scholarly journals Underwater Photogrammetry Captures the Initial Recovery of a Coral Reef at Lalo Atoll

Diversity ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 39
Author(s):  
Atsuko Fukunaga ◽  
Kailey H. Pascoe ◽  
Ashley R. Pugh ◽  
Randall K. Kosaki ◽  
John H. R. Burns

Recovery of coral reefs after physical damage sustained from storm events can be affected by various factors. Here, we examined the initial recovery of a coral reef at the southern end of uninhabited Lalo Atoll of Papahānaumokuākea Marine National Monument after its complete destruction by Hurricane Walaka in 2018. While the site was still mostly (98%) covered by a mixture of rubble and sand, surveys utilizing underwater photogrammetry allowed for detailed quantitative assessments of benthic cover and confirmed colonization of coral (Pocillopora meandrina and Porites lobata), macroalgae and sponges. The proportion of sand in the rubble–sand mixture also decreased from the level observed in 2019. Visual fish surveys confirmed the presence of 35 reef fish species, a large increase from no reef fish in 2019, despite the low biotic benthic cover. Overall, the colonization of benthic organisms and the return of reef fish, which is potentially supported by the benthos and cryptofauna in the rubble bed, offer positive signs of reef recovery. The photogrammetric surveys in the present study captured the subtle changes in the benthic cover and provided us with a procedure to continue monitoring the succession of the site. Continuous monitoring of the site should reveal whether the reef returns to the original state of Acropora coral dominance or progresses towards a coral assemblage with a different composition.

Author(s):  
Sebastien Gislard ◽  
Pauline Bosserelle ◽  
George Shedrawi ◽  
Rateiti Vaimalie ◽  
Liliana Iotebatu ◽  
...  

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Frederieke J. Kroon ◽  
Carine D. Lefèvre ◽  
Jason R. Doyle ◽  
Frances Patel ◽  
Grant Milton ◽  
...  

Abstract The corallivorous Crown-of-Thorns Starfish (CoTS, Acanthaster spp.) has been linked with the widespread loss of scleractinian coral cover on Indo-Pacific reefs during periodic population outbreaks. Here, we re-examine CoTS consumption by coral reef fish species by using new DNA technologies to detect Pacific Crown-of-Thorns Starfish (Acanthaster cf. solaris) in fish faecal and gut content samples. CoTS DNA was detected in samples from 18 different coral reef fish species collected on reefs at various stages of CoTS outbreaks in the Great Barrier Reef Marine Park, nine of which had not been previously reported to feed on CoTS. A comprehensive set of negative and positive control samples confirmed that our collection, processing and analysis procedures were robust, although food web transfer of CoTS DNA cannot be ruled out for some fish species. Our results, combined with the (i) presence of CoTS spines in some samples, (ii) reported predation on CoTS gametes, larvae and settled individuals, and (iii) known diet information for fish species examined, strongly indicate that direct fish predation on CoTS may well be more common than is currently appreciated. We provide recommendations for specific management approaches to enhance predation on CoTS by coral reef fishes, and to support the mitigation of CoTS outbreaks and reverse declines in hard coral cover.


2021 ◽  
Vol 7 ◽  
Author(s):  
Kui Zhang ◽  
Jun Zhang ◽  
Dengfu Shi ◽  
Zuozhi Chen

The South China Sea (SCS) is one of the world’s main centers for coral reef diversity, with more than one-third of all reef fish species being found in this area. Some indications of overfishing have appeared in typical coral reefs of the SCS, as fish diversities have declined and the average body lengths of dominant fish species have decreased. However, only few assessments of coral reef fish stocks have been conducted, due to insufficient available data. In this study, we applied a newly developed length-based Bayesian biomass (LBB) estimation method to assess 10 dominant coral reef fish species from three main reefs (Yongshu Reef, Zhubi Reef, and Meiji Reef) of the Nansha Islands, SCS. Simulations indicated the estimated parameters were not sensitive to sample sizes (more than 100) using the LBB method. Our results showed that the relative biomass levels (B/BMSY) of Cephalopholis spiloparaea, Cephalopholis urodeta, Lutjanus gibbus, Gnathodentex aureolineatus, Pentapodus caninus, and Cheilinus fasciatus were between 0.16 and 0.45, suggesting an overfishing status; the relative biomass levels of Epinephelus merra, and Parupeneus crassilabris were 0.98 and 1.1, respectively, indicating that they were fully exploited; and the relative biomass levels of Lutjanus kasmira and Melichthys vidua were 1.3 and 2.5, respectively, indicating the populations were in good conditions. The estimates of Lc/Lc_opt were less than one for seven stocks, suggesting that the stocks were suffering from growth overfishing. Therefore, we emphasize the need to reduce fishing mortality and increase the mesh size of the coral reef fishery in the Nansha Islands, to achieve a sustainable yield and biomass.


2017 ◽  
Vol 5 (2) ◽  
pp. 155
Author(s):  
Riezky H. S. Wuwumbene ◽  
Ari B. Rondonuwu ◽  
Victor N. R. Watung

Artificial reefs already placed in the coast of the village of Arakan, South Minahasa regency since June 2015. Artificial reef, that would be the location of research are concrete and iron, mostly be the medium of coral transplantation. The pupose of the research are (1). To know the species coral reef fish (2). To know the number of each species and the density of the coral reef fish (3). To know the structure of coral reef fish communities. Data retrieval be done use with Visual Census Method in the 51 squaremeter area (lenght = 8,5 m, width = 6 m). This research find 15 families with 29 coral reef fish species and 1341  individual. The diversity index of artificial reefs with moderate diversity index and relative abudance is found in species Dascyllus trimaculatus 34,731 %,  Plotosus lineatus 21,593 %, and Dascyllus reticulatus 21,174 %.Keywords: Artificial reef, Community Structure, Arakan. ABSTRAKTerumbu buatan sudah diletakan pada perairan desa Arakan Kabupaten Minahasa Selatan pada bulan Juni 2015. Terumbu buatan yang menjadi lokasi penelitian berjenis beton dan besi, model yang terbuat dari besi lebih banyak diarahkan sebagai media transplantasi karang. Penelitian ini bertujuan untuk (1) Mengetahui kekayaan spesies ikan karang (2) Mengetahui kelimpahan individu dan kepadatan relatif ikan karang (3) Mengetahui struktur komunitas ikan karang. Pegambilan data dilakukan menggunakan metode Sensus Visual dengan luas pengamatan pada terumbu buatan  seluas 51 m2 (panjang = 8,5 meter dan lebar = 6 meter). Penelitian ini menemukan 15 famili dengan 29 spesies ikan karang dan kelimpahan individu total 1341 individu. Indeks keanekaragaman di daerah terumbu buatan dengan nilai indeks keanegaraman yang sedang dengan indeks dominasi rendah dan kelimpahan relatif terdapat pada spesies Dascyllus trimaculatus dengan nilai 34,731 %, Plotosus lineatus dengan nilai 21,593 %, dan Dascyllus reticulatus dengan nilai 21,174 %.Kata Kunci : Terumbu Buatan, Struktur Komunitas, Arakan.


2000 ◽  
Vol 3 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Julie P. Hawkins ◽  
Callum M. Roberts ◽  
Victoria Clark

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