Trends in environmental conditions and plankton abundance and composition in the NW Atlantic 1) Observations from BIO cruises on the AR7W line in the Labrador Sea ( ) 2) Observations from Continuous Plankton Recorder sampling in the southern Labrador Sea and on the Newfoundland and Scotian shelves ( ) Erica Head with help from Kumiko Azetsu-Scott, Glen Harrison, Ross Hendry, William Li, Igor Yashayaev, Philip Yeats

Temperature ( o C) SST anomalies relative to “De-seasoned” 0-50 m temperatures during annual cruises and monthly SST anomalies relative to averages. Temperatures increased in all regions of the AR7W line between 1990 and 2006 Trends in temperature along the AR7W line

Silicate (mmol m -3 ) Nitrate (mmol m -3 ) Trends in nutrient levels ( m or 60-bottom on shelves) during annual cruises Silicate decreased everywhere Nitrate increased in the central basin and slope waters and decreased on the Greenland Shelf, with no change on the Labrador Shelf

Trends in integrated (0-100 m) or sea surface chlorophyll concentration in the Labrador Sea In situ integrated chlorophyll (May, June or July, log mg m -2 ) R 2 = 0.18, p = 0.26 R 2 = 0.41, p = 0.05 R 2 = 0.02, p = 0.74 Satellite SS chlorophyll (Average Apr.-Aug., mg m -3 ) Year Labrador Shelf Central Labrador Basin Central Labrador Sea Greenland Shelf Eastern Labrador Sea R 2 = 0.15, p = 0.17R 2 = 0.03, p = 0.55 Chlorophyll concentrations increased on the Labrador Shelf and in the central basin between 1998 and 2006 and in all regions the spring bloom started earlier.

Trends in phytoplankton groups differentiated by size (upper row, flow cytometry) or pigment composition (lower row, HPLC pigment analysis) Labrador Shelf Labrador Basin Large nano- Micro- Large nano- Small nano- Nano- Small nano- Nano- Pico- No. of cells Fraction of chl. in group Between 1996 and 2005 the abundance/proportion of large cells decreased and the abundance/proportion of small cells increased on the Labrador Shelf and in the central basin.

Trends in zooplankton dry weight averaged over stations for different regions of the AR7W line ( ) Data from late May only Zooplankton dry weight (0-100 m, g m -2 ) C. finmarchicusC. glacialisC. hyperboreusOther zooplankton Labrador ShelfCentral Labrador SeaEastern Labrador Sea All data were collected between late May and late July Labrador ShelfCentral Labrador SeaEastern Labrador Sea Zooplankton biomass showed no obvious trend with time, even when data from only one 2-week period of the year was used to eliminate the effect of seasonal dynamics.

Positions where Continuous Plankton Recorder (CPR) samples used in this analysis were collected ( ) Latitude ( o N) Longitude ( o W) WSS ESS SNL <25 Sampling is supposed to be monthly via ships-of- opportunity but there are gaps. Before 1991 for the entire line or parts of the line - some months were missed in some years some years were missed completely From , monthly coverage was good Samples are from ~7 m (near-surface) Data on plankton abundance were averaged over the areas for a given month and year and then over a given month within a “decade” and finally over all months to give an annual average for each decade. The “decades” used were , , , ,

Spatial patterns of phytoplankton abundance Spatial patterns were calculated by averaging the decadal “annual” averages. All three indices of phytoplankton abundance were higher west of 45 o W than to the east. Diatoms and the “Phytoplankton Colour Index” (PCI) co-varied and were most abundant in the o W region, over the Newfoundland Shelf/Slope, in the Labrador Current. Dinoflagellates were most abundant on the south Newfoundland Shelf. Diatom/Dinoflagellate abundance (Cells per sample) PCI (Relative abundance)

Decadal changes in phytoplankton abundance West of 45 o WEast of 45 o W Diatom abundance (Cells per sample) West of 45 o W (i.e. Newfoundland Shelf/Slope, Scotian Shelf) diatom abundance was higher in the 1990s and 2000s than in the 1960s and 1970s. East of 45 o W diatom abundance did not change significantly. Diatom abundance is shown here, but all three indices of phytoplankton abundance behaved in more-or-less the same way. Diatom abundance

Spatial patterns of zooplankton abundance Calanus abundance (Number per sample) Young stage Calanus (Calanus I-IV, which are mostly C. finmarchicus) were most abundant over the Newfoundland Shelf/Slope, in the Labrador Current. Arctic Calanus were most abundant over the Newfoundland Shelf/Slope, in the Labrador Current, but were much less abundant than Calanus I-IV or Calanus finmarchicus. Arctic Calanus species

Decadal changes in zooplankton abundance Calanus I-IV West of 45 o WEast of 45 o W Calanus hyperboreus III-VI In the Newfoundland Shelf/Slope waters (53-45 o W): Calanus I-IV (+ C. finmarchicus) abundance was lower in the 1990s and 2000s, than in the 1960s and 1970s. C. hyperboreus (+ C. glacialis) abundance was higher in the 1990s and 2000s than in the 1960s and 1970s.

Summary Along the AR7W line between 1995 and 2006: Temperatures increased Nitrate levels increased, silicate levels decreased The abundance/proportion of large phytoplankton decreased The phytoplankton bloom started earlier Calanus finmarchicus reproduction/development occurred earlier Along the CPR route between 1957 and 2006: Phytoplankton abundance was highest in the o W region (Newfoundland Shelf/Slope waters, in the Labrador Current) West of 45 o W phytoplankton abundance increased between the 1970s and 1990s. The abundance of three Calanus categories was highest in the o W region. Two Calanus categories are Arctic species and in the o W region their abundance increased between the 1970s and the 1990s. The third category (Calanus I-IV) is a boreal species and its abundance decreased in the o W region between the 1970s and the 1990s. The fourth Calanus category is also a boreal species and it also decreased in abundance in the o W region between the 1970s and the 1990s.

The goal of the ESSAS programme: to compare, quantify and predict the impact of climate variability and global change on the productivity and sustainability of Sub-Arctic marine ecosystems. Primary Sub-Arctic regions: Sea of Okhotsk, Oyashio, Bering Sea, Hudson Bay, Labrador/ Newfoundland shelves, Gulf of St. Lawrence, West Greenland, Iceland, Nordic Seas, and Barents Sea There are national programmes in Japan, Iceland and the US and ESSAS is co-ordinating a series of national and international projects in IPY. Canada is involved with Norway in an international programme (NORCAN) comparing the Barents Sea/Norwegian Sea and Newfoundland/Labrador Shelf/Labrador Sea ecosystems.

The goal of the BASIN programme: to understand and predict the impact of climate change on key species of plankton and fish, and associated ecosystems and biogeochemical dynamics in the North Atlantic Subpolar Gyre System and surrounding shelves, in order to improve ocean management and conservation. The aim is to have a co-ordinated North Atlantic wide programme with the EU and US researchers focussing on the sub-polar gyre and adjacent continental shelves.

Emerging issues: Trans-Arctic invasions? A species of N Pacific phytoplankton (the diatom Neodenticula seminae) that is common in the Pacific Ocean, but that has been absent from the N Atlantic for 800,000 years has been seen in CPR samples in the NW Atlantic since The absence of ice throughout much of the Canadian Arctic archipelago in 1998 may have allowed the species to move east from the Bering Sea, through the archipelago into Baffin Bay and from there south to the Labrador Sea. Will other species follow? Locations where CPR samples containing the Pacific diatom Neodenticula seminae have been collected, and collection years. From Reid et al. (2007) Scanning electromicrograph of Neodenticula seminae

Emerging issues: Ocean acidification Trends in TIC and pH ( m) in the Labrador Sea (AR7W line) Total inorganic carbon concentration (µmol/kg) Year pH TIC pH Total inorganic carbon is increasing – pH is decreasing

Spatial patterns of the abundance of calcifying organisms Foramnifera (Forams) and Coccolithophores have only been counted since the 1980s, before then there are only presence/absence data. So, the abundance index is the frequency of occurrence in samples. Forams (microzooplankton) are more often seen to the east of 45 o W than to the west. Coccolithophores (phytoplankton) are most often seen south of Newfoundland or over the Reykjanes ridge. Limacina spp. (a pteropod, zooplankton species) has always been counted. Here, both frequency of occurrence and abundance show maximum values at o W. Frequency of occurrence Limacina abundance (No. per sample)

Frequency of occurrence Limacina abundance (No. per sample) Decadal changes in the abundance of Limacina spp. W of 45 o W E of 45 o W West of 45 o W the frequency of occurrence and abundance data generally change in the same sense in the 1960s- 1970s and 1990s-2000s, but not over the entire dataset. East of 45 o W the frequency of occurrence data shows a decrease west of 30oW: the abundance data does not. It may be that counting procedures have become more “rigorous” since the 1980s; changes from the 1990s to the 2000s were consistent for both datasets and abundance decreased in most areas.

Longitude ( o W) Latitude ( o N) A B C The Labrador Sea Filled circles are regular sampling stations on the AR7W line – sampled by physicists, chemists and biologists since 1990 or The sampling periods covered during cruises have varied between late May and late July. The boxes are areas over which STT and SSChl measurements were averaged to represent conditions on/in A – the Labrador Shelf B – the Central Labrador Sea C – the Eastern Labrador Sea Bathymetry: Grey line – 200 m Black lines – 1000, 2000 and 3000 m

Trends in the C. finmarchicus Population Development Index in late May, late winter SST ( ) and the timing of the start of the bloom ( ) r 2 = 0.03, p = 0.75r 2 = 0.37, p = 0.20 r 2 = 0.15, p = 0.44 C. finmarchicus PDI (Ab. CI-IIIs/Total ab., %) Day of year when SSChl. reaches 1 mg m -3 r 2 = 0.35, p = 0.10r 2 = 0.14, p = r 2 = 0.47, p = 0.04 Average SST Mar.-May ( o C) r 2 = 0.52, p = r 2 = 0.76, p < 0.001r 2 = 0.26, p = 0.09 Labrador ShelfCentral Labrador SeaEastern Labrador Sea Population Development Index (PDI) = (Sum stages CI-CIII/Sum all stages) x 100

Population development in C. finmarchicus ( ) PDI (%) = (Sum CI+CII+CIII abundance) x 100 (Total abundance) Late Early Late Early Late May June June July July PDI (%) Lab. Shelf Central Lab. Sea Eastern Lab. Sea Population Development Index (PDI) averaged over all 2 week sampling periods for all sampling years Labrador Shelf Central Labrador Sea Eastern Labrador Sea PDI in late May (%) PDI in late May in individual sampling years PDI increased PDI decreased Increasing temperatures and earlier spring blooms lead to earlier reproduction and faster development in C. finmarchicus populations.