Diel Vertical Migration Behaviour of the Northern Krill (Meganyctiphanes norvegica Sars)

Abstract Microplastics in the marine environment are well documented, and interactions with marine biota have been described worldwide. However, interactions with vertically migrating fish are poorly understood. The diel vertical migration of mesopelagic fish represents one, if not the largest, vertical migration of biomass on the planet, and is thus an important link between the euphotic zone, transporting carbon and other nutrients to global deep sea communities. Knowledge of how mesopelagic fish interact and distribute plastic as a marine contaminant is required as these populations have been identified as a potential global industrial fishery for fishmeal production. Ingestion of microplastic by mesopelagic fish in the Northeast Atlantic was studied. Approximately 11% of the 761 fish examined had microplastics present in their digestive tracts. No clear difference in ingestion frequency was identified between species, location, migration behaviour, or time of capture. While ingesting microplastic may not negatively impact individual mesopelagic fish, the movement of mesopelagic fish from the euphotic zone to deeper waters could mediate transfer of microplastics to otherwise unexposed species and regions of the world's oceans.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-171 ◽

2000 ◽

Vol 57 (S3) ◽

pp. 38-50 ◽

Cited By ~ 19

Author(s):

Geraint Tarling ◽

Michael Burrows ◽

Jack Matthews ◽

Reinhard Saborowski ◽

Friedrich Buchholz ◽

...

Keyword(s):

Predation Risk ◽

Vertical Migration ◽

Environmental Conditions ◽

Diel Vertical Migration ◽

Energy Gain ◽

Minor Effect ◽

Risk Of Predation ◽

Meganyctiphanes Norvegica ◽

Optimisation Model ◽

Clyde Sea

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.

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Northern krill, Meganyctiphanes norvegica, come up to see the last eclipse of the millennium?

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315402006367 ◽

2002 ◽

Vol 82 (5) ◽

pp. 919-920 ◽

Cited By ~ 6

Author(s):

J.-O. Strömberg ◽

J.I. Spicer ◽

B. Liljebladh ◽

M.A. Thomasson

Keyword(s):

Light Intensity ◽

Solar Eclipse ◽

Vertical Migration ◽

Diel Vertical Migration ◽

Triggering Mechanism ◽

Downward Movement ◽

Meganyctiphanes Norvegica

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.

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