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Notes 10.1
Kelp Communities
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Directions
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Review
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Introduction
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Kelp
Communities
- Kelp
Beds and Forests
- Kelp
Taxonomy and Anatomy
- Types
of Kelp
- Kelp
Requirements for Survival
- Kelp
Forest Habitats
- Kelp
Forest Ecology
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Kelp
Beds and Forests
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Types of Kelp Communities
- Kelp Beds
- Kelp Forests
Kelp Beds
- Found nearshore in shallow
waters of cold temperate regions with hard subtidal substrates
- Low growing kelps
- No surface canopy
- North Atlantic and Northwest
Pacific
Kelp Forests
- Found nearshore in
cold temperate regions with hard subtidal substrates
- Tall kelps
- To depths of 20-30
meters
- Extensive floating
surface canopy
- Eastern Pacific and
along the northern rim of the Antarctic Ocean
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Kelp
Taxonomy and Anatomy
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Kelp Taxonomy
- Kelps are all Brown
seaweeds
- They have a complex
anatomy and physiology
Kelp Anatomy
- Holdfast
- Stipe
- Pneumatophores
- Fronds (Blades)
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Types
of Kelp
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Laminaria
- Kelps of short stature
- Kelp bed dominant
Nereocystis
- Bull Kelp
- Large kelp
- Found in kelp forests
Egregia
- Feather Boa Kelp
- Large Kelp
- Found in shallows of
kelp forests
Macrocystis
- Giant Kelp
- Found in deeper portions
of kelp forests
- 20-30 m long
- Grow 6-50 cm/day
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Kelp
Requirements for Survival
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Kelps Need
- Light
- Clear Water
- Upwelling
- Runoff from Land
- Wave & Current Action
- Hard Substrate
Depth Limits
- Kelps can become established
only where light penetrates to the bottom in sufficient quantities for
young kelp to grow
- This is typically to
depths of 20-30 meters in clear waters
Kelp Nutrition
- Absorb nutrients directly
from seawater
- Depend on high nutrient
content and constant water movement to replenish the nutrient supply
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Kelp
Forest Habitats
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Kelp Forest Habitats
- Large kelps form an
extensive three-dimensional habitat composed of several layers or vertical
strata
- Provide many potential
microhabitats for other organisms
Kelp Forest Strata
- Substrate Surface
- Kelp Holdfasts
- Bottom Canopy
- Understory Canopy
- Midwater Canopy
- Surface Canopy
Kelp Associates
- High Diversity
- Many algal species
- Numerous invertebrates
- Varied Fish fauna
Substrate Surfaces
- Sponges
- Colonial animals (ex.
tunicates and bryozoans)
- Sea anemones
- Molluscs (ex. abalone
and octopus)
- Echinoderms (ex. sea
urchins and sea stars)
Holdfasts
- Polychaetes
- Crustaceans
- Sea Urchins and Brittle
Stars
Bottom Canopy
- Red Seaweeds
- Demersal Fish
Understory Canopy
- Small Kelps
- Demersal Fish
Midwater and Surface
Canopies
- Large Kelps
- On Kelp Surfaces:
- Polychaetes, Snails,
Isopods and Bryozoa
- In Water Column:
- Pelagic Fishes &
Marine Mammals
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Kelp
Forest Ecology
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Sea Otters as a Keystone
Species
- Control urchin populations
- Promote kelp population
growth
Barren Grounds
- Barren areas where kelp
forests once existed
- populated by large numbers
of sea urchins
- Caused in part by reduced
sea otter abundance
Kelp Forest Productivity
- Extremely productive:
800-2,000 grams of carbon / square meter / year
- Kelps are perennial
often loosing stipes and fronds to wave action but regrowing new ones
from holdfasts
- Life span is 3 to 7
years
Kelp Forest Food Web
- Many nutritional sources
including plankton and detritus
- Relatively few herbivores
feed directly on living kelp tissues
Production and Food
Web
- About 10 percent of
NP is grazed and mostly by sea urchins and fish
- About 90 percent of
NP is eaten as detritus
Kelp Harvesting
- Special Boats "mow"
the surface canopy
- Commercially used
as a source of algin
- Algin is used as a
thickener & stabilizer in many products including: ice cream,
toothpaste and paint
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