Long-term data with high-precision chronology are essential to elucidate past ecological changes on coral reefs beyond the period of modern-day monitoring programs. In 2012 we revisited two inshore reefs within the central Great Barrier... more
Long-term data with high-precision chronology are essential to elucidate past ecological changes on coral reefs beyond the period of modern-day monitoring programs. In 2012 we revisited two inshore reefs within the central Great Barrier Reef, where a series of historical photographs document a loss of hard coral cover between c.1890-1994 AD. Here we use an integrated approach that includes high-precision U-Th dating specifically tailored for determining the age of extremely young corals to provide a robust, objective characterisation of ecological transition. The timing of mortality for most of the dead in situ corals sampled from the historical photograph locations was found to coincide with major flood events in 1990-1991 at Bramston Reef and 1970 and 2008 at Stone Island. Evidence of some recovery was found at Bramston Reef with living coral genera similar to what was described in c.1890 present in 2012. In contrast, very little sign of coral re-establishment was found at Stone I...
The May 15, 1992, earthquake on the Huon Peninsula, Papua New Guinea, resulted in the uplift and large-scale mortality of intertidal fringing coral reefs. Reduction in the highest level of survival of intertidal massive corals was used as... more
The May 15, 1992, earthquake on the Huon Peninsula, Papua New Guinea, resulted in the uplift and large-scale mortality of intertidal fringing coral reefs. Reduction in the highest level of survival of intertidal massive corals was used as a proxy for assessing the amount of coseismic uplift over 45 km of the Huon coastline. Measurements were gathered from three sites one and three months after the earthquake. Sea-level pressure gauges in place in the northern end of Sialum Lagoon showed not uplift, but subsidence, from the earthquake. Uplift ranged from ˜7 to 13 cm, and subsidence ranged from 8 to 14 cm. The May 15, 1992, earthquake corroborates the coseismic origin of the raised reef terraces of the Huon Peninsula. Greater uplift of the land in the southeast relative to the northwest is consistent with the regional Quaternary uplift pattern. The close proximity of subsidence (shown by sea-level gauges) to uplift (shown by coral mortality) is a manifestation of the abundant fault blocks in the area. Uplift rates of 3.0-5.2 m/ka calculated from the earthquake are only marginally higher than previous estimates based on radiometric age dates and terrace geomorphology. The first directly observed earthquake uplift event on the Huon Peninsula has yielded only centimetre-scale coseismic uplift. Thus, individual Holocene and Pleistocene terraces thought to have been the result of metre-scale displacement from single earthquakes may rather have been due to successive episodes of centimetre-scale uplift on constructional reef platforms. The clustered history of earthquakes on the Huon Peninsula throughout the past 100 years indicates the complexity involved in assessment of seismic risk throughout the world.
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Annually-banded corals living on the north coast of Papua New Guinea record changes in SST and salinity in the stable isotopic and trace element composition of their skeletons. Previously, we exploited these attributes and the presence of... more
Annually-banded corals living on the north coast of Papua New Guinea record changes in SST and salinity in the stable isotopic and trace element composition of their skeletons. Previously, we exploited these attributes and the presence of abundant fossil corals to investigate changes in ENSO over the last glacial-interglacial cycle. Here we focus on more detailed analysis of the Holocene interval based on a total of about 400 years of new, near-monthly-resolved, isotopic and trace element coral data from the interval from about 9,500 to 6,500 years BP. Our findings include: INTERANNUAL ENSO VARIABILITY: The amplitude of ENSO-related variability in skeletal delta18O is reduced to about 30% of Modern and late Holocene values in corals from 9.1-9.4 ka through to 6.5 ka. These results support previous inferences of weakened ENSO variability in the early-mid-Holocene. MEAN CONDITIONS: Based on a combination of trace element and delta18O analysis, our initial results suggest that SST was similar to present at around 9.1-9.4 ka. Mean salinity, however, appears to have been higher in the earlier period, similar to what is experienced today during El Niño events. These observations contrast with some previous suggestions of general La Niña-like conditions in the early Holocene based on eastern equatorial Pacific data. INTERDECADAL VARIABILITY: Interdecadal variability in skeletal delta18O of modern corals from the region appears to record salinity changes associated with the Pacific Decadal Oscillation. In our fossil corals, we find that the amplitude of this interdecadal variability is reduced in the early-mid-Holocene, when interannual ENSO-related variability is also weak. These observations lend some support to the suggestion that much of the modern-day PDO variability is related to ENSO, and, therefore, is not a separate mode of climate variability.
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As one of the most prolific and widespread reef builders, the staghorn coral Acropora holds a disproportionately large role in how coral reefs will respond to accelerating anthropogenic change. We show that although Acropora has a diverse... more
As one of the most prolific and widespread reef builders, the staghorn coral Acropora holds a disproportionately large role in how coral reefs will respond to accelerating anthropogenic change. We show that although Acropora has a diverse history extended over the past 50 million years, it was not a dominant reef builder until the onset of high-amplitude glacioeustatic sea-level fluctuations 1.8 million years ago. High growth rates and propagation by fragmentation have favored staghorn corals since this time. In contrast, staghorn corals are among the most vulnerable corals to anthropogenic stressors, with marked global loss of abundance worldwide. The continued decline in staghorn coral abundance and the mounting challenges from both local stress and climate change will limit the coral reefs' ability to provide ecosystem services.
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Coral reefs are biologically diverse and ecologically complex ecosystems constructed by stony corals. Despite decades of research, basic coral population biology and community ecology questions remain. Quantifying trait variation among... more
Coral reefs are biologically diverse and ecologically complex ecosystems constructed by stony corals. Despite decades of research, basic coral population biology and community ecology questions remain. Quantifying trait variation among species can help resolve these questions, but progress has been hampered by a paucity of trait data for the many, often rare, species and by a reliance on nonquantitative approaches. Therefore, we propose filling data gaps by prioritizing traits that are easy to measure, estimating key traits for species with missing data, and identifying 'supertraits' that capture a large amount of variation for a range of biological and ecological processes. Such an approach can accelerate our understanding of coral ecology and our ability to protect critically threatened global ecosystems.
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ABSTRACT Fish spawning aggregations (FSAs) support productive and valuable fisheries yet are extremely vulnerable to overexploitation and depletion. Assessment and subsequent management of FSA fisheries requires analysis of long-term... more
ABSTRACT Fish spawning aggregations (FSAs) support productive and valuable fisheries yet are extremely vulnerable to overexploitation and depletion. Assessment and subsequent management of FSA fisheries requires analysis of long-term spatio-temporal trends in fishery catch and effort to overcome shifting baselines. We compile newspaper archives, fisher knowledge, and contemporary catch logs to reconstruct a century-long commercial catch time series for Australia’s Great Barrier Reef Spanish mackerel FSA fishery (1911-2011). After correcting for changes in fishing power and effort, average catch rates were found to decline nearly 3-fold, from 140 to 40 fish vessel-1 trip-1 between 1934 and 2011. Spatial effort contracted to just 22% of FSA areas presumably as FSAs were extirpated. Fishers travelled further offshore from traditional spawning grounds due to the commercial extinction of the northern spawning fishery, declining catch rates and the incursion of recreational effort. Recreational fishers targeting historic inshore spawning grounds since 1970 are unaware of spawning aggregations, indicating the disappearance of spawning components. Retrospective evaluation of the spatio-temporal dynamics of the Great Barrier Reef Spanish mackerel spawning fishery reveal gross changes in the spawning patterns and productivity that are not evident in contemporary records. We provide empirical evidence relevant for effective management and the long-term sustainability of FSA fisheries.
Climate change is shifting species' distribution and phenology. Ecological traits, such as mobility or reproductive mode, explain variation in observed rates of shift for some taxa. However, estimates of relationships between traits... more
Climate change is shifting species' distribution and phenology. Ecological traits, such as mobility or reproductive mode, explain variation in observed rates of shift for some taxa. However, estimates of relationships between traits and climate responses could be influenced by how responses are measured. We compiled a global dataset of 651 published marine species' responses to climate change, from 47 papers on distribution shifts and 32 papers on phenology change. We assessed the relative importance of two classes of predictors of the rate of change, ecological traits of the responding taxa and methodological approaches for quantifying biological responses. Methodological differences explained 22% of the variation in range shifts, more than the 7.8% of the variation explained by ecological traits. For phenology change, methodological approaches accounted for 4% of the variation in measurements, whereas 8% of the variation was explained by ecological traits. Our ability to p...
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Perhaps the most pressing issue in predicting biotic responses to present and future global change is understanding how environmental factors shape the relationship between ecological traits and extinction risk. The fossil record provides... more
Perhaps the most pressing issue in predicting biotic responses to present and future global change is understanding how environmental factors shape the relationship between ecological traits and extinction risk. The fossil record provides millions of years of insight into how extinction selectivity (i.e., differential extinction risk) is shaped by interactions between ecological traits and environmental conditions. Numerous paleontological studies have examined trait-based extinction selectivity; however, the extent to which these patterns are shaped by environmental conditions is poorly understood due to a lack of quantitative synthesis across studies. We conducted a meta-analysis of published studies on fossil marine bivalves and gastropods that span 458 million years to uncover how global environmental and geochemical changes covary with trait-based extinction selectivity. We focused on geographic range size and life habit (i.e., infaunal vs. epifaunal), two of the most important...
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Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over... more
Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over 23 million years, taxonomic membership and geographic range size consistently explain a large proportion of extinction risk variation in six major taxonomic groups. We assess intrinsic risk-extinction risk predicted by paleontologically calibrated models-for modern genera in these groups. Mapping the geographic distribution of these genera identifies coastal biogeographic provinces where fauna with high intrinsic risk are strongly affected by human activity or climate change. Such regions are disproportionately in the tropics, raising the possibility that these ecosystems may be particularly vulnerable to future extinctions. Intrinsic risk provides a prehuman baseline for considering current threats to marine biodiversity.