An optimisation model of the diel vertical migration of northern krill (Meganyctiphanes norvegica) in the Clyde Sea and the Kattegat

2000 ◽  
Vol 57 (S3) ◽  
pp. 38-50 ◽  
Author(s):  
Geraint Tarling ◽  
Michael Burrows ◽  
Jack Matthews ◽  
Reinhard Saborowski ◽  
Friedrich Buchholz ◽  
...  

An optimisation model was developed to examine the effect of predation risk and environmental conditions on the diel vertical migration (DVM) of adult northern krill (Meganyctiphanes norvegica). Model predictions were compared in two locations with contrasting environmental conditions, the Clyde Sea and the Kattegat. The model was constructed from a combination of parameterised functions and empirical field data obtained during summer conditions. Parameter matrices were set up to cover the entire water column over a 24-h period. The first matrix contained values for "net energy gain," which incorporated empirical data on temperature-dependent respiration, copepod and phytoplankton abundance, and a functional response model for feeding rate. The second matrix expressed the risk of encountering a generalised visual (fish) predator as a function of light levels. The optimisation procedure sought a path through depth and time such that the energy gain was equal to the amount necessary to grow, produce eggs, and moult, while the risk of predation was minimised. The model predicted DVM in both the Clyde Sea and the Kattegat. Sensitivity analyses showed that the predicted DVM pattern was mainly driven by food and predation risk, with temperature effects on metabolic costs having a minor effect.

Hydrobiologia ◽  
2008 ◽  
Vol 614 (1) ◽  
pp. 321-327 ◽  
Author(s):  
Meryem Beklioglu ◽  
Ayse Gul Gozen ◽  
Feriha Yıldırım ◽  
Pelin Zorlu ◽  
Sertac Onde

Author(s):  
J.-O. Strömberg ◽  
J.I. Spicer ◽  
B. Liljebladh ◽  
M.A. Thomasson

Most krill species undergo diel vertical migration (DVM) which is to some extent influenced by light intensity. During a solar eclipse (11 August 1999) the upward and downward movement of krill, Meganyctiphanes norvegica, inhabiting a Swedish fjord followed closely changes in light intensity. Here the eclipse was partial (77%) and the weather overcast and yet krill at 70–90 m depth were able to detect, and respond to very small changes in light. This observation of an event during mid-day which is not pre-programmed confirms light as an important triggering mechanism for krill DVM.


2006 ◽  
Vol 63 (10) ◽  
pp. 2296-2307 ◽  
Author(s):  
Olaf P Jensen ◽  
Thomas R Hrabik ◽  
Steven J.D. Martell ◽  
Carl J Walters ◽  
James F Kitchell

Several hypotheses have been proposed to explain diel vertical migration (DVM); however, they have generally been applied to DVM behavior of a single trophic level. We evaluate the costs (predation risk) and benefits (foraging rate and growth rate potential) of different hypothetical and observed DVM trajectories for a three-level pelagic food chain in Lake Superior containing opossum shrimp (Mysis relicta), deepwater ciscoes (Coregonus spp.), and lake trout (Salvelinus namaycush). Lake trout appear to be maximizing foraging and growth rates by tracking vertically migrating ciscoes, while the DVM trajectories of ciscoes suggests a trade-off between predation risk and growth. For ciscoes, two alternative DVM trajectories both minimize the ratio of risk to growth: a shallow trajectory that follows low light levels down to 80 m during the day and a deep trajectory (below 150 m) that tracks highest Mysis densities. Observed cisco DVM trajectories appear to follow the shallow high risk – high growth trajectory in 2001, but switch to the deep, low risk – low growth trajectory in 2004 when lake trout density was higher and the density of ciscoes was lower.


Author(s):  
Ruping Ge ◽  
Hongju Chen ◽  
Guangxing Liu ◽  
Yanzhong Zhu ◽  
Qiang Jiang

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