1. Secondary Productivity-2
Dr. Jason Turner
MARE 444

2. Ichthyoplankton Planktonic fish Mainly eggs and larval fish (fry)
Seasonal, locally important in planktonic food webs
Prey and predators

3. Fish Embryonic Development
Oviparous
release eggs into water column
Ovoviviparous
eggs kept inside mother, embryos obtain nourishment from egg yolk
Viviparous
embryos obtain nourishment directly from mother

4. Ichthyoplankton
Most bony fishes (Osteichthyes, teleosts) are oviparous
Eggs are either released into the water column, attached to the bottom, sometimes guarded by adult fish

5. Fish eggs Some fish release eggs into the water column
Planktonic eggs are typically 1-2 mm in diameter
Oil droplets may be present for flotation
25,000 to 100 million eggs released per female
Fewer larger versus many smaller

6. Fish eggs High nutrient content Dietary component
Important to life histories

7. Fish fry
Rate of embryo development is dependent on species and temperature (few days to weeks)
Temperature effects
faster development
smaller adults
lower fecundity

8. Fry survival Early life mortality 99.999% in cod
Size matters (temperature?)
chase down prey
escape from predators
Critical phase – endogenous → exogenous
when yolk is used up - there better be food around
r-selection

9. Patchiness Individuals are not distributed uniformly or even randomly
makes research difficult (non-parametric statistics)
Lots versus none

10. Why does patchiness occur?
Circulation patterns
Frontal boundaries
Food distributions
Migratory movements
Nutrient content

11. Factors Limiting Ocean Nutrients
1. Nutrient content not constant
2. Production reduced at depth
3. Organisms reduce water volume
4. Nutrients absorbed by other autotrophs

12. Eddy Haulani
West Longitude

13. Langmuir Circulation Constant wind sets up small-scale vortices
Upwelling and downwelling can occur (upper few meters only)
Concentrates organic particles at surface
Parallel lines of foam/debris/rift

16. Other Examples of Patchiness
Reproduction
Feeding
Schooling