220
role in the immunity of corals, which requires further investigations. This evidence complements recent findings on
White Syndrome agents and allows a glimpse into functional
roles of microbial components in coral holobiont ecology.
8.2.4 Attached or Hanging: Does Maintenance
Method Affect the Response of Pocillopora
damicornis to Thermal Stress?
Sofia Afoncheva
1*
, Pia Kegler
1,2
, Andreas Kunzmann
1
1
Leibniz Centre for Tropical Marine Research,
Fahrenheitstraße 6, 28359 Bremen, Germany
2
CORESea, Chaloklam 94 Moo 7 Koh Phangan, 84280
Surat Thani, Thailand
*corresponding author: sofiyaaf@gmail.com
Keywords: Thermal stress, Coral aquaculture, Coral
fragments
Scleractinian corals are in high demand for marine ornamental trade, reef restoration and bioprospecting. These
activities require regular supply with live corals. In order to
reveal the most efficient method to grow corals in captivity
two different maintenance methods (attached vs. hanging
coral fragments) for fragments of the hermatypic coral
Pocillopora damicornis were compared in response to thermal stress and with regard to the feeding status (fed vs. nonfed). The results showed that respiration was affected by the
maintenance method. Oxygen consumption in attached corals under 30 °C was 26% higher than in hanging corals
whereas hanging fragments did not show acute response to
temperature stress. Physiological parameters (photosynthesis, quantum yield, Chl a, zooxanthellae density, protein content) were not influenced by maintenance method but were
affected by availability of food. Fed fragments maintained a
higher Chl a concentration, symbiont density and protein
content compared to the non-fed ones. Concentration of Chl
a was inversely correlated with fragments’ weight due to the
higher skeleton to tissue ratio in the bigger fragments.
Growth rates of the smaller fragments tended to be higher
than in the bigger ones due to higher metabolic rates and
lower absolute energy demands. Despite of the benefits of
the hanging method for coral growth in the field nurseries
(higher growth rates, resistance to diseases), in closed systems coral growth does not change significantly regardless
which maintenance method is applied. When choosing an
appropriate maintenance method for coral culture in closed
systems several things should be considered: the size of
facilities, number of fragments and individual preferences of
the coral grower between easy-to-handle options or higher
ability to tissue recovery and resistance of corals to
biofouling.
8.2.5 Underwater Vision: How a Coral Reef Fish
(Rhinecanthus aculeatus) Discriminates Color
Emily F. Guevara
1,2,3*
, Naomi F. Green
1
, Andreas Kunzmann
3
,
N. Justin Marshall
4
Karen L. Cheney
1
1
School of Biological Sciences, University of Queensland,
Brisbane, QLD 4072, Australia
2
Universität Bremen, Bibliothekstr. 1, 28359, Bremen,
Bremen, Germany
3
Leibniz-Zentrum für Marine Tropenforschung (ZMT),
Fahrenheitstr. 6, 28359 Bremen, Germany
4
Queensland Brain Institute, University of Queensland,
Brisbane, QLD 4072, Australia
*corresponding author: Emily.guevara1@gmail.com
Keywords: Color thresholds, Visual modeling, Receptor
noise, Neurobiology
Healthy coral reefs are extremely colorful, chaotic, and
dappled environments, cast under a constant flicker of incident sunlight that poses a particular challenge for visual
navigation – a challenge that has been brilliantly solved
using color vision. Color vision is finely tuned and indispensable to identify conspecifics, attract mates, deter or
elude predators, and to find food and shelter. Many shallow
reef fish are trichromats, creating color images much like
humans, by combining light information from three types of
color-sensing ‘cone’ cells in downstream neural opponency
mechanisms. The ability to detect and discriminate colors is
therefore determined by a combination of light availability,
receptor sensitivity, and neural processing capability. We use
visual modeling to investigate the latter; to understand the
processes that underlie color vision. However, these models
rely on key assumptions about animal visual systems that
must be calibrated with behavioral testing – a rarity in the
literature. Our aim is to understand how animals distinguish
color, by examining behavioral threshold differences: when
are two colors different enough to be considered independent? This study is part of the most comprehensive color
vision test that has ever been done on a non-human vertebrate, and uses a new and exciting way to test color vision in
animals that is based on the Ishihara method for human color
blindness tests. Picasso triggerfish show an outstanding ability to generalize across colors, performing remarkably well
in odd-one-out tasks. We therefore trained them to identify a
target spot that differs from a background of spots in either
saturation or hue. Using the Receptor Noise Limited model,
we found that for the tested area of color space, the Picasso
triggerfish exhibits behavioral thresholds that significantly
deviate from the assumptions of the model. This is a novel
finding that could not have been predicted based on modeling alone.
Appendices
role in the immunity of corals, which requires further investigations. This evidence complements recent findings on
White Syndrome agents and allows a glimpse into functional
roles of microbial components in coral holobiont ecology.
8.2.4 Attached or Hanging: Does Maintenance
Method Affect the Response of Pocillopora
damicornis to Thermal Stress?
Sofia Afoncheva
1*
, Pia Kegler
1,2
, Andreas Kunzmann
1
1
Leibniz Centre for Tropical Marine Research,
Fahrenheitstraße 6, 28359 Bremen, Germany
2
CORESea, Chaloklam 94 Moo 7 Koh Phangan, 84280
Surat Thani, Thailand
*corresponding author: sofiyaaf@gmail.com
Keywords: Thermal stress, Coral aquaculture, Coral
fragments
Scleractinian corals are in high demand for marine ornamental trade, reef restoration and bioprospecting. These
activities require regular supply with live corals. In order to
reveal the most efficient method to grow corals in captivity
two different maintenance methods (attached vs. hanging
coral fragments) for fragments of the hermatypic coral
Pocillopora damicornis were compared in response to thermal stress and with regard to the feeding status (fed vs. nonfed). The results showed that respiration was affected by the
maintenance method. Oxygen consumption in attached corals under 30 °C was 26% higher than in hanging corals
whereas hanging fragments did not show acute response to
temperature stress. Physiological parameters (photosynthesis, quantum yield, Chl a, zooxanthellae density, protein content) were not influenced by maintenance method but were
affected by availability of food. Fed fragments maintained a
higher Chl a concentration, symbiont density and protein
content compared to the non-fed ones. Concentration of Chl
a was inversely correlated with fragments’ weight due to the
higher skeleton to tissue ratio in the bigger fragments.
Growth rates of the smaller fragments tended to be higher
than in the bigger ones due to higher metabolic rates and
lower absolute energy demands. Despite of the benefits of
the hanging method for coral growth in the field nurseries
(higher growth rates, resistance to diseases), in closed systems coral growth does not change significantly regardless
which maintenance method is applied. When choosing an
appropriate maintenance method for coral culture in closed
systems several things should be considered: the size of
facilities, number of fragments and individual preferences of
the coral grower between easy-to-handle options or higher
ability to tissue recovery and resistance of corals to
biofouling.
8.2.5 Underwater Vision: How a Coral Reef Fish
(Rhinecanthus aculeatus) Discriminates Color
Emily F. Guevara
1,2,3*
, Naomi F. Green
1
, Andreas Kunzmann
3
,
N. Justin Marshall
4
Karen L. Cheney
1
1
School of Biological Sciences, University of Queensland,
Brisbane, QLD 4072, Australia
2
Universität Bremen, Bibliothekstr. 1, 28359, Bremen,
Bremen, Germany
3
Leibniz-Zentrum für Marine Tropenforschung (ZMT),
Fahrenheitstr. 6, 28359 Bremen, Germany
4
Queensland Brain Institute, University of Queensland,
Brisbane, QLD 4072, Australia
*corresponding author: Emily.guevara1@gmail.com
Keywords: Color thresholds, Visual modeling, Receptor
noise, Neurobiology
Healthy coral reefs are extremely colorful, chaotic, and
dappled environments, cast under a constant flicker of incident sunlight that poses a particular challenge for visual
navigation – a challenge that has been brilliantly solved
using color vision. Color vision is finely tuned and indispensable to identify conspecifics, attract mates, deter or
elude predators, and to find food and shelter. Many shallow
reef fish are trichromats, creating color images much like
humans, by combining light information from three types of
color-sensing ‘cone’ cells in downstream neural opponency
mechanisms. The ability to detect and discriminate colors is
therefore determined by a combination of light availability,
receptor sensitivity, and neural processing capability. We use
visual modeling to investigate the latter; to understand the
processes that underlie color vision. However, these models
rely on key assumptions about animal visual systems that
must be calibrated with behavioral testing – a rarity in the
literature. Our aim is to understand how animals distinguish
color, by examining behavioral threshold differences: when
are two colors different enough to be considered independent? This study is part of the most comprehensive color
vision test that has ever been done on a non-human vertebrate, and uses a new and exciting way to test color vision in
animals that is based on the Ishihara method for human color
blindness tests. Picasso triggerfish show an outstanding ability to generalize across colors, performing remarkably well
in odd-one-out tasks. We therefore trained them to identify a
target spot that differs from a background of spots in either
saturation or hue. Using the Receptor Noise Limited model,
we found that for the tested area of color space, the Picasso
triggerfish exhibits behavioral thresholds that significantly
deviate from the assumptions of the model. This is a novel
finding that could not have been predicted based on modeling alone.
Appendices