223
to alter ecological processes within the oceans including the
outcome of coral-algal interactions. In this study, the combined effect of temperature increase and ocean acidification
on the competition between the coral Porites lobata and the
alga Chlorodesmis fastigiata was assessed. A temperature
increase of +2 °C above preindustrial temperatures and CO 2
level of 450 ppm were used to simulate a RCP2.6 emission
scenario for the mid- to late twenty-first century. Results
show negative effects of both, algal contact and future conditions on coral metabolism. We observed decreased net photosynthesis of P. lobata in contact with C. fastigiata and
increased respiration under RCP scenario. Dark calcification
rates of corals under RCP conditions were negative and significantly decreased compared to ambient conditions. Light
calcification rates were negatively affected by the interaction
of algal contact and RCP scenario, leading to decreased calcification under RCP conditions irrespective of algal contact.
Results indicate that the combined effects of temperature and
CO 2 as well as the interaction with C. fastigiata may alter the
growth and metabolism of P. lobata in the future.
8.3.2 Hide-and-Seek: How Prey Patterning Alters
Detectability to a Marine Predator (Rhinecanthus
aculeatus)
Emily F. Guevara
1,2,3*
, 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 vision, Signal salience, Predator-prey
interactions, Neurobiology
It is natural to presume that all other humans and creatures perceive the world in color in much the same way.
However, color per se does not actually exist in the environment. What we perceive as color is simply the brain’s way of
representing a narrow range of wavelengths of the electromagnetic (EM) spectrum that have been harnessed to give
contrast information where simple, monochromatic vision
would be less helpful. Many reef animals rely heavily on
color vision to attract mates, find food and shelter, signal
their unpalatability or toxicity (i.e., aposematism), and avoid
predators, among others. Clever exploitation of different
ranges of the visual spectrum can result in beneficial communication to selected signal receivers, via detection and
discrimination. There is a trend towards blue and yellow coloration in reef fish; blue light transmits furthest through the
water column, and yellow is its complimentary (therefore
highly contrasting) color; the same applies for green and red
in greenish, eutrophied coastal waters. Both the wavelength
and pattern arrangement of color is important to animals yet
research is largely lacking on how animals process highly
contrasting colors. ‘Signal theory’ states that a higher signal
to background contrast increases the salience (a.k.a. conspicuousness) of that signal. Enhanced borders do exactly this,
playing directly on the viewer’s cognitive mechanism of
edge detection by increasing this contrast. The present study
expands on this idea, using a model coral reef predator, the
Picasso triggerfish Rhinecanthus aculeatus, to behaviorally
assess detectability. Using predator foraging biases on
printed “prey” stimuli, it is possible to break down signal
salience based on the presence of contrasting internal and/or
bordering edges. Picasso triggerfish avoided aposematic signals with enhanced yellow borders faster than if signals contained only red or blue internal patterns, which aligns with
previous theory.
8.3.3 Comparing Food Webs at Both Sides
of the Isthmus of Panama: The Relative
Importance of Mangrove Food Sources for Fish
Communities
Lara Stuthmann
1*
1
Leibniz Centre for Tropical Marine Research,
Fahrenheitstraße 6, 28359 Bremen, Germany
*corresponding author: lara-stuthmann@web.de
Keywords: Mangroves, Stable Isotope Analysis, Fish,
Food web
Mangrove ecosystems are well known for playing an
important role in coastal systems. The importance of mangroves as a primary food source for higher vertebrates is still
in discussion, especially in comparison with other adjacent
productive systems, like coral reefs and seagrass beds.
Panama provides an extraordinary experimental ground to
examine the role of mangroves as feeding area for fish. The
rise of the Central American Isthmus closed the seaway
between the Pacific and Atlantic Ocean around 3 Ma. It
formed two coasts with contrasting environmental features:
The Caribbean coast is shaped by a micro-tidal regime (ca.
0.5 m) with adjacent coral reefs and seagrass beds; while the
Pacific coast is characterized by a macro-tidal regime (ca.
4 m) and the absence of seagrass beds and coral reefs but is
in general more productive than the Caribbean Sea.
Mangroves are present at both coasts. The aim of the study is
to use this contrasting environmental set-up to reveal the
food web structures and examine the relative importance of
mangroves food sources for fish communities of two mangrove systems in Panama in the Caribbean (“Bocas del
Toro”) and the Pacific (“Gulf of Montijo”). Stable isotope
analyses (δ
15
N and δ
13
C) of the sampled prey items, primary
producers, organic matter and fish will give insights in the
food web structure under the different environmental cirAppendices
to alter ecological processes within the oceans including the
outcome of coral-algal interactions. In this study, the combined effect of temperature increase and ocean acidification
on the competition between the coral Porites lobata and the
alga Chlorodesmis fastigiata was assessed. A temperature
increase of +2 °C above preindustrial temperatures and CO 2
level of 450 ppm were used to simulate a RCP2.6 emission
scenario for the mid- to late twenty-first century. Results
show negative effects of both, algal contact and future conditions on coral metabolism. We observed decreased net photosynthesis of P. lobata in contact with C. fastigiata and
increased respiration under RCP scenario. Dark calcification
rates of corals under RCP conditions were negative and significantly decreased compared to ambient conditions. Light
calcification rates were negatively affected by the interaction
of algal contact and RCP scenario, leading to decreased calcification under RCP conditions irrespective of algal contact.
Results indicate that the combined effects of temperature and
CO 2 as well as the interaction with C. fastigiata may alter the
growth and metabolism of P. lobata in the future.
8.3.2 Hide-and-Seek: How Prey Patterning Alters
Detectability to a Marine Predator (Rhinecanthus
aculeatus)
Emily F. Guevara
1,2,3*
, 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 vision, Signal salience, Predator-prey
interactions, Neurobiology
It is natural to presume that all other humans and creatures perceive the world in color in much the same way.
However, color per se does not actually exist in the environment. What we perceive as color is simply the brain’s way of
representing a narrow range of wavelengths of the electromagnetic (EM) spectrum that have been harnessed to give
contrast information where simple, monochromatic vision
would be less helpful. Many reef animals rely heavily on
color vision to attract mates, find food and shelter, signal
their unpalatability or toxicity (i.e., aposematism), and avoid
predators, among others. Clever exploitation of different
ranges of the visual spectrum can result in beneficial communication to selected signal receivers, via detection and
discrimination. There is a trend towards blue and yellow coloration in reef fish; blue light transmits furthest through the
water column, and yellow is its complimentary (therefore
highly contrasting) color; the same applies for green and red
in greenish, eutrophied coastal waters. Both the wavelength
and pattern arrangement of color is important to animals yet
research is largely lacking on how animals process highly
contrasting colors. ‘Signal theory’ states that a higher signal
to background contrast increases the salience (a.k.a. conspicuousness) of that signal. Enhanced borders do exactly this,
playing directly on the viewer’s cognitive mechanism of
edge detection by increasing this contrast. The present study
expands on this idea, using a model coral reef predator, the
Picasso triggerfish Rhinecanthus aculeatus, to behaviorally
assess detectability. Using predator foraging biases on
printed “prey” stimuli, it is possible to break down signal
salience based on the presence of contrasting internal and/or
bordering edges. Picasso triggerfish avoided aposematic signals with enhanced yellow borders faster than if signals contained only red or blue internal patterns, which aligns with
previous theory.
8.3.3 Comparing Food Webs at Both Sides
of the Isthmus of Panama: The Relative
Importance of Mangrove Food Sources for Fish
Communities
Lara Stuthmann
1*
1
Leibniz Centre for Tropical Marine Research,
Fahrenheitstraße 6, 28359 Bremen, Germany
*corresponding author: lara-stuthmann@web.de
Keywords: Mangroves, Stable Isotope Analysis, Fish,
Food web
Mangrove ecosystems are well known for playing an
important role in coastal systems. The importance of mangroves as a primary food source for higher vertebrates is still
in discussion, especially in comparison with other adjacent
productive systems, like coral reefs and seagrass beds.
Panama provides an extraordinary experimental ground to
examine the role of mangroves as feeding area for fish. The
rise of the Central American Isthmus closed the seaway
between the Pacific and Atlantic Ocean around 3 Ma. It
formed two coasts with contrasting environmental features:
The Caribbean coast is shaped by a micro-tidal regime (ca.
0.5 m) with adjacent coral reefs and seagrass beds; while the
Pacific coast is characterized by a macro-tidal regime (ca.
4 m) and the absence of seagrass beds and coral reefs but is
in general more productive than the Caribbean Sea.
Mangroves are present at both coasts. The aim of the study is
to use this contrasting environmental set-up to reveal the
food web structures and examine the relative importance of
mangroves food sources for fish communities of two mangrove systems in Panama in the Caribbean (“Bocas del
Toro”) and the Pacific (“Gulf of Montijo”). Stable isotope
analyses (δ
15
N and δ
13
C) of the sampled prey items, primary
producers, organic matter and fish will give insights in the
food web structure under the different environmental cirAppendices