Follow the light—diurnal and seasonal variations in vertical distribution of the mesopelagic fish Maurolicus muelleri 

Towards developing a general framework for modelling vertical migration in zooplankton

“…We find that the most important issue is not the exact parametrization of J, but its daily periodicity. This strengthens our conclusion on the key role of light in the shaping of the optimal trajectory of DVM [30,56,15,58].…”

“…It is well known that light intensity is one of the key stimuli of the timing of migration and its amplitude -when performing DVM pelagic organisms often follow the depth with a certain constant light intensity which is known as the 'isolume' [30,56,15,58]. The daily variation of the isolume is described by a harmonic-like function, for instance the sinusoidal relationship.…”

Internal wave-mediated shading causes frequent vertical migrations in fishes

“…For example, a 90% reduction in surface light can be compensated by upward movement of~45 m in clear oceanic water (K = 0.05 m −1 ) or 12 m in murkier coastal water (K = 0.2 m −1 , where K represents the attenuation of the downwelling irradiance for the wavelengths relevant to the visual system in question). The characteristic dawn and dusk migrations of species exhibiting DVM occur when changes in incoming solar radiance are the largest, but less extensive vertical migrations have been observed during days with variable radiation due to cloudiness (Baliño & Aksnes 1993, Staby & Aksnes 2011. Rather than showing variations in incoming solar radiance, the results presented here show upward daytime migrations of fish that are concurrent with a reduction in light intensity of 3 to 4 orders of magnitude in the lower part of the water column.…”

“…Migrations due to variations in light are well known, although at other time scales. The best documented example is DVM, such as the DVM of hake and horse mackerel in the Benguela Current (Axelsen et al 2004, Pillar & Barange 1995, but temporal fish migrations have also been observed for light variations related to variable cloudiness (Baliño & Aksnes 1993, Staby & Aksnes 2011. Similarly, spatial variations in the fish depth dis tribution have been associated with cooccurring variations in shading caused by chlorophyll (Kaart vedt et al 1996) and related to turbidity from re suspended sediments (Sassa et al 2010).…”

Evidence for light-controlled migration amplitude of a sound scattering layer in the Norwegian Sea

“…This corresponds to the preferendum or isolume hypothesis (see Cohen & Forward 2009), implying that vertical migration emerges simply because organisms are attracted to a preferred light level. Instead of being attracted to a specific light level, however, light-driven migration also emerges if organisms distribute within a range of light intensities (Frank & Widder 2002, Dupont et al 2009, Staby & Aksnes 2011. Avoidance, rather than attraction, might be involved.…”