Lecture 17ROCKY SUBTIDAL

Substrate Types

Cobble Walls

Horizontal bedrock Sandy

ZONATION

CHART DATUMinfralittoral fringe

littoral

About 200 m

Infralittoral

Circalittoral

Adequate light for photosynthesis

Infralittoral + Circalittoral = Subtidal

ZONATION

CHART DATUMinfralittoral fringe

littoral

Upper infralittoral

Lower infralittoral

Upper circalittoral

Lower circalittoral

Laminaria forest+ foliose algae+ few animals

Foliose algae+ few animals

Few foliose algae+ many animals

No algaemany animals

Rocky Subtidal - Zones

1) Sublittoral fringe

Laminaria

Bryozoan

Anemone (Metridium)

Rocky Subtidal - Zones

2) Infralittoral

Laminaria Anemone (Metridium)

Strongylocentrotus droebachiensis Urchin barrens

Rocky Subtidal - Zones

3) Circalittoral

Anemone (Metridium)

tunicates

Sea stars

Lamp shells

Determinants of Zonation

Slope

Horizontal Vertical

Determinants of Zonation

Slope

Differences in species’ patterns

1. Higher light levels on horizontal surfaces

2. Higher sedimentation on horizontal surfaces

3. Photonegative larvae select walls/overhangs

4. More shelter from disturbance

Determinants of Zonation

DepthD

ensi

ty

Depth 33 m 42 m

% C

over

Depth 28 m 45 m

Brachiopods Sponges

Local Processes Affecting the CommunityTemperature

0

5

10

15

20

25

30

0

5

10

15

20

25

30

11 12 13 19 23 25

Maine (Machias Seal Is)Aug. 1995

Galapagos(May1999)

Local Processes Affecting the CommunityTemperature

Internal waves Upwelling

Physical Disturbance

Depth

Low High

Physical Disturbance

Physical Disturbance

Creation of Patches

Type I Disturbance-death of some residents-patch surrounded by survivors

Type II Disturbance-widespread destruction

Recovery - vegetative growth& asexual budding

Recovery - long distance dispersers-more stochastic

Physical Disturbance

Creation of Patches

Wittman (‘98)

Patch of anemones

Predation by nudibranchs

Got Type I patches

Physical Disturbance

Creation of Patches

Wittman (‘98)

Expect Got

Recruitment of planktonic bryozoans, polychaetes and ascidians

Asexual/vegetative growthof neighbours

Physical Disturbance

Flow Patterns - Reidl ‘71

Primary - effect of flow directly on organisms

Secondary - effect of flow on transport of nutrients, gasses, foods

Tertiary - effect of flow on substrate

Physical Disturbance

Flow Patterns

20 40 60 80 100 120 140

cm/s

2

4

6

8

10

Minimum

Maximum

Depth

Physical Disturbance

SedimentationSedimentation rate = 1/flow

0

5

10

15

20

25

30

Light

0

5

10

15

20

25

30

35

40

45

50

Depth

Percent surface light

.01 .1 1 10 100

Turbid coastal water

Clear open ocean water

Limit for Laminaria

Limit for foliose algae

Rocky Subtidal - communities

Terebratulina septentrionalis Community

Terebratulina septentrionalis

Chiton

Rocky Subtidal - Communities

Crustose coralline algaeCommunity

Terebratulina septentrionalis

Chiton

Bryozoans

Rocky Subtidal - Biotic Factors

Biotic Factors on the Subtidal

Predictions:

1. Predation - reduced in harsh environments

2. Biotic factors set lower distribution limits

3. Physical factors set upper distribution limits

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

+5

0

5

10

15

20

Low HighPredator pressure

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

PREDATOR SURVIVAL

Number of waves

0 100 200

Time (Months)

0 6 12

Denny et al, 1985

Survivorship Lr/2

Lr2Lr

Lr/2

Lr

2Lr

Colisella digitalis

Predator density

Galapagos

Seychelles

Gulf of Maine

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

Absence of predators

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

minutes hours days

Birds

Crabs/lobster

Snails/urchins/seastars

Impact of predator on prey(per capita prey removal rate)

Return time of limiting stress

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

New Zealand

Biotic Factors on the Subtidal

1. Predation - reduced in harsh environments

urchins, sea stars, lobsters

freshwater

mussels

New Zealand

Biotic Factors on the Subtidal

Predictions:

1. Predation - reduced in harsh environments

2. Biotic factors set lower distribution limits

3. Physical factors set upper distribution limits

√

Biotic Factors on the Subtidal

Predictions:

1. Predation - reduced in harsh environments

2. Biotic factors set lower distribution limits

3. Physical factors set upper distribution limits

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

Anderson Ledge, New Hampshire

Laminaria - limit dictated by urchin grazing

Urchins - stay near bottom of Laminaria - physical stress too high to go shoreward

Mytilus - colonized areas grazed by urchins

Sea stars - prevent Mytilus recruitment lower in subtidal

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

Scheibling et al, 1999

Mill Cove

Little Duck Island

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

Strongylocentrotus droebachiensis

Laminaria longicruris

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

Scheibling et al, 1999

kelp

grazed edge

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

Scheibling et al, 1999

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

But ….within limits set by physical factors

Vadas & Steneck, 1988

- depth greater without grazers

Biotic Factors on the Subtidal

2. Biotic factors set lower distribution limits

But ….within limits set by physical factors

Miller and Hay, 1996

Oculina

Biotic Factors on the Subtidal

Predictions:

1. Predation - reduced in harsh environments

2. Biotic factors set lower distribution limits

3. Physical factors set upper distribution limits

√ (with qualifications)

Biotic Factors on the Subtidal

Predictions:

1. Predation - reduced in harsh environments

2. Biotic factors set lower distribution limits

3. Physical factors set upper distribution limits √ (with qualifications)

Biotic Factors on the Subtidal

2. Competition

+5

0

5

10

15

20

Low HighCompetition for space

Biotic Factors on the Subtidal

2. Competition

Competition for space (among algae)

a. allelopathy

Biotic Factors on the Subtidal

2. Competition

Competition for space (among algae)

b. overgrowth

Biotic Factors on the Subtidal

2. Competition

Competition for space (among algae)

c. overtopping

Biotic Factors on the Subtidal

2. Competition

Competition for space (among algae)

d. Algal whiplash

Biotic Factors on the Subtidal

2. Competition

Competition for space

e. Aggression (Cnidaria)acrorhagi

Biotic Factors on the Subtidal

3. Recruitment

+5

0

5

10

15

20

Low High% space covered

Biotic Factors on the Subtidal

3. Recruitment

+5

0

5

10

15

20

Low High% space covered

effect of predators

Biotic Factors on the Subtidal

3. RecruitmentOsman & Whitlach, 1995

Mitrella

Anachis

Without predators

With predators

Mesoscale Processes

High flow

Low flow

km’s

Other mesoscale processes

Disease

Productivity

Thermoclines