Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes
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Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes Yongcui Sha . Huan Zhang . Marcus Lee . Caroline Bjo¨rnera˚s . Martin Sˇkerlep . Raphael Gollnisch . Simon David Herzog . Gustaf Ekelund Ugge . Jerker Vinterstare . Nan Hu . Varpu Pa¨rssinen . Kaj Hulthe´n . P. Anders Nilsson . Karin Rengefors . Christer Bro¨nmark R. Brian Langerhans . Lars-Anders Hansson
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Received: 29 June 2020 / Accepted: 21 October 2020 Ó The Author(s) 2020
Abstract Diel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of
calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophyll a), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM
Handling Editor: Te´lesphore Sime-Ngando Y. Sha H. Zhang M. Lee C. Bjo¨rnera˚s M. Sˇkerlep R. Gollnisch S. D. Herzog G. Ekelund Ugge J. Vinterstare N. Hu V. Pa¨rssinen K. Hulthe´n P. A. Nilsson K. Rengefors C. Bro¨nmark L.-A. Hansson (&) Department of Biology, Aquatic Ecology, Lund University, Lund, Sweden e-mail: [email protected] H. Zhang Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People’s Republic of China
G. Ekelund Ugge School of Bioscience, University of Sko¨vde, Sko¨vde, Sweden K. Hulthe´n R. B. Langerhans Department of Biological Sciences and W.M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, USA P. A. Nilsson Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden
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Aquat Ecol
may vary among systems, but also systematically
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