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All Journal ILMU KELAUTAN: Indonesian Journal of Marine Sciences
Hanif Budi Prayitno
Pusat Penelitian Oseanografi - LIPI, Jl. Pasir Putih 1 Ancol Timur, Jakarta 14430
Earth & Planetary Sciences

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Vertical and Horizontal Variability of Chlorophyll-a and Its Relationship with Environmental Parameters in the Waters of Sangihe and Talaud Islands, North Sulawesi, Indonesia Firdaus, Mochamad Ramdhan; Rachman, Arief; Fitriya, Nurul; Wijayanti, Lady Ayu Sri; Rozirwan, Rozirwan; Purwandana, Adi; Prayitno, Hanif Budi; Alfiansyah, Yustian Rovi; Sianturi, Oksto Ridho; Sugeha, Hagi Yulia
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 29, No 1 (2024): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.29.1.119-132

Abstract

The chlorophyll-a is an important biological parameter that could act as a proxy to indicate the abundance of phytoplankton and the primary productivity of an aquatic ecosystem. This paper investigates the vertical and horizontal variability of chlorophyll-a in the waters of Sangihe and Talaud Islands, Indonesia, and its correlation with water environmental parameters. In this study, the distribution of chlorophyll-a, temperature, salinity, and nutrients (NO3 and PO4) from the surface to a depth of 200 m (photic zone) was measured at 29 research stations. The results showed that the distribution of chlorophyll-a in the waters of the Sangihe-Talaud Islands was varied vertically and horizontally. The waters around the Sangihe Islands generally exhibited a higher chlorophyll-a distribution and shallower Deep Chlorophyll Maxima compared to the water around the Talaud Islands. The concentration of chlorophyll-a varied between 0.0017 and 1.2155 mg.m-3, with most of the water column in Sangihe-Talaud considered oligotrophic, although some stations or depths were mesotrophic or slightly eutrophic. The maximum chlorophyll-a concentration was found in the sub-surface layer at depths between 46 and 101 m. The low N:P ratio (<16) and N:Si ratio (<1) indicate that the water columns of Sangihe-Talaud, up to a depth of 200m, were N-limited. Based on the GAM analysis, chlorophyll-a concentration in Sangihe-Talaud waters was primarily regulated by temperature, salinity, and the N:P ratio, with weak influence from phosphate and the N:Si ratio. The analysis also suggests that primary productivity in Sangihe-Talaud is sensitive to temperature changes, indicating its vulnerability to future warming events.
Variability of Marine Carbonate Systems in Seagrass and Coral Reef Ecosystems of Pari and Lombok Islands, Indonesia Afdal, Afdal; Bengen, Dietriech G.; Wahyudi, A’an Johan; Rastina, Rastina; Purwiyanto, Anna Ida Sunaryo; Prayitno, Hanif Budi; Hamzah, Faisal; Suteja, Yulianto; Adi, Novi Susetyo; Koropitan, Alan F.
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 2 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.2.221-236

Abstract

The increase in anthropogenic CO2 emissions has induced significant physical and biogeochemical alterations in oceans worldwide, including warming, acidification, and oxygen depletion. Coastal areas are particularly vulnerable due to intensified human activities and terrestrial influences, resulting in increased coastal ocean acidification driven by atmospheric CO2 absorption and regional biological and anthropogenic processes. However, research on the collective impact of land-sea interaction and air-sea CO2 exchange on coastal ocean acidification in severely disturbed areas, such as the small islands of Lombok and Pari in Indonesia, remains limited. This study aims to investigate the daily fluctuations in marine carbonate systems and aragonite saturation (Ωarag) levels in the vicinity of seagrass and coral reef habitats in Pari Island and Sire Bay, Lombok. Seawater samples were collected from Sire Bay, Lombok, and the coastal waters of Pari Island to analyze the carbonate systems, CO₂ flux, and metabolic processes. The findings indicate that Pari Island's coastal waters are more susceptible to ocean acidification than Sire Bay, Lombok, showing significantly lower pH values and Ωarag (P<0.05), ranging from 7.60 to 8.00 and 1.04 to 2.54, respectively. This disparity arises from the decreased temperature and salinity in Pari Island's coastal waters during the northwest monsoon, coupled with the deteriorated state of the seagrass and coral reef ecosystems, altering the equilibrium of ecosystem productivity and calcification. The study underscores the necessity of adopting specific coastal management tactics to lessen the effects on fragile ecosystems, highlighting the urgency for additional studies to evaluate adaptive and conservation strategies to preserve coastal biodiversity and ecosystem services.
Co-Authors Adi Purwandana Afdal Afdal, Afdal Alan Frendy Koropitan Alfiansyah, Yustian Rovi Anna Ida Sunaryo Purwiyanto Arief Rachman Dietriech Geoffrey Bengen Faisal Hamzah Firdaus, Mochamad Ramdhan Novi Susetyo Adi, Novi Susetyo Nurul Fitriya Oksto Ridho Sianturi Rastina, Rastina Rozirwan . Sugeha, Hagi Yulia Wahyudi, A’an Johan Wijayanti, Lady Ayu Sri Yulianto Suteja