Bos, A. R., & Gumanao, G. S. (2012). The lunar cycle determines availability of coral-reef fishes at fish markets. J Fish Biol, 81(6), 2074–2079.
Abstract: During 139 visits between March 2009 and May 2011, it was found that the availability of reef fishes at a local fish market in the Philippines was highly affected by the lunar cycle. The number of vendors selling reef fishes was significantly lower (13.4%) during third lunar quarters (full moon periods) than during the first, second and fourth lunar quarters (40.2, 25.0 and 30.0%, respectively). It is recommended that the influence of the lunar cycle on fish availability is considered when designing sampling strategies for catch surveys.
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Czarnecka, M., Kakareko, T., Jermacz, Ł., Pawlak, R., & Kobak, J. (2019). Combined effects of nocturnal exposure to artificial light and habitat complexity on fish foraging. Science of The Total Environment, 684, 14–22.
Abstract: Due to the widespread use of artificial light, freshwater ecosystems in urban areas at night are often subjected to light of intensities exceeding that of the moonlight. Nocturnal dim light could modify fish behaviour and benefit visual predators because of enhanced foraging success compared to dark nights. However, effects of nocturnal light could be mitigated by the presence of structured habitats providing refuges for prey. We tested in laboratory experiments whether nocturnal light of low intensity (2 lx) increases foraging efficiency of the Eurasian perch (Perca fluviatilis) on invertebrate prey (Gammarus fossarum). The tests were conducted at dusk and night under two light regimes: natural cycle with dark nights and disturbed cycle with artificially illuminated nights, in habitats differing in structural complexity: sand and woody debris. We found that nocturnal illumination significantly enhanced the consumption of gammarids by fish compared to dark nights. In addition, the perch was as effective predator in illuminated nights (2 lx) as at dusk (10 lx). Woody debris provided an effective refuge only in combination with undisturbed darkness, but not in illuminated nights. Our results suggest that nocturnal illumination in aquatic ecosystems may contribute to significant reductions in invertebrate population sizes through fish predation. The loss of darkness reduces the possibility of using shelters by invertebrates and hence the effects of elevated light levels at night could not be mitigated by an increased habitat complexity.
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Georgiadis, M., Mavraki, N., Koutsikopoulos, C., & Tzanatos, E. (2014). Spatio-temporal dynamics and management implications of the nightly appearance of Boops boops (Acanthopterygii, Perciformes) juvenile shoals in the anthropogenically modified Mediterranean littoral zone. Hydrobiologia, 734(1), 81–96.
Abstract: A remarkable phenomenon of dense Boops boops shoals appearing almost adjacent to the shoreline during nighttime is known to the locals of island communities of the Aegean Sea (eastern Mediterranean). In this work, we investigated this appearance testing the hypotheses that (a) it may occur only in anthropogenically modified locations (as suggested by previous observations), (b) the migration pattern to the littoral is not arbitrary but synchronized to the sunset/sunrise, (c) fish abundance is affected by location, season and/or natural (moon) light fluctuations. Quantitative sampling included visual observations from the coast at five stations in Syros (Cyclades, Greece) from July 2009 to September 2010. Both hypotheses concerning occurrence only in anthropogenically modified locations and timing with sunset/sunrise were confirmed. Fish abundance was modelled using generalized additive models, demonstrating a seasonal pattern and revealing significant differences among sampling stations, but no moon-phase effects. The phenomenon investigated here has implications for fisheries management, as the shoal proximity to the shore renders them prone to illegal harvesting (seasonally at high abundances), aggravating the problem of illegal, unreported and unregulated fishing. Further considerations on the integrated management of the coastal zone arise, especially concerning the effects of habitat structural modification and light pollution.
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Hou, Z. - S., Wen, H. - S., Li, J. - F., He, F., Li, Y., Qi, X., et al. (2019). Effects of photoperiod and light Spectrum on growth performance, digestive enzymes, hepatic biochemistry and peripheral hormones in spotted sea bass (Lateolabrax maculatus). Aquaculture, 507, 419–427.
Abstract: Growth performance, digestive and metabolic activities, and contents of peripheral hormones of spotted sea bass (Lateolabrax maculatus) juveniles were evaluated under natural light and three different light spectrums (white, blue and red) in combination with three photoperiods (light: dark cycle, 12: 12-h, 18: 6-h and 24: 0-h). Bass in 18-h blue light environment displayed the best growth performance and digestive enzyme activities, while red light environment significantly impeded growth and digestive enzyme activities. Altered contents of melatonin, cortisol, thyroid hormones (T3 and T4), and testosterone (T) were observed in bass reared in red light, suggesting that red light could disturb endocrine homeostasis associated with biological rhythm (melatonin), stress coping (melatonin and cortisol), growth and development (T3 and T4), and aggressive behavior or hyperactivity (T3, T4 and T). Impaired growth performance might be due to energy used to cope with stress. We concluded that the red spectrum environment was stressful to spotted bass and the selection of appropriate light conditions (such as 18-h blue light) might lead to a beneficial outcome for spotted sea bass culture.
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Mehner, T. (2012). Diel vertical migration of freshwater fishes – proximate triggers, ultimate causes and research perspectives: Diel vertical migration in freshwater fishes. Freshwater Biology, 57(7), 1342–1359.
Abstract: 1. Diel vertical migrations (DVM) are typical for many cold-water fish species such as Pacific salmons (Oncorhynchus spp.) and coregonids (Coregonus spp.) inhabiting deep lakes. A comprehensive recent overview of DVM in freshwater fish has not been available, however.
2. The main proximate trigger of DVM in freshwater fish is the diel change in light intensity, with declining illumination at dusk triggering the ascent and the increase at dawn triggering the descent. Additional proximate cues are hydrostatic pressure and water temperature, which may guide fish into particular water layers at night.
3. Ultimate causes of DVM encompass bioenergetics efficiency, feeding opportunities and predator avoidance. None of these factors alone can explain the DVM in all cases. Multi-factorial hypotheses, such as the ‘antipredation window’ combined with the thermal niche hypothesis, are more likely to explain DVM. It is suggested that planktivorous fish move within a layer sufficiently well illuminated to capture zooplankton, but too dark for predators to feed upon the migrating fish. In complete darkness, fish seek layers with a temperature that optimises bioenergetics efficiency. The strength of each factor may differ from lake to lake, and hence system-specific individual analyses are needed.
4. Mechanistic details that are still poorly explored are the costs of buoyancy regulation and migration, the critical light thresholds for feeding of planktivorous and piscivorous fish, and predator assessment by (and size-dependent predation risk of) the prey fish.
5. A comprehensive understanding of the adaptive value of DVM can be attained only if the behaviour of individual fish within migrating populations is explicitly taken into account. Size, condition and reproductive value differ between individuals, suggesting that migrating populations should split into migrants and non-migrants for whom the balance between mortality risk and growth rate can differ. There is increasing evidence for this type of partial DVM within populations.
6. Whereas patterns of DVM are well documented, the evolution of DVM is still only poorly understood. Because experimental approaches at realistic natural scales remain difficult, a combination of comprehensive data sets with modelling is likely to resolve the relative importance of different proximate and ultimate causes behind DVM in fish.
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