Introduction
This report contains the abiotic and biotic features recorded from Long Reef Rock Platform and the measurements of the distribution and abundance data of tidal rock-shelf animals collected in this local ecosystem. MLC students investigated the types of producers and animals that occurred in the tidal rock-shelf ecosystem, the adaptations of the organisms to this area to increase their chance of survival and the relationship between abiotic and biotic features.
Method
Collection of biotic data
The distribution and abundance of tidal rock shelf animals were collected by using a 0.50 square meter quadrat and through using a transect line. Quadrats were used in three locations: Above the high tide mark, in the tidal rock pool and in low tide.
Quadrat method
Randomly place a 0.50 square meter quadrat in the first location.
Identify the animals within the quadrat by using the identification sheet.
Record the number of each the species.
Repeat steps 1-3 in the two remaining locations.
Transect line method
Construct a line transect from the area of extreme low tide up to the high tide area in this part of the rock shelf.
Start at the 0m mark (extreme low tide) and identify the dominant organisms.
Record the results on a small scale diagram by using identification numbers (optional).
Collection of abiotic data
Students measured the pH, salt concentration and temperature of sea water and the water in an isolated rock pool.

Temperature Method
Using a thermometer, record the air temperature at a 1m height above the ground.
Record the temperature at the rock pool at the highest level, 5cm below the surface of the water.
Repeat step 2 with the ocean water.
pH method
Collect a water sample from the ocean so the sample bottle is half full.
Add 5 drops of universal indicator solution.
Compare the colour produced with the colour chart.
Repeat steps 1-3 with rock pool water.
Salt concentration method
Collect water sample in the marked containers from (Container labelled O).
Rinse out the dropper and place a drop of water on the refractometer plate.
Read in grams of salt per Litre on the right hand scale.
Repeat steps 1-3 with a water sample from the rock pool. (Container labelled RP)
Relationship between abiotic factors and biotic
The abiotic and biotic factors in an ecosystem are interrelated. The biotic factors (plants and animals) need suitable abiotic factors (sunlight, temperature etc.) to function. If a factor changes or is removed, the whole system is impacted. Many physical factors influence the rock platform including sunlight, temperature, desiccation, waves, salinity, dissolved gasses and chemical minerals and nutrients.
For example, a small nudibranch living in the intertidal zone requires seawater so it does not dry out and die. It must avoid sandy substances because it can clog its gills. It hides in small crevices to avoid predators and because its not very strong, it uses this to avoid tough waves. If the water is too cold it becomes sluggish, and if the water is too warm the chemicals in its body don’t function properly. It requires the right abiotic features to it to function well in the environment.
Adaptations are essential to suit the constant changes of nature to increase the chance of survival for organisms. For example, the Knobbly Wink has a light coloured shell to reflect sunlight allowing it to stay cooler. The Limpit and Chiton suction onto rocks so it doesn’t get harmed by wave action. Common brown kelp is flexible and has spikes on its leaves to avoid getting harmed by wave action.
Results
Data collected from biotic experiments
Quadrat Method: shows the method allows us to estimate the abundance of organisms. It is useful when the area is too large to do a direct observation.
Location 1: Above the High Tide Mark
Animal Species	Total No. per 0.50 sq.m
Knobbly Wink	79
Little Blue Periwinkle 	23
	Total organisms: 102
Location 2: Tidal Rock Pool
Animal Species	Total No. per 0.50 sq.m
Rock Oyster	19
Conniwink	5
	Total organisms: 24
Location 3: Low Tide
Animal Species	Total No. per 0.50 sq.m
Barnicle	82
Green Anemone	3
Waratah Anemone	11
Conniwink	3
	Total organisms: 99
Transect line method














Data collected from abiotic experiments
	Ocean	Rock Pool	Air
Temperature (degree Celsius)	22	22.5	24
pH	8	8-9
Salinity	37	41	

Observations:
From the results above, there appears to be a larger amount of organisms living on the high tide mark then any other level on the rock platform. However only two species live in this location: Knobby wink and Little blue periwinkle. All the other organisms can be found in the Tidal Rock Pool and Low tide mark.
For the abiotic results, the ocean’s temperature is the lowest and the air temperature is the highest. The pH and salinity is highest int the rock pool.
Discussion
Interpretation of the biotic and abiotic data
Organisms are distributed in certain locations for various reasons. Organisms have different adaptations which allow them to survive there. The Knobby Wink, which lives above high tide mark, has a distinct light coloured shell which is used to reflect light allowing the organism to stay cooler. In the high tide mark, there is more space and reduces competition. The Waratah Anemone lived underwater in cracks. They live here because they require water to feed and because they lack a shell which would allow them to trap water. The Mulberry Shell lives in the low tide mark and in rock pols. The Mulberry Shell is slow and it lives here because it is easier for them to find food; they feed on Barnacles, Oysters and Limpers (organisms which don’t move/move very little).
In order of increasing exposure of wave action are: High tide mark, Rock pool and low tide. Some animals have adapted to withstand the pounding action of waves. For example, barnacles cement themselves on the work, limpits and chiton’s suction on the work and some animals have a streamline shape.
For the abiotic data, the rock pool water is more alkaline because it is an closed environment where animals respire producing carbon dioxide which causes a reaction with carbonate shells. The salinity of the water changes when it rains and due to weather conditions. Fresh water dilutes the water in the rock pool, which decreases the salinity. In hot weather, due to evaporation the salinity is higher. Wind also encourages evaporation. Organisms deal with excess salt in the rock pools by shutting their shells, some are able to control the active transport of minerals and water within themselves.
Organisms use various methods to cope with temperature variations on the rock platform. Some organisms move under the rock platform (into crevices) for shade. Other organisms use evaporative cooling by clustering their shells together. Light colour shells can reduce heat and hard shells retain water loss.
Rock Platform Plant (Producer)
Common Brown Kelp (Ecklonia radiata)
The Common Brown Kelp grows on the edge of rock platforms below the low tide line. It’s phylum is the Phyaephyta. It needs to be surrounded by water and soil to survive. It absorbs water through diffusion by broadening it’s fronds for more surface area. It uses holdfast to anchor itself at the rocks by chemically binding itself. For reproduction, the flagella helps the gannets swim.
Two adaptations that allow the Common Brown Kelp to survive it is stron\g and flexible and has spikes. It is strong and flexible to move with the wave so that the pounding wave doesn’t tear it apart. The spikes on the kelp protects the fronds from being worn down on the rocks. Other adaptations include that it has air pockets and it is slimy. The air pockets allow the plant to be buoyant and to reach the surface for photosynthesis. It is slimy so that organisms cannot attack itself to the plant, weighing it down in the process.
Rock Platform Animal
Surf Barnacle (Catomerus Polymerus)
The Surf Barnacle lives in the Surf Barnacle zone , in the mid to low-tide levels. It is a distinctively flattened barnacle with eight main shell plates, surrounded by many smaller plates, becoming smaller towards the lower edge. It is a grey-white with a greenish tinge. It’s phylum is the Arthropoda.The Barnacle deals with waves by cementing itself on the rocks. It is a filter-feeder, so it only needs to open its shell to absorb water and to feed. It has a light colored, hard shell to protect from the suns heat.
Food Web (interactions)
The food web represents consumers which feed on multiple species and in turn, are fed upon by multiple other species. It displays the movement of energy through the specific habitat. Energy and nutrients move from plants o herbivores consuming them to the carnivores or omnivores. There are many food chains within a food web.
The predator and prey interact to form a delicate balance ensuring the survival of both groups. The predators, by their hunting, keep the number of prey species at a low level which ensured that the prey do not overpopulate and consume all their food supply. The number of predators are limited by the prey numbers.
Example of a Food Web

Food Chain
This is the most basic food system. It represents the predator-prey relationship between species within an ecosystem. In nearly all food chains, sunlight has the biggest impact, and initiates the chain. It is utilized by the autotrophs using photosynthesis. The producers in the rock platform include the filamentous green algae, neptune necklace and sea lettuce. They are eaten by herbivores (Sea urchin, mollusk), followed by omnivores. It is a one way flow of energy as there is little energy at the end and is not recycled, it is lost into the atmosphere and goes into space.
E.g.
Sunlight -> Phytoplankton (producer) -> Seasquirt (herbivore) -> Octopus (omnivore)
Human Impacts
Long Reef Rock Platform is a protected site, which means the human impacts are limited. The main problem for this area is fishing and removing things/taking things. Fishing impacts the balance in the food web. This also relates to removing and taking things away from their original position. The site specifies that whatever is removed must be put back in its original position. Fines apply.
Conclusion
Using quadrats and transect lines, the biotic factors of the rock platform was recorded. The quadrats showed the abundance of animals and the transect lines showed where the organisms were distributed. Results showed that most of the organisms tend to thrive in mid to low tide areas. The organisms which lived in the high tide areas had to adaptions to survive, giving them the advantage of less competition for food.
The abiotic features (temperature, pH and salinity) showed the conditions in which the organisms lives in. The ocean showed a more stable, lower temperature with a lower pH and salinity level than the rock pool. This is because the ocean is a larger mass, and therefore becomes a more suitable environment to many organisms. Organisms need to adapt to suit certain abiotic features, e.g. light shell to keep cooler.
All the organisms in the ecosystem are interrelated and rely on each other to survive. Biotic and abiotic factors influence the abundance and distribution of organisms. Organisms need to adapt to their environments to increase their chance of survival.








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