Marine Communities of San Salvador

1
Marine Communities of San Salvador

• Intertidal - Hardbottom
• White zone Supralittoral zone
• Gray zone
• Black zone
• Yellow zone
• Intertidal - Softbottom

2
The Intertidal Sits Between the Supralittoral and
the Subtidal Zones
Supralittoral
Subtidal
3
Physical/Chemical Factors

• Temperature
• Wave shock
• Tides
• Impact of Slope
• Low tides ? physiological stress
• High tides ? marine conditions are restored
• Light intensity
• Evaporation
• ph

4
An Example Of How Exposure To The Sun Effects
Snail Shell Design
5
How Design And Color Of A Snails Shell
Dissipates/Absorbs Heat
6
What adaptations do you see in this tropical
nerite that help it lose heat?
7
These mussels retain moisture by being densely
packed.
8
Physical/Chemical Factors

• Temperature
• Wave shock
• Tides
• Impact of Slope
• Low tides ? physiological stress
• High tides ? marine conditions are restored
• Light intensity
• Evaporation
• ph

9
Animals Are Subjected to Wave Shock Continuously
at High Tide
10
- Adaptations to Wave Shock - Growth Forms Of The
Giant Green Sea Anemone
In sheltered areas
In areas with heavy wave action
11

• Adaptations to Wave Shock
• Mussels at Intermediate Population Size Are Best
  Adapted

Low
Intermed.
High
Large specimens washed away
Clumps ripped away
Waves dissipated and eddies form
12
Physical/Chemical Factors

• Temperature
• Wave shock
• Tides
• Impact of Slope
• Low tides ? physiological stress
• High tides ? marine conditions are restored
• Light intensity
• Evaporation
• ph

13
Types of Adaptations

• Attachment
• Bore into substrate (chitons and urchins)
• Byssal threads (molluscs)
• Feeding
• Prevention of dessication

14
Boring By Sea Urchins
15
Most organisms in rocky intertidal zones live
attached to rocks
16
Attachment by Byssal Threads
17
Two Types of Barnacles
18
Barnacles Feed Using Appendages on Incoming Tides
19
Intense Competition by Barnacles for Attachment
Sites
southeast Alaska
20
Hardbottom Intertidal Food Webs

• Several different types of producers
• Detritus plays a central role
• Importance of drift into and out of the community
• Plankton are significant, too, as they arrive on
  every wave

21
Predation by a dog whelk (snail) on rock barnacles
22
Hard Bottom Intertidal Community Food Web
23
Intertidal ZoneCharacterized by Two Ecological
Factors
24
The Intertidal Zone Is Characterized By Two
Ecological Attributes

• Zonation of Species moisture and temperature
  gradients are established that influence species
  distribution
• Intraspecific and Interspecific competition for
  attachment to substrate

We will study this while on San Salvador
25
Vertical Zonation in Hardbottom Intertidal
Communities In Temperate Waters Along the Pacific
and Atlantic Coasts
26
Pacific Coast
Atlantic Coast
27
Vertical Zonation In Hardbottom Intertidal
Communities

• The upper limit of an organisms dispersion
  pattern is typically set by physical factors such
  as evaporation or dehydration.
• The lower limit is generally set by biological
  factors such as competition or predation.

Lets see how these factors interplay to
influence the dispersion patterns of two species
of barnacles
28
Why Two Species of Barnacles Live Where They Do
Substantiated by removal studies
29
Slope Gradient of Intertidal Zones Effects
Zonation
w
g
b
w
y
g
b
y
white, gray , black, yellow
30
Zonation of a Rocky Shore
Gradual Slope
Steep Slope
31
Gradual vs. Steep Rocky Shores(Hawaii)
32
Vertical zonation as evidenced by bands of colors

33
Vertical Zones in Tropical Hardbottom Intertidal
Communities

• White largely bleached out and wetted only by
  storm-spring tides (Supralittoral)
• Gray lower margin receives some immersion
• Black completely wetted during spring tides and
  some high tides
• Yellow the true intertidal zone

34
Intertidal Zonation at North Point, San Salvador
White Gray Black Yellow
Subtidal
35
A different view
36
Here, the color zones appear to be reversed. I
dont know why.
37
How Intertidal Communities are Experimentally
Studied

• Transplantation experiments several barnacle
  studies
• Removal studies barnacles limpet studies and
  their grazing abilities
• Caging/barrier experiments spiny lobsters

38
What are the effects of spiny lobsters in the
rocky intertidal zone?
39
Muscles dominate closed-end cages that exclude
spiny lobsters.
Cage removed to take photo
40
Examples of Common Biological Activities Observed
in Rocky Intertidal Zones

• Biological succession
• Keystone species and predation
• Home ranges and homing behavior
• Symbiosis
• Competition
• Food
• Attachment sites

41
How Succession Effects Community Structure in
Tide Pools
42
Ecological Succession In A Mussel Bed
43
How Keystone Species Impact the Structure of a
Tide Pool Community
44

• Intertidal Tide Pools
• Effect of Removal of a Keystone Species on
  Community Structure

45
Homing Behavior in Limpets
46
In what ways does this giant green sea anemone
receive nutrition?
47
Vertical Zonation Can Extend into Subtidal
Communities
48
End