scholarly journals Biophysical and anthropogenic influences on the status of Tonga’s coral reefs and reef fish fishery

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241146
Author(s):  
Patrick Smallhorn-West ◽  
Sophie Gordon ◽  
Karen Stone ◽  
Daniela Ceccarelli ◽  
Siola’a Malimali ◽  
...  

Despite increasing threats to Tonga’s coral reefs from stressors that are both local (e.g. overfishing and pollution) and global (e.g. climate change), there is yet to be a systematic assessment of the status of the country’s coral reef ecosystem and reef fish fishery stocks. Here, we provide a national ecological assessment of Tonga’s coral reefs and reef fish fishery using ecological survey data from 375 sites throughout Tonga’s three main island groups (Ha’apai, Tongatapu and Vava’u), represented by seven key metrics of reef health and fish resource status. Boosted regression tree analysis was used to assess and describe the relative importance of 11 socio-environmental variables associated with these key metrics of reef condition. Mean live coral cover across Tonga was 18%, and showed a strong increase from north to south correlated with declining sea surface temperature, as well as with increasing distance from each provincial capital. Tongatapu, the southernmost island group, had 2.5 times greater coral cover than the northernmost group, Vava’u (24.9% and 10.4% respectively). Reef fish species richness and density were comparable throughout Tongatapu and the middle island group, Ha’apai (~35 species/transect and ~2500 fish/km2), but were significantly lower in Vava’u (~24 species/transect and ~1700 fish/km2). Spatial patterns in the reef fish assemblage were primarily influenced by habitat-associated variables (slope, structural complexity, and hard coral cover). The biomass of target reef fish was greatest in Ha’apai (~820 kg/ha) and lowest in Vava’u (~340 kg/ha), and was negatively associated with higher human influence and fishing activity. Overall mean reef fish biomass values suggest that Tonga’s reef fish fishery can be classified as moderately to heavily exploited, with 64% of sites having less than 500 kg/ha. This study provides critical baseline ecological information for Tonga’s coral reefs that will: (1) facilitate ongoing management and research; and (2) enable accurate reporting on conservation targets locally and internationally.

Author(s):  
Joel G. Becira ◽  
Benjamin J. Gonzales ◽  
Honorio B. Pagliawan

In Palawan, Philippines, Honda Bay is fast becoming a target recreational site for curious domestic and foreign visitors. The general objectives of this resource assessment are to gather information regarding status of the marine resources in Pandan Island, and to provide recommendations for their sustainable use. Assessment was done using line intercept transect (LIT), fish visual census (FVC) and an imaginary transect belt for coral cover, fish, and macro-invertebrates, respectively. Average live coral cover around Pandan Island can be categorized as good (57%), with stations 7 and 1 and 2 categorized as excellent (76-100%) and fair (26-50%) conditions, respectively. Some 178 fish species were recorded in Pandan Island waters of which seven (7) highly target and 29 common commercial fish species were found. The estimated total reef fish biomass around Pandan Island is 588 mt/ km2. A total of eight macro invertebrate (shells, etc.) species belonging to five families was found around Pandan Island. The study concluded that of these eight species, six are commercially important,Tridacnacro cea(taklobo), Tridacnasquamosa (taklobo), Hippopusporcellanus(taklobo), Trochusniloticus(topshell), Pinna nobilis (tarab), and Bohadschiamarmota (sea cucumber). Five of these species the T. crocea, T. squamosa, H. porcellanus, P. nobilis, and T. niloticus are listed as endangered species by International Union for Conservation of Nature.   Keywords - target species, macro-invertebrates, coral cover, coral reefs, reef fish, conservation


2020 ◽  
Vol 23 (3) ◽  
pp. 333-340
Author(s):  
Munasik Munasik ◽  
Aldion Adin Nugroho ◽  
Retno Hartati ◽  
Agus Sabdono ◽  
Sugiyanto Sugiyanto ◽  
...  

Artificial Patch Reef (APR) have been applied as a new method for Biodiversity Conservation Program at Panjang Island, Jepara since 2015. Previous study suggested that design and location of artificial reefs installation affected to abundance of reef fishes, associated with the artificial reef.  This study aims to investigated community structure of reef fishes associated to artificial patch reef comparing to reef fishes in nearby natural reefs. Assessment of coral reef condition on two habitats were conducted on July 2019, after 4 years deployment.  The results show that artificial patch reefs with a percentage of live coral cover are less than half of natural coral reefs, and have succeeded in increasing the abundance of reef fish with nearly the same density and community structure resembling reef fish in natural coral reefs. The similarity in community structure of the two habitats is probably due to the similarity in habitat type and morphology of the hard corals. The results indicate that Artificial Patch Reef (APR) reefs have increased the coral cover of Acropora branching and resulted in increased reef fish abundance which is compatible with reef fish communities associated with natural coral reefs around it. Aplikasi metode baru terumbu buatan Artificial patch Reef (APR) pada Program Konservasi Bioiversitas Pulau Panjang, Jepara telah dilakukan sejak 2015. Hasil studi menunjukkan bahwa pemilihan desain dan lokasi pemasangan terumbu buatan yang tepat akan meningkatkan kelimpahan ikan karang. Tujuan penelitian ini adalah untuk mengetahui keberhasilan penerapan terumbu buatan APR melalui kelimpahan ikan karang yang berasosiasi pada terumbu buatan dan terumbu karang alami di sekitarnya. Penilaian kondisi terumbu karang tersebut telah dilakukan pada Juli 2019 setelah 4 (empat) tahun pemasangan terumbu buatan. Hasil studi menunjukkan bahwa terumbu buatan dengan persentase tutupan karang hidup lebih kecil, separuhnya dari tutupan pada terumbu karang alami telah berhasil meningkatkan kelimpahan ikan karang dengan densitas hampir sama dan struktur komunitasnya menyerupai ikan karang yang berasosiasi dengan terumbu karang alami. Kesamaan struktur komunitas kedua habitat kemungkinan akibat kesamaan tipe habitat dan morfologi karang keras penyusunya. Hasil ini mengindikasikan bahwa terumbu buatan Artificial patch Reef (APR) telah meningkatkan tutupan karang bercabang Acropora dan berakibat terhadap meningkatnya kelimpahan ikan karang yang sesuai dengan komunitas ikan karang yang berasosiasi dengan terumbu karang alami di sekitarnya.


2018 ◽  
Vol 6 (4) ◽  
pp. 333-338
Author(s):  
Fahmi Fahmi ◽  
Supriharyono Supriharyono ◽  
Abdul Ghofar

Ekosistem terumbu karang merupakan kekayaan sumberdaya laut yang memiliki peranan penting dalam mendukung kehidupan berbagai organisme perairan. Salah satu organisme yang memiliki ketergantungan hidup pada terumbu karang adalah ikan karang. Hal ini dikarenakan ikan karang melalui fase hidup sebagian atau seluruhnya di terumbu karang, sehingga terumbu karang menjadi tempat tinggal, tempat mencari makan, tempat berlindung dan tempat berkembang biak.  Penelitian dilaksanakan pada bulan Mei 2017, dengan tujuan untuk mengetahui persentase tutupan karang hidup dan kelimpahan ikan. Serta hubungan persentase tutupan karang dengan kelimpahan ikan karang pada sisi Barat dan Timur Pulau Menjangan Kecil kedalaman 1 dan 3 meter. Metode yang digunakan adalah metode observasi lapangan, dengan metode sampling menggunakan transek garis (line transect) pada data karang dan visual census untuk data ikan sepanjang 25m. Hasil dari penelitian ini menunjukkan bahwa Persentase rata-rata tutupan karang yang diperoleh pada kedalaman 1 meter sisi Barat adalah 73,39%, sedangkan pada kedalaman 3 meter adalah 85,97%. Persentase tutupan karang pada kedalaman 1 meter sisi Timur adalah 63,73%, sedangkan pada kedalaman 3 meter adalah 77,61%. Secara keseluruhan kondisi terumbu karang masih tergolong baik. Kelimpahan rata-rata ikan pada sisi Barat kedalaman 1 meter adalah 70 individu/125 m2, sedangkan pada kedalaman 3 meter adalah 232 individu/125 m2. Kelimpahan ikan sisi Timur kedalaman 1 dan 3 meter masing-masing adalah 49 dan 138 individu/125 m2. Hasil perhitungan indeks korelasi secara keseluruhan menghasilkan nilai 0,8415 dengan koefesien determinasi sebesar 0,7081. Hal ini menunjukkan bahwa pola hubungan persentase tutupan karang dengan kelimpahan ikan karang kuat (signifikan) dan positif (searah). Coral reef ecosystem is a wealth of marine resources that have an important role in supporting the life of various aquatic organisms. One of the organisms that has a living dependence on coral reefs is reef fish. This is because coral fish through a partial or complete life phase on the coral reef, so that coral reefs become a place to live, a place to find food, shelter and breeding ground. The study was conducted in May 2017, with the objective of knowing the percentage of live coral cover and fish abundance. And the correlation of percentage of coral cover with abundance of reef fish on West and East side of Menjangan Kecil Island depth of 1 and 3 meters. The method used is field observation method, with sampling method using line transect on coral data and visual census for fish data along 25m. The results of this study indicate that the average percentage of coral cover obtained at a depth of 1 meter west side is 73.39%, while at a depth of 3 meters is 85.97%. The percentage of coral cover at depth of 1 meter East side is 63,73%, while at depth 3 meter is 77,61%. Overall the condition of coral reefs is still quite good. The average abundance of fish on the west side of 1 meter depth is 70 individuals / 125 m2, while at 3 meters depth is 232 individuals / 125 m2. The abundance of fish on Eastern side, depth of 1 and 3 meters respectively were 49 and 138 individu / 125 m2. Result of calculation of correlation index as a whole yield value 0,8415 with coefficient of determination equal to 0,7081. This shows that the pattern of correlation of percentage of coral cover with abundance of reef fish is strong (significant) and positive (unidirectional).


Oceans ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 509-529
Author(s):  
Ashani Arulananthan ◽  
Venura Herath ◽  
Sivashanthini Kuganathan ◽  
Anura Upasanta ◽  
Akila Harishchandra

Sri Lanka, an island nation located off the southeast coast of the Indian sub-continent, has an unappreciated diversity of corals and other reef organisms. In particular, knowledge of the status of coral reefs in its northern region has been limited due to 30 years of civil war. From March 2017 to August 2018, we carried out baseline surveys at selected sites on the northern coastline of the Jaffna Peninsula and around the four largest islands in Palk Bay. The mean percentage cover of live coral was 49 ± 7.25% along the northern coast and 27 ± 5.3% on the islands. Bleaching events and intense fishing activities have most likely resulted in the occurrence of dead corals at most sites (coral mortality index > 0.33). However, all sites were characterised by high values of diversity (H’ ≥ 2.3) and evenness (E ≥ 0.8). The diversity index increased significantly with increasing coral cover on the northern coast but showed the opposite trend on the island sites. One hundred and thirteen species of scleractinian corals, representing 16 families and 39 genera, were recorded, as well as seven soft coral genera. Thirty-six of the scleractinian coral species were identified for the first time on the island of Sri Lanka. DNA barcoding using the mitochondrial cytochrome oxidase subunit I gene (COI) was employed to secure genetic confirmation of a few difficult-to-distinguish new records: Acropora aspera, Acropora digitifera, Acropora gemmifera, Montipora flabellata, and Echinopora gemmacea.


2020 ◽  
Vol 24 (1) ◽  
pp. 71-80
Author(s):  
Suparno Suparno ◽  
Yempita Efendi ◽  
Arlius Arlius ◽  
Mas Eriza ◽  
Bukhari Bukhari ◽  
...  

Coral reefs condition in the protected marine area at Selat Bunga has decreased every year.  The health of coral reefs is represented by coral index health. The purpose of this study was to analyze the coral reefs health index based on the condition of live coral cover, resilience level and condition of coral fish. Retrieval of coral reefs data using the Under Photo Transect Method and coral fish data collection using the Under Water Visual Census. The results of research at 9 research stations found that the average cover of live coral ranged from 1.40 - 44.68%, fleshy seaweed ranged from 0.13% - 12.87%, rubble ranged from 1.73 - 39.40%, and average total reef fish biomass ranged from 8.93 - 253.23 kg/ha. Coral reef health index values range between 3-6. Coral reefs health index of 67% of research stations is 3. The coral health index value 3 is indicated by a low percent live coral cover, a high resilience rate, and a low reef fish biomass.Kondisi terumbu karang di Kawasan Konservasi Taman Wisata Perairan (TWP) Selat Bunga Laut  telah mengalami penurunan setiap tahun.  Indeks kesehatan karang adalah nilai yang mengambarkan kesehatan karang antar lokasi penelitian. Tujuan penelitian ini adalah menganalisis indeks kesehatan terumbu karang berdasarkan kondisi tutupan karang hidup,  tingkat resiliensi dan kondisi ikan karang.  Pengambilan data terumbu karang dengan metode Under Photo Transect dan pengambilan data ikan karang mengunakan Under Water Visual Census. Hasil penelitian di 9 stasiun penelitian didapatkan persen rata-rata tutupan karang hidup berkisar  1.40- 44.68 %, fleshy seaweed berkisar  0.13% - 12.87%, pecahan karang berkisar 1.73 –39.40 %, dan rata-rata total biomassa ikan karang berkisar 8.93 – 253.23 kg/ha. Nilai indeks kesehatan terumbu karang berkisar antara 3-6. Sebanyak  67% stasiun penelitian mempunyai indeks kesehatan terumbu karang dengan skala 3. Indeks kesehatan karang skala 3 ditunjukkan  oleh  persen tutupan karang  hidup yang rendah, tingkat resiliensi yang tinggi dan biomassa ikan yang rendah.


2020 ◽  
Vol 3 (1) ◽  
pp. 20-28
Author(s):  
Almaarif ◽  
Joko Samiaji ◽  
Thamrin Thamrin

Coral reefs are one of the ecosystems that have ecological functions for marine life, one of which is reef fish. Coral fish are marine biota that live in association with coral reefs. This study aims to determine the abundance of reef fish, the condition of coral reefs and the relationship between abundance of reef fish and coral reefs. This research was conducted in June 2019 in the waters of Tikus Island, Bengkulu City. The method used is a survey method. Data collection on reef fish was carried out using the Underwater Visual Census (UVC) method and coral reefs condition data colletion is done using the Line Intercept Transect (LIT) method. The abundance of reef fish found at the study site averages in the abundant category. At station I, an abundance of reef fish was 2,18 ind/m2, at station II it was 4,18 ind/m2, and at station III it was 1,27 ind/m2. While the average condition of coral reefs at the study site is include in the medium category. At station I, the percentage of live coral cover was 39,30% or include in the medium category. At station II, the percentage of live coral cover was 50,94% or include in the good category. And at station III, the percentage of live coral cover was 46,32% or include in the medium category. Coral fish and coral reefs have a fairly close relationship. Reef fish use coral reefs as a place to find food, shelter and spawn or breed.


Author(s):  
Mosriula Mosriula

Research on an inventory of damage to coastal and marine ecosystems of the Riau Islands was carried out in the waters of the Berakit Village of Bintan Regency and Pulau Pasir Batam City. The purpose of this study was to obtain data on the status and condition of damage to seagrass coastal marine ecosystems and coral reefs in the two locations. The research period is from May to July 2019. The research method uses 'quadrant line transect' and Underwater Photo Transect and GIS analysis. Distribution of seagrass ecosystems 981.65 Ha, coral reefs 4291.73 Ha in Bintan Regency and Batam City. Berakit Beach seagrass cover has an average of 36.55% in the damaged or less rich / unhealthy category, while 71.02% in the Sand Island is in the dense or rich / healthy category. For live coral cover, Berakit Beach is 42.87% of medium condition category, while Pasir Island has an average of 1-2% of damaged condition category.


Author(s):  
Vincentius P. Siregar ◽  
Sam Wouthuyzen ◽  
Andriani Sunuddin ◽  
Ari Anggoro ◽  
Ade Ayu Mustika

Shallow marine waters comprise diverse benthic types forming habitats for reef fish community, which important for the livelihood of coastal and small island inhabitants. Satellite imagery provide synoptic map of benthic habitat and further utilized to estimate reef fish stock. The objective of this research was to estimate reef fish stock in complex coral reef of Pulau Pari, by utilizing high resolution satellite imagery of the WorldView-2 in combination with field data such as visual census of reef fish. Field survey was conducted between May-August 2013 with 160 sampling points representing four sites (north, south, west, and east). The image was analy-zed and grouped into five classes of benthic habitats i.e., live coral (LC), dead coral (DC), sand (Sa), seagrass (Sg), and mix (Mx) (combination seagrass+coral and seagrass+sand). The overall accuracy of benthic habitat map was 78%. Field survey revealed that the highest live coral cover (58%) was found at the north site with fish density 3.69 and 1.50 ind/m2at 3 and 10 m depth, respectively. Meanwhile, the lowest live coral cover (18%) was found at the south site with fish density 2.79 and 2.18  ind/m2 at 3 and 10 m depth, respectively. Interpolation on fish density data in each habitat class resulted in standing stock reef fish estimation:  LC (5,340,698 ind), DC (56,254,356 ind), Sa (13,370,154 ind), Sg (1,776,195 ind) and Mx (14,557,680 ind). Keywords: mapping, satellite imagery, benthic habitat, reef fish, stock estimation


2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Mahmudin Mahmudin ◽  
Chair Rani ◽  
Hamzah Hamzah

Dynamite fishing is one of the causes of damage to the coral reef ecosystem in Indonesia. Fishing activities using explosives (dynamite fishing) occur because of the desire of fishermen to get a lot of catch with low cost in a short time. Kapoposang Water Park (WP) is a region rich in marine biological resources. However, dynamite fishing activities which are still found within the area have caused the coral reef ecosystem to be severely damaged. The results showed a lower difference in the percentage of live coral cover at dynamite fishing locations (DF1, DF2) compared to control locations (K1, K2). In addition, the highest average values of coral fish abundance were found at locations K1, DF1, and DF2. Conversely, the results of the analysis found the lowest fish abundance at the K2 location. Different from the average number of reef fish species that were higher at the control location (K1, K2) compared to dynamite fishing locations (DF1, DF2). For the target fish biomass there is no real difference between the control location and dynamite fishing.


2021 ◽  
Vol 324 ◽  
pp. 03007
Author(s):  
Ni Wayan Purnama Sari ◽  
Rikoh Manogar Siringoringo ◽  
Muhammad Abrar ◽  
Risandi Dwirama Putra ◽  
Raden Sutiadi ◽  
...  

Observations of the condition of coral reefs have been carried out in Spermonde waters from 2015 to 2018. The method used in this observation uses Underwater Photo Transect (UPT), and the data obtained is analyzed using CPCe (Coral Point Count with Excel Extensions) software. The results show that the percentage of coral cover has increased from year to year. The percentage of live coral cover in 2015 was 19.64%, 23.60 in 2016, 23.72% in 2017, and 27.83% in 2018. The increase in live coral cover from year to year is thought to occur due to the availability of nutrients. or increasing public awareness, considering this location is one of the most famous tourist attractions in Makassar. Coral reef health index values can be used to classify coral reef health. Through the analysis of the coral reef health index, an index value of 4 was obtained, which means that the condition of the coral reefs is in the “moderate” category.


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