Abbreviations: 



ALOPE Airborne Lidar Oceanographic Probing Experiment 



PMT photomultiplier tube 



A 6 before a symbol denotes the standard deviation of the parameter. 



IMPORTANCE OF ALGAE AND ALGAL MEASUREMENTS 



The types and concentration of algae in various bodies of water are impor- 

 tant indicators of primary productivity and marine environmental conditions. 

 In the ocean, algae are practically the only producer of organic matter. The 

 photochemical conversion of inorganic matter to organic matter via photosynthe- 

 sis is known as productivity. Also, algae are an important part of the lowest 

 level on the food chain and are thus important to the survival of all higher 

 forms of marine life. 



Marine environmental conditions - such as chemical, thermal, and mechani- 

 cal factors - can have major influence on algal populations in any body of 

 water. Man-created conditions often upset the natural ecological balance, and 

 this leads to growth in some algal species and death in others. The presence 

 of nondegradable heavy metals, for example, mercury and lead, or slowly degrad- 

 able chemicals such as DDT, has a dramatic effect on the survivability of dif- 

 ferent algal species. Likewise, the thermal and mechanical properties of the 

 water which are influenced by electrical power plants, industrial plants, and 

 waste disposal systems, to name only a few, also alter the makeup of algal 

 populations. However, it can be difficult to establish direct effects of a 

 pollution source on algal populations because of changes which are seasonal or 

 locally transient in nature; for example, changes in algal populations can be 

 altered by a sudden weather change . 



Several algal species are toxic to fish and man, and when their concentra- 

 tions reach bloom proportions (typically greater than 10" cells/liter), fish 

 are killed. During this condition the shellfish which are affected concentrate 

 the toxin. People who have eaten contaminated shellfish have been known to die 

 from paralytic shellfish poisoning. Gymnodinium breve , the Red Tide of Florida; 

 Gonyaulax tamarensis , the Red Tide of New England; and Gonyaulax catenella , 

 which is found along the California coast, are examples of toxic algae. 



Research is necessary to learn more about the parameters which affect the 

 marine ecosystem. Since the type, concentration, and distribution of algae are 

 affected by the chemical, thermal, and mechanical properties of the marine 

 environment, remote detection of algae can be used to infer important informa- 

 tion about marine conditions. 



SPECTRAL CHARACTERISTICS OF ALGAE 



All optical methods of algae detection employ the spectral properties of 

 the primary light-absorbing pigments, which are present in different algal 



