Development Of Individual-based Population Dynamic Model Of Calanus Sinicus And Its Application In The Central Yellow Sea

Calanus sinicus (C.sinicus), as the dominant species of copepod widelydistributed in the costal water of China, feeds mostly on algae and is the major sourceof food for many fishes. It plays a significant role in the energy flow in the marinefood web and its population dynamics can influence both the distribution ofphytoplankton and the recruitment of fishery resource. After the two “973programs”conducted separately in1999and2005, there was a big improvement in theunderstanding of both the life circle and the distribution of C.sinicus in the Yellow Sea.However, it is still unclear the roles of the physical and biological processes, such asthe appearance of Yellow Sea Cold Water (YSCW) in summer and the phytoplanktonbloom in spring, on the dynamics of the population of C.sinicus. In addition, previousstudies reveal that these processes have obvious interannual variations. How theseinterannaul variations will affect the population of CS also needs further study.As the difference of influences of physical and biological processes onpopulation in different life history, the life history strategy should be emphasized inpopulation dynamics model of C.sinicus, but it’s difficult for traditionalnutient-phytoplankton-zooplankton-detritus model (NPZD) to achieve this point.Since the individual-based model (IBM) considers individual difference and theindividual response to the environment variation, it is helpful to discuss how thephysical and biological processes influence the population of C.sinicus in Its differentlife history. Therefore, in this paper an individual-based model is developed as a toolto study population dynamics of C.sinicus in Yellow Sea.The present model consists of six parts: growth, development, reproduction,mortality, diapause and diel vertical migration (DVM). The first three parts (growth,development, reproduction) are all affected by temperature and Chl-a concentration. The egg mortality by cannibalism and the abundance-dependent mortality are bothadopted in mortality part. In DVM part, this model considers the difference of DVMof individuals in different stages, and also emphasizes the DVM pattern of individualsin summering period. For most IBMs of copepod, it’s difficult to simulate thediapause, which is the adaption to unfavorable environment for most copepod. Inpresent model the oil sac is considered as the factor controlling diapause, based on thehypothesis that oil sac accumulation and metabolism play the key role in the controlof diapause. And the present model also considers the role of oil sac in gonadmaturation and reproduction. In this study, the IBM of C.sinicus is applied in a sitelocated in middle Yellow Sea, and it is forced by the vertical profile of temperatureand Chl-a concentration. With verification to the observation data, it’s shown that thismodel can simulate generally the seasonal variation of population of C.sinicus.Using the present IBM, a series of numerical experiments are implemented,which are forced by interannual temperature and remote sensing Chl-a data separately,and the influences of temperature, thermocline and food environment on populationdynamics of C.sinicus are discussed separately. The results indicate that both hightemperature and short duration of thermocline can improve abundance of populationin oversummering period, to by changing the energy storage of population in differentways. The changes of food environment in spring can only affect the populationdynamics of C.sinicus in both spring and summer, but in winter the changes ofpopulation are not obvious. Here it is considered the oversummering strategy ofC.sinicus maybe diminish the difference of population. The result also indicates thatthe duration of food supplement in spring is the most important factor affectingpopulation dynamics in oversummering period.A numerical experiment is established to simulate the population dynamics ofC.sinicus in Yellow Sea between1998and2007. The result indicates the factorsaffecting population are not the same in different periods. In spring, the response ofpopulation to variation of temperature field is quicker than that to variation of foodfield, and the high temperature can promote abundance of population in spring. Inoversummering period, the factors affecting population consist of the duration of thermocline, the temperature at bottom and the duration of food supplement in Spring,and the result indicates that the last one is the most important factor affectingpopulation. In recovering period, both temperature and food can affect populationrecovering, in addition, both the higher and lower abundance of C5and adult in theend of oversummering period can make the bad effect on population recovering inlater period.In short, an individual-based model is developed and it successfully simulates thepopulation dynamics of C.sinicus in Yellow Sea, which is helpful to the further studyon population dynamics model of C.sinicus, coupled with the physical environmentmodel.