IMARES. Ecosystem Modelling Wadden Sea. Bert Brinkman IMARES Piet Ruardij NIOZ

Transcription

1 Ecosystem Modelling Wadden Sea Bert Brinkman Piet Ruardij NIOZ

2 Why ecological models? Many questions (what is the effect of.. on the ecosystem functioning) cannot be answered by monitoring or direct measurements Temporal and spatial variations are large => a large amount of data (spread in time and space) is needed, long research period, very expensive Mostly not interested in local effects, but system wide Models that cover relevant ecological processes can help (together with measurements, but on a much reduced scale == costs)

3 What questions are asked and models are needed for (1)? The Wadden Sea is an important bird area; for a number of bird species there are improvement targets (e.g. Oystercatchers, Eider Ducks). But: if measures are taken, do these really improve the conditions for the birds? Or are there other steering factors that reduce the effect of improvement measures?

4 What questions are asked and models are needed for (2)? Mussel Seed Collectors (MZI s): These are introduced to replace the natural mussel seed fisheries and let the natural mussel beds develop in a natural way. MZI-mussels thus are extra, next to the natural mussels (different from the past)

5 What questions are asked and models are needed for (2)? Mussel Seed Collectors (MZI s): competition between natural mussels (& shellfish in general) and MZI-mussels? Mechanism: Affecting the algae species composition (cq size class distribution) by MZi-mussels? Implications for birds?

6 So, we have to deal with questions like: what determines the carrying capacity of the Wadden Sea what are the mechanisms (like: MZI-mussels compete with natural mussels; affecting the algae species composition (cq size class distribution) by MZi-mussels)

7 FAQ s Isn t light the only limiting factor for primary production in the shallow and turbid Wadden Sea (* Colijn&Cadee, 2003 ) >> no nutrient shortage Is the amount of shellfish not solely determined by predation processes? strictly top-down control Is there any limited carrying capacity at all?

8 Algae concentration (chlorophyll-a) Light More transparent Nutrients More nutrients More grazing Grazing Light Day in a year

9 System processes N,P, Si N,P, Si Radiation I 0 N,P, Si Nut (N e ) Alg (Alg e ) Diff Nut (N) Alg (Alg) Filter feeders (FF) Depth, Extinction Temp

10 Yearly primary production Depth E E E E E E E E E+02 2E E E E E E E E E E E E E E E E+03 1E E E E E+02 Extinction coefficient (m -1 ) E E+03 2E E E E+03 1E E E E+02 26

11 Mean FF content Depth E E E E E E E E E E+01 2E E E E E E E E E E E E+02 3E E E+02 2E E E E E+01 Extinction coefficient (m -1 ) * E+02 4E E E E E+02 2E E E E+01

12 Conclusions from the simple model In a shallow system like the Wadden Sea the maximum production and shellfish content is limited light is less important than nutrients limiting the shellfish biomass Responses: phytoplankton<primary production<(nutrients, grazers)

13 Light Nutrients Grazing Light Day in a year

14 A few data

15 A few data Chlorophyll-a Ortho-phosphate Nitrate Silicate

16 Changes in the last 30 years

17

18 DOOVBWT Zomergemiddelden log-analyse & 95% betrouwbaarheid_bs Some trends for the western Wadden Sea DOOVBWT Zomergemiddelden log-analyse & 95% betrouwbaarheid_bs DOOVBWT Zomergemiddelden log-analyse & 95% betrouwbaarheid_bs CHLFa ug/l Chla o-p NO3 PO4P nf mg P /l NO2NO3 mg N/l Jaar Jaar Ja ar DOOVBWT Zomergemiddelden log-analyse & 95% betrouwbaarheid_bs DOOVBWT Zomergemiddelden log-analyse & 95% betrouwbaarheid_bs SIL I mg Si /l Si NH4 mg N/l NH Jaar Jaar

19 Biomassa in westelijke Waddenzee Mosselen Kokkels Nonnetjes Ensis Mya Oesters Filtratiedruk in westelijke Waddenzee Omgerekend uit surveydata

20 First analysis Roel Riegman Annual Primary Production Western Wadden Sea g C.m-2.yr Year Incubator studies Based on chl-a and light Phillipart ea This study

21 Topics: Gross and net primary production (correct use of data) Picophytoplankton and microzooplankton: included or not?

22 Gross and net primary production => correct use of data) CO 2, P,N.. CH 2 O O 2 CO 2, P,N.. O 2 CH 2 O O 2 CO 2 14 C-measurements Annual Primary Production Western Wadden Sea O 2 -measurements g C.m-2.yr Year Phillipart ea This study Incubator studies Based on chl-a and light

23 Model Pico Flagel MicroZoo Diatom Large Diatom Mussels MZI- Mussels RADIATION System data GRAZING MORTALITY, FAECES, PSEUDOFAECES, EXCRETION, North Sea WZ190 6 INPUT DETRITUS P MORTAL ALGAE P GRAZING FAUNA P 5 WZ230 OUTPUT 4 RESPIRATION WZ WZ110 3 WZ200 Lake IJssel WZ310 Map of the western Wadden Sea, including the Rijkswaterstaat monthly monitoring locations WATER SEDIMENT DISSOLVED P DESORPTION ADSORPTION ADSORBED P OVERALL SCHEME OF THE ECOWASP ECOSYSTEM MODEL NOTE THAT ALL PROCESSES RUN IN THE SEDIMENT (SEVERAL LAYERS UP TO CM DEEP) AS WELL

24 Model results 120 Fauna biomass, year average 400 Incubator primary production year Pelagic phytoplankton concentr summer 2000 Gross primary production year

25 2000 Net Primary production <> Gross PP Nett Primary production (g DW/m2/a) Gross primprod <> mussel biomass Mussel biomass (million kg flesh)

26 Silicate <> Gross Prim Prod E E E E E E E-02 Silicate mol Si/m ortho-p <> Gross Prim Prod Ammonium <> Gross Prim Prod 0 0.0E E E E E-03 ortho-p mol P/m ortho-p winter <> Gross Prim Prod 0 0.0E E E E E-02 Ammonium mol N/m Nitrate <> Gross Prim Prod E E E E E E E-03 ortho-p mol P/m E E E E E E E-02 Nitrate mol N/m3

27 How to translate results to food for birds?

28 TEMP OTHER STEERING FACTORS, E.G. HABITAT SUITABILITY EXCRETION Detritus Detritus Algae Fauna FOOD FAUNA FILTER FEEDING ZOOPLANKTON RAPTORIAL ZOOPLANKTON FILTER FEEDING ZOOBENTHOS DEPOSIT FEEDING ZOOBENTHOS RAPTORIAL ZOOBENTHOS FAECES GRAZING MORTALITY RESPIRATION Detritus Fauna Detritus CO2,P,.. PRODUCTS LARVAE CLASS 1 CLASS2 CLASS.. C Age/cohort classes: a number of classes is distinguished: Class 1 contains larvae pelagic phase) Class 2 contains seeds (first benthic phase) Class 3 contains next benthic phase Class 4 is last class 5.0E E E E E E+00 Blue Mussel 15-Mar Oct Apr Nov May Dec-02 Days When class 1 reaches a certain size > a shift to class 2 occurs; class 2 shifts to 3, and 3 and 4 are mixed.

29 Size distribution of mussels to be eaten cm cm

30 Eider Duck : energy budget in a winter period BMR (29.55%) Flying (5.70%) Swimming (0.01%) Salt (6.01%) Digestion (16.00%) Crushing (39.43%) Bottom-search (0.93%) Buoyancy (1.63%) Diving_Drag (0.30%) Acceler (0.17%) Acceler0 (0.04%) Heat surplus (0.23%) Eider Duck energy budget Winter 2.37 E6 Joules/day 2.37 E6 Joules/day food (100.00%) Depth = 5 m Twater = 7 o C Tair = 5.6 o C Breathing (1.23%) CoolingAir (32.98%) AdditWater (2.19%) HeatPrey (56.97%) ExtrBreath (2.88%) CoolingWater (3.75%) Eider Duck heat budget Winter 1.84 E6 Joules/day 1.83 E6 Joules/day Costs BMR (38.16%) Flying (4.42%) Swimming (0.01%) Digestion (4.13%) Crushing (50.91%) Bottom (0.72%) Buoy (1.26%) Drag (0.23%) Accel (0.13%) Accel0 (0.03%) Gain Depth = 5 m Twater = 7 o C Tair = 5.6 o C

31 Eider Duck : energy demand during a year 3.0E+06 Daily energy expenditure Energy need implies roughly: 680 g meat per day in winter 2.6E E E E Daynr = kg shellfish per day per bird = kg shellfish per winter period per bird = physiological need

32 cm Maximum number Oystercatchers cm 3-4 cm 4-5 cm 5-6 cm Maximum number Eider Ducks cm 4-5 cm

33 Example: what is the possible effect of nutrient reduction on the number of birds that can forage in the Wadden Sea? 3.00E+05 Maximum Oystercatchers WWZ 1.5E+05 Maximum Eider Ducks WWZ 1.2E E E E E E E _0.50.5_0.50.8_0.30.8_0.20.5_0.20.5_0.1 Nutrient scenario (P _ N ) 0.0E _ _ _ _ _ _0.1 Nutrient scenario (P _ N ) NIOZ /

34 Near future ZKO : Changing carrying capacity in the Wadden Sea and North Sea coastal zone - Monitoring - Process reasearch - Modelling - Fine scaled hydrodynamics - Including ecological processes: primary production - secondary production

35 Fine scaled hydrodynamics Including ecology into the model: Primary production Grazers Much better spatial resolution N Kilometers Depth (cm relative to NAP) Wadplaten.shp Newned.shp Diepwad No Data

36 The end Wageningen UR NIOZ /

37

38 Growth when food is sufficient 5.0E-02 Blue Mussel 4.0E E E E E Mar Oct Apr Nov May Dec-02 Days

39 Food demand of birds - energy budget Shell characteristics of average prey Winter Salt (2.10%) AFDW (3.28%) Shell (34.49%) Water (60.12%) Summer Salt (2.05%) AFDW (6.30%) Shell (33.12%) Water (58.53%)

40 Eider Duck : energy budget in a winter period BMR (29.55%) Flying (5.70%) Swimming (0.01%) Salt (6.01%) Digestion (16.00%) Crushing (39.43%) Bottom-search (0.93%) Buoyancy (1.63%) Diving_Drag (0.30%) Acceler (0.17%) Acceler0 (0.04%) Heat surplus (0.23%) Eider Duck energy budget Winter 2.37 E6 Joules/day 2.37 E6 Joules/day food (100.00%) Depth = 5 m Twater = 7 o C Tair = 5.6 o C Breathing (1.23%) CoolingAir (32.98%) AdditWater (2.19%) HeatPrey (56.97%) ExtrBreath (2.88%) CoolingWater (3.75%) Eider Duck heat budget Winter 1.84 E6 Joules/day 1.83 E6 Joules/day Costs BMR (38.16%) Flying (4.42%) Swimming (0.01%) Digestion (4.13%) Crushing (50.91%) Bottom (0.72%) Buoy (1.26%) Drag (0.23%) Accel (0.13%) Accel0 (0.03%) Gain Depth = 5 m Twater = 7 o C Tair = 5.6 o C

41 Eider Duck : energy demand during a year 3.0E+06 Daily energy expenditure Energy need implies roughly: 680 g meat per day in winter 2.6E E E E Daynr = kg shellfish per day per bird = kg shellfish per winter period per bird = physiological need

42 Simple model scheme Light Temperature In Out Nutrient Primary Alg Shellfish production Birds Detritus

43 FAQ s So, the conclusions in general are: in system like the Wadden Sea, light, nutrients and grazing all play a role. The question now is, to what extend? >> extended model

44 North Sea Marsdiep tidal inlet Wadden Sea River Ems Lake Lauwers Lake IJssel Currents River IJssel Netherlands River Rhine Lobith Data I) What do we see - Lake IJssel - North Sea coastal zone

45 Total phosphorus Lobith (Rhine, Dutch-German border) Waste water treatment 7.0 (phosphate removal) reduced use of P NO2 + NO3 Reduced use of N Jan-56 Jan-62 Jan-68 Jan-74 Jan-80 Jan-86 Jan-92 Jan-98 Jan Waste water treament Dissolved inorganic phosphorus (ortho-p) Jan-56 Jan-62 Jan-68 Jan-74 Jan-80 Jan-86 Jan-92 Jan-98 Jan-04 Jan-52 Jan-58 Jan-64 Jan-70 Jan-76 Jan-82 Jan-88 Jan-94 Jan-00 Jan Waste water treatment 6.0 (phosphate removal) reduced use of P 3.0 Ammonium NH4 Waste water treament Jan-52 Jan-58 Jan-64 Jan-70 Jan-76 Jan-82 Jan-88 Jan-94 Jan-00 Jan-06