Fish Restoration Program Tidal Wetland Monitoring

Water quality point measurements are taken concurrently with invertebrate and fish sampling using a YSI ProPlus, YSI 6600, Micro TPW Turbidity Meter, and/or YSI EXO2. The YSI ProPlus records water temperature, specific conductance, dissolved oxygen, and pH. The YSI 6600 records the previous measurements in addition to chlorophyll. The Micro TPW Turbidity Meter records turbidity. The YSI EXO2 records all of the previous water parameters in addition to fluorescent dissolved organic matter and phycocyanin.

Water for nutrient samples are collected at the water’s surface and analyzed for chloride, chlorophyll a, pheophytin a, nitrate, nitrite, total inorganic nitrogen, organic carbon, organic nitrogen, ortho-phosphate, phosphorus, total/dissolved solids, and total/volatile suspended solids by DWR’s Bryte Laboratory.

Water quality measurements were recorded at 15-minute intervals over several months at select restoration sites with YSI EXO2 sondes: Sensors include: temperature, specific conductance, dissolved oxygen, turbidity, chlorophyll, phycocyanin, and fluorescent dissolved organic matter.

EXO2 being deployed at the Decker Island breach. CDFW image.

Phytoplankton samples are collected alongside nutrient samples. Each sample is stored in an amber glass bottle with Lugols solutions to act as a stain and preservative. All phytoplankton samples are sent to independent contracting laboratories for identification and enumeration.

Zooplankton are sampled using a 30-inch long microzooplankton net (150 µm mesh). The zooplankton tow is conducted at the water’s surface for 5 minutes. All samples are preserved in 70% ETOH with Rose Bengal dye and processed at the CDFW laboratories in Stockton, California.

Zooplankton net. CDFW image.

Macrozooplankton in the surface water are sampled using a 79-inch long net (500 µm mesh). Macroinvertebrates in vegetation are sampled using a sweep net (500 µm mesh). All collected samples are preserved in 70% ETOH with Rose Bengal dye and processed at the CDFW laboratories in Stockton, California.

Macrozooplankton net. CDFW image.

Emerging insects, Collembola, and other invertebrates found at the surface of the water are sampled with 39-inch long neuston net (500 µm mesh). The neuston net is towed where half of the net is sampling the water’s surface and the other half is under water for 5 minutes. The collected sample is preserved in 70% ETOH with Rose Bengal dye and processed at the CDFW laboratories in Stockton, California.

Neuston net sampling in the water. CDFW image.

A ponar grab or sediment core (aka clam gun) is taken periodically at the tidal wetland sites. The contents of each grab sample are placed on a 500 µm mesh steel sieve and rinsed to remove as much of the substrate as possible. The remaining contents are poured into a jar and preserved in 70% ETOH with Rose Bengal dye.

Ponar grab. CDFW image.

Fish are sampled with a beach seine, otter trawl, or lampara net. The beach seine is 50 ft long and 4 feet high and used to sample fish along the water’s edge. The otter trawl net is 22 ft long and samples the bottom of a channel for demersal fish. The lampara net is 120 ft wide and used in instances where neither a beach seine nor an otter trawl can sample the top 13 feet of surface water in channels or in aquatic vegetation. All captured fish are put into a bin of water and counted by species. The first 30 fish of each species are measured for fork length and then released back into the water.

Fish sampling types. Top left: beach seine. Top right: lampara. Bottom: otter trawl. CDFW images.

Submersed aquatic vegetation (SAV) transects are taken at select tidal wetland locations. Randomly generated points are sampled by lowering a thatch rake into the water, spinning the rake three times, and then bringing it onboard. A visual assessment is made of the SAV species caught on the rake. The contents are then placed in a salad spinner to shake water off the sample and weighed.

SAV sampling with a thatch rake. CDFW image.