplankton

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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

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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
Final analysis

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Final analysis
Community assembly

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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