Abundance of Phytoplankton and Physical Chemical Parameters as Indicators of Water Fertility in Lekok Coast, Pasuruan Regency, East Java Province, Indonesia

The Lekok Coast is part of Pasuruan Regency which has various community activities. The condition of the waters is influenced by natural and anthropogenic factors which receive a lot of input loads from the mainland. These input load can come from human activities such as aquaculture, industry and domestic waste that enters through rivers and then empties into the coasts. These conditions can affect the fertility of eutrophic, mesotropic or oligotropic waters. This study aims to determine the conditions of the waters based on the abundance of phytoplankton and the physical and chemical parameters of the waters to see the fertility status of the waters. The descriptive method is the method used in this study and the determination of the sampling point uses the purposive sampling method, the research was conducted in April – May 2019. Based on the results of the abundance of phytoplankton in the coastal waters of Lekok, it is classified into waters that have oligotrophic fertility levels. The results of observations and measurements of physical and chemical parameters in the coastal waters of Lekok showed that several parameters that support the growth of phytoplankton are less than optimal, such as temperature, brightness and nitrogen elements.