Nutrient Determination in the Belgian Coastal Waters of the North Sea By Sheku Sei and Enyue Xue 1 st Year Ecomama

Content 1. Introduction 2. Sampling Site 3. Materials and Methods 4. Result 5. Discussion 6. Conclusion

Introduction – – The North Sea - situated on the continental shelf of northwest Europe. – – The Belgian part of the North Sea –Belgian part of the North Sea – – 3,600 km², which is about the size of West Flanders. about half a per cent of the surface of the North Sea.

Introduction The basis of the practicals The basis of the practicals To quantify nutrient concentration from sea water samples collected at different stations and different depths To quantify nutrient concentration from sea water samples collected at different stations and different depths To obtain an insight into nutrient variability To obtain an insight into nutrient variability learn Practical techniques how and seasonal variations learn Practical techniques how and seasonal variations

Introduction Nutrients - important for primary production in the sea Nutrients - important for primary production in the sea A limiting factor :light+low nutrient=low pp A limiting factor :light+low nutrient=low pp Concentrations- usually high in winter- why? Concentrations- usually high in winter- why? High mixing processes High mixing processes High nutrient + light =high pp High nutrient + light =high pp Light limiting factor Light limiting factor High nutrient consumption at surface waters

Sampling stations

Method and materials Sampling- survey cruise : Sampling- survey cruise : Research vessel ZEELEEUW Research vessel ZEELEEUW Sampling along the Belgian Continental Shelf Sampling along the Belgian Continental Shelf Sea water –collected –by Niskin Bottles Sea water –collected –by Niskin Bottles Samples filtered in polyethylene bottles and deep frozen Samples filtered in polyethylene bottles and deep frozen Analysis done using the standard protocols of reagents Analysis done using the standard protocols of reagents Equipment: spectrophotometer - absorbance Equipment: spectrophotometer - absorbance Calibration done using different dilutions to generate calibration curve –useful to determine concentrations (Con. (ug/l =corrected extinction –b)/a Calibration done using different dilutions to generate calibration curve –useful to determine concentrations (Con. (ug/l =corrected extinction –b)/a Ammonium determined immediately Ammonium determined immediately

Result Calibration curve -Phosphate

Phosphate Concentration in Samples Station 230 Station 330 Station 435 Conc. (ug/l) Depth (m) SD: SD: Conc. (ug/l) Depth (m) SD: SD: SD: MeanConc. (ug/l) Depth (m) SD: SD: SD:

Calibration Curve for Silicate

Station 230 Station 330 Station 435 Conc.(ug /l) Depth(m) SD: SD: Conc.(ug/l)Depth(m) SD: SD: SD: Conc. (ug/l) Depth(m) SD: SD: SD: Silicate Concentration in Samples

Calibration Curve for Ammonium

StationMean Concentrations(ug/l) Lagoon SD: SD: SD: SD: Nb SD: Nb SD: Nbii SD: Nb2 Ammonium Concentration at Various Stations

Vertical profiles Phosphate Conc.(ug/l) D(m) S 230-P S 435P 330-P

Vertical profiles- Silicate Conc. (ug/l) D(m)

DATA ANALYSIS Hypothesis Hypothesis The Waters of the North Sea has water characteristics as that of the Atlantic Ocean. Since the Southern bight of the North Sea is part of the Atlantic Ocean, the hypothesis is that during winter, nutrient concentrations at different depths don’t vary much with depth The Waters of the North Sea has water characteristics as that of the Atlantic Ocean. Since the Southern bight of the North Sea is part of the Atlantic Ocean, the hypothesis is that during winter, nutrient concentrations at different depths don’t vary much with depth Null Hypothesis (H 0 ) = Mean nutrient concentrations don’t vary significantly with depth and at different stations. Null Hypothesis (H 0 ) = Mean nutrient concentrations don’t vary significantly with depth and at different stations. Alternative Hypothesis(H 1 ) =Mean concentrations vary with depth and at different stations. Alternative Hypothesis(H 1 ) =Mean concentrations vary with depth and at different stations.

DATA ANALYSIS- phosphate We test the difference of two means, assuming the concentrations are all normal and testing at the level of significance of 5% for stations 330 at 3m and 10m: H0: µ2 - µ1 = 0, H1: µ2 - µ1 < 0 We test the difference of two means, assuming the concentrations are all normal and testing at the level of significance of 5% for stations 330 at 3m and 10m: H0: µ2 - µ1 = 0, H1: µ2 - µ1 < 0 N 1 = Number of samples for X = 3 N 1 = Number of samples for X = 3 N 2 = Number of samples for = 3 N 2 = Number of samples for = 3 Critical point at 5% confidence interval = Critical point at 5% confidence interval = Y– X - (µ 1 -µ 2 )H 0 Y– X - (µ 1 -µ 2 )H 0 = > we cannot reject H 0 = > we cannot reject H 0 √s 1 2 /n 1 + s 2 2 /n 2 Hence nutrient concentrations at the two depths do not vary significantly √s 1 2 /n 1 + s 2 2 /n 2 Hence nutrient concentrations at the two depths do not vary significantly

DATA ANALYSIS 2. Station 330-3m and station m 2. Station 330-3m and station m Calculated = , which is > , we cannot reject H 0. Thus nutrient concentrations at this depth do not differ greatly Calculated = , which is > , we cannot reject H 0. Thus nutrient concentrations at this depth do not differ greatly 3. Station 330 –3m and 230 –3m 3. Station 330 –3m and 230 –3m Calculated = , is greater than critical p value. We cannot reject the null hypothesis. Hence nutrient concentrations at these stations do not differ significantly Calculated = , is greater than critical p value. We cannot reject the null hypothesis. Hence nutrient concentrations at these stations do not differ significantly 4. Station 330 –10m and m. 4. Station 330 –10m and m. Calculated = , which is greater than the critical point. We cannot reject null hypothesis Calculated = , which is greater than the critical point. We cannot reject null hypothesis

DATA ANALYSIS- silicate Station 330 –3m and station 330 –10m Station 330 –3m and station 330 –10m Calculated test value = < , we reject H0 the concentrations differ. Calculated test value = < , we reject H0 the concentrations differ. Station 330 –3m and m Station 330 –3m and m Calculated test value = > , we cannot reject Null. The concentrations at this depth do not differ greatly Calculated test value = > , we cannot reject Null. The concentrations at this depth do not differ greatly Station m and station m Station m and station m Calculated = > , we cannot reject Null, the concentrations of silicate do not differ greatly at these depths. Calculated = > , we cannot reject Null, the concentrations of silicate do not differ greatly at these depths.

DATA ANALYSIS Station m and m Station m and m Calculated test value = > , we cannot reject Null, the concentrations at these stations do not differ greatly Calculated test value = > , we cannot reject Null, the concentrations at these stations do not differ greatly Station m and 435 –10m Station m and 435 –10m Calculated test value = > –1.645, we cannot reject H 0, the concentrations of silicate do not vary greatly at this depth. Calculated test value = > –1.645, we cannot reject H 0, the concentrations of silicate do not vary greatly at this depth. Station m and m Station m and m Calculated test value = < , we reject null hypothesis, and say that the concentrations differ at these stations. Calculated test value = < , we reject null hypothesis, and say that the concentrations differ at these stations.

DISCUSSION From the vertical profiles and from the statistical tests, we see that the nutrient concentrations do not vary greatly with depth though there are some variations in the silicate concentrations for instance at stations 330 and 435 at 3m depth, and that also at stations 330-3m and m From the vertical profiles and from the statistical tests, we see that the nutrient concentrations do not vary greatly with depth though there are some variations in the silicate concentrations for instance at stations 330 and 435 at 3m depth, and that also at stations 330-3m and m The concentrations of phosphate is high due to the fact during the period we sampled, there was not much productivity of plankton. Though there were lots of nutrients and mixing, light was limited during that period hence light will be a limiting factor for primary production though there is enough nutrient. The concentrations of phosphate is high due to the fact during the period we sampled, there was not much productivity of plankton. Though there were lots of nutrients and mixing, light was limited during that period hence light will be a limiting factor for primary production though there is enough nutrient.

Discussion 2 well mixed water column and high nutrient concentrations, in the photic zone. The concentrations slightly low at the surface at station 330 well mixed water column and high nutrient concentrations, in the photic zone. The concentrations slightly low at the surface at station 330 and high at the bottom. At station 435, the concentrations are a bit higher at the surface and low at the bottom. and high at the bottom. At station 435, the concentrations are a bit higher at the surface and low at the bottom. Silicate concentrations are also slightly high at the bottom depth. Silicate concentrations are also slightly high at the bottom depth. Such fluctuations may be due to the slower process of consumption by phytoplankton at a very low rate though sunlight is light is limited. Such fluctuations may be due to the slower process of consumption by phytoplankton at a very low rate though sunlight is light is limited.

Discussion 3 The concentration of ammonium is very high in the Spuikom lagoon. The concentration of ammonium is very high in the Spuikom lagoon. May be due to waste disposal in to the lagoon May be due to waste disposal in to the lagoon Ammonium not taken up by phytoplankton Ammonium not taken up by phytoplankton Excretion processes of zooplankton Excretion processes of zooplankton The high concentration of ammonium at the different stations, Nb stations and stations 230, 330, 435, are all as a result of the fact that enormous quantity of ammonium is discharged in to the sea from rivers from industrial and agricultural sources, from estuaries like the Scheldt. The high concentration of ammonium at the different stations, Nb stations and stations 230, 330, 435, are all as a result of the fact that enormous quantity of ammonium is discharged in to the sea from rivers from industrial and agricultural sources, from estuaries like the Scheldt.

CONCLUSION The trend of vertical distribution of silicate and phosphate are similar at station 435 and 230, low concentrations at the surface and high at mid depth and bottom, at station 330 the fluctuation also vary with high concentration at the surface and low at mid depth. These are due to the mixing of the water column and the fluctuations in the photosynthetic activities, which is dependent on as when light is available.

CONCLUSION High mixing takes place, the bottom is close to isothermal. Where nutrient concentrations are low it is due to the utilization by during photosynthesis Seasonal changes in nutrient concentration most evident in the temperate area. expected productivity - higher during spring - enough light, enough nutrient- diatom bloom in the North Sea. The period of study was faced with light limitation.

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