Apr 21, 2023
Measuring Turbidity and Fish Populations around Mo'orea
This protocol is a draft, published without a DOI.
- 1University of California, Berkeley
Protocol Citation: Ellis Gelt 2023. Measuring Turbidity and Fish Populations around Mo'orea. protocols.io https://protocols.io/view/measuring-turbidity-and-fish-populations-around-mo-cs9bwh2n
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: In development
We are still developing and optimizing this protocol
Created: April 21, 2023
Last Modified: April 21, 2023
Protocol Integer ID: 80899
Abstract
The ocean is often viewed as a fridge or pantry for many island communities, especially that of Mo’orea, French Polynesia. But, it's known that sedimentation can cause coral death, and corals are vital places for reef fish around the island, including species consumed daily such as parrot fish. With the rapidly increasing population and amount of agriculture on the island, there's a possibility that levels of sediment in the water are increasing. If turbidity affects fish populations, there could be a problem. For this reason, I will be conducting an experiment designed to answer the question: Does turbidity affect fish populations?
Guidelines
- wear protection on feet while conducting experiment
- avoid stepping on or interfering with sea life
- to accurately count fish populations and measure turbidity, the researchers must be cautious and minimize noise and movement
Materials
- 36 small buoys
- 70 or more m of rope (60 necessary, excess for tying off)
- 6 1L bottles (ideally recycled)
- underwater video camera
- field measuring tape
- nephelometer
Safety warnings
- you are entering parts of the ocean where you will need to swim and tread water
- proceed with caution in each and every marine life encounter
Before start
- Construct buoy (see steps) and gather materials
- Determine 6 locations each 10 km apart the team will be visiting and mark with GPS
GRID CONSTRUCTION
GRID CONSTRUCTION
lay out buoys in a 6x6 grid each a meter apart (5 meters squared)
cut rope into 12 pieces of equal length
tie rope to each buoy in every row of buoys vertically
repeat for each row of buoy horizontally
FIELD
FIELD
arrive to sample site 1 and identify shoreline (defined as the point where the sea water meets bare sand)
use measuring tape to measure 25 meters straight out
place 5x5 meter grid on top of ocean (centered around 25m point)
wait 5 minutes (to allow fish to return)
one researcher holds grid in place
another researcher conducts a visual count of fish and notes species observed
researcher takes video where fish and grid are visible
researcher goes about 1 meter below surface and fills 1 L bottle
repeat steps for sites 2-6
POST-FIELD
POST-FIELD
for each site, observe video to count the number of fish visible and separate into species if possible
for each site, measure turbidity of 1L bottle with a nephelometer