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.

scholarly journals The importance of oceanic atoll lagoons for coral reef predators

2020 ◽  
Vol 167 (2) ◽  
Author(s):  
Christina Skinner ◽  
Aileen C. Mill ◽  
Steven P. Newman ◽  
S. Nadia Alsagoff ◽  
Nicholas V. C. Polunin
Keyword(s):  
Dominant Species ◽  
Outer Edge ◽  
Ecological Role ◽  
Underwater Video ◽  
Visual Census ◽  
Outer Reef ◽  
Underwater Visual Census ◽  
Body Sizes ◽  
Lagoonal Habitat ◽  
Depth And Complexity

AbstractPredators on coral reefs play an important ecological role structuring reef fish communities and are important fishery targets. It is thought that reef predator assemblages increase in density and diversity from inner lagoonal to outer edge reefs. Oceanic atolls may differ though, as nutrients are available throughout. Reef predator populations are declining, but there is little known about how their distributions may vary across oceanic atolls. Using a combination of underwater visual census and baited remote underwater video, this study aimed to compare reef predator populations between inner and outer reefs of North Malé Atoll (Maldives) and determine which reef metrics may drive any differences in assemblage structure. We found that predator assemblages were significantly different between inner and outer atoll. Body sizes of several predator families were consistently larger in the outer atoll, however, abundance, biomass and species richness were similar between outer edge reefs and inner lagoonal reefs suggesting atoll lagoons may be undervalued habitats. Depth and complexity were consistently important predictors of the predator assemblage. Inner atoll lagoonal habitat is equally as important for reef predator assemblages as outer reef slopes, although the dominant species differ. This study provides important information on reef predator populations in the Maldives, where detailed assessments of the reef predator assemblage are lacking but the reef fishery is thriving and annual catch will continue to increase.

scholarly journals Performance of a baited underwater video system vs. the underwater visual census technique in assessing the structure of fish assemblages in a Mediterranean marine protected area

2021 ◽  
Vol 22 (3) ◽  
pp. 480
Author(s):  
GABRIELLA LA MANNA ◽  
IVAN GUALA ◽  
DANIELE GRECH ◽  
FRANCESCO PERRETTI ◽  
FABIO RONCHETTI ◽  
...  
Keyword(s):  
Species Richness ◽  
Protected Area ◽  
Fish Assemblages ◽  
Marine Protected Area ◽  
Fish Fauna ◽  
Underwater Video ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Species Richness And Abundance ◽  
High Level

Accurate, rapid and cost-effective fish assemblage monitoring is fundamental for marine protected area (MPA) management as a pivotal tool to verify whether and to what extent MPA conservation objectives have been achieved and to redefine these objectives in the framework of an adaptive management. Recently, there has been a sharp increase in the number of video-based methods to study fish fauna, such as baited remote underwater video (BRUV) systems, that, depending on the objectives of the monitoring, can provide complementary or additional data to the more commonly used underwater visual census (UVC). Even though BRUV systems have been widely used in a wide range of geographic contexts and habitats, their use in the Mediterranean basin is still sporadic and the evaluation of the efficiency of BRUV systems and whether they can be used to complement other techniques needs investigation. Thus, the objective of this study was to assess the performance of a BRUV system in a Mediterranean MPA and to evaluate its effectiveness in assessing the structure of fish assemblages (abundance and species richness) by comparing estimates with those obtained by the UVC technique. The fish fauna were monitored by BRUV and UVC in the Capo Caccia – Isola Piana Marine Protected Area (Sardinia, Italy), in July and October-November 2020, at four sampling sites and two areas, hundreds of meters apart, for each site. Overall, 46 taxa and a total of 3620 individuals were observed by BRUV, while 36 taxa and a total of 2995 individuals were observed by UVC. The species first observed in front of the camera’s field of view and able to reach the maximum abundance were the planktivores (Chromis chromis and Oblada melanura) followed by several carnivorous species belonging to the families Labridae, Serranidae and Sparidae, and lastly two carnivores (Mullus surmuletus and Mugilidae spp.) and some high-level predators (Dentex dentex, Seriola dumerili, Sphyraena viridensis, Dicentrarchus labrax). The maximum species richness and abundance were reached between 39 and 50 min. The cumulative species richness increased until around 30 min. Species richness was higher during the BRUV compared to the UVC monitoring. The consistency in findings between BRUV and UVC and a better performance of BRUV in detecting some species (mainly high-level predators), supports BRUV as an additional technique for describing and quantifying species richness and abundance also in the Mediterranean Sea. Based on the results of this study, the advantages/disadvantages, shortcomings, suggestions and resources needed for the two techniques are outlined.

Asosiasi ikan pada terumbu buatan di Teluk Tahuna Kabupaten Kepulauan Sangihe

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Wenseslaus Fransiscus Makawaehe ◽  
Lefrand Manoppo ◽  
Revols D.Ch. Pamikiran
Keyword(s):  
Visual Census ◽  
Underwater Visual Census ◽  
Scuba Divers

Minimnya pengetahuan tentang ekologi terumbu buatan merupakan inti masalah perdebatan penggunaannya dalam manajemen sumberdaya perikanan; dan membatasi aplikasi habitat buatan tersebut sebagai alat mitigasi pada berbagai kerusakan lingkungan. Pemahaman ekologi yang lebih baik akan menuntun pada pembuatan desain dan penggunaan struktur buatan secara lebih efektif dan efisien. Hal ini juga akan menjawab pertanyaan tentang manfaat konstruksi habitat buatan pada berbagai kondisi lingkungan. Asosiasi ikan di terumbu buatan bervariasi, namun perlu dilakukan perbandingan jenis ikan yang berasosiasi pada saat air pasang dan air surut. Oleh karena itu penelitian ini bertujuan untuk Membandingkan struktur asosiasi ikan di terumbu buatan pada saat air pasang naik dan pasang surut di perairan Teluk Tahuna. Penelitian ini dilakukan di perairan Teluk Tahuna, Kabupaten Kepulauan Sangihe pada bulan April–Juni 2015; yang didasarkan pada metode deskriptif. Asosiasi ikan di terumbu buatan diamati dengan teknik Underwater visual census (UVC) oleh dua orang SCUBA divers sebanyak 4 kali. Kelimpahan spesies ikan di terumbu buatan dianalisis dengan indeks keragaman dan indeks dominansi. Berdasarkan jumlah individu total ikan yang berasosiasi dengan terumbu buatan, maka nilai tertinggi terdapat pada bulan purnama saat pasang tertinggi (156 ekor), kemudian diikuti bulan kuartir pasang tertinggi (120 ekor), bulan purnama surut terendah (107 ekor) dan bulan kuartir surut terendah (103 ekor). Keanekaragaman spesies ikan, baik pada bulan kuartir maupun pada bulan purnama masih tergolong sedang dan dominansi spesies tergolong rendah

scholarly journals Future Australian Severe Thunderstorm Environments. Part II: The Influence of a Strongly Warming Climate on Convective Environments

2014 ◽  
Vol 27 (10) ◽  
pp. 3848-3868 ◽  
Author(s):  
John T. Allen ◽  
David J. Karoly ◽  
Kevin J. Walsh
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Vertical Wind Shear ◽  
Atmospheric Model ◽  
Global Climate Models ◽  
Historical Period ◽  
Severe Thunderstorm ◽  
Warming Climate ◽  
Eastern Australia

Abstract The influence of a warming climate on the occurrence of severe thunderstorm environments in Australia was explored using two global climate models: Commonwealth Scientific and Industrial Research Organisation Mark, version 3.6 (CSIRO Mk3.6), and the Cubic-Conformal Atmospheric Model (CCAM). These models have previously been evaluated and found to be capable of reproducing a useful climatology for the twentieth-century period (1980–2000). Analyzing the changes between the historical period and high warming climate scenarios for the period 2079–99 has allowed estimation of the potential convective future for the continent. Based on these simulations, significant increases to the frequency of severe thunderstorm environments will likely occur for northern and eastern Australia in a warmed climate. This change is a response to increasing convective available potential energy from higher continental moisture, particularly in proximity to warm sea surface temperatures. Despite decreases to the frequency of environments with high vertical wind shear, it appears unlikely that this will offset increases to thermodynamic energy. The change is most pronounced during the peak of the convective season, increasing its length and the frequency of severe thunderstorm environments therein, particularly over the eastern parts of the continent. The implications of this potential increase are significant, with the overall frequency of potential severe thunderstorm days per year likely to rise over the major population centers of the east coast by 14% for Brisbane, 22% for Melbourne, and 30% for Sydney. The limitations of this approach are then discussed in the context of ways to increase the confidence of predictions of future severe convection.

scholarly journals Complementarity of Rotating Video and Underwater Visual Census for Assessing Species Richness, Frequency and Density of Reef Fish on Coral Reef Slopes

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e84344 ◽  
Author(s):  
Delphine Mallet ◽  
Laurent Wantiez ◽  
Soazig Lemouellic ◽  
Laurent Vigliola ◽  
Dominique Pelletier
Keyword(s):  
Species Richness ◽  
Coral Reef ◽  
Reef Fish ◽  
Visual Census ◽  
Underwater Visual Census
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