scholarly journals Accounting for uncertainty from zero inflation and overdispersion in paleoecological studies of predation using a hierarchical Bayesian framework

Paleobiology ◽  
2021 ◽  
pp. 1-18
Author(s):  
Jansen A. Smith ◽  
John C. Handley ◽  
Gregory P. Dietl
Keyword(s):  
Great Barrier Reef ◽  
Count Data ◽  
Confidence Regions ◽  
Bayesian Framework ◽  
Published Data ◽  
Time Averaging ◽  
Sampling Effort ◽  
Hierarchical Bayesian ◽  
Barrier Reef ◽  
Zero Inflation

Abstract The effects of overdispersion and zero inflation (e.g., poor model fits) can result in misinterpretation in studies using count data. These effects have not been evaluated in paleoecological studies of predation and are further complicated by preservational bias and time averaging. We develop a hierarchical Bayesian framework to account for uncertainty from overdispersion and zero inflation in estimates of specimen and predation trace counts. We demonstrate its application using published data on drilling predators and their prey in time-averaged death assemblages from the Great Barrier Reef, Australia. Our results indicate that estimates of predation frequencies are underestimated when zero inflation is not considered, and this effect is likely compounded by removal of individuals and predation traces via preservational bias. Time averaging likely reduces zero inflation via accumulation of rare taxa and events; however, it increases the uncertainty in comparisons between assemblages by introducing variability in sampling effort. That is, there is an analytical cost with time-averaged count data, manifesting as broader confidence regions. Ecological inferences in paleoecology can be strengthened by accounting for the uncertainty inherent to paleoecological count data and the sampling processes by which they are generated.

Taphonomic bias and time-averaging in tropical molluscan death assemblages: differential shell half-lives in Great Barrier Reef sediment

Paleobiology ◽  
2009 ◽  
Vol 35 (4) ◽  
pp. 565-586 ◽  
Author(s):  
Matthew A. Kosnik ◽  
Quan Hua ◽  
Darrell S. Kaufman ◽  
Raphael A. Wüst
Keyword(s):  
Great Barrier Reef ◽  
Time Averaging ◽  
Burial Depth ◽  
Barrier Reef ◽  
Amino Acid Racemization ◽  
Sedimentary Environments ◽  
Depositional Setting ◽  
Lagoonal Sediment ◽  
Water Carbonate ◽  
Age Estimates

Radiocarbon-calibrated amino acid racemization ages of 428 individually dated shells representing four molluscan taxa are used to quantify time-averaging and shell half-lives with increasing burial depth in the shallow-water carbonate lagoon of Rib Reef, central Great Barrier Reef, Australia. The top 20 cm of sediment contains a distinct, essentially modern assemblage. Shells recovered at depths from 25 to 125 cm are age-homogeneous and significantly older than the surface layer. Taxon age distributions within sedimentary layers indicate that the top 125 cm of lagoonal sediment is thoroughly mixed on a sub-century scale. The age distributions and shell half-lives of four taxa (Ethalia, Natica, Tellina, and Turbo) are found to be largely distinct. Shell half-lives do not coincide with any single morphological characteristic thought to infer greater durability, but they are strongly related to a combined durability score based on shell density, thickness, and shape. These results illustrate the importance of bioturbation in tropical sedimentary environments, indicate that age estimates in this depositional setting are sensitive to taxon choice, and quantify a taxon-dependent bias in shell longevity and death assemblage formation.

scholarly journals The Variable Influences of Sea Level, Sedimentation and Exposure on Holocene Reef Development over a Cross-Shelf Transect, Central Great Barrier Reef

Diversity ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 110 ◽  
Author(s):  
Emma Ryan ◽  
Scott Smithers ◽  
Stephen Lewis ◽  
Tara Clark ◽  
Jian-xin Zhao
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Sea Level Change ◽  
Published Data ◽  
Past Century ◽  
Barrier Reef ◽  
Reef Development ◽  
Level Change ◽  
Terrigenous Sedimentation ◽  
Holocene Reef

Coral reefs globally are impacted by natural and anthropogenic stressors that are compounded by climate change. Understanding past reef responses to natural stressors (cyclones, sea-level change, freshwater inputs, and sedimentation) can provide important insights to further understand recent (within the past century) trends in coral cover and diversity. Here we use a compilation of recently published data to investigate the Holocene development of five fringing reefs that are located on a cross-shelf transect on the central Great Barrier Reef, and that are exposed to varying degrees of natural and anthropogenic sedimentation, storm exposure, and Holocene sea-level change. Forty-two reef cores collected using a combination of manual percussion coring and hydraulic drilling techniques, were analysed and dated using uranium-thorium methods. The chronostratigraphic records of reef development established using 105 recently published radiometric ages and seven new uranium-thorium ages from the reef cores and fossil microatolls preserved across the reef flats were compared to investigate cross-shelf variations in reef development. This is the first study to conduct an internal investigation of reef framework across an inshore–offshore gradient to examine the varying levels of influence of sedimentation, sea level and cyclones. Our observations from the central Great Barrier Reef show that reefs furthest offshore from the mainland coast were typically initiated earliest after the post-glacial marine transgression. Reef flat size, morphology, and growth style varied according to constraints placed on reef development by the composition, depth, shape, and relief of the underlying substrate. We establish that terrigenous sedimentation had a marked effect on the development of inshore reefs closest to the mainland (within 10 km of the mainland coast). Periods of relatively high terrigenous sedimentation correspond with enhanced reef accretion rates, and also resulted in a superior record of palaeo-ecological coral composition (i.e., better preservation) at inshore sites. In contrast, mid-Holocene cyclones played a seemingly more important role in the development of reefs >10 km from the mainland; although cyclones clearly affect reefs closer inshore, their geomorphology is affected by a range of controlling factors. Insights provided by these five Holocene reef chronostratigraphies provide useful baseline understanding of reef condition and growth along a cross-shelf transect where the reefs are exposed to variable stressors.

Management of Water Quality in the Great Barrier Reef Marine Park

1989 ◽  
Vol 21 (2) ◽  
pp. 31-38 ◽  
Author(s):  
Simon Woodley
Keyword(s):  
Water Quality ◽  
Coral Reef ◽  
Great Barrier Reef ◽  
Barrier Reef ◽  
Management Issue ◽  
Reef System ◽  
Marine Park ◽  
World Heritage List ◽  
The World ◽  
Coral Reef System

The Great Barrier Reef is the largest coral reef system in the world. It is recognised and appreciated worldwide as a unique environment and for this reason has been inscribed on the World Heritage List. The Reef is economically-important to Queensland and Australia, supporting substantial tourism and fishing industries. Management of the Great Barrier Reef to ensure conservation of its natural qualities in perpetuity is achieved through the establishment of the Great Barrier Reef Marine Park. The maintenance of water quality to protect the reef and the industries which depend on it is becoming an increasingly important management issue requiring better knowledge and possibly new standards of treatment and discharge.

Circulation and water mass characteristics of the southern Great Barrier Reef

1994 ◽  
Vol 45 (1) ◽  
pp. 1 ◽  
Author(s):  
JH Middleton ◽  
P Coutis ◽  
DA Griffin ◽  
A Macks ◽  
A McTaggart ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Heat Loss ◽  
Barrier Reef ◽  
Low Oxygen ◽  
Geostrophic Balance ◽  
Shelf Slope ◽  
High Nutrient ◽  
Slope Currents ◽  
North And South ◽  
Upper Slope

Data acquired during a winter (May) cruise of the RV Franklin to the southern Great Barrier Reef indicate that the dynamics of the shelf/slope region are governed by the tides, the poleward-flowing East Australian Current (EAC), and the complex topography. Over the Marion Plateau in water deeper than - 100 m, the EAC appears to drive a slow clockwise circulation. Tides appear to be primarily responsible for shelf/slope currents in the upper layers, with evidence of nutrient uplift from the upper slope to the outer shelf proper in the Capricorn Channel. Elsewhere, the bottom Ekrnan flux of the strongly poleward-flowing EAC enhances the sloping isotherms associated with the longshore geostrophic balance, pumping nutrient-rich waters from depth to the upper continental slope. Generally, shelf waters are cooler than oceanic waters as a consequence of surface heat loss by radiation. A combination of heat loss and evaporation from waters flowing in the shallows of the Great Sandy Strait appears to result in denser 'winter mangrove waters' exporting low-oxygen, high-nutrient waters onto the shelf both north and south of Fraser Island; these subsequently mix with shelf waters and finally flow offshore at - 100 m depth, just above the salinity-maximum layer, causing anomalous nutrient values in the region of Fraser Island.

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