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Geological evidence for recurring outbreaks of the crown-of-thorns starfish: a reassessment from an ecological perspective (1992)

Keesing, J. K. ; Bradbury, R. H. ; DeVantier, L. M. ; [et al.]

Springer

Coral reefs 11 (1992), S. 79-85

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ISSN: 1432-0975

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Geosciences

Notes: Abstract The abundance and distribution of Acanthaster planci skeletal elements in reef sediments have been presented as evidence that population outbreaks of the crown-of-thorns starfish on the Great Barrier Reef are not a new occurrence, but have been an integral part of the ecosystem for at least 7000 years on some reefs (Walbran et al. 1989a). Reassessment of the evidence shows that these claims are not justified and challenges the validity of several assumptions that are crucial to their thesis that outbreaks have been a recurrent phenomenon on the Great Barrier Reef. These are: (i) that the majority of starfish from outbreak populations remain and die on the host reef and that their skeletal elements add to the reef sediment, (ii) that reefs which have had recent A. planci outbreaks can be discriminated from those which have not by the abundance of starfish skeletal remains in recent sediments, (iii) that outbreaks will significantly increase the number of skeletal elements in reef sediments above normal background levels and, (iv) that the age of individual skeletal elements can be predicted from the age of their surrounding sediment or their depth in the sediment pile. We conclude that Walbran et al. do not have sufficient data to infer the outbreak history of A. planci from the sediment recored and that there are alternative interpretations of their findings. The possibility cannot be discounted that destructive population outbreaks of A. planci witnessed on the Great Barrier Reef since 1960 are unprecedented. The question of whether A. planci outbreaks are a naturally recurring phenomena or a novel, more recent development remains unanswered.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00357425

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Detrital pathways in a coral reef lagoon (1990)

Riddle, M. J. ; Alongi, D. M. ; Dayton, P. K. ; [et al.]

Springer

Marine biology 104 (1990), S. 109-118

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Coral reef lagoons are generally regarded as zones of net heterotrophy reliant on organic detritus generated in more productive parts of the reef system, such as the seaward reef flat. The abundance and biomass of sediment infauna were measured seasonally for one year (1986) within the lagoon of Davies Reef, central Great Barrier Reef, to test the hypothesis that macrofaunal biomass and production of coral reef lagoons would decrease with distance from the reef flat and would change seasonally. In general, there were no simple relationships between infaunal standing stock or production and distance from the reef flat or season. Bioturbation by callianassid shrimps negatively affected the abundance of smaller infauna, suggesting a community limited by biogenic disturbance rather than by supply of organic material. Polychaetes and crustaceans were dominant amongst the smaller infauna (0.5 to 2mm) while larger animals (〉 2 mm) were mostly polychaetes and molluscs. Mean biomass of infauna at both sites and all seasons was 3 181 mg C m−2. The smaller animals (0.5 to 2 mm) contributed about 40% of total macrofaunal respiration and production although they represented only 15% of the total macrofaunal biomass. The biomass of macrofauna was about equal to that of the bacteria and meiofauna, while respiration represented 10 to 20% of total community respiration. Consumption by macrofauna accounts for only 3 to 11% of total organic inputs to sediment, with a further 14 to 17% being lost by macrofaunal respiration.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01313164

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Detrital pathways in a coral reef lagoon (1992)

Hansen, J. A. ; Klumpp, D. W. ; Alongi, D. M. ; [et al.]

Springer

Marine biology 113 (1992), S. 363-372

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Coral reef lagoons have generally been regarded as sinks for organic matter exported from more productive reef front and reef flat zones. The object of this study was to examine the importance of detritus as a carbon source for benthic communities in the lagoon at Davies Reef, central Great Barrier Reef. We report the results of seasonal measurements, taken in 1986, of bacterial numbers and production, protozoan numbers, community primary production and respiration in the sediments of Davies Reef lagoon. Deposition rates of organic matter in the lagoon were also measured. Deposition rates (±1 SE) of carbon ranged from 9.2 (±1.5) to 140.7 (±10.3) mg Cm-2d-1. Deposition rates were highest in winter and spring, lowest in summer. Rates of bacterial production ranged from 4.7 (±0.2) pmol thymidine incorporated g-1 dry wt (DW) h-1 in winter to 23.5 (±1.0) pmol thymidine incorporated g-1 DW h-1 in spring. The number of ciliates ranged from 65 (±10) to 356 (±50) cm-3 through the year and the number of large (≥20 μm) flagellates from 38 (±7) to 108 (±16) cm-3. There were no clear relationships between the sediment organic content, detrital input or temperature and the rates of bacterial processes, community metabolism or the standing stocks of microbes in the lagoon. The relative significance of detritus and in situ primary production as sources of carbon in the lagoon varied with season. In summer and autumn, detritus was less important than primary production as a source of carbon (4 to 27% of total carbon input). In winter and spring, detritus input became more significant in supply of carbon to the sediments (32 to 67% of the total carbon input). The lagoon does not simply act as a sink for carbon exported from the reef flat. We calculate that only 5% of the net reef flat primary production reached lagoon sediments in summer, but nearly 40% in winter.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00349160

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