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Algae Sampling (76KB)

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For the LIRB, qualitative multihabitat sampling (QMH) and quantitative targeted-habitat sampling of two habitat types were conducted. The two habitats sampled were a richest-targeted habitat (RTH), which supports the taxonomically richest assemblage of organisms within a sampling reach, and a depositional-targeted habitat (DTH), where organisms are likely to be exposed to sediment-borne contaminants for a long period of time.

Qualitative Multihabitat Periphyton Sampling
The objective of QMH periphyton sampling is to obtain as complete a list as possible of periphyton taxa present in the sampling reach in the sampling time available. Qualitative algal samples should represent all possible texture and pigmentation combinations of the three major periphyton growth-forms present on submerged surfaces in the sampling reach. These three growth-forms are macroalgae, which is visible to the eye, microalgae, which is microscopic, and aquatic mosses, which is nonalgal periphyton.

Samples of macroalgae are collected with forceps or by hand and placed into a sample container. Samples of aquatic mosses are also similarily collected.

Microalgae collection is different from macroalgae and aquatic mosses sampling in that samples are obtained by scraping, brushing, or suctioning material from each microhabitat in the reach and placing them in separate containers. A composite sample of microalgae is then created by using the equally weighted composite (EWC) method. With this method, equivalent volumes of biomass from each microhabitat subsample are composited into a single sample container.

Quantitative Targeted-Habitat Periphyton Sampling
The objective of quantitative habitat-based sampling of periphyton is to obtain representative algal samples from the predominant periphyton microhabitat in each of the two instream habitats, RTH and DTH. Sampling begins at the dowstream end of the sampling reach and progresses upstream. Quantitative periphyton samples aim to represent conditions in the stream margins where algae are actively growing, rather than conditions in the stream where streambed scouring and lack of light penetration limit algal growth.

Periphyton microhabitats in the RTH can generally be classified as epilithic, epidendric, or epiphytic. For the LIRB, only epidendric microhabitats were sampled as RTH. Sampling this type of habitat is challenging since it requires collecting samples from the surfaces of submerged tree limbs, trunks, and roots, which are usually irregular and are difficult to remove from the water without significant loss of algal biomass.

Samples taken in the DTH are important because of the large amount of algal species diversity, biomass, and primary production. DTH's are typically dominated by epipelic or episammic periphyton microhabitats. Samples are collected from the upper 5- to 7-mm layer of course (episammic microhabitats) or fine (epipelic microhabitats) streambed sediments in depositional areas of a sampling reach. The top half of a petri dish is pushed into the streambed sediment, and a small spatula is slipped under, sealing the sample inside the petri dish. Then the sample is lifted and rinsed into a sample container. The DTH periphyton sample is prepared by compositing five replicate petri-dish samples, representing a total sampling area of approximately 85 cm².

Quantitative Phytoplankton Sampling
Phytoplankton are algae that are buoyantly suspended in the water column of streams, rivers, reservoirs, and lakes. They reflect water-quality conditions of the water mass in which they occur and are useful in assessing taste and odor problems in domestic water supplies. Phytoplankton species have been used as indicators of eutrophication.

Quantitative phytoplankton samples are obtained by collecting a representative whole-water sample of sufficient volume to ensure adequate phytoplankton biomass for analysis. A sample volume of 1 L is sufficient for samples collect from productive, nutrient-enriched rivers while a larger sample is needed from low-nutrient rivers.