20-Apr-99 WFSC575 Chapt 9
Upwellings
SW Canada to SW California coasts
W coast of S. America
NW coast of Africa
SW coast of Africa
All Antarctic coasts
W coast Australia
Equatorial trade winds generates most upwelling. The Antarctic upwelling caused by currents from Pacific and Atlantic oceans; rapid ice melts and growth; polynayas and fresh and salt water pockets encourage nutrients.
Coastal systems
Ecosystem- Productivity: grams of Carbon/ Meter squared /year:
Coral reefs-2000/5000 gC/m2/yr
Rocky shores- upwelling: 1000 non-upwelling: 100-1000 gC/m2/yr
Salt marshes
Sea-grass- 300-1000 gC/m2/yr
Coastal phytoplankton- 50-250 gC/m2/yr
Mangroves
Sand/mudflats
Sugar cane field- 2000 gC/m2/yr
Benthic =
Attached grows up from the bottom
Theories:
why so many seaweeds? Paradox - Diversity remains high and the late stages to not take overLittner functional form group:
Succession Series: Pioneer Early Stages Gradually to Mid to Late Successional Stages
Palatability: High, Gradual Decrease, to Mid, to Low
Forms- Sheets: Filaments: Coarse/fleshy: Thick/leathery: Jointed/calcified: Crusty calcified
Examples: Ulva: Cladophera: Gracilaria: Dictyota/Padina: Amphiroa: Poralitton
Growth Rate High: Gradual Decrease To Low
Equilibrium
- develop many stable niches algae support each other mutualism; grazing pressure keeps any one type from being dominantNon-equilibrium
- disturbance theory
Seaweed life cycles:
Dispersal stage
(spores) Plankton stage: Pressures: place to land & grow, fish grazing; drift. Solutions: produce many spores at 1 time; do not spend much time in water.Recruitment stage:
spores attach & grow microthallus. Pressures: finding a spot to grow, eaten by fish. Solution: can go into a dormant stage to wait for better conditions.Vegetative growth stage:
macrothallus. Pressures: wave disturbance; larger surface areas to collect nutrients; grazing.Reproductive stage:
back to dispersal stageEnvironmental factors
Tides:
determine how deep seaweed goes light penetration surf exposureSubstrate:
determines where it grows sandy vs. rockyFertility:
nutrient content Oxygen etc.24 hr tide cycles:
Semidiurnal:
2 highs, 2 lows. Ex. MaineDiurnal:
1high 1 low. Ex FloridaMixed tides:
1 really low; 1 really high; 1 shallow low; 1 shallow high. Ex. West coast; creates more niches for tidal zonation: different alga grow in different air exposure.Food chain:
Coastal communities support food chain Seaweeds = benthic producers that trap most light energy not very digestible feed food chain through:Dissolved organic matter
(rot on bottom) bacteria which are eaten by protozoaDetritus
(rot on bottom) benthic - eaten by deposit feeders sea cucumbersDetritus water column
(spores floaties) eaten by: Suspension /filter feeders sponges bivalves (also eat protozoa)Direct feeding
by benthic herbivores: sea urchins snails fish (eaten by sea otters dolphins etc.)Phytoplankton
eaten by : zooplankton that are eaten by planktivorouse fish suspension feeders that are eaten by benthic predators (starfish shrimp snails) that are eaten by predatory fish birds, mammals.