Estuaries: ElkhornSlough
Equipment:
TapesQuadrats
Pasco Temp/Salinity (2)
Pasco w/ Turbidity meter
YSI DO meter
Light weight to attach to YSI meter sensor Plastic shoe boxes and cups (4)
Buckets (4) / Secchi disc w/ rope
Flags (10)
Bottom grab w/ rope
Clipboards (10)
Plastic quadrates (1 of each size)
Sieves (large and medium gage)
Extra rope
Background:
Today we will investigate our largest local estuaries, Elkhorn Slough. An estuary is a place where seawater meets freshwater, and often some sort of embayment forms at the mouth of the river. As we will discuss, there are several different types of estuaries and different ways they can be formed. Estuaries play many important roles, including providing a large ‘nursery’ for many marine organisms, water purification, sediment catchment, and wildlife utilization.
The history of Elkhorn Slough is long and very colorful, with human use stretching back thousands of years, and the Slough has been changed considerably by human use and the natural cycle of coastal processes.
We are going to examine two different areas of Elkhorn Slough and assess the biological and physical characteristics at each location. Our first visitwill be at the estuaries mouth at the Hwy 1 bridge in Moss Landing to talk about physical properties of estuaries and sloughs. These include: types of estuaries, plant systems, animals systems, soft-bottom communities, and salt/fresh issues. We will examine land use, watershed factors, and history of the Elkhorn Slough.
Site 1: Harbor Mouth
We will start by collecting some information on the physical and biological characteristics of this location.
1. We will record the Depth, Turbidity, Temp, Salinity, and Dissolved Oxygen from edge of bridge and then compare these with the same measurements from a location far up inside the slough.
We will use several different digital sensors to collect most of the data, and a Secchi disc to examine water clarity. A Secchi disk is an 8-inch (20 cm) disk with alternating black and white quadrants (sometimes all white). It is lowered into the water until it can be no longer seen by the observer. This depth of disappearance, called the Secchi depth, is a measure of the transparency of the water. The Secchi disk measures the transparency of the water. Transparency can be affected by the color of the water, algae, and suspended sediments.
2. Next let try to assess what animal and algae life my be in the area. Start by looking at the animals and algae found on the sides of the dock. This is a good indication of what might be found on other areas on the harbor. We will also use the bottom grab to see what is on the sea floor in this location. We can see how deep it is at this location, what the bottom is made out of, and what larger animals we might find. We’ll take the grab and empty it into the sieve and see what we can find.
Site 2: Towards KirbyPark
We will visit the turn-out before Kirby park and talk about land-use and agricultural/industrial use and reclamation/restoration of the system. This has a good view of the area and will allow us to see some of the varied uses of the watershed.
Site 3: KirbyPark
Lastly, we will visit KirbyPark and look at the biological and physical environment of this up-slough area and compare it with the harbor mouth. Examine the life on the side of the dock and shoreline. What types of animal/plants do you see? What types do you not see?
- Redo the profiles of Depth, Turbidity, Temp, Salinity, and DO from end of dock.
- We’ll do a bottom grab and see what is there!
- We will also attempt to examine the densities of an invasive species, the Japanese mud snail.
attramentaria –Japanese mud snail counts.
Count the number of snails per meter2 on the muddy shore side. We will talk about sampling techniques and replicates at the site. Use measuring tapes to estimate the total number of snails on our little muddy beach.
Assignment:
Find three different introduced species (other than the mud snail) that are of concern for Elkhorn Slough. Make sure at least two of them are currently in the slough and already causing problems.
- Outline where the species is from and how they think it got into the slough.
- Outline what negative effects are found (or predicted) because of the introduction.
Data Page- Elkhorn Slough
Harbor MouthWeather:Date:
Depth (m) / Temperature / Dissolved Oxygen / Turbidity at surface (NTU) / Salinity at surface0
1
2 / Secchi Depth / Bottom Grab Depth
3
4 / Other Physical Notes:
5
6
7
Biological Notes:
Data Page- Elkhorn Slough
KirbyParkWeather:Date
Depth (m) / Temperature / Dissolved Oxygen / Turbidity at surface (NTU) / Salinity at surface0
1
2 / Secchi Depth / Bottom Grab Depth
3
4 / Other Physical Notes:
5
6
7
Biological Notes: