Moss Beach tide pools
Name:
Objectives:
1) Observe the physical setting of the tide pools.
2) Identify the types of organisms that live in the rocky shore environment.
3) Search for adaptations to the different intertidal zones.
4) Quantitatively assess the human impact on the marine preserve.
Field trip RULES :
(…because this is a preserve and a relatively dangerous environment!)
1. NO COLLECTING of any kind (plant, animal, or inanimate object).
2. Walk cautiously in the tide pool area; seaweed is extremely slippery.
3. Keep an eye on the waves coming in as you observe the tide pools.
4. Return rocks gently to their original position after overturning them; sea life can be
harmed if their habitat is altered.
5. Do not contaminate or litter the beaches or tide pools.
Field trip ACTIVITIES:
1. Meet in the parking lot of the James Fitzgerald Marine Preserve and proceed down to the beach.
First refer to the tidal chart (Figure 1). At what time was the last high tide during the day?
What was the elevation of this tide (with respect to the MLLW-mean lower low waterdatum)? When is the low tide? What is the predicted elevation of the low tide? Estimate the
tidal height at the time we begin our field trip. Is the tide rising or falling?
Refer to the topographic map (Figure 2) and mark our location on it. Use this figure as the
location map in your report.
2. Observe the physical setting of the area. The sedimentary rocks exposed on the wave-cut
platform are part of the Purisima Formation, sediments that were originally deposited on the
continental shelf 2-6 million years ago. What evidence can you observe that suggests deposition
within a marine environment? Briefly describe the texture and appearance of the Purisima
Formation. Do these rocks have any characteristics that make them good habitats for tide
pool organisms?
3. Observe the biological activity in the tide pools. Systematically work your way over the
exposed rocks: check under rocks and ledges (replace rocks); lift seaweed; sift carefully through
sand and pebbles. Practice using your key to identify (at least 5) of the plants and animals that
you see in the intertidal area. Ask questions if you can’t classify an organism. What adaptations
have each of the organisms developed to live in this difficult habitat where water level is ever
changing, water salinity and temperature are highly variable, and waves are crashing in?
Consider lifestyle (attached or free moving), technique for obtaining food, exposure to temperature
and salinity variations and to wave action.
Organism:
1:
2:
3:
4:
5:
Adaptations:
4. Look for any variation in organism type from the highest (supra) tidal zone to the lowest (sub)
tidal zone. In each of the quadrats that have been distributed throughout the intertidal
environment, count the number of individuals present for each of the species in the following
table. The resulting numbers are a measurement of the abundance (or spatial density) of each
species; abundance can change under different environmental conditions. Do you see evidence
that tide pool life is distributed in zones with abundance peaking at a particular elevation in
the intertidal environment? Do your data suggest that the visitors to the preserve may be
damaging the environment in some way that reduces the amount of life in a particular zone?
Organism
# of individuals
in quadrat 1
# of individuals
in quadrat 2
# of individuals
in quadrat 3
# of individuals
in quadrat 4
Isopod/rock louse
Periwinkle
Limpet
Barnacle
Chiton
Hermit crab
Mussel
Sea star
Sea anemone
Shore crab
Sea lettuce
Rock weed
(fucus)
Sea urchin
Shrimp
TOTALS:
Draw a map of the area that illustrates where quadrats 1 through 4 are located. Note how the
environmental conditions differ between quadrats (elevation below high tide line,
sun/wind/wave exposure, amount of time immersed in seawater, human impacts, rock type, etc.).
BACKGROUND ON THE ROCKY SHORE ENVIRONMENT:
Most of the rocky shore is confined to the supralittoral and littoral zones (littoral just means
intertidal). The supralittoral corresponds with the backshore, or spray zone, that is above the spring
high-tide line and covered by water only during storms. The littoral zone, also known as the
foreshore or the intertidal zone, lies between the high and low tidal extremes. Along most shores,
the intertidal zone can be divided into: high tide zone (mostly dry-covered by the highest high tides
but not the lowest high tides); middle tide zone (exposed and covered equally-covered by all high
tides and exposed by all low tides); low tide zone (mostly wet-exposed only during the low tides).
See illustration of these zones in Figure 3. The subtidal zone is always below water and so is not
visible for our perusal.
SUPRATIDAL ZONE: The most obvious inhabitant is the periwinkle snail. The genus
Littorina includes species able to breathe air, like land snails. Limpets and rock louse are also
found.
HIGH TIDE ZONE: Buckshot barnacles are the most conspicuous inhabitants. Plants in
this zone have thick cell walls to reduce water loss during periods of low tide. The variety of life
is greater than in the supratidal zone.
MIDDLE TIDE ZONE: Found here are the larger acorn barnacles, and mussels, which are
fed on by starfish and carnivorous snails. A large variety of organisms include sea anemones, sea
urchins, and hermit crabs. Plants may be less abundant because of grazing by the animals.
LOW TIDE ZONE: This zone is dominated by plants rather than animals. The animals that
exist here are difficult to see because they are hidden by a great variety of seaweeds and surf grass.
Encrusting red algae, seen also in middle zone tide pools, become very abundant in the lower tide
pools. Larger sea anemones, nudibranchs, and shell-less snails are common in quiet tide pools.
Almost all phyla of life are represented in the low tide zone, where life is less rigorous than in the
upper level zones.
Report guidelines:
As usual, the report should have a title and consist of 2-3 pages of TYPED, DOUBLE-SPACED
text, plus location map and checklists. Use your notes as a guide for your report, but please
organize it in narrative form rather than as a list of answers to the questions. Be sure to carefully
record all of your observations during the course of the trip.
The report should include:
1. Title
2. Introductory paragraph.
3. A body that discusses (in narrative form) answers to all questions posed in the handout.
4. Conclusion paragraph
5. Location map (Figure 2) and map of quadrat locations.
6. Attach plant and animal notes and checklists to the back of the report.