WHAT ARE KELP FORESTS

1
WHAT ARE KELP FORESTS? Stands of large brown
algae in the order Laminariales (i.e., kelps)
that provide food and shelter for a diverse array
of marine plants and animals.
2
27 kelp genera
3
High Diversity of Primary Producers
4
High Diversity of Consumers
5
Distribution
6
Macrocystis Morphology
7
Who Cares?

• Big Business

gt 30 million
8
Who Cares?

• Fish, lobsters, sea urchins, seals, sport and
  commercial fishermen, seafood consumers, etc.
  Kelp is an ecosystem engineer

9
Comparisons between terrestrial forests and giant
kelp forests
FOREST TYPE
NET PRODUCTION
PRODUCER MASS
LITTER MASS
Tropical rain forest
2.2
45
0.2
Tropical deciduous forest
1.6
35
0.5
Temperate evergreen forest
1.3
35
3.0
1.2
30
2.0
Temperate deciduous forest
0.8
20
4.0
Boreal forest
2.2
0.35
0.015
Giant kelp forest
10
Percentage of Kelp-Derived Carbon in Kelp Forest
Consumers
(from Duggins et al. 1989)
kelp carbon
Suspension Feeders
Mussel
(Mytilus edulis)
25 - 40
Soft coral
(Alcyonaria sp).
40 - 70
Barnacle
(Balanus
nubilus)
75 85
Sea anemone
(Metridium senile)
15 - 40
Rock jingle
(Pododesmus cepio)
40 - 55
Mysid (
Proneomysis sp.)
45 - 60
Detritivores
Amphipod
(Anonyx sp.)
70 - 95
Crab
(Dermaturus mandtii)
20 - 35
Predators
Rock
greenling
(Hexagrammos lagocephalus)
)
40 65
Sea star (
Leptasterias spp.)
30 - 55
Cormorant
(Phalacorcorax peligicus)
35 - 70
11
Export
12
(No Transcript)
13
Abiotic factors that influence kelp forests

• Kelp is Dynamic

14
Hard Bottom

• Plants anchored to hard substrate
• Distribution of substrate controls distribution
  of kelp- patchy

kelp
15
Water Motion

• Wave action physically removes kelp fronds from
  substrate
• Major cause of seasonal cycles of kelp abundence
  in SBC
• Late winter minimum
• Late summer/early fall maximum

Varies with local conditions
16
Seasonal Variation in SB kelp
17
Light

• Limits depth range (lt3040 m in SBC) and
  densities of kelps
• Macrocystis good at competing for light- dense
  canopy

18
Nutrients and Temperature

• Kelp needs cool nutrient rich waters (lt17C)
  upwelling zones
• High temps and low nitrate reproduction
  problems, low growth rates, and mortality

Healthy
Nutrient Stressed
19
PDO and ENSO
ENSO
ENSO
ENSO
20
Anthropogenic Impact
21
Biological factors that influence kelp forests
COMPETITION
GRAZING
PREDATORS
22
Competition

• Light, nutrients, space, etc.
• Why is Giant Kelp so dominant in SBC and So. Cal?

23
Competition among understory primary producers

• Under kelp, turf dominates in low light
  conditions
• Increasing light harms turf, enhances foliose
  algae

24
Food Web Implications
GELIDIUM (red algae)
KELP
LIGHT
TURF
STRIPED SURFPERCH
BIRTH
GELIDIUM
FOOD
POPULATION
DEATH
BLACK SURFPERCH
BIRTH
POPULATION
TURF
FOOD
DEATH
25
Predation/Grazing
26
A Simple 3 Trophic Level Food Web
PREDATOR
GRAZER 1
ALGAE
27
Trophic Interactions Top Down Effects
X
28
Factors influencing sea urchin populations in
southern California

• Other predators on sea urchins in California,
  which include lobster and fish predators such as
  the sheephead wrasse.
• Sporadic recruitment of sea urchins in California
• Disease, which has been known to greatly reduce
  urchin numbers over relatively wide areas. In
  California these outbreaks of disease are
  generally associated with periods of warm water.
  Expansion of kelp beds have been documented
  following massive urchin die offs.

29
Real Systems have many more Interacting
Populations
Challenge to Understand How Such Systems
Might Respond to Disturbance
30
Ecosystem changes
?
X
X
31
Kelp Population Dynamics Research

• How is the distribution of giant kelp changing in
  the Santa Barbara Channel?
• What are the causes of this change and can we
  predict it?

32
SPOT Satellite Imagery

• Imagery of entire SB Channel (including Channel
  Islands) collected every two months from Jan 2006
  present

SPOT 3,2,1 stretched image
3(NIR)/1(green) band ratio
SPOT 3,2,1 image
Kelp delineation
33
Kelp Cover Variability
1.8 km2
1.2 km2
0.8 km2
34
Assessing the role of forcing processes