Download Zooplankton

Zooplankton
 Major trophic link to the pelagic vertebrates, birds, fish and
whales
 Strong seasonal patterns
Highest amounts are found inshore - spring and summer
Spawning of zooplankton is triggered by phytoplankton
blooms
 Zooplankton consists of both:
Holoplankton - plankton that spends it entire life in the
plankton community (ex. jelly fish)
Meroplankton - plankton that spends only a portion of its
life in the plankton community (ex. Juvenile fish)
 Vertical Migration - daily or seasonal movement of small
marine animals between photic and midwater depths.
 Why do zooplankton migrate vertically?
1. Abundant food resources of the photic zone
2. Escape visual detection by predators
3. Lower temperatures means lower metabolic rate and
energy requirements
 Growth occurs at all depths
Epipelagic (0-200 m) - greatest abundance
Mesopelagic (200-1000 m)
Bathylpelagic (greater than 1000m)
 Common Epipelagic Zooplankton (upper 200 meters)
- Crustaceans are the most numerous species found in the
holoplankton. (Ex. crab and shrimp larvae, copepods)
- *Copepods and Krill are the two main zooplankton in the
ocean. Krill is considered to be a major prey for marine
vertebrates (sharks, whales)
- Gelatinous zooplankton - (ex. jellyfish)
- Their bodies consist of 95% water so buoyancy is not a
problem. These zooplankton are often transparent.
 Mesopelagic zone - (200 - 100 meters)
Very dim light
Zooplankton depend on living and dead organisms from the
epipelagic zone
Advantages to living in the mesopelagic zone
1. Predators find it more difficult to see prey in dim light
2. Lower water temperatures mean decreased metabolic rate that
means a lower oxygen and food requirement.
3. The cold water slows down the sinking rate of food particles.
Deep Scattering Layer - one or mare layers of mid water marine
animals that reflect and scatter the sound pulses of echo sounders.
(this is where submarines like to hide)
 Bathypelagic - Deep Zooplankton - is still being researched.
It is very difficult to study because:
1. Depths
2. Water pressures make it difficult to bring organisms
to the surface with causing harm to their bodies
 Below 500 M deep, most zooplankton is a deep red, brown,
purple or black.
 The colors are associated with the lack of light
 Many of the organisms in this area are bioluminescent