The biological attribute I plan to study nutrient levels in three lakes at FortWhyte Alive, Manitoba. I am observing three lakes, two of which are not aerated, one of which are. The nutrients I am looking at will be nitrogen and phosphorus as these are known limiting macronutrients on plant growth. To measure plant growth in the lakes I will be calculation chlorophyll content and dissolved oxygen content (DOC). Chlorophyll measures plant life as well as algae and bacteria. DOC measures the amount of dissolved oxygen available in the water column. My data was gathered on September 20th, 2023. Data gathered includes: temperature, depth, Secchi disk depth (for measuring photic zone), DOC, phosphorus and nitrogen concentrations (μg/L), and chlorophyll concentration (μg/L).
- Lake Three: 5m in depth, non-aerated
- Lake Devonian: 5m in depth, aerated
- Lake Muir: 7m in depth, non-aerated
Hypothesis: The levels of nutrients will vary with each lake thus affecting plant growth. I predict one lake will have the highest concentrations of both nutrients as well as chlorophyll. Therefore, this lake will be the best for plant growth amongst the three compared lakes.
Response variable: The nutrient concentration in Lake Devonian will be higher.
Explanatory variable: Aeration causes nutrients to float around the water column, rather than sink instantly, thus the plants are able to use more of those nutrients.
I believe this would be a continuous variable.
Hi,
I really like your study subject. Your hypothesis is great however, based on similar feedback I received for my hypothesis. It is best to phrase your hypothesis clearly and in terms that are easily falsifiable:
H1: The levels of nutrient availability will influence the growth of plants in lakes
H0: The levels of nutrient availability will not influence the growth of plants in lakes
Prediction: The lake with the highest concentration of nutrients will have the highest density of plants.
Also, it should be specific to either all plant species or a particular plant species that is your subject of interest. E.g would cattails stems be longer or would there be more of one species or all species of plant etc.
Your predictor and response variables are the independent and dependent variables, respectively.
So, your predictor in this case would be the 3 lakes with their nutrient levels
response would be the sample unit observations e.g the number of plants in a lake or average height of plants in the different lakes or predictor conditions.
Some potential confounding factors to be considered are access to light and the pollution
Overall it sounds like this will work for your study. Your hypothesis is more along the lines of Lake nutrient levels influence aquatic plant growth. Then your prediction will be specific to your lakes. One thing I am not sure of is do you see a different in plant growth between your lakes and you have an observed gradient which led to your testing?
Your response and predictor variables should be worded as what you are measuring and not have predictions mixed in. Also, wouldn’t your response variable be plant growth / chlorophyl levels? And your predictor variable is nutrient concentrations?