The diversity of intertidal fish in Sundak Beach, Yogyakarta, Indonesia, during dry and rainy seasons

The intertidal zone is a transition area between sea and land with unique characteristics. This research aimed to determine the diversity and types of fish in the intertidal zone of Sundak Beach, Yogyakarta, Indonesia. This research was conducted in December 2016-September 2017 along the intertidal zone of Sundak Beach. Fish samples were collected by fishermen twice a month using a hand net and hand line in an area of 22,000 m2 by random sampling. Water quality data included air and water temperatures, pH, salinity, tides, rainfall intensity, and substratum. Fish samples were identified, and the total length and weight were measured. Results showed that carnivores and herbivores were dominant during the rainy season, whereas carnivores and omnivores were dominant during the dry season. Total of 179 fish, which were grouped into 18 families and 31 species. The diversity species index was 1.067 (intermediate diversity) during the rainy season but 0.19 (low diversity) during the dry season. The dominancy index was low (0.11-0.34) during the dry season, whereas during the rainy season was higher (0.18-0.72). The study concluded that the intertidal zone of Sundak Beach has a good condition as nursery, feeding, and spawning grounds for fishes.