Unit 1 Intertidal Zone

Students participated in grade appropriate field excurisions to Onekahakaha Beach Park to study the Intertidal Zone. They have studied the life and habitat of the Hawaiian shoreline.
 K-5 students have learned to recognize tides, count wave sets, sort beach sediments. Students have made observations about weather and water. Students in 5th grade collected beach sediment, discussed its components and examined sediments with microscopes.  


Students in 6-8 have participated in a 6 week monitoring program at Onekahakaha Beach Park. They collected data including gps, tide, weather observations, cloud coverage. They used anemometers to measure wind speed, air temperature, humidity and dew point. Students collected water quality data including pH, salinity, dissolved oxygen, and temperature using refractometers, thermometers, pH meter, and YSI conductivity meter. Students distinguished difference in water perameters between marine sample sites and estuarine sample sites. Students formed hypothesis, collected data and formed conclusions about watershed processes that effect the intertidal zone.

Life in the Intertidal Zone

The intertidal zone occurs where land meets sea.

It includes the ecoystem between the farthest reaches

of high and low tide.

Tides, the periodic rising and falling in the oceans height

at a given location, is caused by the gravitational pull of the sun and moon.

Tidal changes in Hawaii are minor compared to places like

Alaska where tides may range 20 feet.

Mixed  tides  occur  along  the  Pacific  Coast, Alaska,  and  Hawaii.

This tidal pattern is characterized  by  wide variations  in heights  of  successive  high  and  low  waters.  There  are  usually  two  high and  two  low  waters  each  day,  but  occasionally  the  tide  may  become diurnal.

The intertidal habitat is contstantly changing with the tides.

Organisms in the intertidal zone must be adapted to this diverse enviorment.

They may spend part of the day submerged underwater, and other parts

exposed to air and sunlight.

Tidepools, depressions that hold water in the intertidal zone,

are home to many diverse species.

Organisms deal with exposure at low tide by moving to tidepools.

These organisms tolerate extreme changes in salinity and temperature,

due to changes in tide and precipitation.

Other organisms clam up to retain water.

Organisms in the intertidal zone are often exposed to high wave action.

Sessile organisms have adapted by living attached to the bottom.

The intertidal monitoring program will collect data on the follwoing

water perameters in order to gain a better understanding

of how watershed systems effect the intertidal zone.

Salinity

Salinity is the amount of salts in a body of water

Salt enters the ocean from runoff and undersea volcanoes.

Expressed as the amount of salt found in 1,000 grams.

Freshwater salinity is usually less than .5 ppt.

Ocean salinity varys between32 and 37 ppt. 

Brackish water salinity varys between .5 and 17 ppt.

Temperature

Temperature is the measurement of hotness or coldness of an substance.

It is measured in Fahrenheit, Celsius, and Kelvin.

Dissolved Oxygen

Oxygen enters ocean from atmosphere.

Plankton produce oxygen during photosynthesis.

DO is used by bacteria during decomposition.

Temperature and salinity affect how much dissolved oxygen water absorbs.

Units for measurement in ppm (parts per million)

Why is DO important?

Ocean flora and fauna require oxygen for respiration.

pH

pH measures how basic or acidic a substance is. 

It is a measurement of hydrogen ion concentraion.

pH scale range is from 1 to 14.

7 is neutral, pH of freshwater.

The ocean has a pH of 8.