scholarly journals Early trajectories of benthic coral reef communities following the 2015/16 coral bleaching event at remote Aldabra Atoll, Seychelles

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anna Koester ◽  
Valentina Migani ◽  
Nancy Bunbury ◽  
Amanda Ford ◽  
Cheryl Sanchez ◽  
...  
Keyword(s):  
Coral Reef ◽  
Water Temperature ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Bleaching Event ◽  
Hard Coral ◽  
Reef Communities ◽  
Remote Sites ◽  
Hard Coral Cover ◽  
Coral Reef Communities

Abstract Documenting post-bleaching trajectories of coral reef communities is crucial to understand their resilience to climate change. We investigated reef community changes following the 2015/16 bleaching event at Aldabra Atoll, where direct human impact is minimal. We combined benthic data collected pre- (2014) and post-bleaching (2016–2019) at 12 sites across three locations (lagoon, 2 m depth; seaward west and east, 5 and 15 m depth) with water temperature measurements. While seaward reefs experienced relative hard coral reductions of 51–62%, lagoonal coral loss was lower (− 34%), probably due to three-fold higher daily water temperature variability there. Between 2016 and 2019, hard coral cover did not change on deep reefs which remained dominated by turf algae and Halimeda, but absolute cover on shallow reefs increased annually by 1.3% (east), 2.3% (west) and 3.0% (lagoon), reaching, respectively, 54%, 68% and 93% of the pre-bleaching cover in 2019. Full recovery at the shallow seaward locations may take at least five more years, but remains uncertain for the deeper reefs. The expected increase in frequency and severity of coral bleaching events is likely to make even rapid recovery as observed in Aldabra’s lagoon too slow to prevent long-term reef degradation, even at remote sites.

scholarly journals STATUS TERUMBU KARANG DAN IKAN KARANG DI GILI MATRA, NUSA TENGGARA BARAT

2020 ◽  
Vol 14 (1) ◽  
pp. 14
Author(s):  
Eghbert Elvan Ampou ◽  
Suciadi Catur Nugroho ◽  
Nuryani Widagti
Keyword(s):  
Water Quality ◽  
Coral Reef ◽  
Coral Cover ◽  
Reef Fishes ◽  
Coral Mortality ◽  
Hard Coral ◽  
Mortality Index ◽  
Fish Group ◽  
Hard Coral Cover ◽  
Reef Condition

This study aims to identify the status of reef fishes and coral reefs in Gili Meno, Air, and Trawangan or Gili Matra waters. This area is part of the North Lombok Regency, West Nusa Tenggara Province. Field observation was conducted on September 2011 at 11 (eleven) diving points. The video-transect method was used for observing the coral reef condition, while reef fishes abundance was observed by using visual-census method. The parameter that used to determine the condition of coral reef in study location are the percentage of live hard coral cover and index of coral mortality. In general, the result shows that percentage of live hard coral cover in each diving point ranged from 4.4% - 37.2% and the Coral Mortality Index (IMK) ranged form 0.40-0.92. The values describe that the condition of coral reef at eleven diving points vary from fair until poor condition. Current status of coral reef condition showed an insignificant increase from bad to moderate during the period 2011 -2018. There were 23 families of reef fishes from 46 genera were found during the study consisting of 16 genera of target fish groups, 5 genera of indicator fish group, and 25 genera of major fish group. The water quality is still within the limits of environmental quality standards.   Keywords: Reef fish, coral reef, Mortality Index, water quality, Gili Matra

scholarly journals 11-yr of coral community dynamics in reefs around Dahab (Gulf of Aqaba, Red Sea): the collapse of urchins and rise of macroalgae and cyanobacterial mats

Coral Reefs ◽  
2020 ◽  
Vol 39 (6) ◽  
pp. 1605-1618
Author(s):  
Miriam Reverter ◽  
Matthew Jackson ◽  
Nauras Daraghmeh ◽  
Christian von Mach ◽  
Nina Milton
Keyword(s):  
Coral Reef ◽  
Red Sea ◽  
Coral Cover ◽  
Negative Relationship ◽  
Gulf Of Aqaba ◽  
Benthic Fish ◽  
Hard Coral ◽  
Cyanobacterial Mats ◽  
Invertebrate Assemblages ◽  
Hard Coral Cover

AbstractCorals from the Gulf of Aqaba (northern Red Sea) are resilient to high temperatures and therefore this region is regarded as globally important for reef conservation. However, long-term dynamics of coral reef assemblages from the Gulf of Aqaba remain largely understudied. In this study, we analysed the change in benthic, fish and invertebrate assemblages of reefs around Dahab (South Sinai, Egypt) between 2009 and 2019. We also studied the individual trajectories of coral reef benthic categories, key invertebrate and fish species and their relationship. As site emerged as the main factor explaining the variability in coral reef communities, we identified three clusters of sites with similar assemblages. Both benthic, fish and invertebrate assemblages changed considerably at the three site clusters between 2009 and 2019. We found significant increases in fleshy macroalgae (~ 6 to 15%) and cyanobacterial mats (~ 6 to 12%) in all site clusters. Although not observing a significant reduction of hard coral cover, both macroalgae mat cover and cyanobacterial mat cover were significantly negatively related to hard coral cover and hard coral disease. Soft coral cover (mainly corals from the Xeniidae family) decreased significantly in two of the site clusters, their cover being negatively related to macroalgal and cyanobacterial cover. Significant declines in grazer urchins were observed at all site clusters, and a strong negative relationship was found with macroalgae and cyanobacterial mats cover, suggesting urchin decline as one of the main drivers behind algal increases. Different site clusters had different fish trajectories (butterflyfish, parrotfish, surgeonfish and predators), with only damselfish densities significantly decreasing at all sites. A significant decrease in damselfish densities was related to increases in cyanobacterial mats. These findings suggest that if macroalgae and cyanobacteria continue to increase, Dahab coral reefs could undergo degradation, and therefore, more studies are needed to elucidate the drivers behind these algal increases.

scholarly journals KONDISI TERUMBU KARANG PADA KAWASAN WISATA PANTAI MALALAYANG KOTA MANADO PROVINSI SULAWESI UTARA DENGAN MENGGUNAKAN METODE UNDERWATER PHOTO TRANSECT

2021 ◽  
Vol 9 (1) ◽  
pp. 44
Author(s):  
Devidson Daud ◽  
Joshian N. W. Schaduw ◽  
Chatrien Luzianna Sinjal ◽  
Janny D Kusen ◽  
Erli Y Kaligis ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Cover ◽  
Computer Software ◽  
Digital Camera ◽  
Hard Coral ◽  
Software Technology ◽  
Technological Developments ◽  
Moderate Condition ◽  
Hard Coral Cover

Coral reefs are coastal ecosystems with the highest level of diversity with around one million species worldwide. Corals are invertebrates belonging to the Phylum Coelenterate (hollow animals) or Cnidaria. The Underwater Photo Transect (UPT) method is a method that utilizes technological developments, both digital camera technology and computer software technology. Capturing data in the field in the form of underwater photos carried out by shooting using a Canon G-16 camera equipped with a waterproof protector (housing). In this study it can be seen that the percentage of hard corals at point 1 is in the medium category, point 2 is in the medium category, and point 3 is in the bad category with the percentage of hard coral cover as follows: point 1 (one) 29.75%, point 2 (two) 31.16%, and point 3 (three) 24.26%, of the three points can represent the overall condition of the coral reefs in Malalayang Beach which is in moderate condition with a percentage of 28.39%.Keywords: Malalayang Beach, Coral Reef, UPT, CPCe

scholarly journals PERBANDINGAN TUTUPAN KARANG KERAS SEBELUM, SAAT DAN SESUDAH PEMUTIHAN KARANG DI PERAIRAN KRUENG RAYA, ACEH BESAR

2018 ◽  
Vol 10 (3) ◽  
pp. 739-745
Author(s):  
Maria Ulfah ◽  
Chyndy Yolanda ◽  
Sofyatuddin Karina ◽  
Syahrul Purnawan ◽  
Sri Agustina
Keyword(s):  
Mortality Rate ◽  
Data Collection ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Coral Mortality ◽  
Hard Coral ◽  
Average Percentage ◽  
Mortality Index ◽  
Hard Coral Cover

ABSTRAKPenelitian ini bertujuan untuk mengetahui tutupan karang keras pada waktu sebelum (tahun 2015) saat (2016) dan sesudah pemutihan karang (2017) di Krueng Raya, Aceh Besar. Penelitian ini dilakukan pada bulan April 2017 di Krueng Raya, Aceh Besar. Pengambilan data dilakukan di 3 stasiun pengamatan menggunakan metode PIT (Point Intercept Transect) yang meliputi: Benteng Inong Balee, Ahmad Rhang Manyang, dan Lhok Mee. Hasil penelitian menunjukkan persentase rata - rata tutupan karang keras tahun 2015 sebesar 52,83% berkategori baik, tahun 2016 sebesar 32,43% berkategori sedang dan tahun pada tahun 2017 persentase tutupan karang keras menjadi 22,90% dan masuk ke dalam kategori rusak. Terdapat sebanyak 16 genus karang (2015), 18 genus karang (2016) dan 8 genus karang 8 (2017). Indeks Mortalitas (IM) tahun 2015 berkisar antara 0,02-0,20 (tingkat kematian karang yang rendah), tahun 2016 berkisar antara 0,13-0,49 (kematian karang rendah), tahun 2017 berkisar antara 0,63-0,79 (tingkat kematian karang tinggi). Hasil penelitian ini menunjukkan bahwa persentase tutupan karang keras mengalami penurunan hingga mencapai ±50% yang diakibatkan oleh pemutihan karang pada Perairan Krueng Raya Aceh Besar. ABSTRACTThe aim of this study was to determine hard coral cover at the time before (2015), during (2016) and after coral bleaching (2017) in Krueng Raya, Aceh besar. This study was conducted on April 2017 in Krueng Raya, Aceh Besar. Data collection was carried out at 3 observation stations using the PIT (Point Intercept Transect) method which included : Fort Inong Balee, Ahmad Rhang Manyang, and Lhok Mee. The results showed that the average percentage of hard coral cover in 2017 was 22.90% (bad category), it was lower than in 2016 32.43% (medium category) and in 2015 was 52.83% (good category). There were found 16 genera of coral (2015), 18 genera of coral (2016), and 8 genera of coral (2017). Mortality Index (MI) in 2015 ranged between 0.02-0.20 (low coral mortality rate), in 2016 ranged between 0.13-0.49 (low coral mortality rate), in 2017 ranged between 0.63-0.79 (high coral mortality rate). The results of this study indicate that the percentage of hard coral cover has decreased to reach 50% due to coral bleaching in the waters of Krueng Raya Aceh Besar.

scholarly journals The change of coral cover in Ujong Pancu waters, Peukan Bada Sub-District, Aceh Besar

2021 ◽  
Vol 869 (1) ◽  
pp. 012051
Author(s):  
M Ulfah ◽  
M Muliari ◽  
F Azzahara ◽  
N M Razi ◽  
M R Fazillah ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Cover ◽  
Hard Coral ◽  
Ecological Functions ◽  
Coral Genus ◽  
The Earth ◽  
Coral Reef Ecosystems ◽  
Hard Coral Cover

Abstract Coral reef ecosystems are one of the most productive ecosystems on the earth, with large ecological functions. The disruption of coral reef ecosystems has a significant impact on the surrounding biota. This study aims to determine the condition of coral reefs for the last three years in Ujong Pancu waters, Peukan Bada sub-district, Aceh Besar district. This study uses data in 2017, 2018, and 2019 with three observation locations: Lhok Keeutapang, Lhok Mata Ie, and Tuan Island. The method used is Point Intercept Transect (PIT) with a transect length of 20 m with four repetitions. The results showed that the percentage of hard coral cover in the Ujong Pancu waters decreased from the good category (50.31%) in 2017 to moderate (47.81%) in 2019. The percentage with the highest coral cover was at the Lhok Keutapang location at 72, 81% in 2018, while the lowest coral cover at the Tuan Island location was 15.94% in 2017. The composition of the coral genus found also decreased from 12 coral genera (2017) to 9 coral genera (2019).

scholarly journals Kelimpahan dan Biomassa Ikan Karang Famili Scaridae pada Ekosistem Terumbu Karang di Perairan Pulau Kembar, Karimunjawa, Jepara

2020 ◽  
Vol 9 (2) ◽  
pp. 159-166
Author(s):  
Fran Ciputra Tambunan ◽  
Munasik Munasik ◽  
Agus Trianto
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Cover ◽  
Fish Biomass ◽  
Hard Coral ◽  
Coral Reef Ecosystem ◽  
The Family ◽  
Coral Fish ◽  
Hard Coral Cover ◽  
Reef Ecosystem

ABSTRAK : Ikan kakatua merupakan salah satu ikan karang yang dapat membantu kehidupan pada ekosistem terumbu karang. Scaridae mengumpulkan berbagai spesies ganggang dengan cara memakan algae pendek yang menutupi substrat karang sehingga dapat mempengaruhi pertumbuhan terumbu karang. Sebaran Scaridae sangat ditentukan oleh kondisi dan variasi habitat terumbu karang. Penelitian ini bertujuan untuk mengetahui kelimpahan dan biomassa dari ikan Famili Scaridae. Penelitian dilaksanakan pada bulan Oktober 2018 di Perairan Pulau Kembar, Karimunjawa, Jepara. Pengambilan data  ikan karang menggunakan metode UVC dan data substrat terumbu karang diambil menggunakan metode LIT sepanjang 100 meter sejajar garis pantai dengan pengamatan pada dua kedalaman yaitu 3m dan 10m. Berdasarkan hasil penelitian, didapatkan 11.459 individu yang termasuk dalam 49 spesies ikan karang yang berasal dari 14 famili. Ikan karang dari Famili Scaridae ditemukan sebanyak 1059 individu yang termasuk dalam 4 spesies ikan karang yang berasal dari 2 genus. Nilai kelimpahan ikan karang dari Famili Scaridae berkisar antara 48 hingga 204 ind/500m2, kelimpahan terendah berada pada stasiun 1 dan tertinggi berada di stasiun 3.  Nilai biomassa ikan karang dari Famili Scaridae berkisar antara 219,7–2491,7 kg/ha, biomassa terendah berada pada stasiun 1 dan tertinggi berada di stasiun 3.  Berdasarkan hasil penelitian dapat disimpulkan bahawa Pengaruh tutupan karang keras hidup sangat berpengaruh terhadap kelimpahan dan biomassa ikan karang dari Famili Scaridae. ABSTRACT : Parrot fish is one of the reef fish that can help life on the coral reef ecosystem. Scaridae collect various species of algae by eating short algae that cover the coral substrate so that it can affect the growth of coral reefs. Scaridae distribution is highly determined by the condition and variety of coral reef habitats. This study aims to examine the abundance and biomass of Scaridae Family fish. The study was conducted in October 2018 in the waters of the Kembar Islands, Karimunjawa, Jepara. Retrieval of reef fish data using UVC method and coral reef substrate data were taken using the LIT method along 100 meters along the coastline with observations at two depths in 3m and 10. Based on the results, 11,459 individuals were included in 49 species of reef fish originating from 14 families. Coral fish from the Family Scaridae were found as many as 1059 individuals included in 4 species of reef fish originating from 2 genera. The value of coral fish abundance from the Scaridae Family ranges from 48 to 204 ind / 500m2, the lowest abundance is at station 1 and the highest is at station 3. The reef fish biomass value of the Scaridae Family ranges from 219.7 - 2491.7 kg / ha, biomass the lowest is at station 1 and the highest is at station 3. Based on the results of the study it can be concluded that the effect of live hard coral cover is very influential on the abundance and biomass of reef fish from the Scaridae Family.

scholarly journals Implications of 2D versus 3D surveys to measure the abundance and composition of benthic coral reef communities

Coral Reefs ◽  
2021 ◽  
Author(s):  
Niklas A. Kornder ◽  
Jose Cappelletto ◽  
Benjamin Mueller ◽  
Margaretha J. L. Zalm ◽  
Stephanie J. Martinez ◽  
...  
Keyword(s):  
Coral Reef ◽  
Benthic Community ◽  
Trophic Ecology ◽  
Coral Cover ◽  
3D Structure ◽  
Coralline Algae ◽  
Surface Cover ◽  
Reef Communities ◽  
Encrusting Sponges ◽  
Coral Reef Communities

AbstractA paramount challenge in coral reef ecology is to estimate the abundance and composition of the communities residing in such complex ecosystems. Traditional 2D projected surface cover estimates neglect the 3D structure of reefs and reef organisms, overlook communities residing in cryptic reef habitats (e.g., overhangs, cavities), and thus may fail to represent biomass estimates needed to assess trophic ecology and reef function. Here, we surveyed the 3D surface cover, biovolume, and biomass (i.e., ash-free dry weight) of all major benthic taxa on 12 coral reef stations on the island of Curaçao (Southern Caribbean) using structure-from-motion photogrammetry, coral point counts, in situ measurements, and elemental analysis. We then compared our 3D benthic community estimates to corresponding estimates of traditional 2D projected surface cover to explore the differences in benthic community composition using different metrics. Overall, 2D cover was dominated (52 ± 2%, mean ± SE) by non-calcifying phototrophs (macroalgae, turf algae, benthic cyanobacterial mats), but their contribution to total reef biomass was minor (3.2 ± 0.6%). In contrast, coral cover (32 ± 2%) more closely resembled coral biomass (27 ± 6%). The relative contribution of erect organisms, such as gorgonians and massive sponges, to 2D cover was twofold and 11-fold lower, respectively, than their contribution to reef biomass. Cryptic surface area (3.3 ± 0.2 m2 m−2planar reef) comprised half of the total reef substrate, rendering two thirds of coralline algae and almost all encrusting sponges (99.8%) undetected in traditional assessments. Yet, encrusting sponges dominated reef biomass (35 ± 18%). Based on our quantification of exposed and cryptic reef communities using different metrics, we suggest adjustments to current monitoring approaches and highlight ramifications for evaluating the ecological contributions of different taxa to overall reef function. To this end, our metric conversions can complement other benthic assessments to generate non-invasive estimates of the biovolume, biomass, and elemental composition (i.e., standing stocks of organic carbon and nitrogen) of Caribbean coral reef communities.

MONITORING CORAL RECOVERY AT NEARSHORE CORAL REEFS IN PHANGNGA PROVINCE, THE ANDAMAN SEA FOLLOWING THE 2010 CORAL BLEACHING EVENT

2017 ◽  
Author(s):  
Makamas Sutthacheep ◽  
Makamas Sutthacheep ◽  
Thamasak Yeemin ◽  
Thamasak Yeemin ◽  
Sittiporn Pengsakun ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Global Climate ◽  
Andaman Sea ◽  
Live Coral ◽  
Bleaching Event ◽  
Sea Star ◽  
Coral Recovery

Mass bleaching and subsequent mortality of scleractinian corals in response to elevated seawater temperatures has been considered as one of the most impacts of global climate change. Three extensive coral bleaching events in the Andaman Sea were reported, in the years 1991, 1995 and 2010. Studies on survival of coral colonies, coral recruitment and community structure of coral reef associated macrofauna would predict the trends for coral recovery from the impacts of coral bleaching events. The present study aimed to examine the status of coral communities, density of coral recruits and coral reef associated macrofauna at nearshore coral reefs in Phangnga Province, the Andaman Sea following the 2010 coral bleaching event. The dead coral cover was high (>50%) while the live coral cover was in the range of 13-21%. There was high diversity of coral recruits on natural substrates. The average densities of macrobenthic fauna varied from 1.9 to 2.6 individuals.m-2, with significant differences among study sites. The dominant macrobenthic species were a soft coral (Lobophytum sp.), a sea star (Linckia laevigata) and a sea urchin (Echinostrephus molaris). Coral recovery at these coral reefs would be possible but local anthropogenic stressors must be overwhelmingly reduced in order to enhance coral reef resilience. The long-term monitoring programs in the Andaman Sea are required for decision makers to support their adaptive management approaches.

scholarly journals Karakteristik Terumbu Karang di Zona Pemanfaatan Wisata Taman Nasional Karimunjawa (Coral Reef Characteristic of Tourism Zone, Karimunjawa National Park)

2014 ◽  
Vol 19 (3) ◽  
pp. 139
Author(s):  
Rohmani Sulisyati ◽  
Erny Poedjirahajoe ◽  
Lies Rahayu WF ◽  
Chafid Fandeli
Keyword(s):  
Coral Reef ◽  
Deep Water ◽  
National Park ◽  
Diversity Index ◽  
Coral Cover ◽  
Species Abundance ◽  
Hard Coral ◽  
Hard Coral Cover ◽  
Specific Species ◽  
Line Intercept

Karakteristik terumbu karang di suatu lokasi wisata perlu diketahui agar terumbu karang tetap dapat melangsungkan fungsinya dengan optimal. Penelitian ini bertujuan untuk mengetahui karakteristik terumbu karang di zona pemanfaatan wisata Taman Nasional Karimunjawa. Dilakukan pada bulan November 2013 pada 14 lokasi. Pengamatan terumbu karang dengan metode line intercept transect untuk melihat substrat dasar berdasar lifeform. Transek dilakukan pada dua kedalaman yaitu 3 meter dan 6–8 m untuk mewakili perairan dangkal dan dalam. Analisis kualitatif dilakukan untuk melihat tutupan karang keras serta pengukuran nilai indeks keanekaragaman, keseragaman dan dominasi. Hasil pengukuran kondisi fisik perairan termasuk dalam perairan produktif yang dapat menunjang kehidupan organisme di dalamnya. Kondisi terumbu karang pada daerah dangkal ditemukan 15 famili, 41 genus dan 104 species karang. Persentase tutupan karang keras termasuk kategori sedang – sangat baik. Keanekaragaman jenis yang melimpah sedang hingga tinggi dengan kondisi komunitas antara labil hingga stabil dan hampir tidak ditemukan dominasi jenis tertentu. Pada daerah dalam terdapat 15 famili, 39 genus dan 99 species. Tutupan karang keras sedang – baik, dengan keanekaragaman jenis melimpah tinggi dan stabil serta tidak ada jenis yang dominan. Genus Acropora dan Porites dapat ditemui pada seluruh lokasi. Karakteristik terumbu karang berkaitan dengan letak keberadaan pulau, terumbu karang pada pulau terlindung cenderung mempunyai komunitas yang stabil. Kata kunci: terumbu karang, tutupan karang keras, lifeform Coral  reef characteristic in the recreational area should be known to establish the function optimally. This study aims to quantify the characteristic of coral reef throughout tourism utilization zone of Karimunjawa National Park. Surveys were conducted  during November 2013 at 14 locations. Substrate cover was collected using line intercept transect methods. Transects were deployed at two depth i.e 3 meters and 6–8 meters to represent the shallow and the deep water. Qualitative analysis were done to measure the hard coral cover and diversity index, evenness index and domination. The result showed that physical condition of aquatic environment was productive water that can support living organisms. For shallow water there were 15 families, 41 generas and 104 species of hard coral. Hard  coral cover ranged from 36,5-82% and it was categorized as fair–excellent. Species abundance is moderate to high which a condition of community between unstable to stable and hardly found dominance of a specific species. While the deep water there were 15 families, 39 generas and 99 species corals. Hard coral cover ranged from 39,5-67,9% it was categorized as fair into good, with high species diversity and abundance of stable and there is no dominant species. Acropora and Porites genus can be found in all locations. Coral reef characteristic associated with the location where the island, the protected island tend to have stable community. Keywords: coral reef, hard coral cover, lifeform

scholarly journals Will community calcification reflect reef accretion on future, degraded coral reefs?

2021 ◽  
Author(s):  
Coulson A. Lantz ◽  
William Leggat ◽  
Jessica L. Bergman ◽  
Alexander Fordyce ◽  
Charlotte Page ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Elevated Temperatures ◽  
Coral Cover ◽  
Coral Tissue ◽  
Bleaching Event ◽  
Bleached Coral ◽  
Coral Health ◽  
Percent Area

Abstract. Coral bleaching events continue to drive the degradation of coral reefs worldwide, causing a shift in the benthic community from coral to algae dominated ecosystems. Critically, this shift may decrease the capacity of degraded coral reef communities to maintain net positive accretion during warming-driven stress events (e.g., reef-wide coral bleaching). Here we measured rates of net ecosystem calcification (NEC) and net ecosystem production (NEP) on a degraded coral reef lagoon community (coral cover  20 %) during a reef-wide bleaching event in February of 2020 at Heron Island on the Great Barrier Reef. We found that during this bleaching event, rates of community NEP and NEC across replicate transects remained positive and did not change in response to bleaching. Repeated benthic surveys over a period of 20 d indicated an increase in the percent area of bleached coral tissue, corroborated by relatively low Symbiodiniaceae densities (~0.6 × 106 cm−2) and dark-adapted photosynthetic yields in photosystem II of corals (~0.5) sampled along each transect over this period. Given that a clear decline in coral health was not reflected in the overall community NEC estimates, it is possible that elevated temperatures in the water column that compromise coral health enhanced the thermodynamic favourability for calcification in other, ahermatypic benthic calcifiers. These data suggest that positive NEC on degraded reefs may not equate to the net positive accretion of reef structure in a future, warmer ocean. Critically, our study highlights that if coral cover continues to decline as predicted, NEC may no longer be an appropriate proxy for reef growth as the proportion of the community NEC signal owed to ahermatypic calcification increases and coral dominance on the reef decreases.

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