1. Coastal Ecosystems
Dr. Mark A. McGinley
Honors College and Department of
Biological Sciences
Texas Tech University

2. Two Main Coastal Environments
• Estuarine
– Freshwater and sea water meet
• Temperate- salt marshes
• tropics- mangroves
– Intertidal zone
• Mudflats
• Sandy beaches
• Rocky intertidal

3. Intertidal Zones
• Dominated by gradients in two physical
conditions
– Wave exposure
– Tidal exposure

4. Wave Exposure
• Energy in waves can
influence
– Particle size
– Ability of organisms
to remain attached
to substrate

5. Tidal Exposure Gradient
• Vertical gradient
– Higher areas have longer exposure to air than
lower areas
• Exposure to air can have two negative effects
for marine organisms
– Desiccation
• water loss
– Thermal stress
• Getting two hot

6. A Bit of Basic Geology
Particle Size
Aggregate name
Size range Size range
scale (Wentworth Other names
(metric) (approx. inches)
Class)
−8 < 256 mm < 10.1 in < Boulder
−6 to −8 64–256 mm 2.5–10.1 in Cobble
Very
−5 to −6 32–64 mm 1.26–2.5 in Pebble
coarse grave;l
−4 to −5 16–32 mm 0.63–1.26 in Coarse gravel Pebble
−3 to −4 8–16 mm 0.31–0.63 in Medium gravel Pebble
−2 to −3 4–8 mm 0.157–0.31 in Fine gravel Pebble
−1 to −2 2–4 mm 0.079–0.157 in Very fine gravel Granule
0 to −1 1–2 mm 0.039–0.079 in Very coarse sand
1 to 0 ½–1 mm 0.020–0.039 in Coarse sand
2 to 1 ¼–½ mm 0.010–0.020 in Medium sand
3 to 2 125–250 µm 0.0049–0.010 in Fine sand
0.0025–0.0049
4 to 3 62.5–125 µm Very fine sand
in
3.90625– 0.00015–0.0025
8 to 4 Silt Mud
62.5 µm in
>8 < 3.90625 µm < 0.00015 in Clay Mud
> 10 < 1 µm < 0.000039 in Colloid Mud

7. Wave Energy and Shore Particle Size
• Larger particles require more energy to move
them than smaller particles
• Thus, the size of particles on the shore is
influenced by the energy in the waves striking
the shore
• High energy shores contain larger particles
than low energy shores

8. Rocky Shore

9. Boulder Beach

10. Cobble Beach

11. Gravel Beach

12. Sandy Beach

13. Mud Beach

14. Rocky Shore
• Rocky intertidal zone dominated by daily rise
and fall of tides
– Littoral zone
• Part of the time covered by water and part of the day
exposed to air
• Species living in littoral zone must face the
problems with living in both marine and
terrestrial habitats

15. Rocky Shore- Physical Environment
• Two dominant gradients in physical conditions
– 1) Wave exposure
– 2) Tidal exposure
• Vertical gradient
– Higher areas spend more time exposed to air than lower areas
• Exposure to air can have two negative effects
– Desiccation
– Thermal stress

16. Intertidal Zonation

17. Zonation in Rocky Intertidal

18. Intertidal Zone Organisms

19. What Causes These Zonation Patterns?
• The field of ecology is interested in
understanding the factors that influence the
distribution and abundance of organisms
• Determined by abiotic and biotic factors

20. Rocky Intertidal Zone
• Rocky intertidal zones proved to be ideal
natural labs for studying ecology
– Steep vertical gradients
– Variable physical conditions
– Mostly sessile or sedentary organisms
– Small organisms with high density
– Easily manipulated

21. Joe Connell’s Experiments With
Barnacles

22. Connell’s Experiments With Barnacles
• What causes pattern of zonation?
– Physical factors or biotic interactions
• Physical Factors
– Higher regions exposed to air for longer periods
• Thus greater desiccation
– Lower regions exposed to air for shorter period of
times

23. Question
• Can the barnacles tolerate the environmental
conditions outside of the zone where they are
found?
– Too dry higher up and too wet lower down???

24. Question
• Is the distribution of the barnacles influenced
by biotic interactions?
– Competition, predation
• Could they live higher and lower on the shore
in the absence of other species?

25. Manipulative Experiments
• Connell (and others scientists including Bob
Paine who also worked in rocky intertidal
ecosystems) recognized the importance of
manipulative experiments in the field.
• Helped move ecology from a descriptive
science to an experimental science

26. Need to Design an Experiment
• What experiments would you suggest to try to
determine the importance of abiotic and
biotic factors on the distribution of these
barnacles?
• What factors can limit distribution?
– Never got there
– Can’t live there because of abiotic conditions
– Can’t live there because of biotic interactions

27. Questions
• As we talked about in lab, you need to start by
asking a question.
• Let’s start by thinking about the cause of the
boundary between Balanus and Chthamalus
– Q. 1. Is Balanus missing form the upper zone
because it has never reached there?

28. Experiment
• Place Balanus in the Chthamalus zone and see
if it can survive. Make sure that there are no
potential competitors or predators affecting
them
– Control- move Balanus to the Balanus zone
– These barnacles are attached to the rocks, so
Connell was able to move the organisms around
by chipping off pieces of the rock and attaching
them elsewhere on the rocks

29. Results
• Balanus did not survive in the higher zone
• Conclude- Balanus not living in the upper zone
because they can not deal with the abiotic
conditions.
– Hypothesis- too dry in the upper zone
– What experiment could we do to test this?

30. Questions
• Q. 2. Is Chthamalus lacking from the lower
zone because it has never dispersed there?
• Experiment- move Chthamalus to the Balanus
zone with no potential competitors or
predators

31. Results
• Chthamalus was able to grow in the lower
zone
– Thus, not limited by lack of dispersal or by abiotic
conditions
– Hypothesis- Chthamalus limited by competition
for space by Balanus
• Test by moving Chthamalus to the lower level and
allowing it to interact with Balanus

32. Results
• Chthamalus could not live in the lower zone
when Balanus was there
– Competitively excluded by Balanus

33. Rocky Intertidal
• Patterns
– Biomass and species richness increase closer to
the sea

34. Tide Pools
• Pools of water may
become isolated and
hold water for periods
ranging from hours to
several days
• When pools isolated
– Water evaporates
– Salinity increases
– Temperature increases
• Pools can fill during rains
– Salinity decreases
– Temperatures decrease

35. Mangroves
• Mangroves include a number of tropical trees
and shrubs that are able to live in the
intertidal zone along tropical coastlines.
• Have adaptations to allow them to live in
periodically flooded regions with high salt
content.
• Approximately 70 species of mangrove plants
come from 20 different plant families

36. Problems Facing Mangroves
• The soil is very fine and water logged, it is difficult
for the root system to support the plant.
• Because the roots zone is waterlogged, plant
roots are unable to pick up the oxygen they need
through the soil.
• Because they are living in the intertidal zone
mangrove plants have to be able to live in water
with high salt concentrations.
• No oxygen in the saturated soil.

37. Mangroves

38. Aerial Roots and Pneumatophores

39. Mangroves- Cool Fish

40. Importance of Mangrove Ecosystems
• serve as nurseries for a number of marine fish
and invertebrates.
– juveniles of many species hide out among the
mangrove roots until they are large enough to move
out to the reef.
• Second, the mangrove roots protects the shore
from the effects of storms and tsunamis.
– It has been well documented that parts of SE Asia
that were protected by mangroves were much less
negatively affected by the big tsunami than those
regions where the mangroves have been removed.

42. Mangrove Restoration
Thailand