Week 5: Invertebrates 1 Flashcards
7 reasons why we need to study zooplankton
- Dominate the biomass in the ocean
- Key part of biological processes in the largest liveable place on the planet
- A link between phytoplankton and higher trophic levels in the ocean (benthic animals/fish/marine mammals and birds)
- Drive the biological pump, which removes CO2 from the atmosphere
- Most marine species spend part of their lifecycle in the plankton as zooplankton (recruitment in fisheries)
- Drive many of the biological res[onses of the ocean to climate variability
- Many ‘pest’ species (toxic algae, jellyfish outbreaks
Zooplankton definition
Animals living in the pelagic zone at the mercy of water movement
Diversity and classification of zooplankton
Size, taxa, life history, diet and trophic level
Plankton classification by size
- Nano plankton (2-20 pm)
- Micro zooplankton (20-200 pm)
- Mesoplankton (0.2 - 20mm)
- Macro zoo plankton (2-20cm
- Mega plankton (> 20cm)
7 major zooplankton phyla
- Arthropods
- Cnidarians
- Ctenophores
- Chordata
- Chaetognatha
- Molluscs
- Polychaetes
Estimated and known zooplankton species
Known = 5,700
Estimated = 28,000
Most zooplankton are crustaceans, the most common species are
- Copepods
- Euphausiids
- Amphipods
- Ostracods
- Mysids
Two types of cnidarians
- Hydroza (feed with tentacles and have a float/can’t swim)
- Scyphozoans/Cubozoans (Capture food with tentacles, true jellyfish, can swim)
Ctenophores are also known as
Comb jellies (use ciliated bands for locomotion)
Urochordata characteristics
- Salps
- Movement by contracting circular muscles to cause jet propulsion
- Intake of water also used for feeding
- Can form massive aggregations through asexual reproduction
- Grows very quickly and can increase body weight by 40% per day
Chaetognath characteristics
- Arrow worms, 2nd only to crustaceans in abundance
- Important predators intermediate between small zooplankton and fish
- 3mm to 12cm
- Head has grasping spines used to capture prey
Mollusca characteristics
- Shell lost/thinned or used for floatation and shelter
- Swim by wing like parapoda
- Important predators in polar waters
Mero plankton and holoplankton
Meroplankton are planktonic for parts of their life (fish and benthic species)
Holoplankton are planktonic throughout their whole life (Copepods, salps, larvaceans, etc)
What percent of marine species have a planktonic larval stage
80-90%
Importance of larval stages in marine ecology
- Drive population dynamics (distribution, recruitment, abundance, movement)
- Connectivity and population genetics
- Aquaculture and fisheries
- Invasive processes
- Responses to environmental change
Planktonic larval stages influence
Recruitment in fisheries and hence catch sizes and sustainability
The oceans biologically driven sequestration of carbon from the atmosphere
The biological pump
If the biological pump was switched off
Atmospheric CO2 concentrations would increase to 700 ppm in 200 years
Zooplankton lifespan
Weeks to months
Zooplankton are a measure of
Health in the ocean
Physical processes of zooplankton variability
- Ocean circulation, upwelling
- Stratification
- Fronts, eddies
- Tides
- Internal waves
Biological processes of zooplankton variability
- Primary productivity
- Behaviors (vertical migration)
- Life-cycles (larval stages)
Productivity drives differences in
Zooplankton and food pelagic foodwebs
How is patchiness caused by the interaction of plankton behavior and water movement
Krill are good swimmers, and when they are displaced into deeper water, they will return to the surface, and when combined with water movement, this behavior leads to aggregations and patchiness.
