The majority of algal species require microscopic examination to confirm their identity and as such it is often necessary to take a small sample of the alga to preserve temporarily for identification or for longer term preservation if voucher specimens need to be retained. All samples should be appropriately labelled with the sampling date, geographical position (GPS and/or maps), collector, elevation (m), depth (m), habitat, substratum type, ecological data etc. Seaweed collections should include a description of shore, position on shore of collection, height above or below chart datum (CD), degree of water exposure, associated plants/animals, etc. Photographic records of key sites are always useful. Remember to thoroughly clean all sampling equipment after use to avoid contamination of the next sample and to minimize the risk of transporting noxious algae or other pest organisms between sampling sites.  
 
Follow these links for detailed advice on how to sample and preserve freshwater algae and marine macroalgae.