scholarly journals Colour thresholds in a coral reef fish

2016 ◽  
Vol 3 (9) ◽  
pp. 160399 ◽  
Author(s):  
C. M. Champ ◽  
M. Vorobyev ◽  
N. J. Marshall
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Colour Vision ◽  
Visible Spectrum ◽  
Reef Fishes ◽  
Colour Discrimination ◽  
Visual Model ◽  
The World ◽  
Different Parts ◽  
Receptor Noise

Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are ‘tuned’ differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish. Here, the coral reef associated triggerfish, Rhinecanthus aculeatus , was tested behaviourally to determine the limits of its colour vision. This is the first demonstration of behavioural colour discrimination thresholds in a coral reef species and is a critical step in our understanding of communication and speciation in this vibrant colourful habitat. Fish were trained to discriminate between a reward colour stimulus and series of non-reward colour stimuli and the discrimination thresholds were found to correspond well with predictions based on the receptor noise limited visual model and anatomy of the eye. Colour discrimination abilities of both reef fish and a variety of animals can therefore now be predicted using the parameters described here.

scholarly journals Condition of Coral Fish in Tapanuli Tengah Waters

2018 ◽  
Vol 3 (2) ◽  
pp. 105
Author(s):  
Sasanti Retno Suharti ◽  
Isa Nagib Edrus
Keyword(s):  
Community Structure ◽  
Coral Reef ◽  
Coral Reefs ◽  
Reef Fish ◽  
Reef Fishes ◽  
The Other ◽  
Human Being ◽  
The World ◽  
Coral Fish ◽  
Complex Architecture

Coral reefs is a center for biodiversity in the world with a complex architecture and has an aesthetics value. It also offers beneficial for human being in many aspects such as economics, social and culture. Research was conducted in July 2016 and aim to understand community structure and biomass of coral reef fishes in Tapanuli Tengah waters. Result from all stations in Tapanuli Tengah waters showed that 49 species from seven families of economically reef fish i.e.  Acanthuridae, Serranidae, Haemulidae, Lutjanidae, Lehtrinidae, Siganidae and Scaridae were found. Density average of those seven families was 163 individual/350 m<sup>2</sup> or 4668 individual/ha with biomass average of 1.564 ton/ha. Moreover, biomass from other target fishes from nine families was accounted as 0.56 ton/ha. On the other hand, over all coralifore fish represented by Chaetodontidae was eight species from two genus, namely <em>Chaetodon</em> and <em>Heniochus </em>with four species. The density from family Chaetodotidae varies among station between 3-28 individual/350 m<sup>2</sup>

scholarly journals Colour vision and information theory: the receptor noise-limited model implies optimal colour discrimination by opponent channels

2020 ◽  
Author(s):  
Sebastián Risau-Gusman
Keyword(s):  
Colour Vision ◽  
Theoretical Models ◽  
Ideal Observer ◽  
Discrimination Function ◽  
Colour Discrimination ◽  
Biologically Relevant ◽  
Visual Systems ◽  
The World ◽  
The One ◽  
Receptor Noise

AbstractIn order to interpret animal behaviour we need to understand how they see the world. As colour discrimination is almost impossible to test directly in animals, it is important to develop theoretical models based in the properties of visual systems. One of the most successful is the receptor noise-limited (RNL) model, which depends only on the level of noise in photoreceptors and opponent mechanisms. Here optimal colour discrimination properties are obtained using information theoretical tools, for the early stages of visual systems with and without colour opponent mechanisms. For most biologically relevant conditions the optimal discrimination function of an ideal observer coincides with the one obtained with the RNL model. Many variants of the model can be cast into the same framework, which permits meaningful comparisons across species. For example, it is shown that the presence of opponency seems to be the preferred hypothesis for bees, but not for budgerigars. Since this is a consequence of the presence of oil droplets, this could also be true for most other species of birds.

scholarly journals Thresholds and noise limitations of colour vision in dim light

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160065 ◽  
Author(s):  
Almut Kelber ◽  
Carola Yovanovich ◽  
Peter Olsson
Keyword(s):  
Shot Noise ◽  
Colour Vision ◽  
Absolute Threshold ◽  
Colour Discrimination ◽  
Dark Noise ◽  
Visual Threshold ◽  
Light Intensities ◽  
Purkinje Shift ◽  
Dim Light ◽  
Receptor Noise

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod–cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones. This article is part of the themed issue 'Vision in dim light’.

scholarly journals Colour vision and response bias in a coral reef fish

2013 ◽  
Vol 216 (15) ◽  
pp. 2967-2973 ◽  
Author(s):  
K. L. Cheney ◽  
C. Newport ◽  
E. C. McClure ◽  
N. J. Marshall
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Response Bias ◽  
Coral Reef Fish ◽  
Colour Vision

6. Reef fish and other major predators

2014 ◽  
Author(s):  
Charles Sheppard
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Reef Fish ◽  
Feeding Ecology ◽  
Natural Habitat ◽  
Marine Species ◽  
Reef Fishes ◽  
Symbiotic Relationships ◽  
The Earth ◽  
Reef Communities

Healthy reefs provide a habitat for an immense number of fish that come in a variety of shapes, sizes, and colours. No other natural habitat in the ocean shows this diversity and abundance. About a quarter of all marine species may be found on coral reefs even though this habitat occupies only one or two per cent of the area of the earth. ‘Reef fish and other major predators’ describes the diverse feeding ecology of reef fishes; coral reef predators such as the colourful crown of thorns starfish, Acanthaster plancii; symbiotic relationships between different species of fish or with different invertebrates; and the dangers of overfishing in reef communities.

scholarly journals DNA-based identification of predators of the corallivorous Crown-of-Thorns Starfish (Acanthaster cf. solaris) from fish faeces and gut contents

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Frederieke J. Kroon ◽  
Carine D. Lefèvre ◽  
Jason R. Doyle ◽  
Frances Patel ◽  
Grant Milton ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Fish Species ◽  
Coral Reef Fish ◽  
Coral Cover ◽  
Fish Predation ◽  
Reef Fishes ◽  
Positive Control ◽  
Gut Contents ◽  
Reef Fish Species

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.

scholarly journals Olfactory responses of coral-reef fishes to coral degradation and crown-of-thorns (Acanthaster planci)

2016 ◽  
Vol 67 (5) ◽  
pp. 605 ◽  
Author(s):  
Amy G. Coppock ◽  
Naomi M. Gardiner ◽  
Geoffrey P. Jones
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Chemical Cues ◽  
Fish Assemblages ◽  
Reef Fishes ◽  
Live Coral ◽  
Acanthaster Planci ◽  
Olfactory Responses ◽  
Olfactory Stimuli ◽  
Coral Reef Ecosystems

Coral degradation is a major threat towards the biodiversity of coral-reef ecosystems, either through the physical effects of environmental change, or biological agents such as crown-of-thorns (Acanthaster planci). Coral loss is leading to significant declines in reef-fish assemblages, particularly those dependent on live coral as settlement sites. Most reef fishes use olfactory stimuli at settlement; however, their ability to detect chemical stimuli from degraded corals or A. planci is unknown. Here, olfactory responses of juvenile reef fishes to the presence of stressed corals and A. planci were tested. Juveniles of eight common coral-associated species were subjected to a series of pair-wise choice tests, where the period of time spent in two differing water sources was noted. All species demonstrated a significant attraction towards healthy coral (≥76%), avoiding cues emitted by stressed coral colonies. When given the choice between a control water (untreated reef water) and water containing chemical cues from A. planci, most species elicited no response. Finally, when given the choice between chemical cues derived from feeding A. planci or the control, all species avoided A. planci (≥70%). Our results indicated that juvenile reef fish are capable of distinguishing the state of coral health, but not directly from disturbance agents.

scholarly journals Coral Fishes in Coral Reef Waters of Sub District Maba, East Halmahera egency North Maluku Province

2014 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Ari Rondonuwu
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Diversity Index ◽  
Economic Value ◽  
Reef Fishes ◽  
Visual Census ◽  
Transect Line ◽  
Species Population ◽  
Target Fish ◽  
Species Richness And Abundance

This study aims to determine the distribution and abundance of reef fish in coral reef waters of Sub District Maba and was conducted at 10 stations. Data were collected by conducting visual census on the 50-meter transect line at 5 meters depth. In addition to revealing the number of species and abundance of coral fishes, data were analyzed to determine the diversity index (Shannon-Wiener). Based on field observations, most of the reef fishes  found in the Sub-district of Maba surrounding waters are being categorized to have less potential category (50%);  fair potential (41.67%); potential (8:33%); and  there is no population being classified in very potential category. Several locations have the potential reef fish condition were Jara-jara Cape, Gee Island, and Para-para Island.  Based on the existence of the target species population, in term of species richness and abundance, it is assumed that largely dominated by the target fish species that has low economic value. On the other hand target fish that has high economic value only consists of few species such as grouper, jacks, sweetlips, and snappers.   Keywords : coral fishes,  coral reef, sub district maba ABSTRAK Penelitian ini bertujuan untuk mengetahui distribusi dan kelimpahan ikan karang di perairan terumbu karang Kecamatan Maba. Penelitian dilakukan di 10 lokasi. Pengambilan data dilakukan dengan metode sensus visual pada transek garis sepanjang 50 meter, kedalaman 5 meter. Selain mengungkapkan jumlah spesies dan kelimpahan individu, analisis data diarahkan untuk mengetahui indeks keanekeragaman (Shannon-Wiener).  Berdasarkan hasil pengamatan, sebagian besar sumberdaya ikan karang di wilayah Kecamatan Maba, telah masuk dalam kategori kurang potensial (50 %); cukup potensial (41,67 %); potensial (8.33%); dan tidak ada yang tergolong dalam kategori sangat potensial.  Lokasi-lokasi yang memiliki kondisi ikan karang yang potensial,  Tanjung Jara-jara, Pulau Gee, dan Pulau  Para-para. Keberadaan populasi spesies target, baik kekayaan spesies maupun kelimpahan individu, ternyata sebagian besar didominasi oleh jenis ikan target yang bernilai ekonomi/pasar rendah.  Beberapa jenis ikan yang memiliki nilai ekonimis penting ditemukan  seperti, kerapu, Sweetlips (bibir manis), Bobara, dan kakap. Keywords : coral fishes,  coral reef, sub district maba

scholarly journals DIVERSITY OF REEF FISH FUNGSIONAL GROUPS IN TERMS OF CORAL REEF RESILIENCES

2017 ◽  
Vol 22 (2) ◽  
pp. 109
Author(s):  
Isa Nagib Edrus ◽  
Muhammad Abrar Abrar
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Functional Groups ◽  
Data Gathering ◽  
Reef Fishes ◽  
Fish Diversity ◽  
Infrastructure Development ◽  
Management Actions ◽  
Resilience Indicators

Infrastructure development in the particular sites of  Seribu Islands as well as those in main land of Jakarta City increased with coastal population this phenomenon is likely to increase the effects to the adjacent coral waters of Seribu Islands.  Chemical pollutants, sedimentation, and domestic wastes are the common impact and threatening, the survival of coral reef ecosystem. Coral reef resiliences naturaly remained on their processes under many influences of supporting factors. One of the major factor is the role of reef fish functional groups on controling algae growth to recolonize coral juveniles. The  aim of this study to obtain data of a herbivory and other fish functional groups of reef fishes in the Pari Islands that are resilience indicators, or that may indicate the effectiveness of management actions. A conventional scientific approach on fish diversity and abundance data gathering was conducted by the underwater visual cencus. Diversity values of the reef fish functional groups, such as the abundance of individual fish including species, were collected and tabulated by classes and weighted as a baseline to understand the resilience of coral reed based on Obura and Grimsditch (2009) techniques. The results succesfully identified several fish functional groups such as harbivores (21 species), carnivores (13 species) and fish indicator (5 species) occurred in the area. Regarding the aspects of fish density and its diversity, especially herbivorous fish functional group, were presumably in the state of rarely available to support the coral reef resiliences. Resilience indices ranged from 1 (low level) to 3 (moderate level) and averages of the quality levels ranged from 227 to 674. These levels were inadequate to support coral reef recolonization.

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