11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10-25
Herbivory Under Altered Community States -Is What You See What You Get?
Rebecca FOX* 1 , David BELLWOOD 2
1 ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical
Biology, James Cook University, Fadden, ACT, Australia, 2 ARC Centre of Excellence
for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University,
Townsville, QLD, Australia
Herbivorous fishes are widely acknowledged as a key element in maintaining the health
and resilience of coral reef ecosystems. Quantifying the relative impact of individual
species of herbivore is essential if we are to identify systems at risk of undergoing phaseshifts
and develop an understanding of how such shifts could be reversed. Traditional
approaches have used diver-based observations of herbivore abundance to quantify
herbivory. But is what we see in terms of herbivore distribution really representative of
all herbivorous activity occurring on coral reefs? We made use of remote underwater
video cameras to observe the process of herbivory in the absence of divers under natural
and altered community states, the latter being created using macroalgal transplants.
Continuous recordings of the diurnal feeding activity of roving herbivores were made
across different reef habitat zones and the impact (area of reef grazed per day) of each of
the major species was quantified. While the overall pattern of relative grazing intensities
across the reef under natural and degraded conditions coincided, the process of herbivory
differed dramatically between the two states. Of the three dominant taxa recorded at the
location under natural conditions, none played a role in the removal of macroalgae in the
altered state. Instead, the agent of macroalgal removal was a species not previously
recorded at the location. Our findings highlight that species critical to the healthy
functioning and resilience of reef systems may have gone unnoticed in previous
observations of natural foraging patterns. The implications of the differences in grazing
activity among community states will be discussed in the context of herbivory as an agent
of disturbance, and the potential roles of individual species in the resilience and recovery
of coral reef ecosystems will be highlighted.
10-26
Herbivory On Coral Reefs: The Challenge Of Change
David BELLWOOD* 1,2
1 Marine Biology, James Cook University, Townsville, Australia, 2 ARC Centre of
Excellence for Coral Reef Studies, Townsville, Australia
This presentation will examine our understanding of the role of herbivorous fishes on
coral reefs. Herbivory is widely accepted as one of the most important processes on coral
reefs. Yet, despite over four decades of research on herbivory we are still at the stage of
identifying the players and their respective roles. This apparent lack of progress reflects
rapid changes in our understanding of the potential role of herbivorous fishes in
ecosystem processes and the emergence of new challenges. Global warming and direct
human activity are rapidly changing coral reef ecosystems. Herbivorous fishes have
switched from animals that eat algae to critical functional groups with important roles in
supporting reef resilience, preventing coral-algal phase shifts and underpinning reef
regeneration. The key question now is: which of the herbivorous fishes are important for
the future of coral reefs and why? In this presentation I will: a) provide an historical
overview of research on fish based herbivory, with an emphasis on the Great Barrier
Reef; b) examine the implications of recent methodological advances in the application of
remote underwater video techniques; and c) explore our ability to critically evaluate the
status of today’s coral reefs.
10-27
Continuing Decline Of montastraea Populations On Protected And Unprotected Reefs in
The Florida Keys National Marine Sanctuary.
Struan SMITH* 1 , Richard ARONSON 2 , John OGDEN 3
1 Georgia State University, Atlanta, GA, 2 Dauphin Island Sea Lab, Dauphin Island, AL, 3 Florida
Institute of Oceanography, St. Petersburg, FL
Coral populations in Fully Protected Zones and on adjacent unprotected reefs in the Upper and
Lower Florida Keys were assessed in terms of percent cover, recruitment, and juvenile and
adult colony survival rates from 1998 to 2005. Analysis of random video transects showed that,
overall, percent coral cover has declined by 50% on both protected and unprotected reefs during
this period. The framework-building corals Montastraea spp. have declined in absolute cover
from 5% to 2% in the Lower Keys and from 2% to 1% absolute cover in the Upper Keys on
both protected and unprotected reefs. Censuses of corals in permanent quadrats revealed that
three coral genera recruited successfully every year: Siderastrea spp. (5-10 m-2 yr-1), Porites
spp. (1-2 m-2 yr-1), and Agaricia spp. (0.5-1 m-2 yr-1). However, the Montastraea annularis
species complex have shown very low recruitment rates (