Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 1,2 Discussions Biogeosciences , L. Mousseau 1,2 1,2 ´ eanologique, 06234, , S. Gasparini , and G. Gorsky 1,2 3,4 9176 9175 ´ eanologique, 06234, Villefranche/mer, , L. Berline 1,2 , J.-M. Guarini 1,2 ´ eanographie, Environnements Marins, 4 Place Jussieu, 75005 Paris , L. Stemmann 1,2 , O. Passafiume 1,2 This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. CNRS, UMR 7093, LOV, Observatoire oc UPMC Univ. Paris 06, Oc CNRS, INstitute Environment Ecology, INEE, 3 Rue Michel-Ange, 75016 Paris UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire oc Received: 8 November 2010 – Accepted: 18Correspondence November 2010 to: – L. Published: Stemmann 15 ([email protected]) December 2010 Published by Copernicus Publications on behalf of the European Geosciences Union. Biogeosciences Discuss., 7, 9175–9207, 2010 www.biogeosciences-discuss.net/7/9175/2010/ doi:10.5194/bgd-7-9175-2010 © Author(s) 2010. CC Attribution 3.0 License. Zooplankton communities fluctuations from 1995 to 2005 inVillefranche-sur-Mer the (Northern Bay Ligurian of , France) P. Vandromme Villefranche/mer, France 2 3 4 F. Prejger 1 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ; Al- ; 2003 , ` 2004 de , Mazzocchi 2001 , Fern ` andes de Puelles ). From a joint study Perry et al. Fern Reid et al. ect of climate variability ff 2008 , ). Notably, the use of long-term and nutrients, seawater salinity, a ). Recently, temperature changes 2005 , 2010 , cient to detect those links. 9177 9178 ffi Hays et al. ; ). The authors pointed out the positive trend of sur- 2004 , 2010 , ` andes de Puelles and Molinero erent zooplankton groups (small and large copepods, chaetog- Mackas and Beaugrand ff Fern ; ; Perry et al. ; ). Regarding Mediterranean plankton, very few studies on long-term 2010 , 2007 2002 , Conversi et al. 2004 , ecting the zooplankton community was observed between Trieste, Naples ). Recently, it has been highlighted the appearance of regime shifts with , studied period: 1994–2003) a decrease of zooplankton abundance was , ff 2007 2007 , , Taylor et al. Plankton, becauseexploitation of as commercial their speciesnon-linear and rapid processes, their had amplification response of been( subtle pointed to changes out through ecosystem to follow variability, the e their non- 1 Introduction et al. plankton time-series can be aheit key and tool Bakun to detecthave those been changes suggested ( to causethe regime Atlantic shifts , in a plankton1987, regime ecosystems. has shift For been from example, described in cold andface temperature related to anomalies to warm in the biotopes, the North Northern withBeaugrand Atlantic Hemisphere a Oscillation (NHT, turning (NAO) and pointvariation sur- in have been conducted, due to the paucity of long-term time series ( turning points in 1987 inLigurian two Sea) northern and Mediterranean their coastal synchrony with ecosystemsBlack changes (Adriatic in and the ( and the Baltic and and Villefranche-sur-Mer, with, again, a main turning point in 1987 from high to low hold for most of theto time be series, explained but byavailability specific in other years spring/summer factors. with was contradicting then Themoderate patterns proposed or needed limitation as even a of reverse secondary phytoplanktondid the driving growth not force winter that by reveal forcing. can a the Finally,plex clear light dynamics the link linking eleven with large years scale the of climateof North to the observation Atlantic Ligurian plankton Sea Oscillation, monitoring ecosystems suggesting is or not a that yet the more su length com- changes in such far andet diverse al. locations. In the Balearic Sea ( Puelles et al. of six zooplankton timewarming series a in the a synchronous cooling and tain groups. The observedis patterns mostly suggest set that byface the the sustaining winter pelagic the forcing ecosystem spring on bloom. trophicnitrate However, the state low convection and phytoplankton concentrations that zooplankton in upwells higher plankton conditions nutrients is to during controlled the the sur- by well grazers. mixed The years proposed suggest mechanisms that of phyto- convection regimes face temperature in the as the main forcing for the concomitant temperature and density and localurian weather at Sea). the Point From B January coastalca. 1995 station to 2000. (Northern December Lig- 2005,sea From a surface shift 1995 density. in to These most yearston variables 2000 showed concentrations occurred lower winters while than phytoplankton were average biomasscolder nutrients wet was and and higher. and zooplank- dryer After mild 2000, resultingshowed resulting winters higher in were in concentrations higher while lower sea2000 phytoplankton winter surface shift was density. was lower observed than Nutrients for average. and most The zooplankton zooplankton ca. groups with a one year delay for cer- observed from 1995 to 1998,2000. a recovery Such of an mainlyphase, inter-annual all the variability groups NAO was was drive thenward linked colder observed spread temperature to from of during the rich winter northern NAO months Mediterranean forcing. enhancing waters in the In the south- its Balearic Sea positive ( An integrated analysis of the pelagicbining ecosystems time of series the Ligurian of Sea di isnaths, performed appendicularians, com- pteropods, thaliaceans, decapodsother larvae, gelatinous other and crustaceans, other zooplankton), chlorophyll- Abstract 5 5 10 15 25 25 15 20 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , . ; , ) ), ´ 1 an − ), air ) with 2008 Marty 2007 θ ( ; σ , µmol L 2004 , ), is located 2004 3 2005 Berline et al. 1 Duarte et al. Gorsky et al. , , Garcia-Comas Garcia-Comas ; ´ Bustillos-Guzm erouel ). Water for nitrate ; 1 1994 ) and − , erent depths, i.e. sur- d ff 2 1989 − 2008 Nezlin et al. , ( ) fit the observed dynamic. ; http://www.obs-vlfr.fr/Rade Arnone Molinero et al. erent part of the ecosystem. ff ` ; andes de Puelles et al. ) can miss important changes. Aminot and K 2008 2002 , , ). Fern 2002 2010 was determined by spectrometry and , , E; 85 m water depth). All basic physi- ) – yet, no significant links with large Underwood ). Therefore, temporal studies based C), salinity (psu) and density ( 2005 0 a ◦ ( 2005 ´ , Molinero et al. erini art et al. 2010 2007 biomasses, nitrates concentration, sea wa- ff , 18.94 , ◦ a ). A Seabird SBE25 CTD was used for weekly 9180 9179 art et al. Go ) and irradiance (J cm ff ). A more recent study from the same time se- 1 − N, 7 Go 0 1977 , 2008 Molinero et al. , 41.10 ´ ◦ an and Estrada Berline et al. Marty and Chiav ; ). The monitored station, called Point B (Fig. ) and Mor 1 ; 2010 2010 ) with, yet, not consideration of the zooplankton. In addition, the ( ), sea water temperature ( , 1 2004 − , ` analysis was sampled by Niskin bottles at 6 di andes de Puelles et al. Molinero et al. 2010 a , C), precipitation (mm d ◦ (µg L Fern Strickland and Parsons ; a ). Such a recovery around year 2000 was also observed by ). Sample analysis was done using the ZooScan instrument ( ´ erini 1995 2010 2010 Nezlin et al. ) in Villefranche-sur-Mer and Naples, and by ( , , ), using it, abundance and biovolume for 10 zooplankton groups was produced ; ect of dry winters was observed on the entire zooplankton community suggesting The aim of the present work is to extract the main causes of inter-annual variabil- ff 2010 The Bay of Villefranche-sur-Mer is locatedMediterranean in Sea, the Northern Fig. part of the (NW dataset is used together withter chlorophyll- temperature, salinity andtions, density and and solar meteorological irradiance) data for a (temperature, combined precipita- analysis of di 2 Materials and methods 2.1 Sampling site and environmental datasets 1995 to 2005, independent fromet the al. work of 2010 (small and large copepods,decapods chaetognaths, larvae, appendicularians, other pteropods, crustaceans, thaliaceans, other gelatinous and other zooplankton). This Here we are analyzing a new time series, weekly sampled with a WP2 net, covering The environmental variables selectedchlorophyll- for the analysistemperature ( are: nitrateand chlorophyll- (NO face, 10, 20, 30, 50 andin 75 our m analysis. depth – Nitrates depth were averagedan analyzed values autoanalyzer by (0–75 Technicon Alliance, m colorimetry chlorophyll- depth) ( were used fluorimetry ( at the entrance of thecal, Bay hydrological, (43 chemical and biological parameters1995. have Further been sampled information weekly about since this station is available at sea water temperature, salinity and densitywork, analysis of mean the values water column. of In temperature, the present salinity and density of the upper layer were used on monthly sampling orGarcia-Comas et less al. (e.g., that it was controlledinitiated by by it’s resource. the intensity Thisthe of hypothesis southern the of and winter a central convection strong is Ligurian “bottom-up” also Sea control supported ( by observations in their initial concentrations after 2000et suggesting al. a quasi decadal cycle ( in the Balearic Sea.cold The higher winter abundance resulting of in zooplanktonin high were surface correlated winter density to mixing. increasing dryenhancing the and Dry nutrients winter and replenishment convection cold and ande as strengthening winters suggested the lead by spring to the bloom. an authors, increase The positive scale climate indicators suchSea, as based the on NAO aecosystem were long was found. time heading series toward Other (1963–1993)the a studies early have more in also 1990’s regenerated ( the suggested systemries that Ligurian dominated extended the until by 2003 pelagic jellyfish revealed that in the zooplankton and mainly copepods recovered abundances of zooplankton ( ( limitation of phytoplankton growthas by a light possible additional in1999 factor the of Mediterranean inter-annual Sea variability was ( suggested ity of zooplankton inGarcia-Comas the et Ligurian al. SeaYet, and in to oligotrophic seas, test such whethertions as hypotheses and the formulated Mediterranean, plankton by changes occurs inet at environmental al. short condi- time scales ( and Chiav 5 5 10 20 15 25 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ) ). ). Van- 2010 2010 Gorsky , , national ). ) developed ). However 600 000 - ≈ Rakotomalala 2010 , Gorsky et al. . These percentages Gorsky et al. 1 for examples of thumb- eng/Home.html . Sampling was carried 2 ) were utilized for the auto- 2010 ). To assess the performance of , NO Vellele http://www.zooscan.com ´ emaphore, located on Cap-Ferrat at Vandromme et al. in “EBv” was proposed (more or less 2010 “EBv”) account for an average of 42% 3 , 3 and ). Local weather was provided daily by 9182 9181 Gorsky et al. http://www.domino.u-bordeaux.fr/somlit . Several variables were measured from each ex- 0.724 mm > . 2 ). All these environmental measurements fit the qual- NO Sagitta 2) / cient classification of copepods (recall rate of 0.92 and Vandromme et al. 3.2.2 ; ). The resulting time series included 489 samples (7–8 ) based on Tanagra data mining software ( ffi 2 ´ eanographie de Villefranche-sur-mer” ( (Minor · 2010 2007 2) , ). Images were analyzed by dedicated imaging software called , / erent from biomass, especially when comparing crustaceans and ff http://www.obs-vlfr.fr/Rade 2010 , (Major · http://www.zooscan.com which is equivalent of a spherical diameter larger than ca. 350 µm ( π ). Gasparini · 3 3 Gorsky et al. / 4 2010 ). Unknown objects were automatically sorted into categories defined in a learn- , = The zooplankton was successfully separated from non-living objects with a recall Each sample was gently separated into two subsamples with a 1000 µm mesh. Then All other variables (see Appendix 4 in http://www.obs-vlfr.fr/Rade/RadeZoo/RadZoo/eng/RadeZoo nails). These large organisms (i.e. of the totalically zooplankton classified, apparent biovolume. tenthese zooplankton categories Adding categories and the were representative species smallmust defined. be are copepods taken given with automat- Percentages in precaution Table concerning becausevolume they which stand is for percentages di ofjellies. the Yet apparent the bio- present workabsolute focalizes concentration on the in variation the ofsupposed field. constant these throughout groups the and Biases time not in lag on the considered. their evaluation of their biovolume were ual separation of objects1.5 larger mm than length). 0.724 mm Inidentified from the non-living present objects work,pendicularians, and chaetognaths, all classified copepods, objects into decapods nine largernous, larvae, zooplankton than other pteropods, categories: this crustaceans, thaliaceans ap- value gelati- and were other visually zooplankton (Fig. domly chosen samples. Thecorrectly recall identified rate and was the the contamination proportion rateprecision was of is defined positive as the cases being that proportion 1-precision,et were where al. of the predicted positive cases thatrate were of correct 0.94 ( this and is a mainly contamination duecontamination rate of to of 0.02). the 0.04 e ( However these rates decrease for large objects and a man- and Major axes,EBv an equivalent apparent elliptical biovolume (“EBv”) was estimated: matic classification of objectsIdentifier” which was ( performed using2005 the free software “Plankton ing set ( the classifier, recall and contamination rates were computed for each category on ran- ration of small andtwo size large classes objects prevents and underestimationThis of subsequent procedure, large separate rare WP2 image0.032 objects mm and acquisition ( of ZooScan, the dromme enables et to al. quantitativelyZooProcess record objectstracted from object such asand “Major”: “Minor”: secondary primary axis axis of of the the best best fitting fitting ellipse ellipse for for the the object. object, From the Minor at the “LaboratoireThe d’Oc zooplankton sampling was( carried out in the frame ofeach the subsample was RADE-ZOO fractionated program separatelyare with the generally Motoda more box. Since abundant small than objects large ones, they were fractionated more. Sepa- 2.2 Zooplankton data The net samples usedtil in December this 2005 studyout aboard vertically were the collected between 60 weeklymouth m from aperture and February of the 1995weeks surface 0.25 m un- were with a missingjects WP2 per digitized net with year the (mesh on ZooScan size imaging average) of system and ( 200 µm, contained a total of Meteo-France at a meteorological138 m station, height the and 1.2 S kilometer away from Point B. ity controls and protocols of SOMLITand ( SO-RADE ( (10 to 40 m depth, see Sect. 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , , ) ) z 3 a (2) (1) − m . For Raick 1988 3 3 ( (Systat − ) is then I I ˜ ® nez et al. ) and Iba ) with a visual c, d). Weeks of 2002 ( 3 b), yet anomaly of 2010 3 and the abundance ( 3 ). The maximum bio- 3 − a, b), a clear opposition ´ egoire − 3 m 3 Andersen and Nival is the irradiation at depth z I ). Mieruch et al. 3, and was maximum during week . ) which is calculated from the mea- ). the less abundant year was 1995 2 3 chl − Lacroix and Gr 2005 value. Cumulative sums ( ± ( K m 3 p . 3  1 dz 9184 9183 ) . Units and values used are the same as in + ] z ) ) ( s ext ) developed for the bay of Villefranche-sur-Mer was /I z,t and the average abundance was 614.9 # m z Raick et al. K . Years with the maximum annual biovolume were I cient and depends on the attenuation by the water 3 3 z ( 0 ) − − ffi · Z s Chl( I 1988 [ . The light limitation on phytoplankton growth ( m − ( /I β a 3  z ) and · chl I ( 2 K ect of light limitation on the ecosystem a combination of the ). exp + (the Mathworks Company, inc.) and SigmaStat 3.5 + ff 1 · 2002 2 ) ( ) with the corresponding ® z s ( s r (the optimal irradiance) are taken from /I z s I I ( water and 1089.6 # m · ´ albedo) egoire . The poorest year in term of total biovolume was 1998 (66 mm K 3 ) 3 I − − − and = β I ) developed for the central Ligurian Sea and of the model of phytoplankton m ) and the most abundant one was 2000 (1468 # m ) (1 β 3 + 3 Andersen and Nival · z − ( 7, i.e. an average of 4.2 weeks after the start. The earliest years were 1997, . 0 ). Spring peak started during week 7 (1 2 comes from Eq. ( ext = ) and by the phytoplankton shadowing ( 2005 · 2 ( z ) enable a fast representation of shifts dates and were computed as the first dif- z K ± I is the light attenuation coe I 2 5 . = Following the anomalies of biovolume and abundance (Fig. Next, to assess the e water = ext K I z year 1999 increase and anomalyinstead of year of 2004 biovolume. decrease when considering This abundance highlight changes in the average mean size, with year appears between years beforeage and biovolume was after 67.2 ca. mm the 2000. second period During these values130.0 the mm almost first doubled (1.93 period and2001, the 1.77, 2000, aver- respectively) 2004 to and 2003, reach to followed by the years average, 2005, then 2002to and years annual 1996 1998, abundance which means, were 1995, close the 1999 pattern and was 1997 almost similar were (Fig. the lowest. According 11 2001 and 2002 withand a 2002 start (week on 7) week andwas 4, 1997 only and observed (week the for 10). earliest yearsspring A maximum 2002, peak second 2003 was for peak and for year in 2005 years 2002 late – 2001 only. summer/early it was autumn of the same order than the 3 Results 3.1 Zooplankton community dynamics The global average ofwas zooplankton 937 biovolume # was m 113whereas mm the richest one(448 was # 2004 m (201 mm volume and abundance occurredstart generally and from maximum March of to theTable spring May peak (Fig. were recorded from abundance time series (see I and K ( sured quantity of chlorophyll- calculated as Values of with Lacroix and Gr model of light attenuation in theet water al. column of Software, inc.). Anomalies were computedto on regularized fill data with scarce lineartions gaps interpolation referred in to as time1993 series. Correlationsferences were of Spearman anomalies. rank Finally,from order timing smoothed of time correla- start seriescontrol following and the of maximum results. method of of peaks were recorded growth of I Results will focus on thezooplankton description compartment of and seasonal then andwater the inter-annual column environment, variation physics including on and nitrates, first meteorological chlorophyll- the variables.using Graphs Matlab and R2009b analyses were made used. The light attenuation is formulated as follows 2.3 Analysis 5 5 20 25 15 10 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | for was 3 peak . The − 2 and a . 2 a 2 ± with years . The max- 5 . 3 1 6 weeks, i.e. with the min- − . 8, the earliest ). Strong neg- . 3 3623 # m 1 1 1 − , and year 2004 ± ± − ), and year 1995 3 ± in 1997 and 2001 1 1 . − 3 − erent categories. The ff c. Nitrates concentration 5 weeks 6 to 22). The start and (0.229 µg L peak was observed during the ≈ erent years even if years 1995, a a ff was for year 2001 and occurred weeks 1 to 13) with maximum val- ) were on average at 5 a 2 ∼ whereas it was 11 796 ). Through the year, chlorophyll- 1 3 − − in 1998 and 2004 according to biovolume, b) were on average 0.301 µg L 5 3 9185 9186 − m 3 323 # m a) were on average of 0.44 µmol L 5 ± a (in 2003 from the weekly data). On these winter/spring erent taxonomic groups whereas year 2000 were abun- erences appeared among the di 1 ff spring bloom (Table ff − ) and the maximum in 2003 (0.70 µmol L a 1 − concentrations (Fig. a ) concentration (Fig. 3 erence was between year 2000 and years 2001 to 2005. Years 2001 to 2005 ff a–c with the computation of cumulative sum on yearly means for each cat- peaks. The earliest start of the chlorophyll- 8 weeks respectively, i.e. 3.5 and 3.1 weeks after the start and maximum of 4 . 3 2 ± 2 . The chlorophyll- In addition, zooplankton taxonomic groups abundance globally changed from year 1998 and 1999 withspectively. A a high maximum variability during occurredhaving for the a years first maximum before 2000 and duringweeks with weeks eleventh 3, years 10 weeks 1995 2, and of and 1 11, 1999 which thethis are and winter/spring year the maximums, years re- no first 1996, second threewere peak, 1997 earliest at observed and nitrates the except, 1998 concentration end to maximums. of during somepeak summer After extent, is and in even early higher autumn 2001, than 2002 the and first 2005. one. In 2005, this second 10 the NO third week for years 1997, 2000the and ninth 2002, and week. the latestduring start Earliest the was fifth maximum for week, year of 2005 whichwas during chlorophyll- is for also the year week 1996summer/early of and the autumn start. occurred cannot The be during1996 latest identified and the chlorophyll- 2002 for fourteenth seem the to week. di have one. Second peaks in late was at maximum from Januaryues to reaching March/April about (i.e. 2.7 µmol L start of peak ofstart nitrates concentration was occurs recorded on for averagethe year on previous 1998 week year with 2 and a the5. peak latest starting The was maximum on recorded of week foraround the 50 year five nitrates (mid-December) week 1999, concentration after of with was the a on start. start average The during at earliest 7 week and latest maximums were also for years 1995 to 2000 abovewas this the mean year and with yearswas the 2001 the minimum to year mean 2005 withmaximum below of the on this chlorophyll- average maximum mean. from (0.385 February µg L maximum Year to 2004 of April/May the (i.e. chlorophyll- imum in 1996 (0.18 µmolative L anomalies occurredanomalies from occurred 1995 from to 2002The to 1998 annual 2005, and cycles and as in 1999 monthly means 2001, and are 2000 whereas presented were on strong close Fig. to positive the mean. peaks, start and maximum were measured for each year and reported in Table 3.2 Environmental variability 3.2.1 Nitrates and chlorophyll- Nitrates (NO biggest di were globally abundant in all di dant in copepods butchaetognaths, showed appendicularians, negative thaliaceans anomalies and gelatinous of predators. abundance of decapods larvae, according to abundance (from weekly samples).of From the 1995 annual to maximum 1999, was thethe average 5144 second value period. 2000, with larger concentrations after.on The Fig. exact years of these changes are reported small copepods and pteropods, 2002ever, from for year thaliaceans, 2000, 2003 some for di large copepods). How- 1999 showing the smallestshowing organisms the largest, with almost an 2.44 average timesimum larger, of value with 0.063 of an mm average the ofof spring 0.154 mm peak 270 followed and a aand similar maximum between pattern of a varying 1685 minimum between mm of a minimum 3676 and a maximum of 17 750 # m egory. Most groups changed from negative to positive anomalies in 2001 (2000 for 5 5 10 25 15 20 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . ). θ 1 C). σ − ◦ with ) and ), and 1 1 C, with 1 − − ◦ − d d 2 2 (for a fixed d–f). The − − 001). Years 7 θ , with 1995, . 1 σ 0 − C). The coldest ). However, due ◦ p < (fixed temperature 4.2 θ σ 026). The mean solar . 972, . 0 0 c) with a mean density of = = of 0.9834 and a maximum 6 p s s r r , with years 1995, 1996 and between the surface layer (0– 1 ). Years 1997, 1998 and 2001 − θ ). θ 629, C, year 2003 being far warmer d 1 . σ ◦ σ 2 − 0 − during this period, with a maximum d = 2 1 s − − r C), and that variation in winter means of ◦ 9188 9187 a, b). Taking the equation of state of seawater 6 ). Winters 1995, 1998, 1999, 2000 and 2002 1 − d C) and a minimum for 1999 (10.56 2 erences of 0.0879 ◦ − ff 001; density vs. salinity: . with the maximum for year 1999 (975 J cm 0 1 − ) it appears that the amplitude of variation of winter means d p < on average and the minimum for 2000, with an average of temperature of 13.5 2 1 − 0 C, on average), and year 2004 being the coldest (19.25 ◦ − T 1981 C) accounts for a variation of density of about 0.39 923, ◦ . , ). Within this work, the layer 10–40 m was chosen since surface C) and high salinity (above the mean of 38.04 psu) and vice versa 0 ◦ 9 − salinity of 38 psu) whereas the variation of winter means of density is − ). Years 1995 to 1999 and year 2002 showed below average irradi- a–c. The average temperature through this period was 11.13 0 = 1 7 S s − r d , almost 6 times less than in 2001. The driest winters were 1995, 1999, 2 1 − − whereas year 1997 was the lowest (28.41 . Thus temperature and salinity should be both considered to account for the C and θ θ ◦ σ σ The spring/summer climate was also studied (April to August, Fig. Year 2005 presented the greatest positive anomaly (Fig. value of 9.5 10 Millero and Poisson The average light perceived inApril the to water August column for (average from the 0 eleventh to years 75 m is depth) 435 J from cm 1998, 2000, 2002 and1996, 2004 2001, being 2003 rainyThe and (maximum springs/summers 2005 for being showed 2002years the an and driest 2.02 2000 average mm (minimum d solar to(2365 for J irradiance cm 2001 2005, of andance 2247 except 0.57 J mm with cm d 1999 2002, being the being less sunny sunny. (2137 J3.2.4 cm 2003 Light availability was and phytoplankton growth the in spring/summer sunniest year average temperature duringthan this the period others was (21.69 Precipitations 19.85 during springs/summers were on average of 1.23 mm d The late autumn/winter timethe (i.e. mentioned year) from precipitation, November airsented of temperature on and the Fig. solar previous irradiance year means are until pre- March of were the sunniest and winters 1996, 2001 and 2004 the less sunny. 3.2.3 Local weather a maximum for year 1998winters (11.89 were 1995, 1999 andThe 2005, precipitation whereas were the an warmest averagein were of 1997, 2001 2.40 1998 mm and d and 5.15 2001. 0.87 mm mm d d 2000, 2002, 2004 and 2005and and precipitations the rainiest during were winter 1996, are 1997irradiance correlated and ( was 2001. 882 Temperatures J cm the minimum for 1996 (760 J cm the mean of 13.60 for years with low winter densities (Fig. of temperature (1.25 salinity of 38 psu and a salinity (0.4 psu) accounts for aof variation 13.5 of density ofof about 0.5 0.31 observed density variations. were far below themean, mean, and years years 1996, 1995, 2002,of and 1999, temperature and 2003 2000, salinity were and 2004 closetemperature: was to and significantly the correlated 2005 mean. to were both Densitywith of above is high them the a (density densities function vs. observed in winter corresponded to low water temperature (below 10 m) and the bottombetween layer (70–80 all m) layers with are a gradual significantlyp increase correlated – (minimum yet, density anomalies processes will be analyzedto (i.e. the the winter strong convection,changed observed the see correlation results Sect. and between conclusions. all layers, another28.79 choice will not have ( From average yearly variation ofbetween the density 4 it and appearsDuring 17 that this weeks the period the of density water the maximum columndepth was year occurs with almost reaching homogeneous an from densities almost the between surface constant to 28.5 di 80 and m 29 3.2.2 Hydrology 5 5 25 15 20 10 25 15 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ects ff 2008 ( ). Years ), dolioli- 1 Marty and − Marty and d 2 1997 − , ) and phytoplankton ). In addition, in the Molinero et al. ) and more complete ). The poor sampling 2010 2010 , 2010 2002 , ) and year 2001 the highest , , 1 Buecher et al. − ; d ´ erini 2 − 1997 art et al. , ff erent net (WP2 net instead of the Juday Go Goy ff , 1974–2003) and the present work (1995– 9189 9190 Garcia-Comas et al. ). In those studies, jellyfish seemed to out com- Marty and Chiav 2010 Garcia-Comas et al. erent components of the plankton communities ( ff ; 2008 , 2008 , ). 2005 ) found by analyzing 10 more years of the same time series , ), zooplankton ( 2010 , 2010 ( 1997 ) follow a similar pattern, with an average value of 0.623, a minimum , ´ 2 erini ). Convection as deep as 2000 m has been reported by ) to occur from winter 1999 to 2006 (except for 2001 and 2002). Deep Garcia-Comas et al. ), far ahead of year 2003, the second highest (459 J cm Molinero et al. 1 − Molinero et al. d 2010 2010 ( 2 , − ´ ´ erini erini Menard et al. In order to further understand the pelagic ecosystem functioning, we have analyzed Marty and Chiav blooms were reportedlower to mixing decrease related from topointed 1978 a to salinity to entail decrease 1998 less andfrequency nutrient as temperature (only replenishment possible increase, ( 5 consequence which yearsthe in was of detailed a ap- controlling 20 years factors.nant time to But series) structure surface the prevented pelagic salinity thein ecosystem author appears the or to to part NW determine of be Mediterranean it sea the as for main in medusae this determi- ( work and in other studies coastal zone of the Bay of Calvi (northern Corsica, Ligurian Sea), the phytoplankton ( a zooplankton time seriesBogorov obtained with as a in di ids ( Chiav Chiav convection brought to the surfacetoplankton high bloom load of of mainly nutrients diatoms that ( triggered an intense phy- and notably precipitations and phytoplankton production and composition ( data provided by the extension1967–1993) of by the zooplankton time series of observations of nutrients andthe Ligurian phytoplankton. Sea (Dyfamed) A support recent the hypothesis study of a in link the between climate open variability sea site of data on climatology, hydrology, nutrients and phytoplankton. In the light of the new but at the community level, thatabundance total of copepods the and 1980’s chaetognaths by recoveredlong almost year the term 2003 while trend, jellyfish thein remained authors abundant. winter proposed Instead mixing a of intensity quasiduction. a decadal acting fluctuation They through driven suggested the byincrease that input changes surface dry of salinity nutrient yearsdeep in in and winter the phytoplankton winter convection pro- 1980’s and in andplankton hence the from would density coastal 1999 benefit Ligurian close to of Sea. higher 2003 to phytoplankton would deep The biomass. authors values However, proposed causing their that study zoo- lacked 2005), it appears thatin the pelagic the ecosystem first in yearsof the of the Ligurian 2000 pelagic Sea ecosystem the may did conditionthe have not recovered length of occurred. of the Instead, the 1980’s. there zooplanktonof seems time The long-term to series zooplankton projected be is changes oscillations, oligotrophication not due yet long to enough climate from to inter-annual disentangle variability. the e pete chaetognaths and to bethe detrimental to late copepods, 1980’s. which abundance Thetion dropped related from authors to proposed increasing stratification aGarcia-Comas driven trophic by et water reorganization al. warming due in to the 1990’s. oligotrophica- However, 1999 the lowest (respectively 373,(547 391 J cm and 393 J cm 1995 to 1999 are below theitation mean factor whereas (Eq. years 2000 to 2005 are above. The light lim- late 1980’s ( for years 1995, 1996 and 1999years (respectively 2001 0.536, and 0.566, 2003 0.572) (0.692 and and the 0.673). maximum for 4 Discussion 4.1 Previous analysis of the pelagicPrevious ecosystem in time the series NW Mediterreanean analysisat Sea Point on B di highlighted thecomposition correspondence of between some changes key in species the and the abundance and/or shift in the local climate that occurred in the 5 5 10 15 25 20 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , , ; ) ect ff 726, 001) Lea- ´ erini . . 2002 2010 ), and 0 0 ( , = Marshall s ; p < r 2006 ´ erini , Nezlin et al. ). ; Vargas-Yanez 026). Air tem- ´ c et al. . ; 1993 888, 0 ˇ . ci , 0 = 2010 2002 − Ga , p 2010 , = , Marty and Chiav s Sommer and Sommer ; , except for year 2000, r ; 4 629, ´ . erini 0 2008 art et al. Marty and Chiav = Schott et al. ) occurred during continuous 2002 cient to explain the observed Frederiksen et al. ff , s , ; r ffi Go 2009 ). This results in increased density , 1990 , erent trophic levels were already ob- ff Garcia-Comas et al. 2002 a, b). This temporal dynamic stands odd , Marty and Chiav 001 for both cases). Katara et al. 5 . ; ; 0 ), we suggest that “top-down” control by zoo- 9192 9191 Vage et al. 1998 ; p < 2009 , 2004 Graneli and Turner , 2010 , ( a, b and ). In addition, the favorable conditions (dry and cold 2004 Aebischer et al. 3 , 2010 ), such a strong “top-down” control decreasing the whole , Ludwig et al. Bethoux et al. Nezlin et al. ´ ; erini 2008 ; ; , 0.783 respectively, Soriano et al. 2007 1991 − ; 2003 , ). This appears particularly visible for year 2001, which showed low rmation is supported by the observed strong correlation ( , , Garcia-Comas et al. ffi ). Such positive forcing across di 1999 ). Observed anomalies of precipitations in the Bay of Villefranche-sur-Mer 3.2.2 , 4.3 804 and . erence of about 0.3 psu was observed over these years for winter months. This 0 Wiltshire et al. Marty and Chiav 2010 ff 006) between winter surface density and nitrates. Skliris et al. . ; ). This a ; , − 0 = A striking results of the time series analysis is a clear opposite patterns in the inter- The main consequence of an increase in winter convection is a stronger replenish- = s r in the common conceptualtoplankton model concentration. that favorable The nutrient opposite conditionsand inter-annual zooplankton result variability in between in periods with phytoplankton high highers phy- nutrient control concentrations strongly primary suggest producers. that graz- Thereforeesis in raised addition by to theplankton “bottom-up” may control be hypoth- important to“top-down” explain control the of observed variability phytoplankton of byscales phytoplankton. zooplankton is Even at an if both accepted seasonal phenomenon ( and inter-annual also after recent studies at the same location ( annual variability between nitrateplankton and concentrations zooplankton and (Figs. phytoplankton and also phyto- 2006 served at various locations (e.g., phytoplankton community stocks has rarely been observed either in field’s studies or trate concentration in February than yearsFrom 2005, the which literature, showed the such highestat increase convection. the in nitrates end and ofproductivity, more and winters mainly generally were diatoms nutrients in always availability the related Ligurian to Sea ( a significant increase in phytoplankton see Sect. observed in theary central of Ligurian about 3 Sea timesyears an between 1997/1998, which years increase showed with the of low lowest and convection, nitrate were high almost concentration convection. 7 In in times the lower Febru- in present ni- work, 2010 p winters) and the quality ofon phytoplankton the (i.e. more whole diatoms) zooplankton have had identified a taxonomic positive e groups (Fig. 2004 Backhaus et al. In the NW Mediterraneanand Sea Schott “winter convection” (e.g., ment of nutrients through a deepening of the mixed layer (e.g., 4.2 Winter forcings on the ecosystem (see Sect. densities but close to averagethe salinities highest anomalies, of yet the the sea timeof water series. sea temperature Considering water was the salinity wholealike and time anomalies temperature series, of are however, precipitations anomalies strongly andperature correlated air and ( temperatures precipitations ( seem tothe determine observed the ecosystem intensity and of( the are winter both convection strongly in correlated to the winter water density et al. during winters tend to confirm1998 this hypothesis and with 2001, wetter winters correspondingHowever, mainly the to in 1996, increase years 1997, of with salinityincrease low of alone anomalies winter appears surface of not density surface and su the water temperature salinity. must also be taken into account and allows surface water to sinksea into water the salinity deep was layer, observed mixingcurring in the at the water the present column. beginning study, of A with the shiftwhereas less observed higher in saline period salinity winter until were waters 2000 observed (minimum oc- fromage in 2001 di 1997 to and 2005 1998), (maximum in 2005).increased salinity An aver- was mainly relateddecrease to of a precipitations decrease (present in data)(e.g., freshwater and inputs, rivers both flow due in to the NW a Mediterranean Sea cooling and saltening of theman surface and water Schott by atmospheric forcing during winters ( 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , in or ´ an art 3 009 ff a . − erent 0 ff Mor Durant Go = ; p Andersen MacIntyre ). The co- ; ); compared 2004 Edwards and ) do not reach , ; 706, . 2008 1998 0 , 2001 , Feuchtmayr et al. = ) is, then, not sup- , 3.2.4 ; 2002 s r , ). Copepods alone will 2010 ); 45–105 mgDW m 2002 , Sommer , , Sect. Nezlin et al. ). Phytoplankton appears 1 ; erent driving forces ( 2008 ) it appears that 1995, 1996 ff 005 and 2004 , . ) were not correlated to any Geider et al. Skliris et al. , 0 2 2.3 2010 ; Ji et al. 1999 , = ; , p Edwards et al. ; 1989 ect the ecosystem productivity is by Shurin et al. Sommer , ff 2010 ( ; 734, , . 1990 0 , being positively correlated. This is poten- ), nor in the southern Ligurian Sea ( = 1999 a s 9194 9193 , r ´ and zooplankton – the low abundance of filter- ). According to these studies, the coupling de- ee et al. Duarte et al. Bakun Gasparini et al. ; ; a Daphnia 2010 cient to explain the main observed inter-annual , ffi Cushing Broh 2008 Vandromme et al. ; , 1997 2007 ´ , , erini 1981 Micheli et al. , in Dyfamed, ( Sommer ; 3 ), occurs possibly at smaller scales of analysis (both temporal, in Point B ( − 3 cient to explain the case of years 1995, 1999 and 2001. Indeed − Durant et al. 2005 ). The calculated irradiation values (Eq. ffi 2010 ; , ( Sciandra et al. Hecq et al. ; erent trophic levels are conditioned by di Marty and Chiav ff blooms and zooplankton peaks (Table 2005 2004 , ) – nutrients and chlorophyll- a , ). Even if the “match-mismatch”, among other ecological mechanisms, re- ). Using a light limitation model (see Sect. 1988 Bakun , ect of spring/summer irradiation and other patterns ff 2002 2007 2002 Borer et al. , ; , , A way through which solar irradiation may a Finally, changes in timing of water column stratification, nitrate concentrations peaks, et al. saturation of phytoplankton growth generally observed ( and Estrada diation and vice-versa. Inplankton addition, and spring/summer positive irradiance correlations ( wererespectively observed for between zooplankton zoo- biovolumetion and being abundance) the – only the parameter spring/summer which show irradia- a significant correlationlight with limitation zooplankton. on phytoplankton growth as suggested by previous studies ( winter convection during 1995eleventh years, and yet, 1999 zooplankton were concentrationsobserved among were during low. the year The strongest opposite 2001centration observed situation of with in was zooplankton. a the These particularlyconvection three strength weak years anomalies winter correspond and to spring/summer convectionremaining years irradiation but years are in high a opposed. which strong con- the For winter all winter convection the corresponded to high spring/summer irra- spatial or taxonomic) inand the “top-down” Bay controls ofvariability. seems Villefranche-sur-Mer, su the interplay of “bottom-up” 4.3 E The “bottom-up” control caused by nutrientdoes replenishment not by seem intense winter su convection and Nival viewed in Richardson ported by the presentpearance observations. of A di “match-mismatch” occurset when al. the time of ap- The “match-mismatch” hypothesis ( This strong control ofin phytoplankton the central through ( zooplankton grazing was not observed feed only on largephytoplankton), phytoplankton or (thus decreasing will the feedsure competitive on on pressure microzooplankton phytoplankton); on (thus small pteropods while decreasing here) filter-feeders the will (thaliaceans, feed grazing onexistence appendicularians pres- and the and whole high phytoplankton abundance also sizesthe of decline ( filter-feeders of and phytoplankton copepods stocks.concentrations after Yet, of year 2000 nitrates, 2000 may chlorophyll- appears explain asfeeders an during exception these with year high (only pteropods were present) may explain this particularity. pends mainly on the sustainedparts co-existence of between the zooplankton feeding phytoplanktonexample, on size a di spectrum. long-term This coexistencewith of can a tunicates be co-existence and the of copepods case copepods is in and observed, or where, in for lakes in mesocosm experiments ( 2004 et al. tially due to lower zooplanktonsite biomasses – in 15–30 those mgDW m locationsCalvi, compared Corsica, to ( the present ton growth is not determined by other factors than the phytoplankton development. to 20–700 mgDW m to be grazed fasterphytoplankton), than which it can is only growing, be evidenced hiding by the rate “bottom-up” measurements. controlchlorophyll- (i.e., nutrients to inter-annual variability in annualzooplankton. anomalies of The nitratetween concentrations, maximum 0 chlorophyll- of and zooplankton, 2 weeks despite after its the maximum variability, of was phytoplankton, always suggesting that be- zooplank- 5 5 25 15 20 10 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Ne- Garcia- erent groups ff increase. This a ). ). A possible expla- 4.2 ) and this work we pro- 2010 erent taxonomic groups. ). In winter, precipitations ff , 8 2010 ( ect of the strong winter convection. ). It appears that most of the large ff 4 ) and would further decrease the available Cloern and Jassby 9196 9195 ). Yet, considering or not the microplankton will 1999 , ) is multiplicative, any decrease in the light limita- Garcia-Comas et al. 2008 , 1988 ( ect of winter convection. Years 1995, 1996, 1997, 1998, ff ). This gives an explanation of the peculiarities of year 2000 ect on phytoplankton growth. In addition, the light attenuation ff Duarte et al. 4.3 Klaas et al. ; ) in the 1981/1983 and 1999/2000 switches. The reason for the time erent reproductive strategies among the di erent taxonomic groups (see Fig. ff . The presence of copepods feeding on large phytoplankton decrease 2001 ff a 2010 , ( Andersen and Nival Another inter-annual variability was observed in the time-lag between the appear- (mainly filter-feeders) changing characteristics of theton “top-down” control to from phytoplankton. zooplank- due Yet this to global a scheme lackglobal do of functioning data. not of the take This presented microplankton ecosystem couldgrazing since into possibly of they account modify are phytoplankton, known the to to represent proposedin contribute to a hypotheses the the food about bay resource the of forjstgaard Villefranche-sur-Mer) small et and copepods al. to (especially contribute to the recycling of nutrients ( as regards zooplankton concentrations.spring/summer This climate. suggests In addition again high anyear abundance would important of have zooplankton role an during of impact thelarge on previous the ones some taxonomic (see groups Sect. ofwhich zooplankton had – high especially abundance the of copepods but low abundance of gelatinous zooplankton the competitive pressure for small phytoplankton and the chlorophyll- counteract or reinforce the e 1999 and 2002 had an1997, unfavorable spring/summer 1998 climate. and In 2002winter the case this convection of assuming may years that have 1996, 1999 nutrients positively the were moderate not unfavorable the limiting spring/summertions) weak may even. climate (or have negatively For (i.e. intermediate) moderate year the lowBy positive 1995 irradiance contrast, e and years and 2000, highmate. 2001, precipita- Especially 2003, for year 2004 2001 and which 2005 was a weak as favorable regards spring/summer winter cli- convection but high not modify the positiveof link chlorophyll- between the presence of copepods only and the increase 1998 and 2001 showed weak wintertemperatures. convection Years due 1995, to 1999, high 2000 winterlated and precipitations 2005 and/or to showed low strong winter precipitations2004 convection, and/or were re- low intermediate. temperaturesity The in strength in winter. of nitrates, the Years and 2002, winter thus 2003 convection phytoplankton controls and growth. the availabil- In spring/summer light limitation, can and temperatures controlled the strength of the winter convection. Years 1996, 1997, time (euphausiids, amphipods) or bystrong the initiation production the of following diapause year. eggs Yet,can the enabling explain time a the lag more of particularity responses ofmainly of the composed the of year di copepods 2000 and in noton which of phytoplankton filter-feeders, the from reducing herbivorous zooplankton the community previously “top-down” was control mentioned (Sect. 4.4 Conceptual scheme On the basis of the new data by lag is not truly understoodalso but in seems various to location be innation a the lies constant world in feature (e.g. di inSome the may studied area respond and immediatelypods). Other through groups an may respond increase with a fecundity/natality certain (small time-lag because cope- of longer generation centration to the light attenuationthe model water and column. of new Additional measurementsfrom of experiments the available of sampling light site light in will limitation be on also phytoplankton needed species toances validate this of hypothesis. the di groups increased in 2001one whereas year before. smaller Such zooplankton, a mainly time-lagComas was copepods, et already al. increased observed at the same location by model of tion factor will have an e model does not consider thein turbidity from this terrestrial coastal discharge. setting Thislight may ( in be the important water column. There is a need of the addition of suspended particles con- pose an explanation whereby the climategroups forcing in modifies the the NW dynamics of Mediterranean zooplankton Sea in four patterns (Fig. and 1999 were the three more limited years and 2001 was the less limited. Since the 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ; , ). in − 2010 2008 2010 , , ( Conversi ; were found. ), were years 2007 4.3 , ` andes de Puelles Fern ). In the present time Goberville et al. ; ; ) where no significant links 2010 2004 Garcia-Comas et al. 2010 , , , (2001). This lack of correlation 2010 − ( ). zooplankton dynamics ` andes de Puelles and Molinero 2010 , ` andes de Puelles et al. Fern strong NAO Fern 9198 9197 ; ≈ Hurrell and Deser Batten and Welch erent. A global decrease of phytoplankton can sensu ; Cloern and Jassby ff ; 2008 Berline et al. , ; 2003 ect of the winter convection (see Sect. Garcia-Comas et al. 2009 , ff , 2005 2010 ). For the periods presently studied (1995–1999 poor and , , , nitrates concentration, hydrology and local weather with weekly ) and in occurred in 1995, 1999, 2000 and 2005 and strong NAO 2010 ´ erini a ( + (1995 and 1999) or was observed suggesting a strong “top-down” control of phytoplank- Payne et al. 2010 a ( + even if the link is di ; Stenseth et al. a ; Molinero et al. 2007 , . . . ). Particularly, strong ( , 1995 1) positive phase of the NAO are known to generally drive colder and drier , > 2010 A recovery at ca.occurred 2000 in of the the 1990’s ecosystem waszooplankton from found, abundances low with zooplankton quasi confirming abundances decadal hypothesisSuch fluctuation that by from a low shift to high components in of ca. ecosystems 2000 (e.g. was also observed at diverse locations and for other compared to smaller one. A clear opposite trend inchlorophyll- the inter-annual dynamic of nitrateston and by zooplankton zooplankton. vs. A one-year time lag was observed in the recovery of large zooplankton groups et al. Marty and Chiav , ± – – – Berline et al. In summary, dry, cold late autumns and winters are beneficial for phytoplankton Hurrell used, 11-years, may also be not long enough to detect significant links. 5 Conclusions From the present work anplankton, chlorophyll- eleven years time-series ofvalues the was Ligurian analyzed. Sea includingarea. It zoo- It is was presently found that, the most complete time series analyzed in this and 2001. Surprisingly, these yearseven in reversed, which the the predicted spring/summer e climatewith moderated, strong or NAO can be due todrivers the in interplay the between control various of climate coastal indicators zooplankton and dynamics. also local The climate length of the time series series, strong NAO 1996, it was also lowNAO in and 2001. the Yet, zooplankton no significant totalin relationships abundance were and found biovolume. between Similar the results were found 2000–2005 rich in zooplankton), this appears to be mainly due to years 1995, 1999 Yet, some significant links wereGarcia-Comas found et between al. the local environment and the NAO in i.e. winters over the Western( Mediterranean and vice-versa for strong negative phases between any climate indicator and Ligurian Sea 4.5 links with the North AtlanticAs Oscillation was (NAO) suggested by severalfluctuations studies seem in linked the to Western largeNAO Mediterranean scale (e.g., Sea, atmospheric ecosystems patterns andet more al. specifically the growth and zooplankton development that ultimatelyton control the by biomass of grazing. phytoplank- further All increased groups if of previousThese year zooplankton factors seem was are to favourable present set orlong-term the and if ecosystem monitoring their light dynamics of for conditions concentrations these thebefore are are any whole variables attempt increased. year. is to Continuing forecast the needed ecosystem to state is confirm made. the propose dynamics grazing pressure on phytoplankton byof microplankton, chlorophyll- which result alsoonly in be an reached increase byto the deal presence of with filter-feeders. theSea Further microplankton coastal ecosystems. studies to will assess have, its however, role in the global functioning of Ligurian is similar to the presence of copepods feeding on microplankton and so decreasing the 5 5 15 10 20 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 9192 ´ eanographique ects zooplank- ff 9192 9180 for their field work. We finally thank NO Velelle 9200 9199 and 9179 9178 ect of the spring/summer climate. 9195 ff , NO Sagitta II ´ Education et de la Recherche and CNRS (France). 9198 9194 This study was supported by the SESAME IP of the European Com- , 9194 ´ erouel, R.: Dissolved organic carbon, nitrogen and phosphorus in the N-E ` ere de l’ 9184 , ´ evost, of the 9183 A second drivinggrowth factor in was spring/summer, which proposed, moderated i.e. or even the reversed the light system initiation limitation of phytoplankton The main drivingvection factor mainly of determined these byconsequence fluctuations being winter is a precipitations stronger the replenishment andton strength in temperature. through nutrients of a which “bottom-up” the a The control. main winter con- of the winter convection. Correlations between NAO andto zooplankton the were moderation insignificant. e This can be due ´ eo France for providing the meteorological data. Pieter Vandromme was financially sup- – – – Pacific associated with the possible51, climatic regime 863–873, shift 2004. of 1998/1999, Deep-Sea Res. Pt. II, vection and primary production in winter, Mar. Ecol.-Prog. Ser., 251,non-simple 1–14, dynamics: 2003. Conceptual templates361–373, and 2010. schematic constructs, J. Marine Syst., 79, ranean, Seasonal and interannual variabilitytuar. Stud., of 46, the 195–225, Western 1994. Mediterranean Sea, Coast. Es- degradation, Deep-Sea Res. Pt. I, 51, 1975–1999, 2004. tion of Biogenic Particles1988. – Role of Salps and Copepods, Mar. Ecol.-Prog. Ser., 44, 37–50, Syst., 79, 267–285, 2010. Atlantic and the N-W Mediterranean with particular reference to non-refractory fractions and marine trophic levels and weather, Nature, 347, 753–755, 1990. teleconnections and implications as to physical-biological linkage mechanisms, J. Marine ´ et Batten, S. D. and Welch, D. W.: Changes in oceanic zooplankton populations in the north-east Bakun, A.: Linking climate to population variability in marine ecosystems characterized by Backhaus, J. O., Hegseth, E. N., Wehde, H., Irigoien, X., Hatten, K., and Logemann, K.: Con- Arnone, R. A.: The Temporal and Spatial Variability of Chlorophyll in the Western Mediter- Aminot, A. and K Andersen, V. and Nival, P.: A Pelagic Ecosystem Model Simulating Production and Sedimenta- Aebischer, N. J., Coulson, J. C.,Alheit, and J. and Colebrook, Bakun, J. A.: M.: Population synchronies Parallel within long-term and between trends ocean across basins: 4 Apparent The publication of this article is financed by CNRS-INSU. References Acknowledgements. to include measurements of growthconcentration rates as of a proxy phytoplankton to and monitority zooplankton, phytoplankton in pigments communities the and also water lightof column availabil- zooplankton to models investigate the coupledto light to achieve limitation phytoplankton a hypothesis. and deeper environment analysis The are of development the also main underway driving forces of the long-term dynamic. ported by Minist A monitoring of microbialreal and “end phytoplanktonic to communities end” isthe analysis underway proposed of to hypothesis the and perform presented deepens a ecosystem. the analysis. This In will addition, allow further to works will test have some of mission’s Sixth Framework Programme,Change and under Ecosystems, the Contract No. priorityleagues GOCE-2006-036949. who Sustainable The helped Development, authors collecting gratefully and Global abelle thank processing Palazzoli col- the and Caroline data Warembourg. used Authors inWe are this also grateful study: to thank Marc Corinne the Picheral Desnos, for servicesde all Is- RADE-ZOO his Villefranche-sur-mer help. and (OOV) SO-RADE forJean-Luc at hydrobiological the data Pr Observatoire and Oc theM crews, Jean-Yves Carval and 5 5 25 20 15 10 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 9198 9194 , 9197 , ect, Geophys. ff 9179 9194 9191 , user manual, 2007. 9197 , 9193 9217 , 9178 9198 , ` andes de Puelles, M. L., Maz- 9197 9198 , , 9195 9193 9178 9197 9194 , Identifier/index.php 9198 , 9179 9190 9191 9178 9195 , 9197 9195 , , 9202 9201 9192 , ´ c, I., Vidjak, O., Fern 9179 9194 , , ˜ nez, F., Gasparini, S., Mazzocchi, M. G., Berline, L., 9192 9190 gaspari/Plankton 9191 eler, F., and Tailliez, D.: Deep water in the western Mediter- , ∼ ff 9178 9179 9193 ´ es planctoniques en baie de Calvi (Corse) en relation avec les 9189 , 9180 , 9193 9179 ˜ nez, F., Gasparini, S., Stemmann, L., and Gorsky, G.: Intercomparison of six art, A., Frankignoul, C., Henri, V., Mouchet, A., and Hecq, J. H.: Variations ff ´ an, J., Claustre, H., and Marty, J. C.: Specific Phytoplankton Signatures and http://www.obs-vlfr.fr/ ` eres des communaut 9194 ´ ` ` ´ ee, M., Go c, M., Civitarese, G., Miserocchi, S., Cardin, V., Crise, A., and Mauri, E.: The open-ocean andes de Puelles, M. L., Alemany, F., and Jansa, J.: Zooplankton time-series in the andes de Puelles, M. L. and Molinero, J. C.: Decadal changes in hydrographic and eco- ˇ ci convection in the Southernbloom, Cont. Adriatic: Shelf Res., a 22, controlling 1897–1908, 2002. mechanism of the spring phytoplankton station, Pangaea, doi:10.1594/PANGAEA.183618, 2004. organisms, 9182 revision, 2010. Balearic Sea (WesternOceanogr., Mediterranean): 74, 329–354, 2007. Variability during the decadein 1994–2003, an enclosure Prog. 1495–1504, experiment: 2004. insights from stable isotope analyses,ton to Freshwater top Biol., predators:Anim. 49, Ecol., bottom-up 75, control 1259–1268, of 2006. a marine foodPicheral, web across M., four and trophicSea: Gorsky, levels, G.: Decadal J. periodicity Zooplankton forced long-term by large-scale changes atmospheric in changes?, the J. NW Marine Mediterranean Syst., in anomalies and the ecology of the , Mar. Ecol.-Prog. Ser., 239, 1–10, 2002. and trophic mismatch, Nature, 430, 881–884, 2004. logical time-series in theclimate and Balearic zooplankton, Sea ICES J. (western Mar. Sci., Mediterranean), 65, identifying 311–317, links 2008. between mismatch between predator requirements and resource2007. availability, Clim. Res., 33, 271–283, Oceanogr., 44, 245–270, 1999. Mediterranean since the 1940s,Res. their Lett., 25, possible 1023–1026, relation 1998. to the greenhouse e of the Match Mismatch Hypothesis, Adv. Mar. Biol., 26, 249–293, 1990. quences, Prog. Oceanogr., 60, 245–262, 2004. zocchi, M. G., Assimakopoulou, G.,Comas, C., Zervoudaki, Iba S., Fonda Umani,Mediterranean zooplankton S., time Conversi, series, A., Prog. Garcia- Oceanogr., accepted, 2010. ranean: peculiar 1999 and1970 2000 and characteristics, geochemical shelf inferences, formation J. hypothesis, Marine variability Syst., since 33, 117–131,Cooper, 2002. S. D., andEcology, 86, Halpern, 528–537, 2005. B. S.: What determinesprintani the strength ofcontraintes a physiques locales, trophic Cah. cascade?, Biol. Mar., 30, 321–328, 1989. ope tetraphylla in Villefranchepopulations, bay Oceanol. between Acta, 20, 1966 145–157, and 1997. 1993 compared toTheir Pelagia Relationship noctiluca To Hydrographic Conditionssea, In Mar. the Ecol.-Prog. Coastal Ser., Northwestern 124, 247–258, Mediterranean- 1995. The Mediterranean Sea regime shiftother at european the basins, end PLoS of ONE, the 5, 1980s, e10633, and 2010. intriguing parallelisms with for Mediterranean marine ecosystems: the example of the northeast Spanish littoral, Prog. Coastal Ecosystems, Estuar. Coast., 33, 230–241, 2010. Geider, R. J., MacIntyre, H. L., and Kana, T. M.: A dynamic regulatory model of phytoplanktonic Ga Gasparini, S., Mousseau, L., and Marty, J. C.: Zooplankton biomass at DYFAMED time series Gasparini, S.: PLANKTON IDENTIFIER: a software for automatic recognition of planktonic Fern Frederiksen, M., Edwards, M., Richardson, A. J., Halliday, N. C., and Wanless, S.: From plank- Garcia-Comas, C., Stemmann, L., Iba Feuchtmayr, H., Zollner, E., Santer, B., Sommer, U., and Grey, J.: Zooplankton interactions Edwards, M., Beaugrand, G., Reid, P. C., Rowden, A. A., and Jones, M. B.: Ocean climate Fern Durant, J. M., Hjermann, D. O., Ottersen, G., and Stenseth, N.Edwards, C.: M. Climate and and Richardson, the A. match or J.: Impact of climate change on marine pelagic phenology Bethoux, J. P., Gentili, B., and Tailliez, D.: Warming and freshwater budget change in the Cushing, D. H.: Plankton Production and Year-class Strength In Fish Populations – An Update Berline, L., Siokou-Frangou, I., Marasovi Bethoux, J. P.,de Madron, X. D., Ny Borer, E. T., Seabloom, E. W., Shurin, J. B., Anderson, K. E., Blanchette, C. A., Broitman, B., Buecher, E., Goy, J., Planque, B., Etienne, M., and Dallot, S.: Long-term fluctuations of Liri- Conversi, A., Fonda Umani, S., Peluso, T., Molinero, J. C., Santojanni, A., and Edwards, M.: Duarte, C. M., Agusti, S., Kennedy, H., and Vaque, D.: The Mediterranean climate as a template Beaugrand, G.: The North Sea regime shift: evidence, causes, mechanisms and conse- Broh Bustillos-Guzm Cloern, J. E. and Jassby, A. D.: Patterns and Scales of Phytoplankton Variability in Estuarine- 5 5 30 25 15 20 10 30 10 20 15 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 9194 9192 9181 , , 9198 9190 9180 , , ´ 9190 e Royale Scien- 9193 ´ et 9179 , 9192 9192 , 9191 9191 , 9191 ´ ecologiques et biochimiques de 9190 , 9193 9179 9197 ´ ects, Mar. Ecol.-Prog. Ser., 357, 195–206, eristiques ff 9197 ´ eguer, P., and SOMLIT-Team: Climate-driven 9204 9203 ´ eanogr. Paris, 73, 159–171, 1997. 9194 9193 9190 9178 9194 9191 ´ ee, 11–12, 440–445, 1981. 9178 ´ erini, J.: Hydrological changes in the Ligurian Sea (NW Mediterranean, 9192 ´ egoire, A.: Revisited ecosystem model (MODECOGeL) of the Ligurian Sea: 9213 ` 9183 , ege 50e ann ` eme planctonique en baie de Calvi (Corse), Bulletin de la Soci 9196 9183 9198 art, A., Hecq, J. H., and Legendre, L.: Changes in the development of the winter-spring ´ ecosyst ˜ nez, F., Fromentin, J. M., and Castel, J.: Application of the Cumulated Function To the ff Keitt, T. H., Kendall,variability, Oikos, B. 85, E., 161–169, 1999. Klug, J. L., and Rusak, J. A.: The dual nature of community J. C., Nival, P.,Mediterranean and Sea Siokou-Frangou, over I.: seasonal-to-decadal9178 scales, Temporal variability Prog. Oceanogr., of 72, Centropages 214–232, typicus 2007. in the in the bay ofOceanol. Acta, Villefranche-sur-Mer 20, (Northwestern 733–742, 1997. Mediterranean Sea) from 1967 to 1990, Geophys., 37, 1–64, 1999. DYFAMED site) during 1995–2007 and2117–2128, biogeochemical doi:10.5194/bg-7-2117-2010, 2010. consequences, Biogeosciences, 7, irradiance response curves andJ. photosynthetic Phycol., pigments 38, 17–38, in 2002. microalgae and cyanobacteria, 79, 286–304, 2010. ents to the Mediterranean andand Black future Sea: decades?, Prog. Major Oceanogr., drivers 80, for 199–217, ecosystem 2009. changes during past of Lions – Winter 1987, J. Phys. Oceanogr., 21, 575–598, 1991. Processing of Chronological Data1993. In Oceanography, Cr. Acad. Sci. III-Vie,phenology 316, and 745–748, life historyPlankton in Res., a 32, 1355–1368, changing 2010. climate: current research and future directions, J. concentration in the Mediterranean, Hydrobiologia, 612, 33–48, 2008. communities: correcting for2008. trophic cascade e seasonal and interannual variability258, due 2002. to atmospheric forcing, J. Marine Syst., 37, 229– precipitations, Science, 269, 676–679, 1995. l’ tifique de Li Oscillation, J. Marine Syst., 79, 231–244, 2010. 9193 wood, A., Pesant, S., Garcia-Comas,using C., and the Prejger, ZooScan F.: Digital integrated9182 zooplankton system, image J. analysis Plankton Res., 32, 285–303,north-western 2010. Mediterranean, Ann. I. Oc acclimation to light, nutrients, and temperature, Limnol. Oceanogr., 43, 679–694, 1998. changes in coastal marine systems2010. of western , Mar. Ecol.-Prog. Ser., 408, 129–148, phytoplankton bloom in theresponse Bay to of changing Calvi climate?, (NW Mar. Ecol.-Prog. Mediterranean) Ser., over 236, the 45–60, last 2002. two decades: a phytoflagellate communities in coastal239, 57–68, waters: 2002. a mesocosm study, Mar.Ecol. Ecol.-Prog. Evol., 20, Ser., 337–344, 2005. Micheli, F., Cottingham, K. L., Bascompte, J., Bjornstad, O. N., Eckert, G. L., Fischer, J. M., Mieruch, S., Freund, J. A., Feudel, U., Boersma, M., Janisch, S., and Wiltshire, K. H.: A new Mazzocchi, M. G., Christou, E. D., Di Capua, I., de Puelles, M. L. F., Fonda-Umani, S., Molinero, Menard, F., Fromentin, J. M., Goy, J., and Dallot, S.: Temporal fluctuations of doliolid abundance Marty, J. C. and Chiav Marshall, J. and Schott, F.: Open-ocean convection: Observations, theory, and models, Rev. Mackas, D. L. and Beaugrand, G.: Comparisons of zooplankton time series, J. Marine Syst., MacIntyre, H. L., Kana, T. M., Anning, T., and Geider, R. J.: Photoacclimation of photosynthesis Ludwig, W., Dumont, E., Meybeck, M., and Heussner, S.: River discharges of water and nutri- Katara, I., Illian, J., Pierce, G. J., Scott, B., and Wang, J. J.: Atmospheric forcing on chlorophyll Leaman, K. D. and Schott, F. A.: Hydrographic Structure of the Convection Regime In the Gulf Klaas, C., Verity, P. G., and Schultes, S.: Determination of copepod grazing on natural plankton Lacroix, G. and Gr Ji, R. B., Edwards, M., Mackas, D. L., Runge, J. A., and Thomas, A. C.: Marine plankton Iba Hurrell, J. W.: Decadal Trends in the North Atlantic Oscillation – Regional temperature and Hecq, J. H., Gaspar, A., and Dauby, P.: Caract Hurrell, J. W. and Deser, C.: North Atlantic climate variability: The role of the North Atlantic Gorsky, G., Ohman, M. D., Picheral, M., Gasparini, S., Stemmann, L., Romagnan, J.-B., Ca- Goy, J.: The medusae (Cnidaria, Hydrozoa) and their trophic environment: An example in the Goberville, E., Beaugrand, G., Sautour, B., Tr Go Hays, G. C., Richardson, A. J., and Robinson, C.: Climate change and marine plankton, Trends Graneli, E. and Turner, J. T.: Top-down regulation in ctenophore-copepod-ciliate-diatom- 5 5 30 20 25 15 10 30 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ ees, 9178 9192 9197 , 9190 , 9189 , 9180 , 9193 9194 , 9179 ´ 9192 erimentation pour la fouille de donn 9194 , , 9178 9179 9179 9194 9206 9205 9193 ects on ecology through the use of climate indices: ff 9187 9198 9178 9182 9197 9183 art, A., Frangoulis, C., and Hecq, J. H.: One-dimensional modelling 9183 ff 9180 9191 9191 9191 ˜ nez, F., Souissi, S., Buecher, E., Dallot, S., and Nival, P.: Climate con- ˜ nez, F., Nival, P., Buecher, E., and Souissi, S.: North Atlantic climate and 9193 9197 , 9189 , ´ an, X. A. G. and Estrada, M.: Winter pelagic photosynthesis in the NW Mediterranean, Printer, Ottawa, 1977. and Adlandsvik, B.: Studyingthe climate North e Atlantic Oscillation, ElBio., Nino 270, Southern 2087–2096, Oscillation 2003. and beyond, P. Roy. Soc. Lond. B ter convection: Convective precipitation1241–1247, and 2004. cloud-to-ground lightning, Int. J. Climatol., 24, 506–516, 2008. controls on freshwater and marine phytoplankton, Oecologia, 147, 183–194, 2006. relation to changes in65, the 400–416, freshwater 2007. budget: A numerical modelling study, J. Marine Syst., Denis, M., Lefevre, D., Copin-Montegut, C.,in and continuous Avril, B.: cultures Growth-compensatingLimnol. of phenomena Oceanogr., Dunaliella 42, 1325–1339, tertiolecta 1997. limited simultaneously by light and nitrate, namics of phytoplankton in theC07013, doi:10.1029/2000JC000628, Ligurian 2004. Sea in 1997–1999, J. Geophys. Res.-Oceans, 109, the zooplankton of the NorthOceanogr., 12, Sea 260–269, during 2003. the twentieth century linked to oceanicthe inflow, Fish. Central During14401–14421, 1993. the Winter of 1988–1989, J. Geophys. Res.-Oceans, 98, Cooper, S. D., and Halpern,cascades, B. Ecol. S.: Lett., A 5, cross-ecosystem 785–791, comparison 2002. of the strengthof of the trophic plankton ecosystemrological of constraints, the J. north-western Marine Syst., Corsican 27, coastal 337–362, area 2001. in relation to meteo- 9196 trol on the long-termMediterranean, anomalous Glob. changes Change Biol., of 14, zooplankton 11–26, communities 2008. in theDeep-Sea Northwestern Res. Pt. I, 52, 1806–1822, 2005. growth, diet andmicrozooplankton-dominated reproductive plankton success blooms, compared Mar. in Ecol.-Prog. simultaneous diatom- Ser., and 221, flagellate- 77–91, 2001. method of describingSyst., phytoplankton 79, blooms: 36–43, 2010. Examples from Helgoland Roads,Deep-Sea J. Res., Marine 28, 625–629, 1981. northwestern Mediterranean plankton variability,9179 Limnol. Oceanogr., 50, 1213–1220, 2005. Licandro, P., Llope, M.,cruitment Munk, in P., Rockmann, a changing C.,J. environment: Schmidt, Mar. the Sci., J. 66, 2000s O., 272–277, North and 2009. Sea Nash, herring R. recruitment D. failure,H. M.: Ices M.: Re- Identifying globaltunities, synchronies Ices in J. marine Mar. zooplankton Sci., 61, populations: 445–456, issues 2004. and oppor- to changes in the North Sea horse mackerel fishery, Fish. Res., 50, 163–171, 2001. MODULAD, 32, 71–85, 2005. biogeochemical processes in theSyst., Ligurian 55, Sea 177–203, using 2005. a ID interdisciplinary model, J. Marine Taylor, A. H., Allen, J. I., and Clark, P. A.: Extraction of a weak climatic signal by an ecosystem, Strickland, J. D. H. and Parsons, T. R.: A practical handbook of seawater analysis, Queen’s Stenseth, N. C., Ottersen, G., Hurrell, J. W., Mysterud, A., Lima, M., Chan, K. S., Yoccoz, N. G., Soriano, L. R., De Pablo, F., and Tomas, C.: Impact of the North Atlantic oscillation on win- Sommer, U.: Trophic Cascades in Marine andSommer, Freshwater U. and Plankton, Sommer, Int. F.: Cladocerans Rev. versus copepods: Hydrobiol., the 93, cause of contrasting top-down Skliris, N., Sofianos, S., and Lascaratos, A.: Hydrological changes in the Mediterranean Sea in Sciandra, A., Gostan, J., Collos, Y., Descolas-Gros, C., Leboulanger, C., Martin-Jezequel, V., Schott, F., Visbeck, M., and Fischer, J.: Observations of Vertical Currents and Convection In Nezlin, N. P., Lacroix, G., Kostianoy, A. G., and Djenidi, S.: Remotely sensed seasonal dy- Reid, P. C., Edwards, M., Beaugrand, G., Skogen, M., and Stevens, D.: Periodic changes in Shurin, J. B., Borer, E. T., Seabloom, E. W., Anderson,Skliris, K., N., Elkalay, Blanchette, K., C. Go A., Broitman, B., Mor Nejstgaard, J. C., Hygum, B. H., Naustvoll, L. J., and Bamstedt, U.: Zooplankton Molinero, J. C., Iba Reid, P. C., Borges, M. D., and Svendsen, E.: A regime shift in the North Sea circa 1988 linked Millero, F. J. and Poisson, A.: International one-atmosphere equation of state of seawater, Perry, R. I., Batchelder, H. P., Mackas, D. L., Chiba, S., Durbin, E., Greve, W., and Verheye, Molinero, J. C., Iba Payne, M. R., Hatfield, E. M. C., Dickey-Collas, M., Falkenhaug, T., Gallego, A., Groger, J., Rakotomalala, R.: TANAGRA: une plate-forme d’exp Raick, C., Delhez, E. J. M., Soetaert, K., and Gregoire, M.: Study of the seasonal cycle of the 5 5 30 25 20 15 15 10 10 20 25 30 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 9191 omnivores carnivores (copepods) carnivores filter-feeders omnivores feeders/suspensivores microplanktono- phage/herbivores omnivores , ), , ... spp. Pelagia spp. . . . filter-feeders sp. ), percentage of abundance 9191 , Agalma 3 . . . filter- )... sp. ... , Farranula spp. , Lensia ´ e larvæ of mostly , Clausocalanus sp. 0.724 mm , Pleurobrachia > spp. ) and mysidacea sp. , Temora stylifera, Calanus , Oncaea Muggia , Euchaeta marina 9208 9207 Beroe Meganyctiphanes norvegica, spp. ´ spp. e and Metazo ), Medusæ (Ephyrula of , Oithona ... spp. ) represent 1.8 and 31.5% of total zooplankton abun- ... 3 spp. ´ e, Protozo 9193 Nyctiphanes couchii elegans . . . Acartia Oikopleura albicans, Fritillaria pelucida Sagitta inflata Centropages minor, Calanus gracilis, Pleuromamma siphonophores ( noctiluca, Rhopanolema velatum, Liriope Tetraphylla, Solmissus albecans . . . Cavolinia inflexa, Creseis laciculata Thalia democratica, Salpa fusiformis,gegenbauri, Dolioleta Doliolum nationalis, Pyrosoma atlanticum Paracalanus Candacia crabs, langoustine and lobsters rostrata , 9178 0.724 mm > 9182 , 9181 and the percentage given applies on zooplankton of this size range only. 3 Large zooplankton categories ( 9179 Taxonomic groupsCopepods (small) %Ab./EBv Representative species 61.4/46.5 AppendiculariansChaetognaths 1.2/0.5 Copepods (large) 6.1/4.4 12.7/4.8 Decapods larvæ Dominant diet Crustaceans (other) 3.3/2.4 5.1/3.2 Zo Gelatinous predators Euphausiids 19.6/34.1 ( ctenophores ( PteropodsThaliaceans 4.7/9.3 Zooplankton (other) 6.9/12.8 1.7/1.2 fish larvæ, annelids . . . mixed M. D., and Tel, E.:Geophys. Res.-Oceans, How 115, much C04001, is doi:10.1029/2009JC005816, the 2010. western Mediterranean really warming and salting?, J. parini, S., Guarini,computing J.-M., size Prejger, spectra F., ofpreparation, 2010. Sun, automatically X., classified zooplankton and using Gorsky, imaging G.: systems, Assessing in the biases in analysis of long-term data9192 at Helgoland Roads, Limnol. Oceanogr., 53, 1294–1302, 2008. and Ribergaard, M. H.:Ocean Surprising in winter return 2007–2008, of Nat. deep Geosci., convection 2, to 67–72, the 2009. subpolar North Atlantic F. J., and Boersma, M.: Resilience of North Sea phytoplankton spring bloom dynamics: An 1989. Nature, 416, 629–632, 2002. Vargas-Yanez, M., Zunino, P., Benali, A., Delpy, M., Pastre, F., Moya, F., Garcia-Martinez, Table 1. (“Ab.”)/apparent elliptical biovolume (“EBv”) of theserange categories (for among indication zooplankton only), ofthis this representative size work. species or The groups category0.032 and “Copepods to dominant (small)” 0.724 mm diet comes considered from copepods in automatically sorted from The large zooplankton (i.e., Vandromme, P., Stemmann, L., Garcia-Comas, C., Colbert, S., Berline, L., Picheral, M., Gas- dance and apparent biovolume, respectively. Wiltshire, K. H., Malzahn, A. M., Wirtz, K., Greve, W., Janisch, S., Mangelsdorf, P., Manly, B. Underwood, A. J.: The Analysis of Stress In Natural-populations, Biol.Vage, K., J. Pickart, Linn. R. Soc., S., 37, Thierry, 51–78, V., Reverdin, G., Lee, C. M., Petrie, B., Agnew, T. A., Wong, A., 5 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Strat. 1717 34 19 30 19 34 17 33 32 1714 29 20 31 16 32 18 33 15 35 36 start max Zoo. 9 12 47 10 8 11 8 12 4 15 47 7 9 7 12 11 10 15 10 14 start max a 9210 9209 chl- 66 11 3 14 58 8 10 3 12 5 13 38 5 4 7 10 9 9 13 start max ), the zooplankton total abundance (Zoo.) and the stratification 3 a NO 2 1 − (chl- start max a 200220032004 12005 2 2 9 4 8 10 10 Year 1995 3 10 199619971998 21999 12000 3 2001 5 2 3 11 1 5 9 ´ em.) situated in Cap Ferrat 1.2 km from Point B. The cyclonic circulation of the Timing (week number) of starting and maximum of seasonal variables, i.e. the nitrates Location of the sampling site (Pt. B) in the Ligurian Sea and the meteorological station ), the chlorophyll- 3 ´ emaphore (S S Ligurian Sea with the Current, Liguro-Provenc¸al theCorsican Western Current Corsican are also Current shown and on thefrom this Eastern more map. coastal The areas central zone by of the the frontal Ligurian zone. Sea is separated Fig. 1. Table 2. (NO of the water column (Strat.). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) from 3 − annual anomalies of total abun- ) and abundance (in # m 3 − (B) m 3 monthly values of total abundance. (D) 9212 9211 annual anomalies of total biovolume; (A) monthly values of total biovolume; Dynamic of total zooplankton biovolume (in mm Example of thumbnails directly issued from the ZooScan/ZooProcess of the ten identi- (C) Fig. 3. 1995 to 2005. dance; fied zooplankton taxonomic groups.except All the thumbnails small have copepods the which have same their scale own (bottom scale right on corner) top left. Fig. 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | co ), a (A) 1993 ( monthly values annual anomalies (D) ˜ nez et al. ; 3 (A) th for thaliaceans, ge Iba . 1 − (C) in µg L a monthly values of NO (C) ; and chlorophyll- a 9214 9213 1 − whereas the other groups account for individuals larger than ) in µmol L 3 3 . a annual anomalies of chlorophyll- . The cumulative sum method was first used in ecology by 3 (B) Cumulative sum of annual anomalies of the ten identified taxonomic groups: Dynamic of nitrates (NO ; 3 ch for chaetognaths, ap for appendicularians, pt for pteropods; Fig. 5. of chlorophyll- of NO for small copepods, Co(B) for large copepods, defor for gelatinous decapods predators, ot larvae, for crbetween other for zooplankton. 0.032 other Small and crustaceans; copepods 0.724 account mm 0.724 mm only for individuals negative slope means a negative anomaly and vice-versa. Fig. 4. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ): ), θ 1 σ density (in (A) ) and solar irradiance in E ´ emaphore station (see Fig. and B ( 1 − 9216 9215 salinity (in psu). ), precipitation in mm d (C) D and C) and ◦ A C( ). A, B and C report anomalies from autumn and winter months, i.e. from ◦ F and C ( 1 − Annual anomalies of climatic variables measured at the S Annual anomalies of hydrological characteristics of the water column (averaged from 10 d 2 − sea temperature (in air temperature in J cm Fig. 7. November of the previousport year anomalies from to spring March(AMJJA). and of summer the months, current i.e. from year April (NDJFM). to And August D, of E the and current year F re- (B) to 40 m) during thevalues winter of period, i.e. sea from water the surface 4 to density the (unpresented 17 weeks data). which showed Anomalies the maximum of Fig. 6. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | for 4.4 D

05 in 1

Garcia-Comas ‐ +

00/05 year ++ Zoo

00 C +

+

++ very high WINTER 3

functioning ++

feeders 05

++ a ‐

NO phyto. down” high;

‐ + ‐ chl 04, Sunlight

:

all

zoo. crust. filter CONVECTION

D of “top

in on 1 03,

low;

STRONG ‐

+ ‐ 95/99

B large large small case 01, year ecosystem Zoo

Grazing decrease • 95/99 very low; 05 00 ‐‐ 95/99 D Villefranche) 03/04

‐

+

of +

++ Following step phyto.

9217 a (Bay down”

‐ Sunlight : ‐ chl

large zoo. gelatinous crust.

C INTERMEDIATE of

“top in 1 Sea

Precipitations + Temperatures + on

‐

02 02 Int. 02/03/04 +

A large large case 00 small year Zoo increase Grazing • No Ligurian 98 01

96/97 the

Yes

of in 1

‐ +

D 01 year 01 Zoo +

‐ process Scheme 02 3

‐‐ ‐ WINTER ‐‐ ‐‐

Key NO 98, : :

Sunlight zoo. zoo. zoo. zoo.

B A 99

CONVECTION 97,

WEAK 98 96/97 General A

case large small large 95*, small 96, case

) the beginning of the 1990’s were low in zooplankton.

SUMMER • •

WINTER Proposed general scheme of Ligurian Sea ecosystems dynamics, see Sect. SPRING/ 2010 ( ) the quantity of previous year zooplankton can not be verified, however from ∗ details. The legend of( line and boxes iset at al. the bottom of the scheme (Int. is for intermediate). Fig. 8.