Question

exploring ecosystems: brine shrimp and environmental changes
step 1: your group’s choice of environmental change:
step 2: hypothesis (use the iv affects dv formula) and include a reason for your choice.
step 3: identify your variables
independent variable:
dependent variable:
controlled variables (constants):
step 4: set up experiment
picture with labels of experimental setup
description of experimental procedure (steps)

Explanation:

This is a brine shrimp ecosystem experiment worksheet. We select water salinity as the environmental change, as brine shrimp live in saline environments and salinity directly impacts their survival. We frame a hypothesis following the required format, identify variables clearly, and outline a controlled experimental setup.

Answer:

Step 1: Your Group's Choice of Environmental Change:

Water salinity level (varying concentrations of salt in the water)

Step 2: Hypothesis (Use the IV affects DV formula) and include a reason for your choice.

Hypothesis: Increasing water salinity (independent variable) will increase the survival rate of brine shrimp (dependent variable).
Reason: Brine shrimp are adapted to live in highly saline environments like salt lakes, so higher salinity levels match their natural habitat needs better than lower, freshwater-like conditions.

Step 3: Identify your Variables

Independent Variable: Concentration of salt in the water (measured in g/L)
Dependent Variable: Survival rate of brine shrimp (percentage of shrimp alive after 72 hours)
Controlled Variables (constants): Initial number of brine shrimp per container, water volume, temperature, light exposure, feeding frequency/amount

Step 4: Set up experiment

Picture with labels of experimental setup:

(Description of labeled diagram: 4 clear plastic containers labeled "0 g/L (Control)", "10 g/L", "20 g/L", "30 g/L". Each container holds 500 mL of water with the labeled salt concentration. 10 brine shrimp are added to each. A thermometer is placed in each container to monitor temperature, and all are placed under the same grow light.)

Description of experimental procedure (steps):

1. Prepare 4 containers with 500 mL dechlorinated water each.
2. Add 0g, 10g, 20g, 30g of sea salt to each container respectively; stir to dissolve.
3. Add 10 healthy brine shrimp to each container.
4. Place all containers under the same 12-hour light/dark cycle at 25°C.
5. Feed each container 0.1g of brine shrimp food daily.
6. Count and record the number of alive brine shrimp in each container every 24 hours for 72 hours.
7. Calculate the survival rate for each salinity group after 72 hours.