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  • 1
    Electronic Resource
    Electronic Resource
    Soft coral abundance on the central Great Barrier Reef: effects of Acanthaster planci, space availability, and aspects of the physical environment (1997)
    Springer
    Coral reefs 16 (1997), S. 159-167 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract.  The distribution and abundance of soft coral genera on reefs of the central Great Barrier Reef was investigated in relation to reef position, recent history of disturbance, wave exposure, substratum slope and depth. Eighty-five 25 m long transects were surveyed at 10 m depth on windward sides of 14 mid- and outer-shelf reefs. A further 75 transects in different zones on one mid-shelf reef (Davies Reef) between 5 and 30 m depth were investigated. The crown-of-thorns starfish Acanthaster planci had caused large-scale mortality of scleractinians on eight of these reefs five to ten years prior to the study, and as a result, scleractinian cover was only 35–55% of that on the six unimpacted reefs. On the impacted reefs, stony corals with massive and encrusting growths form had smaller average colony diameters but similar or slightly lower numerical abundance. In contrast, mean colony size, cover and abundance of branching stony corals showed no difference between impacted and unimpacted reefs. Twenty-four genera of soft corals (in eight families) were recorded, and none showed different abundance or cover in areas of former A. planci impact, compared to unaffected sites. Similarly, no difference was detected among locations in the numbers or area cover of sponges, tunicates, zoanthids, Halimeda or other macro-algae. Mean soft coral cover was 2 to 5% at 10 m on sheltered mid-shelf reefs, and 12 to 17% on more current-exposed reefs. Highest cover and abundances generally occurred on platforms of outer-shelf reefs exposed to relatively strong currents but low wave energy. On Davies Reef, cover and colony numbers of the families Nephtheidae and Xeniidae were low within the zone of wave impact, in flow-protected bays and lagoons, on shaded steep slopes, and at depths above 10 and below 25 m. In contrast, distributions of genera of the family Alcyoniidae were not related to these physical parameters. The physical conditions of a large proportion of habitats appear “sub-optimal” for the fastest growing taxa, possibly preventing an invasion of the cleared space. Thus, in the absence of additional stress these shallow-water fore-reef zones appear sufficiently resilient to return to their pre-outbreak state of scleractinian dominance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050070
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Internal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions (2016)
    In:  EPIC3Scientific Reports, 6, pp. 30688, ISSN: 2045-2322
    Details
    Publication Date: 2018-05-04
    Description: The resilience of tropical corals to ocean acidification depends on their ability to regulate the pH within their calcifying fluid (pHcf). Recent work suggests pHcf homeostasis under short-term exposure to pCO2 conditions predicted for 2100, but it is still unclear if pHcf homeostasis can be maintained throughout a corals lifetime. At CO2 seeps in Papua New Guinea, massive Porites corals have grown along a natural seawater pH gradient for decades. This natural gradient, ranging from pH 8.1–7.4, provides an ideal platform to determine corals’ pHcf (using boron isotopes). Porites maintained a similar pHcf (~8.24) at both a control (pH 8.1) and seep-influenced site (pH 7.9). Internal pHcf was slightly reduced (8.12) at seawater pH 7.6, and decreased to 7.94 at a site with a seawater pH of 7.4. A growth response model based on pHcf mirrors the observed distribution patterns of this species in the field. We suggest Porites has the capacity to acclimate after long-time exposure to end-of-century reduced seawater pH conditions and that strong control over pHcf represents a key mechanism to persist in future oceans. Only beyond end-of-century pCO2 conditions do they face their current physiological limit of pH homeostasis and pHcf begins to decrease.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 3
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    Ocean acidification caused abundance loss in residential zooplankton living within coral reefs (2015)
    In:  EPIC32015 Aquatic Sciences Meeting - Aquatic Sciences: Global And Regional Perspectives — North Meets South, Granada, Spain, 2015-02-22-2015-02-27
    Details
    Publication Date: 2016-03-01
    Description: Most of what is known about the effects of ocean acidification on zooplankton relates to a few species composed of calcium carbonate, or comes from laboratory and mesocosm studies that observe a relatively small number of species, primarily copepods. So far little is known about how entire zooplankton communities may change due to elevated carbon dioxide levels. We examined changes in zooplankton residential to coral reefs at two reefs in Papua New Guinea where underwater seeps create a natural pH gradient. Traditional net tows, emergence traps, and acoustical instruments were used to collect and observe zooplankton over three separate seasons and emerging from different types of substrata. All methods indicated a dramatic loss in zooplankton abundance where pH was reduced to 7.8 compared to healthy reefs with a normal pH of 8.1. We observed both changes in the overall zooplankton community, and examined each taxonomic group separately to investigate differences in the sensitivity between taxonomic groups. Reduced quantities of zooplankton will likely affect marine organisms that feed on them.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 4
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    Internal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions (2016)
    In:  EPIC3Scientific Reports, 6(1), ISSN: 2045-2322
    Details
    Publication Date: 2020-07-26
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 5
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    In situ changes of tropical crustose coralline algae along carbon dioxide gradients (2015)
    In:  EPIC3Scientific Reports, 5(1), ISSN: 2045-2322
    Details
    Publication Date: 2017-06-08
    Description: Crustose coralline algae (CCA) fulfill important ecosystem functions in coral reefs, including reef framework stabilization and induction of larval settlement. To investigate in situ the effects of high carbon dioxide on CCA communities, we deployed settlement tiles at three tropical volcanic CO2 seeps in Papua New Guinea along gradients spanning from 8.1 to 7.4 pH. After 5 and 13 months deployment, there was a steep transition from CCA presence to absence around pH 7.8 (660 μatm pCO2): 98% of tiles had CCA at pH 〉 7.8, whereas only 20% of tiles had CCA at pH ≤ 7.8. As pH declined from 8.0 to 7.8, the least and most sensitive CCA species lost 43% and 85% of cover, respectively. Communities on upward facing surfaces exposed to high light and high grazing pressure showed less steep losses than those on shaded surfaces with low grazing. Direct CO2 effects on early life stages were the main mechanisms determining CCA cover, rather than competitive interactions with other benthic groups. Importantly, declines were steepest at near-ambient pH, suggesting that CCA may have already declined in abundance due to the recent seawater pH decline of 0.1 units, and that future severe losses are likely with increasing ocean acidification.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    Reduced heterotrophy in the stony coral Galaxea fascicularis after life-long exposure to elevated carbon dioxide (2016)
    In:  EPIC3Scientific Reports, 6, pp. 27019
    Details
    Publication Date: 2017-01-06
    Description: Ocean acidification imposes many physiological, energetic, structural and ecological challenges to stony corals. While some corals may increase autotrophy under ocean acidification, another potential mechanism to alleviate some of the adverse effects on their physiology is to increase heterotrophy. We compared the feeding rates of Galaxea fascicularis colonies that have lived their entire lives under ocean acidification conditions at natural carbon dioxide (CO2) seeps with colonies living under present-day CO2 conditions. When provided with the same quantity and composition of zooplankton as food, corals acclimatized to high CO2 showed 2.8 to 4.8 times depressed rates of zooplankton feeding. Results were consistent over four experiments, from two expeditions and both in field and chamber measurements. Unless replenished by other sources, reduced zooplankton uptake in G. fascicularis acclimatized to ocean acidification is likely to entail a shortage of vital nutrients, potentially jeopardizing their health and survival in future oceans.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Format: application/pdf
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  • 7
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    Effects of transparent exopolymer particles and muddy terrigenous sediments on the survival of hard coral recruits (2003)
    In:  EPIC3Estuar. Coast. Shelf. Sci., 57, pp. 613-621
    Details
    Publication Date: 2019-07-16
    Description: Sedimentation is a major cause of mortality in scleractinian coral recruits.In this study, we compared the effects of muddy coastal sediments, withand without enrichment by "marine snow" on the survivorship of recruits ofthe hard coral Acropora willisae. Transparent exopolymer particles (TEP)were measured as characteristic components of marine snow using astaining method (Passow&Alldredge 1995). Four-week old recruits wereexposed to (i) muddy coastal sediments, (ii) TEP, (iii) TEP-enriched muddycoastal sediments, and (iv) unfiltered sea water, for 43 h in aerated flowchambers. Thirty-three percent (± 5 SE) of coral recruits died after 43-hexposure to TEP-enriched muddy coastal sediments (~14 mg cm-2sediments enriched with 3.8 ± 0.2 mg cm-2 gum xanthan equivalents [GX]TEP). In contrast, no or minimal mortality was observed in the other threetreatments. Mortality increased to 〉80% when the amount of deposited TEPwas almost tripled (10.9 ± 1.3 mg cm-2 GX) and sediment increased by50%. Thus, coral recruits survived short-term exposure to low levels of TEPand low levels of muddy sediments, but sediments enriched with TEP atconcentrations recorded at some of the inshore stations proved to bedetrimental. Concentrations of TEP were measured around and away fromreefs in inshore and shelf regions ???of the central Great Barrier Reef(latitude 16 ? 18° S) in summer, the season of coral spawning andrecruitment. Within 〈10 km off the coast, TEP concentrations were high(mean = 291 ± 49 SE mg GX L-1, range = 152 - 791 mg GX L-1).Concentrations declined with increasing distance from the coast, andaveraged 83 (± 26 SE) mg GX L-1 around oceanic reefs 〉40 km off thecoast. Our study suggests that both sediment composition and short-term(43 h) sediment deposition affect survivalof coral juveniles, which has implications for the capacity of inshore reefs to be recolonised by corals to recover from large-scale disturbance events.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , notRev
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  • 8
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    Effects of marine snow and muddy terrigenous sediments on the survival of hard coral recruits (2003)
    In:  EPIC3Estuarine coastal and shelf science, 56, pp. 1-9
    Details
    Publication Date: 2019-07-16
    Description: Sedimentation is a major cause of mortality in scleractinian coralrecruits. In this study, we compared the effects of muddy coastalsediments, with and without enrichment by "marine snow" on thesurvivorship of recruits of the hard coral Acropora willisae. Transparentexopolymer particles (TEP) were measured as characteristiccomponents of marine snow using a staining method (Passow&Alldredge1995). Four-week old recruits were exposed to (i) muddy coastal sediments, (ii) TEP, (iii) TEP-enriched muddy coastal sediments, and (iv) unfiltered sea water, for 43 h in aerated flow chambers. Thirty-three percent (± 5 SE) of coral recruits died after 43-h exposure to TEP-enriched muddy coastal sediments (~14 mg cm-2 sediments enriched with 3.8 ± 0.2 mg cm-2 gum xanthan equivalents [GX] TEP). In contrast, no or minimal mortality was observed in the other three treatments. Mortality increased to 〉80% when the amount of deposited TEP was almost tripled (10.9 ± 1.3 mg cm-2 GX) and sediment increased by 50%. Thus, coral recruits survived short-term exposure to low levels of TEP and low levels of muddy sediments, but sediments enriched with TEP at concentrations recorded at some of the inshore stations proved to be detrimental. Concentrations of TEP were measured around and away from reefs in inshore and shelf regions ???of the central Great Barrier Reef (latitude 16 ? 18° S) in summer, the season of coral spawning and recruitment. Within 〈10 km off the coast, TEP concentrationswere high (mean = 291 ± 49 SE mg GX L-1, range = 152 - 791 mgGX L-1). Concentrations declined with increasing distance from thecoast, and averaged 83 (± 26 SE) mg GX L-1 around oceanicreefs 〉40 km off the coast. Our study suggests that both sedimentcomposition and short-term (43 h) sediment deposition affect survivalof coral juveniles, which has implications for the capacity of inshorereefs to be recolonised by corals to recover from large-scaledisturbance events.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 9
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    Internal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions (2016)
    Nature Research
    In:  Scientific Reports, 6 (Art. Nr. 30688).
    Details
    Publication Date: 2020-06-18
    Description: The resilience of tropical corals to ocean acidification depends on their ability to regulate the pH within their calcifying fluid (pHcf). Recent work suggests pHcf homeostasis under short-term exposure to pCO2 conditions predicted for 2100, but it is still unclear if pHcf homeostasis can be maintained throughout a corals lifetime. At CO2 seeps in Papua New Guinea, massive Porites corals have grown along a natural seawater pH gradient for decades. This natural gradient, ranging from pH 8.1–7.4, provides an ideal platform to determine corals’ pHcf (using boron isotopes). Porites maintained a similar pHcf (~8.24) at both a control (pH 8.1) and seep-influenced site (pH 7.9). Internal pHcf was slightly reduced (8.12) at seawater pH 7.6, and decreased to 7.94 at a site with a seawater pH of 7.4. A growth response model based on pHcf mirrors the observed distribution patterns of this species in the field. We suggest Porites has the capacity to acclimate after long-time exposure to end-of-century reduced seawater pH conditions and that strong control over pHcf represents a key mechanism to persist in future oceans. Only beyond end-of-century pCO2 conditions do they face their current physiological limit of pH homeostasis and pHcf begins to decrease.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/srep30688
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Ocean acidification affects productivity but not the severity of thermal bleaching in some tropical corals (2016)
    Oxford University Press
    Details
    Publication Date: 2016-02-27
    Description: Increasing carbon dioxide (CO 2 ) emissions are raising sea surface temperature (SST) and causing ocean acidification (OA). While higher SST increases the frequency of mass coral bleaching events, it is unclear how OA will interact to affect this process. In this study, we combine in situ bleaching surveys around three tropical CO 2 seeps with a 2-month two-factor (CO 2 and temperature) tank experiment to investigate how OA and SST in combination will affect the bleaching susceptibility of tropical reef corals. Surveys at CO 2 seep and control sites during a minor regional bleaching event gave little indication that elevated p CO 2 influenced the bleaching susceptibility of the wider coral community, the four most common coral families (Acroporidae, Faviidae, Pocilloporidae, or Poritidae), or the thermally sensitive coral species Seriatopora hystrix . In the tank experiment, sublethal bleaching was observed at 31°C after 5 d in S. hystrix and 12 d in Acropora millepora , whereas controls (28°C) did not bleach. None of the measured proxies for coral bleaching was negatively affected by elevated p CO 2 at pH T 7.79 (vs. 7.95 pH T in controls), equivalent to ~780 µatm p CO 2 and an aragonite saturation state of 2.5. On the contrary, high p CO 2 benefitted some photophysiological measures (although temperature effects were much stronger than CO 2 effects): maximum photosystem II quantum yields and light-limited electron transport rates increased in both species at high p CO 2 , whereas gross photosynthesis and pigment concentrations increased in S. hystrix at high p CO 2 . The field and laboratory data in combination suggest that OA levels up to a pH T of 7.8 will have little effect on the sensitivity of tropical corals to thermal bleaching. Indeed, some species appear to be able to utilize the more abundant dissolved inorganic carbon to increase productivity; however, these gains offset only a small proportion of the massive bleaching-related energy losses during thermal stress.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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