Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes

Research output: Contribution to journalArticle

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 may vary among systems, but also systematically by latitude.

Details

Authors
Organisations
External organisations
  • Institute of Hydrobiology, Chinese Academy of Sciences
  • University of Skövde
  • North Carolina State University
  • Karlstad University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Ecology

Keywords

  • Bahamas, Blue hole, Calanoid copepod, Cyclopoid copepod, Food availability, Predation, Ultraviolet radiation, Vertical distribution
Original languageEnglish
JournalAquatic Ecology
Publication statusE-pub ahead of print - 2020 Nov 2
Publication categoryResearch
Peer-reviewedYes

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