Regional scale nutrient modelling: exports to the Great Barrier Reef World Heritage Area

McKergow, Lucy A.; Prosser, Ian P.; Hughes, Andrew O.; Brodie, Jon

doi:10.1016/j.marpolbul.2004.11.030

Cited by 49 publications

(30 citation statements)

References 33 publications

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“…Over the last century, there has been a substantial increase in the terrestrial run-off of both nutrients and sediments into the coastal regions of the GBR (McCulloch et al 2003, McKergow et al 2005. While there has been some indication that the abundance of macroalgae has increased over time at a few inshore locations on the GBR (Done et al 2007), it is still unknown whether 'fleshy' macroalgal-dominated inner-shelf reefs represent a 'natural' state or are a preliminary indicator of a localized phase shift (McCook et al 1997).…”

Section: Distribution Of Macroalgae On the Gbrmentioning

confidence: 99%

Cross-shelf benthic community structure on the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass

Wismer¹,

Hoey²,

Bellwood³

2009

Mar. Ecol. Prog. Ser.

170

153

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The Great Barrier Reef (GBR) is one of the most extensively studied coral reef systems in the world, yet to date, there has been no comprehensive multi-spatial scale evaluation of its benthic community structure. Such descriptions provide a useful reference point for evaluating future community changes. Moreover, large-scale associations between macroalgae and herbivory on the GBR are yet to be investigated. Our aim, therefore, was to quantify all major substratum categories across multiple spatial scales and investigate cross-shelf relationships between macroalgal cover and herbivore biomass. Using point-intercept transects and timed underwater censuses, individual benthic components and roving herbivorous fish densities were quantified across 3 spatial scales: latitude, continental shelf position and within-reef habitat. Principal component analysis and analysis of similarities (ANOSIM) revealed a distinct separation of inner-shelf reef habitats from all mid-and outer-shelf habitats in both northern and central regions of the GBR. Macroalgal cover was generally high on inner-shelf reefs (36 to 66%) and decreased markedly on all mid-and outer-shelf habitats (0 to 15%). A significant negative correlation was found between macroalgal cover and total herbivorous fish biomass, but no relationship was found between macroalgal cover and macroalgal browser biomass. In contrast to macroalgae, the cover of crustose coralline algae and live scleractinian corals increased markedly across the shelf in both regions of the GBR. These patterns appear to be shaped by both physical and biological factors, including wave energy, sedimentation and grazing intensity.KEY WORDS: Benthic community structure · Macroalgae · Phase shift · Herbivory · Coral reef · Baseline Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 376: [45][46][47][48][49][50][51][52][53][54] 2009 (Done 1992, Hughes et al. 2003, Bellwood et al. 2004). Nevertheless, it has been argued that reefs can also be dominated by macroalgae and still be considered healthy with all essential ecological processes intact. For instance, some reefs of the Northwestern Hawaiian Islands are largely dominated by turf and fleshy macroalgae (Vroom et al. 2005(Vroom et al. , 2006. Their isolation and subsequent limited anthropogenic disturbance suggest that this may represent the 'natural' state of these reefs.Within the Great Barrier Reef (GBR), which is widely regarded as the world's most intact coral reef system (Pandolfi et al. 2003, Bellwood et al. 2004, Wilkinson 2004, macroalgae (particularly Sargassum) have frequently been reported from inshore reefs (e.g. Done 1992, Martin-Smith 1993, McCook et al. 1997. Despite this, there is still a lack of quantitative data on both the distribution and abundance of macroalgae within the GBR (McCook et al. 1997). Previous studies have provided detailed descriptive data on the distribution patterns of other substratum categories, including scleractinian corals (Done 1982), soft coral...

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Section: Distribution Of Macroalgae On the Gbrmentioning

confidence: 99%

Cross-shelf benthic community structure on the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass

Wismer¹,

Hoey²,

Bellwood³

2009

Mar. Ecol. Prog. Ser.

170

153

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“…Our current estimates of DIN loads are based on modelling using the SedNet/ANNEX model (McKergow et al 2005b;Armour et al 2009) and long-term monitoring data (Mitchell et al 2001(Mitchell et al , 2009Furnas 2003). The most recent estimate from ANNEX modelling for the Tully basin is an average annual load of 1160 t DIN year −1 , which makes the target load 232 t (i.e.…”

Section: Target Setting For the Tully-murray Basin For Nitratementioning

confidence: 99%

“…The level of uncertainty in the load estimates for the Tully basin is moderate (Table 2), because (i) modelled and monitored DIN concentrations at six sampling locations were in general agreement (Armour et al 2009); (ii) compared to pre-1850 loads, the current total nitrogen (TN) load appears to have increased by a factor of around 3 (McKergow et al 2005b), which corresponds to the estimated 80% reduction required in DIN concentrations at the end-of-river site for the Tully River (Euramo); (iii) the Tully River has a low level of interannual variation compared with most Australian rivers (Mitchell et al 2009);and (iv) much of the load is missed at Euramo due to the overbank flow components discussed above.…”

Section: Target Setting For the Tully-murray Basin For Nitratementioning

confidence: 99%

“…On its western boundary, 35 basins discharge into the GBRWHA over ∼2000 km of Queensland coastline. Loads of pollutants discharging from these basins have increased greatly with the development of the river catchments for agriculture over the past 150 years (Furnas 2003;McKergow et al 2005aMcKergow et al , 2005b. Pollutant loads have increased by up to five times for suspended sediment from some rivers (McKergow et al 2005a), and up to six times for nitrate in others (Hunter and Walton 2008;Mitchell et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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Target setting for pollutant discharge management of rivers in the Great Barrier Reef catchment area

Brodie

Lewis

Bainbridge

et al. 2009

Mar. Freshwater Res.

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Abstract. Water Quality Improvement Plans (WQIPs) are being developed for individual river basins on the Great Barrier Reef (GBR) catchment associated with the GBR Water Quality Protection Plan. Within each WQIP, marine ecosystem targets are linked to end-of-river pollutant (suspended sediments, nutrients and pesticides) load targets and to farm level management practice targets. The targets are linked through quantitative models; e.g. one model connects GBR chlorophyll concentrations (marine target) to end-of-river nitrate loads, a second connects the end-of-river nitrate loads to fertiliser management targets in the catchment, whereas a third model links fertiliser application to nitrate loss at the farm scale. The difficulties of applying these linked models to derive credible and practical management targets are great, given the high degree of uncertainty in each model. Our understanding of the generation of suspended sediments, nutrients and pesticides in catchments and the relationship to on-farm management, the transport of these materials to the ocean, their transport in coastal waters and their effects on marine ecosystems is incomplete. The challenge is to produce estimates from the models, with known levels of uncertainty, but robust enough for management purposes. Case studies from the Tully-Murray basin and the Burdekin basin in north Queensland are discussed.

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“…Important catchment land uses include rangeland beef grazing (314,000 km 2 ), sugarcane cultivation (5,700 km 2 ), horticulture (630 km 2 ), other cropping including grain and cotton cultivation (11,600 km 2 ), urban areas (2,600 km 2 ) and native forest (55,900 km 2 ) (Gilbert and Brodie 2001;Waterhouse et al 2009). The dominance of grazing and cropping agriculture in the region has promoted the hypothesis that nutrient (and other pollutant) discharge from adjacent catchments to the GBR has increased greatly due to agricultural development over the last 150 years (Furnas 2003;McKergow et al 2005;Haynes et al 2007). Examination of a growing collection of data from GBR waters prompted discussion and debate about the status of GBR waters in the 1990s and helped elevate the perception of importance of management of water quality (Kinsey 1991).…”

Section: Introductionmentioning

confidence: 99%

Assessment of the eutrophication status of the Great Barrier Reef lagoon (Australia)

et al. 2010

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Current scientific consensus is that inshore regions of the central and southern Great Barrier Reef, Australia, are at risk of impacts from increased nutrient (as well as sediment and pesticide) loads delivered to Reef waters. Increases in the discharge of water quality contaminants to the Reef are largely a consequence of the expansion of agricultural practices in northern Queensland catchments following European settlement in the 1850s. In particular, the presence of elevated chlorophyll a and nutrient concentrations in many parts of the inshore Great Barrier Reef together with intense and extensive phytoplankton blooms following the discharge of nutrient-rich river flood waters suggest that the central and southern inshore area of the Great Barrier Reef is likely to be significantly impacted by elevated nutrient loads. The biological consequences of this are not fully quantified, but are likely to include changes in reef condition including hard and soft coral biodiversity, macroalgal abundance, hard coral cover and coral recruitment, as well as change in seagrass distribution and tissue nutrient status. Contemporary government policy is centered around promotion and funding of better catchment management practices to minimize the loss of catchment nutrients (both applied and natural) and the maintenance of a Reef wide water quality and ecosystem monitoring program. The monitoring program is designed to assess trends in uptake of management practice improvements and their associated impacts on water quality and ecosystem status over the next 10 years. A draft set of quantitative criteria to assess the eutrophication status of Great Barrier Reef waters is outlined for further discussion and refinement

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Regional scale nutrient modelling: exports to the Great Barrier Reef World Heritage Area

Cited by 49 publications

References 33 publications

Cross-shelf benthic community structure on the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass

Cross-shelf benthic community structure on the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass

Target setting for pollutant discharge management of rivers in the Great Barrier Reef catchment area

Assessment of the eutrophication status of the Great Barrier Reef lagoon (Australia)

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