Marine Plankton and Pelagic Ecology

Comprehensive vocabulary flashcards covering marine plankton classification, cnidarian and ctenophore anatomy, copepod biology and life history, vertical migration, and physical mechanisms driving plankton patchiness.

Plankton

•Any free floating, drifting or weak swimming organism in the open water of the oceans

• “wanderers”

Phytoplankton

Drifting, capable of photosynthesis

Zooplankton

Drifting animals

Nekton

Animals that can control their movement in the water

Holoplankton

Organisms that spend their entire life cycle as plankton within the water column.

Meroplankton

Organisms that are planktonic only during their larval stages before maturing into benthic or nektonic forms.

Cnidocytes

Specialized cells that carry stinging nematocysts

Mesoglea

The gelatinous layer situated between the inner and outer epithelial tissue layers in cnidarians and ctenophores.

Gastrovascular Cavity

The central digestive cavity of cnidarians that connects to a centrally located mouth surrounded by tentacles.

Ctenophore Anatomy

Mesoglea between 2 epithelial layers

No stingers

Have rows of “combs”, cilia

1 mm to 1.5 m across

Phylum Ctenophora

–Similar to cnidarians superficially (look like a jellyfish), but have some very different characteristics

–No stinging cells

–Pair of anal pores, which is a trait of bilaterian animals (more advanced with bilateral symmetry: worms, fish, humans)

Copepods

Small arthropod crustaceans (usually $< 1\text{--}2\,\text{mm}$) with weak, jerky swimming locomotion that molt their exoskeleton as they grow and serve as major ocean grazers.

Copepod Biomass

$70\text{--}90\%$ of all oceanic biomass.

Diel Vertical Migration

A daily pattern where zooplankton migrate downward into deeper waters during daylight and ascend near the surface at night, driven by a negative behavioral response to light.

Why vertical migration?

1. To avoid predation by visual predators

2. Light-damage avoidance

3. By sinking and rising they may arise in a different surface water mass, potentially ungrazed

4. Zooplankton obtain an energetic advantage by spending a portion of time in cold, deep waters rather than maintaining themselves constantly in warm upper layers

Adaptations to increase Buoyancy

–Stored fats and oils

–Blubber

–Gas-filled floats

–Lungs full of air

–Swim bladders

Langmuir Cells

Shallow, wind-driven paired helical water circulations forming alternating surface zones of convergence (where plankton sink and collect into streaks) and divergence (where plankton rise).

Gulf Stream Rings

Mesoscale oceanic eddies pinched off from Gulf Stream meanders

Chlorophyll Maximum Layer

A subsurface layer in the water column where the concentration of chlorophyll and phytoplankton reaches its peak, producing horizontal and vertical patchiness.

Patches of plankton

•Gyres & eddies and rings

•Langmuir cells

•Chlorophyll maximum layer

•Marine snow