Bearing 285 degrees

This area has a fairly constant slope for the 12.5 meters over a vertical range of 3 meters.

The photos, one half meter in length, were taken from a video at low tide, in APRIL 1998 by Garry and Sebastian.

2. Determine the percentage coverage of the different species of algae shown.

3. The physical factors of the habitat of an algae living high in the intertidal zone like Porphyra changes with the seasons. In this area, our low tides occur in the daytime in the summer and in the night time during the winter. It would be revealing to compare the exposure during the daytime in February or March with the exposure in June. First determine from the profile drawn above, the range of tidal level where this species lives intertidal. Then go to the data page where you can access the Tidal Predictions for Race Rocks . From the tidal level profile for Victoria, you will be able to see a graph of the tide levels .Determine how many hours this Porphyra will be exposed to the air by recording the cumulative lengths of time that the water level does not go above the lower limit of the algae. If you do this for different times of the year, you will be able to quantify the time spent submerged or emmerged over a number of days. Be sure to take into account the time of the tidal cycle when choosing days to measure, because you will notice a two week pattern of Spring ( maximum range ) and Neap( minimum range) tides.

Based on your evidence, suggest a hypothesis that could explain why this algae disappears from this area for most of the summer.