WE PROPOSE A TYPE 1 PROJECT TO THE CITIZEN SCIENCE FOR EARTH SYSTEMS PROGRAM TO EXAMINE THE IMPACTS OF INCREASING GLACIER MELTWATER ON LOCAL ECOSYSTEMS AT THE ICE-OCEAN INTERFACE OF THE WESTERN ANTARCTIC PENINSULA (WAP). THE PROPOSED CITIZEN SCIENCE MODULE ENTITLED FJORDPHYTO BUILDS UPON AN EXISTING COLLABORATION WITH THE INTERNATIONAL ASSOCIATION OF ANTARCTIC TOUR OPERATORS (IAATO). CITIZEN SCIENTISTS WILL PARTICIPATE IN A VALIDATION SAFARI IN WHICH SATELLITE DATA WILL INFORM SAMPLING OF PHYSICAL AND BIOLOGICAL OCEANOGRAPHIC MEASUREMENTS TO VALIDATE AND REFINE A NEW OCEAN COLOR ALGORITHM TO DETECT THE GLACIAL MELTWATER CONTENT OF SEAWATER FROM SPACE. THE IN-SITU MEASUREMENTS FROM CITIZEN SCIENTISTS WILL BE COMBINED WITH REMOTE SENSING DATA PRODUCTS TO ADDRESS SCIENTIFIC QUESTIONS RELATED TO THE IMPACTS OF GLACIAL MELTWATER ON PHYTOPLANKTON COMMUNITY ABUNDANCE AND TAXONOMIC COMPOSITION DURING THE AUSTRAL GROWING SEASON. THIS PROJECT WILL SUPPORT A PH.D. STUDENT TO DEVELOP THE REMOTE SENSING CITIZEN SCIENCE MODULE INCORPORATE NEW FIELD SAMPLING TECHNIQUES INTO THE PROGRAM AND CONDUCT ANALYSES OF PHYTOPLANKTON DIVERSITY THROUGH A GENOMICS APPROACH. THE AIR AND OCEAN WARMING IN ANTARCTICA IS MOST NOTICEABLE IN THE WAP WHERE GLACIERS SHOW POSITIVE AND STATISTICALLY SIGNIFICANT TRENDS IN DURATION OF MELTING CONDITIONS. A NET INPUT OF FRESHWATER OCCURS IN NEARSHORE WATERS DURING AUSTRAL SUMMER INFLUENCING PHYTOPLANKTON BIOMASS DIVERSITY AND PRIMARY PRODUCTION. THE SCIENTIFIC GOALS OF THIS CITIZEN SCIENCE PROJECT ARE TO DETERMINE THE SPATIAL EXTENT OF GLACIAL MELTWATER THROUGH THE SEASONS AND IDENTIFY CONCOMITANT SHIFTS IN PHYTOPLANKTON ABUNDANCE AND COMMUNITY DIVERSITY IN COASTAL ANTARCTIC WATERS AFFECTED BY GLACIAL MELTING EXPECTED TO INCREASE IN THE COMING DECADES. SAMPLING OF THIS REGION FROM OCTOBER THROUGH MARCH ALONG 3-6 DEGREES OF LATITUDE (62S TO 65S AND UP TO 68S) IS ONLY FEASIBLE WITH TOURIST SHIPS OR THROUGH REMOTE SENSING. THE ADDITION OF A REMOTE SENSING COMPONENT VALIDATED BY CITIZEN SCIENTISTS IS CRUCIAL FOR DESCRIBING LONG-TERM SYNOPTIC TRENDS AND VARIABILITY IN THE ABUNDANCE AND SPATIO-TEMPORAL EXTENT OF PHYTOPLANKTON IN THIS REGION AND FOR DISCERNING HOW THESE PATTERNS ARE LIKELY TO ALTER IN RESPONSE TO CHANGES IN CLIMATE. DURING THE PILOT PHASE WE WILL DEVELOP A NEW SAMPLING MODULE AND DOCUMENTATION FOR SATELLITE REMOTE SENSING OF THE OCEAN AND INTEGRATE IT INTO THE FJORDPHYTO CITIZEN SCIENCE PROGRAM. THE SAMPLING MODULE WILL ADD NEW MEASUREMENTS RELATED TO GLACIAL MELTWATER FRACTION OF SEAWATER PHYTOPLANKTON ABUNDANCE THROUGH CHLOROPHYLL-A FLUORESCENCE AND GENOMIC SAMPLING OF PHYTOPLANKTON COMMUNITY COMPOSITION. FIELD SAMPLING BY VOLUNTEER CITIZEN SCIENTISTS WILL OCCUR IN OCTOBER TO MARCH OF 2021-2022 AND SUPPLEMENTED WITH REMOTE SENSING DATA PRODUCTS TO EXAMINE THE SEASONAL EVOLUTION OF GLACIAL MELTWATER EXTENT AND PHYTOPLANKTON COMMUNITY RESPONSE. IF SELECTED FOR THE IMPLEMENTATION PHASE AN ADDITIONAL 3-YEARS OF CITIZEN SCIENCE SAMPLING IN CONJUNCTION WITH ANALYSIS OF LONG-TERM TIME SERIES OF SATELLITE DATA PRODUCTS WILL BE USED TO EXAMINE INTERANNUAL VARIABILITY IN THESE PATTERNS AND THE ROLE OF CLIMATE RELATED ENVIRONMENTAL INDICES. AS NO INTERNET IS AVAILABLE IN ANTARCTIC TOURIST SHIPS THE NETWORKING WITH LARGE CITIZEN SCIENCE SITES LIKE INATURALIST WILL BE SUPPORTED AS AN AFTER-CRUISE ACTIVITY AND THROUGH SOCIAL MEDIA. QUESTIONNAIRES WILL BE EMPLOYED TO OBTAIN EVALUATION OF THE PROGRAM BY CITIZEN SCIENTISTS AND HELP REFINE THE NEW VARIABLES COLLECTED DURING THE VALIDATION SAFARIS IN SUPPORT OF NASA OCEAN COLOR MISSION. THIS STUDY WILL PROVIDE A FOUNDATION TO BETTER UNDERSTAND PHYTOPLANKTON DIVERSITY UNDER CURRENT AND POTENTIAL FUTURE OCEAN CONDITIONS AND LEAD TO MORE ROBUST PREDICTIONS ON POTENTIAL IMPACTS TO UPPER TROPHIC LEVELS AND BIOGEOCHEMICAL CYCLING WITHIN THIS RAPIDLY CHANGING ECOSYSTEM.