Name ______________________________________ Group _______ Period ________
Ecology Lab: Intertidal Zonation
Developed by Anne Maben, UCLA Science Coach for Fremont HS
Introduction:
Scientists have been aware of vertical zonation in intertidal habitats since the early 1800’s,
long before “ecology” was even recognized as a branch of science. Early naturalists observed
that the organisms found between the high and low tide marks seemed to vary in a consistent
way. Where organisms are found in the intertidal depends upon their responses to exposure
to air, heat, and sunlight, predation or grazing, and competition for space.
Scientists have since discovered that intertidal habitats can be divided into four zones
according to % coverage by the tides: the splash zone (never covered by water) and the high
(covered ¼ of the day), middle (covered ½ of the day), and low (covered ¾ of the day)
intertidal zones. For example, periwinkle seashells might be found in the upper splash zone,
gooseneck barnacles and mussels in the middle intertidal, and sea hares and octopuses in the
lowest levels. Wave action and substrate (sand, rock or mud) and chemical factors (pH,
salinity, dissolved oxygen, nitrates, phosphates and pollutants) other also play important roles.
We will try to document zonation by running a transect line from high to low levels in the local
intertidal habitat, and comparing the species diversity (number of different species) and
abundance (number of individuals from one species) of the various animals and plants along
that transect. Our data will help us understand the biodiversity of our coastal marine life and
how different abiotic factors (chemical and physical variables) may influence a species
survival.
Materials and Methods:
1) From your starting location place a 1x1 wooden square on a rock observe and record the
organisms you see within the box.
2) Move your box approximately ten feet towards the ocean and repeat step one. Continue
to this method until you have data for ten boxes.
3) Use field guides to select species that are easy to identify and fairly common or especially
interesting to observe. Remember that many of these animals are small, often
camouflaged, and may be hiding. Get down on your hands and knees for a closer look. Be
sure to examine the undersides of rocks (please replace them in their original position),
ledges, and even blades of algae. DO NOT TURN YOUR BACK TOWARDS THE OPEN
OCEAN.
4) Record the data on your data sheet.
Results and Analysis:
Table 2. (Give it a proper title)
# of Organisms per Species
Name of Species
QUAD
1
QUAD
2
QUAD
3
QUAD
4
QUAD
5
QUAD
6
QUAD
7
QUAD
8
QUAD
9
QUAD
10
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
11.
12. Unidentified
3) Prepare graphs showing the relative abundance of each species in each quadrat. You
will do this on your own at home. Ask your teacher for graph paper.
DISCUSSION QUESTIONS: (to be answered on a separate paper, pen or typed, in detail.)
1. Discuss the general trends of biodiversity and species distribution of intertidal plants
and animals in your study area. Did you find any species which appeared to cluster
together in about the same places along the transect? Give examples of any species
clusters you observed, and discuss why they may have occurred.
2. What ecological forces might be influencing the different distributions of these species?
For example, what stresses could animals have if they lived higher in the intertidal?
What stresses come with living lower in the intertidal?
3. If you could go back to the site next year, what additional data would you want to collect
or what questions would you like to research about your study site?