Investigate theRelationship between Summer Storms and Shelf Sea Primary Production

Haotian Sun

Introduction

Net primary production， which refers to the rate of net energy production by plants， is significant for aquatic organisms and it is the foundation of food chain. Moreover， about 15%-30% primary production are contributed by shelf seas among oceans （Wollast， 1998）， which is a main importance that investigates possible factors of changing primary production in shelf seas. According to Olesen （1999）， nutrients and light are direct reasons that can effect primary production， and the net primary production in summer will be restricted by nutrients mainly. It is well established that wind-driven mixing supplies nutrients to the thermocline during summer in shelf seas. Therefore， short-term summer storms is a dominantly driving force to increase shelf sea primary production in some cases. Following that， the aim of this report is to investigate the relationship between summer storms and shelf sea primary production based on the S2P3 model. It is assumed that summer storms can increase primary production in shelf seas.

Methods

The S2P3 model is the physics-primary production model that downloaded in Vital and used in this experiment. There is a no-storm data in S2P3 model when it set up， which is used to do comparison with altered data. Opening the main window of the model and clicking RUN， then the no-storm data will list in the folder. Subsequently， wind speed in day 182 （Noticeable： summer storms are focused on， so just changing the day 182 during whole year） was changed from 6.01m/s to 30m/s in the Celtic_met.dat file， and opening changed Celtic_met.dat file to achieve data that corresponding to respective wind speeds. In addition， 10m/s， 14m/s， 18m/s， 22m/s， 26m/s and 30m/s took the place of 6.01m/s in day 182. Ultimately， Cnet on July （the net amount of carbon fixed by the phytoplankton on July） and Netp （the net primary production） were putted out to Excel to draw relation curves from Monthly.dat file and Surface.dat file respectively.

Results

After finishing the experiment， based on recorded data， three figures have been listed and demonstrated as following.

In the Figure1， a strong positive correlation between wind speed and the net amount of carbon fixed by the phytoplankton has been showed with a trend line and R2. The Figure2 and Figure3 illustrate the complex relationship between wind speed and net primary production. Additionally， it is not clear if seven lines in one figure so there are two figures to draw the relation， and they have a common line that stands for 18m/s wind.

Discussion and Conclusion

Consequently， the net amount of carbon fixed by the phytoplankton has an outstanding increase with increasing wind speed. More carbon fixed reflects stronger photosynthesis of phytoplankton in shelf seas， so it also reflects that plants have a more powerful capacity to produce useful energy owing to summer storms in large extent.In the Figure2， the line of netp00， netp01 and netp02 are almost superposition and netp04 has a marked different with them， which means that the net primary production keep stable when wind speeds in day 182 are 10m/s and 14m/s.Thus the net primary production in shelf seas can be effected by summer storms that are strong enough. In the Figure3， the changed wind speed in day 182 are 18m/s， 22m/s， 26m/s and 30m/s， which are strong enough to influence the net primary production. Moreover，it is necessary to emphasize that changing one-day wind speed will effect long-term net carbon fixed and net primary production combine with the three figures. The four lines in Figure3 almost have the same fluctuate from day 182 to day 210， but the difference is that larger wind speed results in more net primary production from day 275 to day 310 approximately. Following that， the more powerful summer storms trend to last longer time to effect the net primary production. As highlighted by Zhang （2013）， cyclone effects the marine plankton ecosystem， and the primary production increases around 90% after storms. It is a similar consequence compared with our results.

To sum up， summer storms that are strong enough can increase the net amount of carbon fixed by the phytoplankton and net primary production in shelf seas. However， there are still some limitations in our experiment. For instance， other factors that caused by summer storms will also effect the net primary production. According to Nelson （1999）， physical disturbance of sediments and resuspension of fine particles will be intensely effected by strong storms on the shelf， which restricts light penetration to the sediment surface then effecting the primary production. Therefore， in future studies， more factors owing to increased wind speed should be considered to reduce some errors.

Reference list

Nelson， J. R. et al. （1999） ‘Benthic microalgal biomass and irradiance at the sea floor on the continental shelf of the South Atlantic Bight： Spatial and temporal variability and storm effects， Continental Shelf Research， Vol. 19， pp. 477-505. [Assessed： 25 April 2018]

Olesen， M.， Lundsgaard， C.& Andrushaitis， A. （1999） ‘Influence of nutrients and mixing on the primary production and community respiration in the Gulf of Riga， Journal of Marine Systems， Vol. 23， pp. 127-142. [Assessed： 25 April 2018]

Wollsat， R. （1998） ‘Evaluation and comparison of the global carbon cycle in the coastal zone and in the open ocean， In the Sea， Vol. 10， pp. 213-252. [Assessed： 26 April 2018]

Zhang， J. et al. （2013） ‘The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves， JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS， Vol. 1， pp. 297-312. [Assessed： 25 April 2018]

作者简介：：孙皓天 出生于1996年05月，男，汉族，内蒙古赤峰人，本科在读，研究方向為环境科学