Are increased nutrient inputs responsible for more outbreaks of crown-of-thorns starfish? An appraisal of the evidence

Brodie, Jon; Fabricius, Katharina; De’ath, Glenn; Okaji, Ken

doi:10.1016/j.marpolbul.2004.10.035

Cited by 262 publications

(211 citation statements)

References 64 publications

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“…Central and southern rivers now carry five-to ninefold higher nutrient and sediment loads from cleared, fertilized, and urbanized catchments into the GBR compared with pre-European settlement (16). Global warming is also increasing rainfall variability (26), resulting in more frequent intense drought-breaking floods that carry particularly high nutrient and sediment loads (16,18). River runoff of Table 1.…”

Section: Discussionmentioning

confidence: 99%

“…On these reefs, coral cover does not directly depend on water quality (17); however, reefs exposed to poor water clarity and elevated nutrient concentrations show significant increases in macroalgal cover and reduced coral species richness and recruitment (12,17). There is also strong evidence that water quality affects the frequency of COTS outbreaks in the central and southern GBR (5,18). Survival of the plankton-feeding larvae of COTS is high in nutrient-enriched flood waters, whereas few larvae complete their development in seawater with low phytoplankton concentrations.…”

Section: Discussionmentioning

confidence: 99%

“…Nonetheless, the GBR has been subject to severe disturbances, including COTS outbreaks, mass coral bleaching and declining growth rates of coral due to increasing seawater temperatures, terrestrial runoff, tropical cyclones, and coral diseases (2,3,(12)(13)(14). The runoff of soils, fertilizers, and pesticides from agricultural and coastal development has significantly affected inshore coral reefs (12,(15)(16)(17), and has likely increased COTS outbreak frequencies (5,18). Conclusions of scientific studies on the condition of the GBR, based on different datasets and various time periods, have ranged from evidence for fluctuations from localized disturbances (13,14) to ecosystem-wide declines (1,2).…”

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confidence: 99%

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The 27–year decline of coral cover on the Great Barrier Reef and its causes

De’ath

Fabricius

Sweatman

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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1,494

1,191

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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 a major 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 improving water 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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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The 27–year decline of coral cover on the Great Barrier Reef and its causes

De’ath

Fabricius

Sweatman

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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1,494

1,191

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“…The addition of limiting nutrients enhances the growth of phytoplankton, providing more food for A. cf. solaris larvae, and thereby increasing larval survival and ultimately recruitment into the reproductive population [20].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Salinity and pH on Fertilization, Early Development, and Hatching in the Crown-of-Thorns Seastar

et al. 2017

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Understanding the influence of environmental factors on the development and dispersal of crown-of-thorns seastars is critical to predicting when and where outbreaks of these coral-eating seastars will occur. Outbreaks of crown-of-thorns seastars are hypothesized to be driven by terrestrial runoff events that increase nutrients and the phytoplankton food for the larvae. In addition to increasing larval food supply, terrestrial runoff may also reduce salinity in the waters where seastars develop. We investigated the effects of reduced salinity on the fertilization and early development of seastars. We also tested the interactive effects of reduced salinity and reduced pH on the hatching of crown-of-thorns seastars. Overall, we found that reduced salinity has strong negative effects on fertilization and early development, as shown in other echinoderm species. We also found that reduced salinity delays hatching, but that reduced pH, in isolation or in combination with lower salinity, had no detectable effects on this developmental milestone. Models that assess the positive effects of terrestrial runoff on the development of crown-of-thorns seastars should also consider the strong negative effects of lower salinity on early development including lower levels of fertilization, increased frequency of abnormal development, and delayed time to hatching.

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“…However, along the Great Barrier Reef (GBR) in Australia, 'primary' outbreaks are the origin of successive 'secondary' outbreaks. The mechanisms of outbreaks seem to be a response to an increase in terrestrial nutrients discharges (that may be natural or enhanced by human activities), which triggers phytoplankton blooms, thus favouring the survival of A. planci larvae and consequently the recruitment of juveniles [3]. The decrease of natural predators such as the Giant Triton (Charonia tritonis), the Bullmouth Helmet (Cypraecassis rufa) or the Giant Helmet (Cassis cornuta) (Gastropoda, Mollusca), which are over-harvested by collectors, also favours A. planci adults survival in low density.…”

Section: Introductionmentioning

confidence: 99%

Assessment of three mitochondrial loci variability for the crown-of-thorns starfish: A first insight into Acanthaster phylogeography

Gérard¹,

Roby²,

Chevalier³

et al. 2007

Comptes Rendus. Biologies

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Acanthaster planci (L.) is one of the major threats to coral reefs, whose genetic diversity has been mainly studied with allozymes. Allozymes revealed the low genetic differentiation between A. planci populations in the Indo-Pacific area. We obtained sequences of A. planci from Kenya, Mayotte and Madagascar at the three loci cytochrome oxydase subunit I (COI), 16S rDNA (16S) and five tRNAs, analysed together with available sequences of Acanthaster from the Pacific Ocean. The level of genetic diversity varied among the three loci, tRNAs being on average three times less divergent than COI and 16S genes. The genus Acanthaster appeared monophyletic, the two species A. brevispinus (Fisher) and A. planci forming distinct clades in agreement with data from morphology and systematics. The A. planci clade split into a West Indian Ocean group and a Pacific group, in agreement with allozyme data on population differentiation.

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Are increased nutrient inputs responsible for more outbreaks of crown-of-thorns starfish? An appraisal of the evidence

Cited by 262 publications

References 64 publications

The 27–year decline of coral cover on the Great Barrier Reef and its causes

The 27–year decline of coral cover on the Great Barrier Reef and its causes

The Effects of Salinity and pH on Fertilization, Early Development, and Hatching in the Crown-of-Thorns Seastar

Assessment of three mitochondrial loci variability for the crown-of-thorns starfish: A first insight into Acanthaster phylogeography

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