Cockles were collected from Blueskin Bay. Three transects were set up, perpendicular to a high tide line, three metres apart. Numbers were then randomly selected to figure out how far down the transect measurements would be taken (up to 73m). The random numbers also doubled as a mechanism to determine which side of the transect the quadrat would go on (odd numbers on the left and even numbers on the right). A 50cm by 50cm quadrat was placed where indicated by the random numbers. All of the cockles within the top 2cm of sand within quadrat were counted and measured to the nearest mm. 20 cockles were randomly collected and taken back to the lab. A further 13cm was dug (15 cm from the surface), all cockles were counted and measured and an additional
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The cockles were kept in a container with a 350ml of sea water at a temperature of 18 C to begin with. There was also an extra container with no cockles in as a control. The cockles were left untouched in the container for 20 minutes to allow them to acclimatise to the temperature. After the 20 minutes 50mL of phytoplankton (previously prepared in falcon tubes) was deposited into each container. The Phytoplankton was mixed well into the sea water. Then 4mL of seawater was removed from each container and placed into cuvettes. Then the absorbance of the liquid in each of the cuvettes was measured using a spectrophotometer After measurements were taken the cuvettes were poured back into their original containers. Every two minutes the number of cockles feeding (this was determined by whether the cockles had their siphons visible) in each container was recorded. This continued for 20 minutes. After the 20 minutes the absorbance was once again measured and compared to the initial abundance. The cockles were then removed from the water and dried, then individually weighed. A bar graph was produced from this data and an ANOVA was …show more content…
An ANOVA was then run on this graph to determine whether size is influenced by tidal zone. A scatter plot was also created, with cockle size plotted against distance. A similar graph was then created but with age plotted against tidal zone instead of size. These two graphs included an R^2 value to help determine if there was significant statistical trend in the scatterplots.
Results:
Cockles were more abundant in low tide with abundance increasing towards high tide. Feeding rates were lowest at low tide with an increase in mid and high tidal zones. There was a positive correlation between size and length of cockles. Large cockles have a higher frequency at low tide and size decreases down the intertidal gradient to the high tide line. Similarly, the age within the intertidal gradient increases from the low to high tidal zone. All these findings are outlined by the graphs and tables
The cockles were kept in a container with a 350ml of sea water at a temperature of 18 C to begin with. There was also an extra container with no cockles in as a control. The cockles were left untouched in the container for 20 minutes to allow them to acclimatise to the temperature. After the 20 minutes 50mL of phytoplankton (previously prepared in falcon tubes) was deposited into each container. The Phytoplankton was mixed well into the sea water. Then 4mL of seawater was removed from each container and placed into cuvettes. Then the absorbance of the liquid in each of the cuvettes was measured using a spectrophotometer After measurements were taken the cuvettes were poured back into their original containers. Every two minutes the number of cockles feeding (this was determined by whether the cockles had their siphons visible) in each container was recorded. This continued for 20 minutes. After the 20 minutes the absorbance was once again measured and compared to the initial abundance. The cockles were then removed from the water and dried, then individually weighed. A bar graph was produced from this data and an ANOVA was …show more content…
An ANOVA was then run on this graph to determine whether size is influenced by tidal zone. A scatter plot was also created, with cockle size plotted against distance. A similar graph was then created but with age plotted against tidal zone instead of size. These two graphs included an R^2 value to help determine if there was significant statistical trend in the scatterplots.
Results:
Cockles were more abundant in low tide with abundance increasing towards high tide. Feeding rates were lowest at low tide with an increase in mid and high tidal zones. There was a positive correlation between size and length of cockles. Large cockles have a higher frequency at low tide and size decreases down the intertidal gradient to the high tide line. Similarly, the age within the intertidal gradient increases from the low to high tidal zone. All these findings are outlined by the graphs and tables