Diel vertical migration

Animation of diel migration

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Diel Vertical Migration (DVM) is a behavior exhibited by many aquatic organisms, including zooplankton, fish, and some marine invertebrates. This phenomenon involves the movement of these organisms up and down the water column over a 24-hour period, typically ascending to the surface waters at night and descending to deeper waters during the day.

Mechanisms and Triggers

Diel vertical migration is primarily driven by the need to balance feeding opportunities with predator avoidance. During the night, the cover of darkness reduces the risk of predation, allowing organisms to move to the nutrient-rich surface waters to feed. Conversely, during the day, they retreat to deeper, darker waters to avoid visual predators.

Light and Predation

Light is a significant factor influencing DVM. Many organisms have light-sensitive mechanisms that trigger their vertical movements. The presence of predators such as fish and marine mammals also plays a crucial role in this behavior. By migrating to deeper waters during daylight hours, these organisms reduce their visibility to predators.

Temperature and Oxygen

Temperature gradients and oxygen levels in the water column can also influence DVM. Some species may migrate to avoid temperature extremes or to find optimal oxygen levels for their metabolic needs.

Ecological Significance

Diel vertical migration has profound implications for aquatic ecosystems. It affects nutrient cycling, energy transfer, and the distribution of biomass in the water column. The vertical movement of organisms can transport nutrients from the surface to deeper waters and vice versa, influencing primary productivity and the overall health of the ecosystem.

Examples of DVM

Several species exhibit diel vertical migration, including:

• Krill: These small crustaceans are known for their extensive vertical migrations, which can span hundreds of meters.
• Copepods: These tiny zooplankton are a crucial part of the marine food web and exhibit DVM to avoid predation.
• Mesopelagic fish: Species such as the lanternfish migrate vertically to feed on zooplankton at night and avoid predators during the day.

Research and Observation

The study of diel vertical migration involves various methods, including acoustic surveys, net sampling, and the use of bioluminescence sensors. These techniques help scientists understand the patterns and drivers of DVM and its impact on marine ecosystems.

Related Pages

• Zooplankton
• Marine invertebrates
• Predation
• Nutrient cycling
• Primary productivity
• Marine ecosystems

Categories

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