AIM: To determine how moisture content of sand influences the distribution of fauna along a sandy beach. MATERIALS: 100m transect,1m x 1m quadrat,shovel,30cm ruler,40cm x40cm sieve, digital probe, sweep net PROCEDURE:
1.The area was selected for the 100m transect to be laid.
2.The transect was carefully placed ensuring that the end of the transect was in the moist part of sand. 3.The quadrat was placed along the transect on either sides. 4.The area which the quadrat covered was marked off using a stone. 5.The quadrat was then removed.
6.A probe which measured moisture content was then inserted within the quadrat at 3 different places. 7. The 3 readings obtained were recorded and the averages were calculated. 8.The area within the quadrat was then dug to a depth of 10cm 9.The sand which was dug out was then sifted using a sieve. 10.The number of chip-chip found during the sifting process were counted and recorded in the results table below along with the averages found in part (7).
The more into the surf zone, the higher the moisture content. The lowest moisture content recorded was in the dry backshore sand. There was also a higher distribution of chip-chip, sea cockroach and sand dollars in the moist parts of the sand while there were the least fauna in the moisture deficient sand. Areas of little moisture lacked species diversity as compared to the areas that were moist. There was a water-logged piece of land which we had to walk through before arriving the sandy beach coast.
Moisture content on dry basis is the amount of water per unit mass of dry solids in the sample. Conversely, the wet-basis moisture content expresses the ratio of moisture mass to the total mass of the substance. A clear zonation of species diversity was noticed alone the sandy beach coast. Ants we only seen in the dry sand since that is the only type of sand they can survive in .Sea cockroaches were only found in the wet sand since these species need loose sand. However, chip-chips needs wet sand because it helps them to move and feed. They also need water in order to aid survival else their bodies would become desiccated because their bodies are made up of mostly water. A lot more chip-chips were found in the submerged sand as compared to the dry sand.
From the table above, site 3 had a moisture content of 2.8 units and site 4 had a moisture content of 4 units. The high moisture content of site 4 is one of the reason as to why 150 chip-chips were found at that site(refer to table 1.) The backshore is rarely moistened and therefore cannot sustain the living requirements or they would exceed the fauna’s tolerance ranges hence the unequal fauna distribution. The ants cannot live in very moist sand as they would drown due to the moisture contents. Their nests would also be washed away due to the wave action that occurs on the coastline which moistens the sand. Chip-chip and sea-cockroaches would be highly distributed in moistened areas and ants would be in areas with low moisture content CONCLUSION:
The moisture content of the soil attracts different species of fauna due to various reasons like tolerance ranges for example. Moist sand has a higher fauna distribution as contrasted with dry sand which has low moisture content. The higher the moisture content the larger the number of fauna such as chip-chip would be found because they are filter feeds and rely on moisture and water to filter their food.