The frequency of algal bloom's event has been increased in Jakarta Bay, recently. Most of the bloom events were tend to be reoccurred after the rainy season. The research was conducted from 2008 until 2015 to study the linkage of nutrients and the ratios on the growth of the phytoplankton population. Collecting samples were conducted using a canonical plankton net of 20 µm mesh size, 125 cm length and 30 cm diameter of the opening mouth. The results of the study showed that the concentration of phosphate in the waters ranged from 0.01-12.5 µg/l (average 4.58 µg/l) and nitrate ranged from 0.01-15.89 µg/l (average 0.72 µg/l). The N/P ratio during the study ranging from 0.2 up to 45.4. High ratios of nutrients were mostly recorded in 2010 where the overall abundance of phytoplankton is very high. There is a strong correlation of N/P ratio with the community structure or composition of the phytoplankton population. The variability of phytoplankton abundance appears to be related to nutrient ratios of nitrate and phosphate.
Seagrass has the ability to store carbon through photosynthesis. The ability is influenced by environmental factors. This study was aimed to examine the diversity of seagrass and investigate the carbon storage in seagrass’ biomass in two stations at Teluk Bakau Village, Bintan Island. This research was conducted at two stations including Beralas Pasir Island (small island) and Teluk Bakau Village Beach (mainland). Measure of seagrass biomass with dried seagrass sample was carried out at 60°C temperature. The analysis of carbon content was carried out on the biomass of the four dominant seagrass species found in the Teluk Bakau Village namely Cymodocea rotundata, Enhalus acoroides, Syringodium isoetifolium, Thalassia hemprichii. The results show that the carbon storage on seagrass has a correlation with seagrass biomass. Enhalus acoroides has the highest carbon content compared to the other three seagrass species. In general, seagrass located in Teluk Bakau Village Beach have higher biomass than seagrass located in Beralas Pasir Island, and it means that they have high carbon storage. This is expected to occur considering that the area of Teluk Bakau Village Beach is close to the mainland, where there is a high nutrient input support for the growth of seagrass biomass.
Abstract. Madduppa H, Putri ASP, Wicaksono RZ, Subhan B, Akbar N, Ismail F, Arafat D, Prabuning D, Sani LMI, Srimariana ES, Baksir A, Bengen DG. 2020. Morphometric and DNA Barcoding of endemic Halmaheran walking shark (Hemiscyllium halmahera, Allen, 2013) in North Maluku, Indonesia. Biodiversitas 21: 3331-3343. The walking shark (Hemiscyllium halmahera) commonly referred to as bamboo shark, is a shark species that belongs to the Hemiscyllidae family which is endemic in North Maluku, and Indonesian waters. These Hemiscyllium species are generally confined to the Australian-New Guinea region, save a specie which originates from Halmahera, an Indonesian island. Ever since its discovery, sufficient information on its existence has been largely unavailable. Hence, the purpose of this study is (1) to assess the morphology, using meristic measurements and length-weight relationship, and (2) to determine the molecular characteristics through DNA barcoding, phylogenetic reconstruction, and genetic diversity. The samples used in this research were obtained from Halmahera Archipelago, North Maluku, including Halmahera, Tidore, Ternate, Maitara, and Guraici in several expeditions between March 2017 and January 2018. 36 individuals in total were measured for morphometric parameters including Total Length (TL), Standard Length (SL), Head Length (HL), Body Circumference (BC), and Body Weight (BW). Out of a total of 36 sharks, tissue samples were obtained from 32 individuals for molecular identification. After the required measurements were obtained, all individuals sharks were released back to their habitat safely. Equations of linear regression were used to analyze the relationship between length and weight. Morphometric measurements indicated that the average total length of the walking shark samples obtained, were not more than 75± cm for both male and female specimens. The length-weight analysis revealed a positive allometric growth pattern in H. halmahera species, where weight was gained faster than an increase in length. The results of the DNA fragment length analysis from all samples were 793-bp. All 32 tissue samples identified as H. halmahera consisted of 3 samples from Ternate Island, 14 samples from Maitara Island, 9 samples from Guraici Island (South Halmahera), 10 samples from Central Halmahera, and 2 samples from Tidore Island. These results confirmed that DNA subsequence analysis indicates that H. halmahera is different from those sequences extracted from Genbank in the Australia-New Guinea region. This study successfully identified H. halmahera based on their morphological and molecular characters, and has therefore contributed to international genetic database (Barcoding Of Life Database-BOLD) for further studies.
Cengkok coastal waters of Banten Bay are one of the waters that have many anthropogenic, industrial, and aquaculture activities. Zooplankton would like to become a bioindicator for the water’s condition. This study aimed to analyze the biodiversity and structure of the zooplankton community in waters. The study was carried out, from May to September 2019 at five stations. Data analysis calculating the value of composition, abundance, similarity index, biological index, and PCA. Based on the study obtained, the zooplankton consisted of 17 classes and 47 genera. Based on location and time, respectively, the average composition of Malacostraca (47.2% and 49.8%) and Ciliata (40.6% and 37%). Based on location and time observation, the average diversity index (H’) was (0.8-1.6) and (1.2-1.6); evenness index was (0.7-0.8) and (0.6-0.9); and index dominance was (0.3-0.6) and (0.3-0.4) respectively. The PCA results divided into 3 groups and the results of the similarity index showed the zooplankton abundance had the highest similarity value at Stations 3 and 5 (0.829) and based on water parameters showed that the highest similarity is 0.98. Based on the community structure index, it is found that the condition of the zooplankton structure community in Cengkok coastal waters (Banten Bay) was medium stressed.
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