188,801 research outputs found
State of the Reef Report 2006: Birds
No full textThe Great Barrier Reef has an abundant and diverse array of bird life that is important to the
ecology, natural heritage, and social and cultural values of the Great Barrier Reef World
Heritage Area
Fluorescent protein-mediated colour polymorphism in reef corals: multicopy genes extend the adaptation/acclimatization potential to variable light environments
No full textThe genomic framework that enables corals to adjust to unfavourable conditions is crucial for coral reef survival in a rapidly changing climate. We have explored the striking intraspecific variability in the expression of coral pigments from the green fluorescent protein (GFP) family to elucidate the genomic basis for the plasticity of stress responses among reef corals. We show that multicopy genes can greatly increase the dynamic range over which corals can modulate transcript levels in response to the light environment. Using the red fluorescent protein amilFP597 in the coral Acropora millepora as a model, we demonstrate that its expression increases with light intensity, but both the minimal and maximal gene transcript levels vary markedly among colour morphs. The pigment concentration in the tissue of different morphs is strongly correlated with the number of gene copies with a particular promoter type. These findings indicate that colour polymorphism in reef corals can be caused by the environmentally regulated expression of multicopy genes. High-level expression of amilFP597 is correlated with reduced photodamage of zooxanthellae under acute light stress, supporting a photoprotective function of this pigment. The cluster of light-regulated pigment genes can enable corals to invest either in expensive high-level pigmentation, offering benefits under light stress, or to rely on low tissue pigment concentrations and use the conserved resources for other purposes, which is preferable in less light-exposed environments. The genomic framework described here allows corals to pursue different strategies to succeed in habitats with highly variable light stress levels. In summary, our results suggest that the intraspecific plasticity of reef corals’ stress responses is larger than previously thought
Rapid recycling of coral mass-spawning products in permeable reef sediments.
No full textDuring the annual synchronous release of gametes by corals, a large amount of energy-rich organic material is released to the reef environment. In November 2001, we studied a minor spawning event at Heron Island in the Great Barrier Reef (GBR), Australia. Laboratory experiments showed that egg release by the staghorn coral Acropora millepora amounted to 19 ± 15 g dry mass (mean ± SE, n = 8) per m2 coral surface. Carbon content reached 60.1 ± 4.0% and nitrogen content 3.6 ± 0.4% of the egg dry mass. During this minor spawning period, Acropora corals from the reef crest released 7 g C and 0.4 g N as eggs m-2 reef. In situ experiments (n = 11) using stirred benthic chamber measurements revealed that the sedimentary O2 consumption (SOC) of the lagoon sediments increased sharply immediately after the coral spawning. Extreme SOC rates of 230 mmol O2 m-2 d-1 were reached 2 d after the event, exceeding the pre-spawning rate by a factor of 2.5. This maximum was followed by a steep decrease in SOC rates that gradually levelled off and reached pre-spawning values 11 d after the event. The immediate and strong response of SOC shows that the coral spawning event provides a strong food impulse to the benthic food chain. Our results demonstrate high decomposition efficiency of permeable carbonate reef sands and underline the role of these sediments as a biocatalytical recycling system in the oligotrophic reef environment
Climate change and the Great Barrier Reef: a vulnerability assessment
No full textReef-building corals (Order Scleractinia Class Anthozoa) form extensive skeletons of calcium
carbonate (limestone), depositing enough material over time to form vast reef structures that may be
easily seen from space. The majority of reef-building corals are hard (stony) scleractinian corals. Many
octocorals (especially soft corals in the family Alcyoniidae and the blue coral Heliopora) and some
hydrozoan corals (such as Millepora) also contribute to reef-building. Corals form the framework of
reef structures, while other organisms such as calcareous algae (especially red coralline algae) play a
key role in cementing and consolidating the reef framework. This chapter focuses on the vulnerability
of reef-building corals to climate change. The implications of climate change for macroalgae are
covered in chapter 7 and a broader treatment of reef processes is provided in chapter 17.This is Chapter 10 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13
Caribbean coral reef fishery resources
No full textReef fisheries, Coral reefs, Fishery management, Fishery biology, Fishery resources, Reef fish, Caribbean,
Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems
No full textCoral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution
of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the
associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local
management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef
fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions
and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the
1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites
and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure,
diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale
integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales,
with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas
still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance.
This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should
be integrated into existing management frameworks and combined with policies to improve system-wide resilience to
climate variation and change
Oceanographic and morphodynamic monitoring of a multi-purpose reef at Mount Maunganui, New Zealand
No full textThe innovative concept of an offshore submerged multi-purpose reef combining a
coastal protection function with recreational benefits including improved surfing,
diving, or fishing conditions provides an appealing solution for the management
of beaches. However, since the technology is relatively recent, there is still a lack
of empirical knowledge about its performance in the field. The present research
monitored the effect of the prototype research reef constructed at Mount
Maunganui in New Zealand on the local beach morphodynamics and
oceanographic conditions, being primarily concerned with implications on the
coastal protection function of the technology.
The beach morphodynamic response to the reef was investigated from a set of
already available high resolution bathymetric surveys imaging the foreshore and
surfzone morphology prior to, and throughout reef construction, and a new postconstruction
survey collected as a part of this research. The reef implementation
was found to disturb the pre-existing beach state functioning including the
onshore/offshore migration of the underlying long shore bar, rather than cause a
persistent salient response. A possible additional beach width of ~ 20 m,
extending ~ 150 m alongshore was identified in the lee of the reef from shoreline
analysis, but the pattern was transient throughout the monitoring period since it
was superimposed on comparatively large pre-existing fluctuations. In addition,
the reef structure provided a control point on the offshore morphology able to trap
sediment updrift and erode sediment downdrift.
Both field measurements and numerical modelling of waves and currents were
used to monitor the effect of the reef on the oceanographic conditions. Wave
propagation over the reef without breaking (H less than 0.5 m) resulted in transmitted
heights larger than incident by up to a factor of 2. When the reef triggered
breaking, transmitted heights were reduced by up to ~40 %. A concurrent process
was the shift of the wave energy spectra towards higher frequencies landward of
the reef that resulted in reduced transmitted wave periods. Wave modelling
showed that the wave shadowing was associated with significant wave rotation
around the reef that induced two zones of divergent wave angles near the
shoreline in the lee of the reef. The hydrodynamic response to the wave energy
dissipation was the development of stronger onshore directed currents landward of
the reef. Hydrodynamic modelling indicated that the reef-induced flow forced a
cellular circulation in the lee side under shore normal waves, and an onshore
deviation of the ambient (unidirectional) long-shore currents under oblique waves.
The research provided a rare empirical test to the theoretical design concepts, and
potential supplements or refinements. To obtain the required beach protection, the
reef impact on the beach morphodynamic coupling including wave
transformation, nearshore hydrodynamics, and small/large scale beach state
response needs to be carefully assessed
Coastal wetland management in the Great Barrier Reef: Farmer perceptions
No full textPoor water quality caused by intensive sugarcane farming has been among the main causes of coastal degradation around the Great Barrier Reef (GBR). Despite regulations and incentives, water quality in the GBR has yet to reach government targets, and there is an urgent need to investigate alternative management approaches. In this study, we have employed a social-ecological approach to understand farmers' attitudes to existing nutrient and sediment management approaches, assess farmers' perceptions of managing coastal wetlands to ameliorate agricultural run-off, and propose how these findings could inform integrative policy development for the GBR. We conducted semi-structured interviews with sugarcane farmers in the Wet Tropics to understand perceptions of ecosystem services, coastal wetlands and industry challenges. We linked our analysis of key issues of concern to farmers with broader environmental and land use issues and have outlined future policy considerations in the face of socio-economic and climatic change. Our conclusions emphasise the need to rethink future land tenure in low-lying areas of North Queensland, the importance of considering ecosystem services provided by coastal wetlands in policy models and the need for a payments for ecosystem services (PES) model to safeguard the future of the GBR.No Full Tex
The 27–year decline of coral cover on the Great Barrier Reef and its causes
No full textThis study investigates the spatial and temporal dynamics of coral cover, identifies the main drivers of coral mortality, and quantifies the rates of potential recovery of the Great Barrier Reef.The world’s coral reefs are being degraded, and the need to reduce local pressures to offset the effects of increasing global pressures is now widely recognized. This study investigates the spatial and temporal dynamics of coral cover, identifies the main drivers of coral mortality, and quantifies the rates of potential recovery of the Great Barrier Reef. Based on the world’s most extensive time series data on reef condition (2,258 surveys of 214 reefs over 1985–2012), we show amajor decline in coral cover from 28.0%to 13.8% (0.53%y−1), a loss of 50.7% of initial coral cover. Tropical cyclones, coral predation by crown-of-thorns starfish (COTS), and coral bleaching accounted for 48%, 42%,and 10%of the respective estimated losses,amounting to 3.38% y−1 mortality rate. Importantly, the relatively pristine northern region showed no overall decline. The estimated rate of increase in coral cover in the absence of cyclones, COTS, and bleaching was 2.85%y−1, demonstrating substantial capacity for recovery of reefs. In the absence of COTS, coral cover would increase at 0.89% y−1, despite ongoing losses due to cyclones and bleaching. Thus, reducing COTS populations, by improvingwater quality and developing alternative control measures, could prevent further coral decline and improve the outlook for the Great Barrier Reef. Such strategies can, however, only be successful if climatic conditions are stabilized, as losses due to bleaching and cyclones will otherwise increase. Image: Wibble_Roisin / flick
Chapter 11: Vulnerability of benthic invertebrates of the Great Barrier Reef to climate change
No full textThis chapter deals with benthic invertebrates inhabiting the extensive inter-reef soft bottom habitats
and those occurring on the reef, excluding corals. For the remainder of the chapter, the term ‘benthic
invertebrate’ refers to all invertebrates excluding corals. An assessment of the impacts of climate
change on non-coral benthic invertebrates poses particular challenges: i) benthic invertebrates
include an extraordinary diversity of marine organisms, including many microscopic, infaunal,
boring or ephemeral species that can be difficult to sample and are poorly known taxonomically; ii)
benthic invertebrates employ a diversity of reproductive strategies, broadly including planktotrophy
(development through feeding larvae), lecithotrophy (development through non-feeding larvae) and
direct development (release of post-metamorphic juveniles), as well as asexual reproduction, making
broad generalisations of dispersal capabilities difficult; iii) factors determining species distributions are
poorly known for most species; iv) benthic invertebrates exhibit a tremendous variety of lifestyles and
forms, including colonial, sedentary and errant species; v) many species include either a pelagic larval
or adult stage, so effects of climate change may vary during their lives (see McKinnon et al. chapter 6
for comments on planktonic forms); and, vi) research on the biogeography of benthic invertebrates
on the Great Barrier Reef (GBR) is strongly biased towards commercial or destructive species.This is Chapter 11 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13
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