BIOINDICATION IN AQUATIC ECOSYSTEMS

Periphyton

Periphyton as indicators Periphyton are used as indicators of environmental condition because they respond rapidly and are sensitive to a number of anthropogenic disturbances, including: habitat degradation nutrient enrichment metals herbicides hydrocarbons acidification

Periphyton Biomass Measurements Ash-Free Dry Weight Pigment Analysis Biovolume Measurement

Periphyton – Sampling methods One way to scrape a known area is to lay a plastic 35 mm slide (film removed) over the rock and scrape off the material within the slide area scrub area = 2.3cmX3.5cm=8cm2

Rocks don’t always look like they have much on them Nearly all the stuff scrubbed off this one was organic matter –most of it living algae S.Loeb and J.Reuter images Periphyton – Sampling methods

Material from a rock scrub contains macro and micro invertebrates, detritus, fungi, bacteria, as well as algae Periphyton – in situ sampling

Periphyton – III. Preservation methods Lugols’s iodine can used if the algae of interest are soft bodied forms (i.e. blue-greens and green algae). If interested only in diatoms, it may be best to preserve in 70% ethanol. Freeze sediment samples if they are to be analyzed for surficial chlorophyll.

Here’s a portion of the previous sample after being deposited on a glass fiber filter in preparation for chlorophyll extraction or AFDW determination. Periphyton – sample prep

Periphyton – pigment analysis Chlorophyll extraction: Tear filter into several pieces Place in a test tube Add 10 mLs of 90% acetone Extract overnight at 4 o C Chlorophyll analysis After hr extraction, centrifuge to settle filter debris Read absorbance or fluorescence of the supernatant

Periphyton – biomass estimation Wet weight Dry weight (dried at 103–105 o C) Ash free dry weight (AFDW) Loss on ignition (LOI) Combust at o C Chlorophyll (extract as per phytoplankton) Particulate organic carbon and/or nitrogen (POC or PON) Muffle furnace

Once you have a measure of chlorophyll or AFDW you’ll need to calculate per unit area. Periphyton – biomass calculations