Zooplankton community structure and size spectra linked to phytoplankton and hydrographic features on the Faroe Shelf in spring Sólvá Jacobsen, Eilif Gaard, Karin M. H. Larsen, Sólvá K. Eliasen
Faroe Islands Background
Sea surface temperature 8. April 3 Inner shelf Outer shelf Temperature ( o C) Courtesy of P. Miller Plymouth Marine Lab
Sea surface temperature 8. April 3 Inner shelf Cold Outer shelf Warm Temperature ( o C) Courtesy of P. Miller Plymouth Marine Lab
Sea surface temperature 8. April 3 Inner shelf Cold Outer shelf Warm Front Temperature ( o C) Courtesy of P. Miller Plymouth Marine Lab
Sea surface temperature 8. April 3 Inner shelf Cold Mixed water Outer shelf Warm Front Temperature ( o C) Courtesy of P. Miller Plymouth Marine Lab
Sea surface temperature 8. April 3 Inner shelf Cold Mixed water Outer shelf Warm Front Temperature ( o C) Courtesy of P. Miller Plymouth Marine Lab
Inner shelf in late April Inner Faroe shelf ecosystem is bottom-up controlled First-feeding fish larvae feed on zooplankton
Aim What controls the zooplankton community and size structure on the inner Faroe shelf in late April?
Sampling Annual cruise in late April 997-5 (except and ) Temperature and salinity (CTD) Phytoplankton (fluorometer) Zooplankton (Bongo µm) Total: 58 hydrographic stations and 38 zooplankton stations
Image analysis - Taxonomic classification - Community size spectra
Average -5 m Temperature April 997-5 Outer shelf Inner shelf Results
Chlorophyll a April 997-5 Average chlorophyll a -5 m average 997-5 Outer shelf Inner shelf Results
Abundance (number m -3 ) Zooplankton April 997-5 Inner shelf Neritic copepods Meroplankton C. finmarchicus CIV-CVI C. finmarchicus CI-CIII Other Copepod nauplii Copepod eggs Outer shelf Results
Zooplankton groups on inner shelf plotted by size April 997-5 C. finmarchicus CIV-CVI Neritic copepods C. finmarchicus CI-CIII Other Meroplankton Copepod nauplii Copepod eggs
Zooplankton groups on inner shelf plotted by size April 997-5 C. finmarchicus CIV-CVI Neritic copepods C. finmarchicus CI-CIII Other Meroplankton Copepod nauplii Copepod eggs
Abundance (number m -3 ) Abundance (number m -3 ) Inner shelf Outer shelf C. finmarchicus CI-CIII C. finmarchicus CIV-CVI Year Year Results
Relative abundance (%) Relative abundance (%) Abundance (number m -3 ) Abundance (number m -3 ) Inner shelf Outer shelf C. finmarchicus CI-CIII C. finmarchicus CIV-CVI
Relative abundance (%) Relative abundance (%) Abundance (number m -3 ) Abundance (number m -3 ) Inner shelf Outer shelf C. finmarchicus CI-CIII C. finmarchicus CIV-CVI
Relative abundance (%) Relative abundance (%) Abundance (number m -3 ) Abundance (number m -3 ) Inner shelf Outer shelf C. finmarchicus CI-CIII C. finmarchicus CIV-CVI C. finmarchicus phenology shift
Relationship between PP-index and modelled exchange rate between the inner and outer shelf water masses Eliasen et al. 5 99-3
Temperature difference ( o C) Relationship between chl. a and temperature difference between the inner and outer shelf water masses temperature difference Chlorophyll a a.5 R² =.367 P =.65.5 997 5 9 3 Year.5.5 Temperature difference ( o C) Results
Temperature difference ( o C) Relationship between chl. a and temperature difference between the inner and outer shelf water masses temperature difference Chlorophyll a a.5 997 5 9 3 Year.5.5 R² =.367 P =.65.5 Temperature difference ( o C) Positive relationship between chl. a concentration and temperature difference between inner and outer shelf
Zooplankton (number m -3 ) Relationship between local zooplankton groups and chlorophyll a on inner shelf a a Results
Zooplankton (number m -3 ) Relationship between local zooplankton groups and chlorophyll a on inner shelf Zooplankton (number m -3 ) a a?
Zooplankton (number m -3 ) Relationship between local zooplankton groups and chlorophyll a on inner shelf Zooplankton (number m -3 ) a High positive correlation between neritic copepod species and chlorophyll a concentration and between a meroplankton and chlorophyll a concentration?
Zooplankton (number m -3 ) 8 6 4 Relationship between C. finmarchicus and chlorophyll a on inner shelf C. finm. CI-CIII Chlorophyll a.5 3 5 5 5 C. finm. CIV-CVI Chlorophyll a.5 997 5 9 3 Year Results
Zooplankton (number m -3 ) Zooplankton (number m -3 ) 8 6 4 Relationship between C. finmarchicus and chlorophyll a on inner shelf C. finm. CI-CIII Chlorophyll a.5 5 5 3 5 5 5 C. finm. CIV-CVI Chlorophyll a 997 5 9 3 Year.5 3 5 5 5 3
Zooplankton (number m -3 ) Zooplankton (number m -3 ) 8 6 4 3 5 5 5 Relationship between C. finmarchicus and chlorophyll a on inner shelf C. finm. CI-CIII Chlorophyll a C. finm. CIV-CVI Chlorophyll a 997 5 9 3 Year.5.5 5 5 3 5 5 5 No correlation 3
Zooplankton (number m -3 ) 7 6 5 4 3 5 5 5 Relationship between eggs and nauplii and chlorophyll a on inner shelf Copepod eggs Chlorophyll a Copepod nauplii Chlorphyll a.5.5 997 5 9 3 Year Results
Zooplankton (number m -3 ) Zooplankton (number m -3 ) 7 6 5 4 3 5 5 5 Relationship between eggs and nauplii and chlorophyll a on inner shelf Copepod eggs Chlorophyll a Copepod nauplii Chlorphyll a 997 5 9 3 Year.5.5 8 6 4 5 5 5 3
Zooplankton (number m -3 ) Zooplankton (number m -3 ) 7 6 5 4 3 5 5 5 Relationship between eggs and nauplii and chlorophyll a on inner shelf Copepod eggs Chlorophyll a Copepod nauplii Chlorphyll a 997 5 9 3 Year.5.5 8 6 4 5 5 5 No correlation 3
Conclusions Phytoplankton concentration strongly affects the abundance of neritic copepod species (and meroplankton) in the inner shelf ecosystem during spring C. finmarchicus phenology shift in outer shelf since 7
Inner Faroe shelf ecosystem Suggested mechanism: water exchange rate between the inner and outer Faroe shelf Low exchange Phytoplankton biomass High exchange Phytoplankton biomass Neritic copepod species and meroplankton (small to medium sized zooplankton) Neritic copepod species and meroplankton (small to medium sized zooplankton)
Acknowledgements