Analyze the rocky shore ecosystem and the changes in the bio-diversity in the rock pools along the rocky shore as we move from the high tide mark to the low tide mark.

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                                                                  Karishma Rawtani

ROCKY SHORE LAB REPORT

AIM: 

To analyze the rocky shore ecosystem and the changes in the bio-diversity in the rock pools along the rocky shore as we move from the high tide mark to the low tide mark.

HYPOTHESIS: 

If we move from the high-tide mark to the low-tide mark the bio-diversity will increase. This could be due to the several reasons:

  1. The bio-diversity will be more at the low tide mark because, this area being covered in water most of the time has a low saline concentration as compared to the high tide mark. Due to the constant wave action, salt is deposited at the high tide mark and the water close to the low tide mark is continuously replenished.
  2. Since the area around the low tide mark is covered in water most of the time, more organisms will be found here because more aquatic animals can thrive in this region.
  3. Evaporation of water in the high tide regions will cause the animals to die. This is because, these regions anyways lack water and with evaporation, these animals will dry out. On the other hand, even though evaporation occurs in the low tide regions, there is still enough water present in the rock pools of these regions due to the constant wave action. Therefore, the possibility of the animals drying out decreases.
  4. The rock pools present in the high tide mark, will have water with very high salinity. This causes the organisms in such pools to die due to plasmolysis in such a hypertonic solution. On the other hand, rock pools near the low tide mark will have water with low salinity. This is because the water in these pools is constantly replenished due to the wave action, thus making the water more suitable for the aquatic organisms to thrive in.
  5. The number, the size and the amount of water in the pools will increase as we approach the low tide mark.

FACTORS AFFECTING THE ROCKY SHORE: 

The following are the factors that affect the rocky shore and even could be responsible for the shape of the rocky shore:

PHYSICAL FEATURES:

  • Salinity
  • Wave force (frequency and the power)
  • Tides
  • Temperature

BIOLOGICAL FEATURES:

  • Competition for survival amongst the aquatic organisms in a limited area
  • Predation
  • Human impact

‘Competition and predation play strong roles in the lower, more resource rich zone. This forces some species to live in areas that are sub optimal for their growth and reproduction.’

APPARATUS:

ON SITE (AT ROCKY SHORE):

  1. Measuring tape
  2. Metre ruler
  3. Plastic sieve
  4. Surgical gloves
  5. Punctured plastic containers for the samples
  6. Glass bottles for the water samples
  7. Shovels
  8. Dry and wet bulb thermometer
  9. Clipboard pencils and paper

LABORATORY APPARATUS:

  1. Intel digital microscope
  2. Light microscope
  3. pH meter
  4. Tongs
  5. Petri dishes
  6. Slides
  7. Cover slips

PROCEDURE: 

On approaching the site we were divided into six different groups between the high tide mark and the low tide mark and the following procedure was carried out:

AT THE SITE:

  1. A rock pool was identified between the high tide and the low tide mark.
  2. A rough sketch of the pool was drawn.
  3. The approximate dimensions of the rock pool were noted.
  4. The pool was divided into four regions.
  5. The dimension of each region was measured using the metre scale.
  6. The depth of each region was also found using the metre scale.
  7. The number of each species of plants and animals present in every region was counted.
  8. A sample of each species was collected in the empty punctured containers along with the pool water, ensuring that they received enough oxygen supply.
  9. A sample of water was also collected in an empty bottle for further research.
  10. The approximate distance from the high tide mark was estimated.

IN THE LABORATORY:

  1. The sample of organisms was taken and examined under a light microscope.
  2. The pictures and slides of various organisms were also taken in order to have a better study of the adaptations of the species in order to survive.
  3. Sketches of the collected species were drawn and the adaptations for organisms surviving on the shore were found.
  4. The total number of species in the rock pool was estimated.
  5. Using the Simpson’s Diversity Index (SDI), the bio- diversity in different pools was found and a comparative study was done.
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DATA COLLECTION AND DATA PROCESSING;

OBSERVATIONS:

  • It was noticed that the size of the pools and the amount of water in every pool increased as we approached the low tide mark.
  • The water was not very clear. It was cloudy and had certain suspended particles in it.

Distance of the rock pool from the High Tide Mark = 130m {Estimate}

PROFILE OF THE ROCK POOL

TABLE SHOWING THE ANIMAL AND PLANT LIFE IN EACH REGION

Formula for finding the SDI ...

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