Notes 10.1
Kelp Communities

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  Introduction


Kelp Communities
  1. Kelp Beds and Forests
  2. Kelp Taxonomy and Anatomy
  3. Types of Kelp
  4. Kelp Requirements for Survival
  5. Kelp Forest Habitats
  6. Kelp Forest Ecology

Top  Kelp Beds and Forests

Types of Kelp Communities

  1. Kelp Beds
  2. Kelp Forests

Kelp Beds

  1. Found nearshore in shallow waters of cold temperate regions with hard subtidal substrates
  2. Low growing kelps
  3. No surface canopy
  4. North Atlantic and Northwest Pacific

Kelp Forests

  1. Found nearshore in cold temperate regions with hard subtidal substrates
  2. Tall kelps
  3. To depths of 20-30 meters
  4. Extensive floating surface canopy
  5. Eastern Pacific and along the northern rim of the Antarctic Ocean

Top  Kelp Taxonomy and Anatomy

Kelp Taxonomy

  1. Kelps are all Brown seaweeds
  2. They have a complex anatomy and physiology

Kelp Anatomy

  1. Holdfast
  2. Stipe
  3. Pneumatophores
  4. Fronds (Blades)

Top  Types of Kelp

Laminaria
  1. Kelps of short stature
  2. Kelp bed dominant

Nereocystis

  1. Bull Kelp
  2. Large kelp
  3. Found in kelp forests

Egregia

  1. Feather Boa Kelp
  2. Large Kelp
  3. Found in shallows of kelp forests

Macrocystis

  1. Giant Kelp
  2. Found in deeper portions of kelp forests
  3. 20-30 m long
  4. Grow 6-50 cm/day

Top  Kelp Requirements for Survival

Kelps Need

  1. Light
  2. Clear Water
  3. Upwelling
  4. Runoff from Land
  5. Wave & Current Action
  6. Hard Substrate

Depth Limits

  1. Kelps can become established only where light penetrates to the bottom in sufficient quantities for young kelp to grow
  2. This is typically to depths of 20-30 meters in clear waters

Kelp Nutrition

  1. Absorb nutrients directly from seawater
  2. Depend on high nutrient content and constant water movement to replenish the nutrient supply

Top  Kelp Forest Habitats

Kelp Forest Habitats

  1. Large kelps form an extensive three-dimensional habitat composed of several layers or vertical strata
  2. Provide many potential microhabitats for other organisms

Kelp Forest Strata

  1. Substrate Surface
  2. Kelp Holdfasts
  3. Bottom Canopy
  4. Understory Canopy
  5. Midwater Canopy
  6. Surface Canopy

Kelp Associates

  1. High Diversity
  2. Many algal species
  3. Numerous invertebrates
  4. Varied Fish fauna

Substrate Surfaces

  1. Sponges
  2. Colonial animals (ex. tunicates and bryozoans)
  3. Sea anemones
  4. Molluscs (ex. abalone and octopus)
  5. Echinoderms (ex. sea urchins and sea stars)

Holdfasts

  1. Polychaetes
  2. Crustaceans
  3. Sea Urchins and Brittle Stars

Bottom Canopy

  1. Red Seaweeds
  2. Demersal Fish

Understory Canopy

  1. Small Kelps
  2. Demersal Fish

Midwater and Surface Canopies

  1. Large Kelps
  2. On Kelp Surfaces:
  3. Polychaetes, Snails, Isopods and Bryozoa
  4. In Water Column:
  5. Pelagic Fishes & Marine Mammals

Top  Kelp Forest Ecology

Sea Otters as a Keystone Species

  1. Control urchin populations
  2. Promote kelp population growth

Barren Grounds

  1. Barren areas where kelp forests once existed
  2. populated by large numbers of sea urchins
  3. Caused in part by reduced sea otter abundance

Kelp Forest Productivity

  1. Extremely productive: 800-2,000 grams of carbon / square meter / year
  2. Kelps are perennial often loosing stipes and fronds to wave action but regrowing new ones from holdfasts
  3. Life span is 3 to 7 years

Kelp Forest Food Web

  1. Many nutritional sources including plankton and detritus
  2. Relatively few herbivores feed directly on living kelp tissues

Production and Food Web

  1. About 10 percent of NP is grazed and mostly by sea urchins and fish
  2. About 90 percent of NP is eaten as detritus

Kelp Harvesting

  1. Special Boats "mow" the surface canopy
  2. Commercially used as a source of algin
  3. Algin is used as a thickener & stabilizer in many products including: ice cream, toothpaste and paint