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The Occurrence of Marine Debris and Its Impacts on Coral Reefs in the Sempu Island Nature Reserve, Malang, Indonesia

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Isdianto A. , Pangestu W. S. , Yamindago A. , Dewi C. S. U. , Aliviyanti D. , Luthfi O. M. , Setyoningrum D. , Fathah A. L. , Putri B. M. , Puspitasari I. D.

Journal of Ecological Engineering

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2024

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tom Vol. 25, nr 9

70--80

EN

Marine debris significantly impacts coral ecosystems, especially in regions with high biodiversity like the Sempu Island Nature Reserve in Malang, Indonesia. According to the guidelines of ReefCheck and KLHK 2020, this indepth study looked at the types, amounts, and impacts of marine debris on coral health at five different sites close to the Pondokdadap Coastal Fishing Port. This study employs a belt transect method measuring 100×5 meters to systematically collect data. The obtained results indicate that cloth refuse is the most substantial form of waste, accounting for 84.65% of the weight of marine waste. The primary locations for this form of waste are areas with high human activity, particularly those near fishing ports. The impact of marine debris on coral reefs depends on its proximity to human activity, as it exhibits a wide range of density and composition. Millepora, a coral species characterized by its branching structure, was the most severely impacted, with damage levels spanning from 12.07% to 48.65%. This indicates its vulnerability to debris accumulation. The study determined the prevalence of a variety of waste categories, with plastic being the most prevalent. The study also focused on other types of inorganic waste, such as packaging, fishing lines, raffia ropes, rubber (flip-flops and tires), fabric, metal (cans and metal cutlery), glass bottles, and other items, primarily in the port area. The density of debris is an important indicator of the environmental pressure exerted on coral ecosystems. Among the examined locations, the Jetty station displayed the highest concentration of inorganic debris, with a density of 0.100 items/m2. In contrast, Watu Meja Station had the lowest density of inorganic waste at 0.008 items/m2, but the highest concentration of organic waste at 0.066 items/m2. This indicates that there is less human impact but more accumulation of natural refuse. This study highlights the pressing necessity for effective marine waste management strategies, particularly near active ports like Pondokdadap, to mitigate the detrimental effects on coral reefs. The health and sustainability of this critical marine ecosystem can be ensured by reducing refuse accumulation through enhanced waste management protocols and community engagement.

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Water Quality Impact Christmas Tree Worms (Spirobranchus spp.) Distribution and Community Structure on Hard Corals At Sempu Island Nature Reserve, Malang, Indonesia

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Isdianto A. , Amanda S. S. , Yamindago A. , Dewi C. S. U. , Aliviyanti D. , Luthfi O. M. , Fathah A. L. , Atikawati D. , Putri B. M. , Puspitasari I. D.

Journal of Ecological Engineering

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2024

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tom Vol. 25, nr 5

175--186

EN

The Christmas tree worm (Spirobranchus spp.) is a biota that lives in association with hermatypic corals. This bioeroder damages the structural integrity of corals, making them susceptible to breakage. Therefore, further investigation is required to determine the distribution, diversity, uniformity, and predominance of CTW on hard corals in the Sempu Island Nature Reserve’s waters. The method used is the belt transect method, which refers to the reef check. CTW species will be identified based on their operculum, and corals will be identified based on their growth form, genus, and species. The data gathered were processed, and the abundance value and ecological index were obtained. The CTW species found at the five stations were Spirobranchus gardineri, Spirobranchus cruciger, and Spirobranchus spp., associated with massive corals of the genus Porites and genus Goniastrea. Water quality factors such as currents, sedimentation, and nitrates affect CTW’s presence. Medium-to-fast currents circulate around Sempu Island, where high sedimentation rates of 73.73 mg/ cm2/day decrease light penetration into the waterways. Additionally, elevated nitrate levels contribute to the growth of CTW operculum-covering turf algae. CTW abundance values ranged from 0.018 to 0.084 individuals/m2, diversity index (H’) ranged from 0.403 to 0.760 (low), and uniformity index (E) ranged from 0.582 to 0.966 (unstable to stable). The dominance index (C) values ranged from 0.513 to 0.705 (medium). Based on the index value, it was found that the CTW in Sempu Island was in the unstable category, so there was moderate dominance.

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Assessment of Community Structure of Macroinvertebrates, Coral Cover and Water Quality in Sempu Strait, Malang Regency, East Java

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Isdianto A. , Kurniawan A. , Wicaksono A. D. , Taufik M. Z. , Putri B. M. , Fathah A. L. , Setyanto A. , Luthfi O. M. , Pratiwi D. C. , Harahab N.

Journal of Ecological Engineering

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2023

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tom Vol. 24, nr 12

99--111

EN

Due to the sensitivity of invertebrates to environmental changes, their presence can serve as an indicator of coral reef health and water quality. This study seeks to ascertain the abundance of invertebrates, the structure of the invertebrate community, and their relationship with coral cover and water quality parameters in the waters of Sempu Strait. The belt transect method and the underwater photo transect (UPT) are used to determine the abundance of invertebrates and coral cover, respectively. Temperature, pH, DO, salinity, and water clarity are measured for water quality. According to the study’s findings, seven of the nine invertebrate species were found. Between October 2021 and May 2022, seven of nine invertebrate biota categories, 733 species, and 606 species dominated by Diadema sea urchins were observed every two months. The invertebrate abundance ranged from 0.024 to 0.512. A low and imbalanced invertebrate diversity ranges from 0.078 to 0.493 (H’ < 1). The range of the equality index (E < 0.4) is between 0.04 and 0.22, indicating a low community index. There are three levels of dominance index values: low, medium, and high. Due to their abundance, Diadema sea urchins dominate the Sempu Strait, particularly near the Jetty Station with its port activity. Coverage of coral reefs varies between 6% and 21.3%, indicating low and damaged corals. The correlation between coral cover and invertebrate abundance is moderate in Banyu Tawar and Rumah Apung (0.480 to 0.490), whereas it is weak in Waru-Waru, Watu Meja, and Jetty (-0.037–0.225). The abundance of invertebrates has a weak link with values ranging from -0.037 to -0.283 for water clarity, temperature, salinity, DO, and pH, but it has a strong correlation with a value of 0.610 for current velocity. The environment, including human activities and water quality, has a significant impact on macroinvertebrate communities. Environmentally tolerant macroinvertebrates will outcompete the vulnerable ones.

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Observation of Coral Reef and Macroalgae Competition in the Sempu Strait, Malang

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Isdianto A. , Kurniawan A. , Wicaksono A. D. , Marhaendra Q. N. I. , Putri B. M. , Fathah A. L. , Asadi M. A. , Luthfi O. M. , Pratiwi D. C. , Harahab N.

Journal of Ecological Engineering

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2023

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tom Vol. 24, nr 10

174--184

EN

Competition for space between coral reefs and macroalgae has a significant impact on coral cover and, consequently, on the sustainability of coastal ecosystems. This study aimed to ascertain the Sempu Strait’s substrate coverage, dominant coral reef lifeform, coral-macroalgae competition, and water quality. The Underwater Photo Transect method and the CPCe software are used to monitor coral reefs. The condition of the approximately 11.5% of living corals was deemed to be substandard. The western portion of the Sempu Strait is dominated by encrusting, branching, and massive corals, whereas the eastern portion is dominated by Acropora corals. Temperature varied between 26 and 35 °C, salinity varied between 17 and 35 ppt, pH varied between 7 and 8, water clarity varied between 2.25 and 2.73 m, and dissolved oxygen varied between 6.28 and 6.71 mg/L. Competition between corals and macroalgae is observed at multiple stations, including Banyu Tawar, Waru-Waru, and WatuMeja. This phenomenon can be attributed to the presence of suitable substrates such as sand, rubble, and pebbles, as well as favorable seasonal conditions and water quality that promote the growth of macroalgae. Essentially, macroalgae grow more rapidly than corals, resulting in competition for growing space.