Differences in Swim Bladder Histology of <i>Anguilla bicolor bicolor</i> at Various Stages of Sexual Maturity

The current study observed the histological differences of the swim bladder of the tropical eel, Anguilla bicolor bicolor, as an adaptation resulting from hydrostatic change. A total of 15 eels were collected from Pasir Puncu, Keburuhan, Purworejo and Segara Anakan, Cilacap, Indonesia in June 2017, September 2020, and April 2021. The eels were grouped into 4 stages based on the silvering stage and sex, namely: yellow undifferentiated, yellow female, silver male, and silver female. The average length and body weight of yellow undifferentiated eels were 255.07 ± 45.91 mm and 13.66 ± 8.5 g, respectively; for yellow female, the values were 374.35 ± 41.51 mm and 56.5 ± 12.02 g; for silver male, the values were 432.43 ± 15.15 mm and 140.29 ± 13.85 g; and for silver female were 702 ± 0.00 mm and 545 ± 11.31 g. The present study successfully recorded the histological structure of the swim bladder of A. bicolor bicolor in silver male and silver female stages. Silver males and females displayed a greater significant development of the swim bladder than yellow stages in the gas gland, mucosa, and submucosa layers. These results suggest that an increase in the gas gland thickness allows a greater contribution from gas to gas secretion, the mucosa exerts a mechanical effect on the newly formed gas bubbles, and the submucosa thickness reduces gas conductivity from the swim bladder wall

Macroalgae diversity at Porok Beach, Gunungkidul, Yogyakarta, Indonesia

Indonesia is one of the world's richest nations in terms of its biodiversity. One of the biological resources that has an important role in marine life is macroalgae. As a primary producer, macroalgae play an important role in the coastal environment. Porok Beach is a beach in the Gunungkidul district of Yogyakarta, Java Island, Indonesia. Porok beach is dominated by a rocky substrate, which would be the ideal substrate for macroalgae. The development of coastal areas as a tourism destination is feared to have an impact on macroalgae biodiversity. Comprehensive efforts are required to protect the coastlines of Porok Beach as sources of macroalgae germplasm that will ensure the survival of coastal biodiversity in Gunungkidul. So, it is necessary to study macroalgae diversity in Porok Beach to obtain a preliminary data to conserve. the macroalgae in the area.&nbsp; This study aims to monitor the presence of the macroalgae on Porok Beach. Purposive random sampling was used in the study, which took place on October 17th, 2020. Water temperature and pH are the ecological parameters that are measured. Seaweed specimens were collected only from those that were attached to the substrate (no floating specimens were collected) during low tide and then placed in ziplock plastic bags. Macroalgae species were identified to determine macroalgae species based on taxonomic keys using FAO species identification Guide for Fishery From the results of the study, Porok Beach was home to 17 species of macroalgae, eight of which were classified as Chlorophyta, 3 species are classified as Phaeophyta, and 6 species are classified as Rhodophyta