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6.3 Diel vertical migration

6 min readLast Updated on August 20, 2024

Diel vertical migration is a fascinating behavior where aquatic organisms move up and down the water column daily. This movement plays a crucial role in ecosystem structure, nutrient cycling, and food web dynamics, making it a key focus for limnologists.

Zooplankton typically ascend to surface waters at night and descend during the day, while phytoplankton remain in upper layers. This pattern helps zooplankton avoid predators, conserve energy, and access food, shaping the complex interactions in aquatic environments.

Diel vertical migration

  • Diel vertical migration (DVM) is a widespread behavior in aquatic ecosystems where organisms move up and down the water column on a daily cycle
  • DVM plays a crucial role in the structure and function of aquatic ecosystems, influencing nutrient cycling, food web dynamics, and water clarity
  • Understanding DVM is essential for limnologists studying the complex interactions between biotic and abiotic factors in aquatic environments

Zooplankton vs phytoplankton

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  • Zooplankton, such as copepods and cladocerans, exhibit pronounced DVM patterns, typically ascending to surface waters at night and descending to deeper layers during the day
  • Phytoplankton, being photosynthetic organisms, remain in the upper layers of the water column to access light for primary production
  • The contrasting migration patterns of zooplankton and phytoplankton create a dynamic interplay between predators and prey in the water column

Predator avoidance

  • One of the primary drivers of DVM is predator avoidance, as zooplankton seek to minimize their exposure to visually oriented predators (fish) during daylight hours
  • By migrating to deeper, darker waters during the day, zooplankton reduce their risk of predation
  • Predator avoidance through DVM has evolved as a key survival strategy for many zooplankton species

Metabolic advantages

  • DVM also confers metabolic advantages to zooplankton by allowing them to exploit the cooler temperatures of deeper waters during the day
  • Lower metabolic rates in cooler waters help zooplankton conserve energy and reduce their oxygen requirements
  • Migrating to warmer surface waters at night enables zooplankton to enhance their growth and reproduction rates

Light as a cue

  • Light intensity serves as the primary cue for triggering DVM in zooplankton
  • Changes in light levels at dawn and dusk stimulate the upward and downward migrations, respectively
  • Zooplankton possess light-sensitive organs (compound eyes or ocelli) that detect changes in light intensity and guide their vertical movements

Patterns of migration

  • DVM patterns can vary among species, life stages, and environmental conditions
  • Some zooplankton exhibit a "nocturnal" DVM pattern, ascending to the surface at night and descending during the day
  • Others display a "reverse" DVM pattern, moving deeper during the night and shallower during the day
  • The specific migration pattern adopted by a species depends on factors such as predation risk, food availability, and physiological requirements

Impacts on nutrient cycling

  • DVM plays a significant role in nutrient cycling within aquatic ecosystems
  • Zooplankton transport nutrients vertically through the water column as they migrate, a process known as the "biological pump"
  • By consuming phytoplankton near the surface and excreting fecal pellets at depth, zooplankton facilitate the downward flux of carbon and other nutrients
  • This vertical transport of nutrients influences primary productivity and the overall biogeochemistry of the ecosystem

Role in aquatic food webs

  • DVM shapes the structure and dynamics of aquatic food webs
  • Zooplankton serve as a critical link between primary producers (phytoplankton) and higher trophic levels (fish)
  • The vertical migration of zooplankton affects the distribution and availability of prey for predators at different depths
  • Trophic interactions and energy transfer in aquatic food webs are heavily influenced by the DVM behavior of zooplankton

Influence on water clarity

  • DVM can have a significant impact on water clarity in aquatic systems
  • When zooplankton migrate to deeper waters during the day, they reduce grazing pressure on phytoplankton in the surface layers
  • Reduced grazing allows phytoplankton populations to increase, leading to decreased water clarity
  • Conversely, when zooplankton return to the surface at night, their grazing activity can help control phytoplankton abundance and improve water clarity

Seasonal variations

  • DVM patterns can exhibit seasonal variations in response to changes in environmental conditions and biotic interactions
  • Seasonal changes in temperature, light availability, and food resources influence the timing and magnitude of DVM
  • In temperate regions, DVM may be more pronounced during summer months when temperature gradients and predation pressure are higher
  • Seasonal shifts in DVM behavior have implications for ecosystem functioning and trophic dynamics

Behavioral adaptations

  • Zooplankton have evolved various behavioral adaptations to optimize their DVM strategies
  • Some species exhibit flexible migration patterns, adjusting their vertical position based on environmental cues and predation risk
  • Certain zooplankton can alter their body orientation or swimming behavior to enhance their vertical movement efficiency
  • Behavioral adaptations enable zooplankton to fine-tune their DVM in response to changing ecological conditions

Costs vs benefits

  • DVM involves trade-offs between the costs and benefits of vertical migration for zooplankton
  • The energy expenditure associated with swimming vertically through the water column is a significant cost of DVM
  • However, the benefits of reduced predation risk, access to favorable temperatures, and exploitation of food resources often outweigh the energetic costs
  • The balance between costs and benefits shapes the evolution and maintenance of DVM behavior in zooplankton populations

Implications for fisheries

  • DVM has important implications for fisheries management and productivity
  • Many commercially important fish species rely on zooplankton as a primary food source
  • The vertical distribution and availability of zooplankton prey, as influenced by DVM, can affect the feeding behavior and growth of fish populations
  • Understanding the linkages between DVM and fish ecology is crucial for sustainable fisheries management and predicting the impacts of environmental changes on fish stocks

Climate change effects

  • Climate change is expected to have profound effects on DVM in aquatic ecosystems
  • Rising water temperatures can alter the thermal stratification of water bodies, affecting the vertical gradients that drive DVM
  • Changes in temperature and stratification patterns may disrupt the timing and magnitude of zooplankton migrations
  • Climate-induced shifts in phytoplankton communities and primary productivity can also influence the food resources available to migrating zooplankton
  • Predicting the impacts of climate change on DVM requires a comprehensive understanding of the complex interactions between physical, chemical, and biological factors

Research methods

  • Various research methods are employed to study DVM in aquatic ecosystems
  • Traditional techniques involve net sampling at different depths and times to assess zooplankton vertical distribution
  • Acoustic methods, such as echosounders, provide high-resolution data on zooplankton abundance and migration patterns
  • Optical instruments, like the Laser Optical Plankton Counter (LOPC), enable continuous monitoring of zooplankton size and concentration
  • Advances in molecular techniques, such as DNA metabarcoding, offer new insights into the diversity and community structure of migrating zooplankton

Modeling approaches

  • Modeling approaches play a crucial role in understanding and predicting DVM dynamics
  • Individual-based models (IBMs) simulate the behavior and interactions of individual zooplankton, considering factors such as swimming behavior, predator-prey relationships, and environmental cues
  • Ecosystem models incorporate DVM processes into the broader context of aquatic ecosystem functioning, accounting for nutrient cycling, trophic interactions, and physical forcing
  • Coupled physical-biological models integrate hydrodynamic processes with DVM behavior to predict the spatial and temporal patterns of zooplankton distribution
  • Modeling efforts help elucidate the underlying mechanisms driving DVM and forecast the impacts of environmental changes on zooplankton communities and aquatic ecosystems


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AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
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