Assessing range shifts of tropical reef fishes: a comparison of belt transect and roaming underwater visual census methods

2014 ◽  
Vol 90 (2) ◽  
pp. 705-721 ◽  
Author(s):  
Hayden J Beck ◽  
David A Feary ◽  
William F Figueira ◽  
David J Booth
Keyword(s):  
Reef Fishes ◽  
Range Shifts ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Census Methods ◽  
Tropical Reef ◽  
Belt Transect

scholarly journals Comparing environmental DNA metabarcoding and underwater visual census to monitor tropical reef fishes

2020 ◽  
Author(s):  
Andrea Polanco Fernández ◽  
Virginie Marques ◽  
Fabian Fopp ◽  
Jean‐Baptiste Juhel ◽  
Giomar Helena Borrero‐Pérez ◽  
...  
Keyword(s):  
Environmental Dna ◽  
Reef Fishes ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Dna Metabarcoding ◽  
Tropical Reef

scholarly journals HUBUNGAN ANTARA KOMPOSISI IKAN TARGET DAN PRESENTASE TUTUPAN KARANG HIDUP DI KEPULAUAN KEI KECIL, MALUKU

2020 ◽  
Vol 26 (3) ◽  
pp. 147
Author(s):  
Ana Faricha ◽  
Isa Nagib Edrus ◽  
Rizkie Satriya Utama ◽  
Ahmad R. Dzumalex ◽  
Abdullah Salatalohi ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fishes ◽  
Average Density ◽  
Species Variation ◽  
Live Coral ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Ecological Values ◽  
Average Biomass ◽  
The Relationship

Ikan terumbu karang memiliki peranan penting baik secara ekonomi maupun ekologi, namun kondisi terumbu karang termasuk di perairan Indonesia yang menjadi habitat utama ikan karang mengalami degradasi. Penelitian ikan karang sudah banyak dilakukan, namun di Indonesia kondisi habitat ikan karang memiliki karakter yang berbeda-beda. Tujuan penelitian ini adalah untuk mengetahui hubungan antara komposisi ikan karang target dan tutupan karang hidup. Penelitian ini dilakukan pada bulan Oktober 2019 di Kepulauan Kei Kecil, Maluku. Metode yang digunakan adalah UVC (Underwater Visual Census) untuk data ikan karang dan UPT (Underwater Photo Transect) untuk mengkaji tutupan karang hidup. Hasil pengamatan menunjukkan bahwa terdapat 130 spesies ikan karang target yang mewakili 19 famili, dengan variasi jenis ikan target antar lokasi pengamatan berkisar antara 25-66 spesies. Kepadatan rata-rata ikan karang target sebesar 8.811 ± 4.107 Ind/ha, dan biomassa rata-rata 1.335 ± 899 Kg/ha. Komposisi ikan karang target yang memiliki kedekatan dengan tutupan karang hidup yaitu famili Siganidae, Serranidae, Lutjanidae, Holocentridae, dan Pomacentridae. Akan tetapi hubungan tersebut rendah, dan kemungkinan besar ada faktor lain yang mempengaruhi. Reef fishes have an important economic and ecological values. However, the coral reef of the globe including in the most of the Indonesian waters which is the vital habitat for reef fishes is degraded. Study on the reef fishes is an abundance, while the habitat characteristic of reef fishes in Indonesian waters has a differences. The aim of this study is to determine the relationship between the target reef fishes compositions and the percentage live coral covers. This study was carried out in October 2019 at the Kei Kecil islands, Maluku. The method used in this study is UVC (Underwater Visual Census) for collecting the reef fishes data, and the UPT (Underwater Photo Transect) for assessing the live coral coverage. The result shows that there are about 130 fishes, which representing 19 families, with species variation ranges from 25 to 66 species among the observation sites. The average density of target fishes was about 8.811 ± 4.107 Ind/ha, whereas the average biomass of target fishes was 1,335 ± 899 Kg/ha. The target reef fishes compositions that has relation with live coral covers is family Siganidae, Serranidae, Lutjanidae, Holocentridae, and Pomacentridae. However, this relationship is weak, and may influenced by other factors.

scholarly journals Effect of underwater visual survey methodology on bias and precision of fish counts: a simulation approach

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5378 ◽  
Author(s):  
Miguel Pessanha Pais ◽  
Henrique N. Cabral
Keyword(s):  
Survey Methodology ◽  
Rotation Speed ◽  
General Point ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Factors Affecting ◽  
Point Counts ◽  
Mobile Species ◽  
Census Methods ◽  
Length Width

Bias in underwater visual census has always been elusive. In fact, the choice of sampling method and the behavioural traits of fish are two of the most important factors affecting bias, but they are still treated separately, which leads to arbitrarily chosen sampling methods. FishCensus, a two-dimensional agent-based model with realistic fish movement, was used to simulate problematic behavioural traits in SCUBA diving visual census methods and understand how sampling methodology affects the precision and bias of counts. Using a fixed true density of 0.3 fish/m2 and a fixed visibility of 6 m, 10 counts were simulated for several combinations of parameters for transects (length, width, speed) and point counts (radius, rotation speed, time), generating trait-specific heatmaps for bias and precision. In general, point counts had higher bias and were less precise than transects. Fish attracted to divers led to the highest bias, while cryptic fish had the most accurate counts. For point counts, increasing survey time increased bias and variability, increasing radius reduced bias for most traits but increased bias in the case of fish that avoid divers. Rotation speed did not have a significant effect in general, but it increased bias for fish that avoid divers. Wider and longer transects and a faster swim speed are beneficial when sampling mobile species, but a narrower, shorter transect with a slow swim is beneficial for cryptic fish.

Compensating for length biases in underwater visual census of fishes using stereo video measurements

2015 ◽  
Vol 66 (3) ◽  
pp. 286 ◽  
Author(s):  
Tom Davis ◽  
David Harasti ◽  
Stephen D. A. Smith
Keyword(s):  
Marine Protected Areas ◽  
Reef Fishes ◽  
Fish Length ◽  
Correction Factors ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Observer Bias ◽  
Stereo Video ◽  
Non Destructive ◽  
Specific Correction

Underwater visual census (UVC) is a widely used technique for estimating species richness, abundance, and lengths of reef fishes. The technique has the advantage of being non-destructive, and can therefore be used for monitoring in marine protected areas. However, acquisition of robust data using UVC is reliant on the ability of individual divers to accurately identify fish, and estimate their lengths. Both of these variables can be affected by observer bias, which may also differ among observers. This study examines a technique with the potential to quantify and correct for observer bias in individual divers. We used simultaneous diver-operated stereo video and underwater visual census surveys, and compared the results to generate diver-specific correction factors. These correction factors were subsequently applied in additional estimates of fish length, with measurable improvement in the accuracy of the data.

scholarly journals Analisis Kelimpahan dan Identifikasi Predator Abalon (Haliotis squamata) di Pantai Geger, Nusa Dua, Bali

2020 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Jefry Cristian Bulan ◽  
I Gede Hendrawan ◽  
Ni Luh Putu Ria Puspitha
Keyword(s):  
Visual Census ◽  
Underwater Visual Census ◽  
Belt Transect

Penelitian ini dilakukan di Pantai Geger, Nusa Dua, Bali selama 30 hari. Tujuan penelitian ini adalah mengetahui kelimpahan predator abalon Haliotis squamata di Pantai Geger, Nusa Dua, Bali dan mengetahui jenis-jenis predator abalon Haliotis squamata. Metode yang digunakan adalah Underwater Visual census dengan menggunakan belt transect sepanajng 50 meter dengan jarak sebelah kiri 2,5 meter dan sebelah kanan 2,5 meter dengan luas arae total 250 m2 . Penelitian ini dilakuakan di 3 titik berbeda dengan tambahan area drum abalon sebagai pengamatan predator abalon lebih spesifik dengan bantuan kamera. Hasil dari penelitian ini ditemukannya predator morey eel (Gymnothorax thyrsoideus) pada arae dalam drum abalon Haliotis squamata dan pada area transek ditemukan morey eel (Gymnothorax thyrsoideus) dan Epinephelus sp. Hasil kelimpahan predator pada titik 1 didapat sebesar 0,0053 individu/m2  untuk jenis Gymnhotorax thyrsoideus dan untuk jenis Epinephelus sp memiliki nilai sebesar 0,0013 individu/m2, pada titik 2 adalah sebesar 0,013 individu/m2 untuk jenis Gymnhotorax thyrsoideus dan untuk jenis Epinephelus sp memiliki nilai sebesar 0,040 individu/m2, pada titik 3 adalah sebesar 0,027 individu/m2  untuk jenis Gymnhotorax thyrsoideus dan untuk jenis Epinephelus sp memiliki nilai sebesar 0,0013 individu/m2

Locating faunal breaks in the nearshore fish assemblage of Victoria, Australia

2012 ◽  
Vol 63 (3) ◽  
pp. 218 ◽  
Author(s):  
Madhavi A. Colton ◽  
Stephen E. Swearer
Keyword(s):  
Global Climate ◽  
Range Shifts ◽  
Effective Management ◽  
Underwater Video ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Study Region ◽  
Marine Communities ◽  
Eastern Australia ◽  
Distance Data

Marine communities are frequently biogeographically structured, despite the potential for dispersal. Previous research on a variety of marine taxa in south-eastern Australia has suggested that a biogeographic break occurs along the coastline of Victoria. However, little of this research has focussed on nearshore ichthyofauna and the location of the break remains debated. Using fish abundance measured by two methods: underwater visual census (UVC); and baited remote underwater video (BRUV) at six locations along the open coast of Victoria, we examined (1) whether there is sufficient concordance among species to indicate the presence of a faunal break; and if present (2) where any such breaks occur. Differences in assemblage composition between locations were tested with analyses of similarity and examination of residuals from regressions of pairwise dissimilarities against coastline distance. Data collected using UVC revealed two large faunal breaks co-located with a habitat discontinuity, the convergence of two currents and a thermal gradient. Data collected by BRUV revealed only a gradation of change across the study region. Greater understanding of the biogeographic structure of these communities will facilitate more effective management, especially in light of anticipated range shifts in response to global climate change.

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