Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined wit... more Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined with broader cumulative impacts from climate change. Coral aquaculture will play an important role in active reef restoration and attempts to preserve some semblance of coral reefs in highly impacted areas. Achieving maximum growth and survivorship of cultured corals is necessary to achieve optimal results. This is not possible without the study of coral pests and diseases which can be detrimental to coral health. Here we review the complex relationships between corals and their associated symbiotic organisms, identify invertebrates that may harm the corals and suggest known management techniques in captivity. Groups considered included acoels (Xenacoelomorpha: Acoela), digeneans (Trematoda: Digenea), polyclads (Rhabditophora: Polycladida), gastropods (Mollusca: Gastropoda), decapods (Malacostraca: Decapoda), copepods (Hexanauplia: Copepoda) and pyrgomatids (Cirripedia: Pyrgomatidae). There are few empirically validated management techniques for coral pests, particularly in terms of large‐scale aquaculture, emphasizing the need for further directed research in this area. Information generated through the ornamental trade and hobbyists is valuable to inform future research direction targeted towards captive coral husbandry, reef ecosystem management and restoration strategies.
Abstract High post-settlement mortality in ex situ sexually propagated coral recruits remains a s... more Abstract High post-settlement mortality in ex situ sexually propagated coral recruits remains a significant bottleneck to production of corals for reef restoration, scientific experiments and the ornamental trade. Co-culture with grazing herbivores represents a potentially cost-effective method to reduce recruit competition with algae, thus improving the survival and yield of corals. Here we examined the effectiveness of co-culture of coral recruits of Acropora millepora, A. tenuis, A. secale, Porites lobata and Platygyra daedalea with herbivorous gastropods, Calthalotia strigata and Turbo haynesi, and herbivorous juveniles of the Asteroid Acanthaster cf. solaris. Coral recruits (200 per species) were settled onto individual aragonite plugs, with 10 plugs per species introduced to twenty 50 L experimental tanks. Each tank was randomly assigned to one of five grazing treatments; (1) Thalotia, 30 C. strigata per tank, (2) Turbo, 30 T. haynesi per tank, (3) CoTS, 30 A. cf. solaris per tank, (4) Mix, 10 C. strigata, 10 T. haynesi and 20 A. cf. solaris per tank, and (5) Control, no grazers added. We found that over a 2-month period single species co-culture with C. strigata significantly improved the survival of A. millepora, A. tenuis, A. secale and P. lobata, whilst P. daedalea benefitted most from co-culture with T. haynesi. Over 6-months, C. strigata produced the highest survival in A. millepora (51.6% ± 5.24%), A. tenuis (46.6% ± 3.16%) and A. secale (38.5% ± 3.48%), but T. haynesi co-culture resulted in higher survival in P. lobata (67.3% ± 3.76%) and P. daedalea (100% ± 0%). These results were all significantly higher than the survival of corals in controls, which after 6 months averaged ~1.87% for the Acropora species, 43.0% ± 4.79% and 57.6% ± 8.60% for P. lobata and P. daedalea respectively. Increase in basal surface area of recruits was varied, with the highest relative increases in recruit basal disk area occurring in Thalotia treatments for A. millepora and A. secale, in Turbo for A. tenuis, and in the Control tanks for P. lobata and P. daedalea. This study provides strong evidence that co-culture with C. strigata can improve ex situ sexual coral propagation, with minimal additional intervention from aquarists. The large increase (23.6× higher) in survival of ecologically and economically important coral species such as A. millepora demonstrates the potential of co-culture to enhance ex situ coral propagation.
Photographs were taken at the time of collection. Image file name indicates coral colony number c... more Photographs were taken at the time of collection. Image file name indicates coral colony number corresponding to raw TagSeq reads. Labels within images contain date/time/GPS information
The effects of the herbicide diuron on the early life history stages of broadcast spawning and br... more The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 microg l(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 microg l(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24 h exposure to diuron at 1000 microg l(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 microg l(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F(m)') in illuminated P. damicornis recruits after a 2 h exposure to 1 microg l(-1) diuron. The dark-adapted quantum yields (F(v)/F(m)) also declined, indicating chronic photoinhibition and damage to photosystem II.
Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentr... more Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentrations has deleterious effects on the performance of many marine organisms. However, few empirical or modelling studies have addressed the long-term consequences of ocean acidification for marine ecosystems. Here we show that as pH declines from 8.1 to 7.8 (the change expected if atmospheric carbon dioxide concentrations increase from 390 to 750 ppm, consistent with some scenarios for the end of this century) some organisms benefit, but many more lose out. We investigated coral reefs, seagrasses and sediments that are acclimatized to low pH at three cool and shallow volcanic carbon dioxide seeps in Papua New Guinea. At reduced pH, we observed reductions in coral diversity, recruitment and abundances of structurally complex framework builders, and shifts in competitive interactions between taxa. However, coral cover remained constant between pH 8.1 and ~7.8, because massive Porites corals established dominance over structural corals, despite low rates of calcification. Reef development ceased below pH 7.7. Our empirical data from this unique field setting confirm model predictions that ocean acidification, together with temperature stress, will probably lead to severely reduced diversity, structural complexity and resilience of Indo-Pacific coral reefs within this century.
Manganese (Mn) is an essential element and is generally considered to be one of the least toxic m... more Manganese (Mn) is an essential element and is generally considered to be one of the least toxic metals to aquatic organisms, with chronic effects rarely seen at concentrations below 1000 µg/L. Anthropogenic activities lead to elevated concentrations of Mn in tropical marine waters. Limited data suggest that Mn is more acutely toxic to adults than to early life stages of scleractinian corals in static renewal tests. However, to enable the inclusion of sufficient sensitive coral data in species sensitivity distributions to derive water quality guideline values for Mn, we determined the acute toxicity of Mn to the adult scleractinian coral, Acropora muricata, in flow‐through exposures. The 48‐h median effective concentration was 824 µg Mn/L (based on time‐weighted average, measured, dissolved Mn). The endpoint was tissue sloughing, a lethal process by which coral tissue detaches from the coral skeleton. Tissue sloughing was unrelated to superoxidase dismutase activity in coral tissue, ...
Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined wit... more Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined with broader cumulative impacts from climate change. Coral aquaculture will play an important role in active reef restoration and attempts to preserve some semblance of coral reefs in highly impacted areas. Achieving maximum growth and survivorship of cultured corals is necessary to achieve optimal results. This is not possible without the study of coral pests and diseases which can be detrimental to coral health. Here we review the complex relationships between corals and their associated symbiotic organisms, identify invertebrates that may harm the corals and suggest known management techniques in captivity. Groups considered included acoels (Xenacoelomorpha: Acoela), digeneans (Trematoda: Digenea), polyclads (Rhabditophora: Polycladida), gastropods (Mollusca: Gastropoda), decapods (Malacostraca: Decapoda), copepods (Hexanauplia: Copepoda) and pyrgomatids (Cirripedia: Pyrgomatidae). There are few empirically validated management techniques for coral pests, particularly in terms of large‐scale aquaculture, emphasizing the need for further directed research in this area. Information generated through the ornamental trade and hobbyists is valuable to inform future research direction targeted towards captive coral husbandry, reef ecosystem management and restoration strategies.
Abstract High post-settlement mortality in ex situ sexually propagated coral recruits remains a s... more Abstract High post-settlement mortality in ex situ sexually propagated coral recruits remains a significant bottleneck to production of corals for reef restoration, scientific experiments and the ornamental trade. Co-culture with grazing herbivores represents a potentially cost-effective method to reduce recruit competition with algae, thus improving the survival and yield of corals. Here we examined the effectiveness of co-culture of coral recruits of Acropora millepora, A. tenuis, A. secale, Porites lobata and Platygyra daedalea with herbivorous gastropods, Calthalotia strigata and Turbo haynesi, and herbivorous juveniles of the Asteroid Acanthaster cf. solaris. Coral recruits (200 per species) were settled onto individual aragonite plugs, with 10 plugs per species introduced to twenty 50 L experimental tanks. Each tank was randomly assigned to one of five grazing treatments; (1) Thalotia, 30 C. strigata per tank, (2) Turbo, 30 T. haynesi per tank, (3) CoTS, 30 A. cf. solaris per tank, (4) Mix, 10 C. strigata, 10 T. haynesi and 20 A. cf. solaris per tank, and (5) Control, no grazers added. We found that over a 2-month period single species co-culture with C. strigata significantly improved the survival of A. millepora, A. tenuis, A. secale and P. lobata, whilst P. daedalea benefitted most from co-culture with T. haynesi. Over 6-months, C. strigata produced the highest survival in A. millepora (51.6% ± 5.24%), A. tenuis (46.6% ± 3.16%) and A. secale (38.5% ± 3.48%), but T. haynesi co-culture resulted in higher survival in P. lobata (67.3% ± 3.76%) and P. daedalea (100% ± 0%). These results were all significantly higher than the survival of corals in controls, which after 6 months averaged ~1.87% for the Acropora species, 43.0% ± 4.79% and 57.6% ± 8.60% for P. lobata and P. daedalea respectively. Increase in basal surface area of recruits was varied, with the highest relative increases in recruit basal disk area occurring in Thalotia treatments for A. millepora and A. secale, in Turbo for A. tenuis, and in the Control tanks for P. lobata and P. daedalea. This study provides strong evidence that co-culture with C. strigata can improve ex situ sexual coral propagation, with minimal additional intervention from aquarists. The large increase (23.6× higher) in survival of ecologically and economically important coral species such as A. millepora demonstrates the potential of co-culture to enhance ex situ coral propagation.
Photographs were taken at the time of collection. Image file name indicates coral colony number c... more Photographs were taken at the time of collection. Image file name indicates coral colony number corresponding to raw TagSeq reads. Labels within images contain date/time/GPS information
The effects of the herbicide diuron on the early life history stages of broadcast spawning and br... more The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 microg l(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 microg l(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24 h exposure to diuron at 1000 microg l(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 microg l(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F(m)') in illuminated P. damicornis recruits after a 2 h exposure to 1 microg l(-1) diuron. The dark-adapted quantum yields (F(v)/F(m)) also declined, indicating chronic photoinhibition and damage to photosystem II.
Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentr... more Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentrations has deleterious effects on the performance of many marine organisms. However, few empirical or modelling studies have addressed the long-term consequences of ocean acidification for marine ecosystems. Here we show that as pH declines from 8.1 to 7.8 (the change expected if atmospheric carbon dioxide concentrations increase from 390 to 750 ppm, consistent with some scenarios for the end of this century) some organisms benefit, but many more lose out. We investigated coral reefs, seagrasses and sediments that are acclimatized to low pH at three cool and shallow volcanic carbon dioxide seeps in Papua New Guinea. At reduced pH, we observed reductions in coral diversity, recruitment and abundances of structurally complex framework builders, and shifts in competitive interactions between taxa. However, coral cover remained constant between pH 8.1 and ~7.8, because massive Porites corals established dominance over structural corals, despite low rates of calcification. Reef development ceased below pH 7.7. Our empirical data from this unique field setting confirm model predictions that ocean acidification, together with temperature stress, will probably lead to severely reduced diversity, structural complexity and resilience of Indo-Pacific coral reefs within this century.
Manganese (Mn) is an essential element and is generally considered to be one of the least toxic m... more Manganese (Mn) is an essential element and is generally considered to be one of the least toxic metals to aquatic organisms, with chronic effects rarely seen at concentrations below 1000 µg/L. Anthropogenic activities lead to elevated concentrations of Mn in tropical marine waters. Limited data suggest that Mn is more acutely toxic to adults than to early life stages of scleractinian corals in static renewal tests. However, to enable the inclusion of sufficient sensitive coral data in species sensitivity distributions to derive water quality guideline values for Mn, we determined the acute toxicity of Mn to the adult scleractinian coral, Acropora muricata, in flow‐through exposures. The 48‐h median effective concentration was 824 µg Mn/L (based on time‐weighted average, measured, dissolved Mn). The endpoint was tissue sloughing, a lethal process by which coral tissue detaches from the coral skeleton. Tissue sloughing was unrelated to superoxidase dismutase activity in coral tissue, ...
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