Assessing the resilience of coral reefs against macroalgae invasion in the Sempu Island Nature Reserve, Malang District, Indonesia

ANDIK ISDIANTO (Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
PUTRI DEVI YORARIZKA (Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
DIAN ALIVIYANTI (Coastal Resilience and Climate Change Adaptation Research Group, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
SYARIFAH HIKMAH JULINDA SARI (Marine Resources Exploration and Management Research Group, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
ADI TIYA YANUAR (Coastal and Marine Research Centre, Universitas Brawijaya. Jl. Veteran, Malang, 65145, East Java, Indonesia)
MUHAMMAD ARIF ASADI (Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
ARIEF SETYANTO (Department of Fisheries, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
GATUT BINTORO (Department of Fisheries, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
TRI DJOKO LELONO (Department of Fisheries, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia)
DINI ATIKAWATI (Doctoral Program of Environmental Studies, Graduate School, Universitas Brawijaya. Jl. MT Haryono 169, Malang 65145, Indonesia)
AULIA LANUDIA FATHAH (Graduate Program of Environmental Management and Development, Postgraduate School, Universitas Brawijaya. Jl. MT Haryono 169, Malang 65145, East Java, Indonesia)
BERLANIA MAHARDIKA PUTRI (Graduate Program of Environmental Sciences, Universitas Gadjah Mada, Jl. Teknika Utara, Sleman 55284, Yogyakarta, Indonesia)
SUPRIYADI SUPRIYADI (Doctoral Program of Ocean Resource and Environmental Changes, National Taiwan Ocean University. Keelung City 202, Taiwan (R.O.C))
OKTIYAS MUZAKY LUTHFI (Institute of Marine and Environmental Sciences, University of Szczecin. Mickiewicza 16a, Szczecin, 70-383, Poland)

Biodiversitas Journal of Biological Diversity
Vol. 25 No. 7 (2024)

Abstract. Isdianto A, Yorarizka PD, Aliviyanti D, Sari SHJ, Yanuar AT, Asadi MA, Setyanto A, Bintoro G, Lelono TD, Atikawati D, Fathah AL, Putri BM, Supriyadi, Luthfi OM. 2024. Assessing the resilience of coral reefs against macroalgae invasion in the Sempu Island Nature Reserve, Malang District, Indonesia. Biodiversitas 25: 2877-2887. The living coral cover in the Sempu Strait is known to be stuck in the range of 37% due to average data from 2009-2016. Several coral diseases have been documented in this region, which can result in the transformation of coral reefs into algae-dominated communities. This study examines the dynamic interplay between coral reefs and macroalgae within the marine ecosystems of the Sempu Island Nature Reserve, Malang District, Indonesia. Conducted across five research stations, our analysis utilized the Underwater Photo Transect (UPT) method, combined with image analysis tools CPCe and Image-J, and statistical analysis through SPSS. The findings indicate a persistent competition between corals and macroalgae, exacerbated by sedimentation from port activities and river discharges, and significant nutrient loads from human settlements. The average living coral coverage varied significantly, with a range from 12% to 53% across the study period, while macroalgae coverage showed an increase, especially in turf algae. The correlation analysis revealed a 'quite strong' relationship (r=0.783 between coral and macroalgae coverage, suggesting that increases in coral cover could potentially facilitate macroalgae proliferation under current environmental conditions. Notably, the study highlighted the critical role of water quality parameters such as temperature, pH, and salinity, which were within optimal ranges yet facilitated competitive interactions. This research underscores the complexity of coral-macroalgae relationships and the pressing need for integrated management strategies focusing on water quality and habitat preservation to ensure the resilience of these critical marine ecosystems.