1.
Burdett, Heidi L., et al.
(författare)
Community-level sensitivity of a calcifying ecosystem to acute in situ CO2 enrichment
2018
Ingår i: Marine Ecology Progress Series. - : Inter-Research. - 0171-8630 .- 1616-1599. ; 587, s. 73-80
Tidskriftsartikel (refereegranskat) abstract
The rate of change in ocean carbonate chemistry is a vital determinant in the magnitude of effects observed. Benthic marine ecosystems are facing an increasing risk of acute CO2 exposure that may be natural or anthropogenically derived (e.g. engineering and industrial activities). However, our understanding of how acute CO2 events impact marine life is restricted to individual organisms, with little understanding for how this manifests at the community level. Here, we investigated in situ the effect of acute CO2 enrichment on the coralline algal ecosystem - a globally ubiquitous, ecologically and economically important habitat, but one which is likely to be sensitive to CO2 enrichment due to its highly calcified reef-like structures engineered by coralline algae. Most notably, we observed a rapid community-level shift to favour net dissolution rather than net calcification. Smaller changes from net respiration to net photosynthesis were also observed. There was no effect on the net flux of DMS/DMSP (algal secondary metabolites), nor on the nutrients nitrate and phosphate. Following return to ambient CO2 levels, only a partial recovery was seen within the monitoring timeframe. This study highlights the sensitivity of biogenic carbonate marine communities to acute CO2 enrichment and raises concerns over the capacity for the system to 'bounce back' if subjected to repeated acute high-CO2 events.
2.
Kamenos, Nicholas A., et al.
(författare)
Reconstructing Four Centuries of Temperature-Induced Coral Bleaching on the Great Barrier Reef
2018
Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 5
Tidskriftsartikel (refereegranskat) abstract
Mass coral bleaching events during the last 20 years have caused major concern over the future of coral reefs worldwide. Despite damage to key ecosystem engineers, little is known about bleaching frequency prior to 1979 when regular modern systematic scientific observations began on the Great Barrier Reef (GBR). To understand the longer-term relevance of current bleaching trajectories, the likelihood of future coral acclimatization and adaptation, and thus persistence of corals, records, and drivers of natural pre-industrial bleaching frequency and prevalence are needed. Here, we use linear extensions from 44 overlapping GBR coral cores to extend the observational bleaching record by reconstructing temperature-induced bleaching patterns over 381 years spanning 1620-2001. Porites spp. corals exhibited variable bleaching patterns with bleaching frequency (number of bleaching years per decade) increasing (1620-1753), decreasing (1754-1820), and increasing (1821-2001) again. Bleaching prevalence (the proportion of cores exhibiting bleaching) fell (1670-1774) before increasing by 10% since the late 1790s concurrent with positive temperature anomalies, placing recently observed increases in GBR coral bleaching into a wider context. Spatial inconsistency along with historically diverging patterns of bleaching frequency and prevalence provide queries over the capacity for holobiont (the coral host, the symbiotic microalgae and associated microorganisms) acclimatization and adaptation via bleaching, but reconstructed increases in bleaching frequency and prevalence, may suggest coral populations are reaching an upper bleaching threshold, a "tipping point" beyond which coral survival is uncertain.
3.
Mao, Jinhua, et al.
(författare)
Carbon burial over the last four millennia is regulated by both climatic and land use change
2020
Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 26:4, s. 2496-2504
Tidskriftsartikel (refereegranskat) abstract
Carbon sequestration by sediments and vegetated marine systems contributes to atmospheric carbon drawdown, but little empirical evidence is available to help separate the effects of climate change and other anthropogenic activities on carbon burial over centennial timescales. We used marine sediment organic carbon to determine the role of historic climate variability and human habitation in carbon burial over the past 5,071 years. There was centennial-scale sensitivity of carbon supply and burial to climatic variability, with Little Ice Age cooling causing an abrupt ecosystem shift and an increase in marine carbon contributions compared to terrestrial carbon. Although land use changes during the late 1800s did not cause marked alteration in average carbon burial, they did lead to marked increases in the spatial variability of carbon burial. Thus, while carbon burial by vegetated systems is expected to increase with projected climate warming over the coming century, ecosystem restructuring caused by abrupt climate change may produce unexpected change in carbon burial whose variability is also modulated by land use change.
4.
Kamenos, Nicholas A., et al.
(författare)
Commentary : Commentary on Reconstructing Four Centuries of Temperature-Induced Bleaching on the Great Barrier Reef by Hoegh-Guldberg et al. 2019 and DeCarlo 2020
2020
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
Tidskriftsartikel (refereegranskat) abstract
Mass coral bleaching events during the last 20 years have caused major concern over the future of coral reefs worldwide. Despite damage to these key ecological cornerstones, little is known about bleaching frequency prior to 1979 when regular modern systematic scientific observations began on the Great Barrier Reef (GBR). To understand the longer-term relevance of current bleaching trajectories, the likelihood of future coral acclimatization and adaptation, and thus persistence of corals, we reconstructed centennial length GBR bleaching records in Kamenos and Hennige (2018) (hereafter KH18). We thank Hoegh-Guldberg et al. (2019) and DeCarlo (2020) (hereafter HG19 and DeC20, respectively) for considering our paper. HG19 and DeC20 question our approach; however here we demonstrate: 1) our use of ERSST data is during their most accurate and precise time period, 2) that linear extension is recording bleaching and that within and between-coral colony variability exists, necessitating a decadally binned approach, 3) that HG19 make errors in their dataset comparisons (also detected by DeC20), and 4) that HG19 and DeC20 use the observational data record beyond its power as it is not resolved by effort or species. Overall, we demonstrate the value of sclerochronological-type approaches over longer time-scales and the existing evidence of historic coral mortality, in contrary to Commentary assertions.
5.
Kamenos, Nicholas A., et al.
(författare)
Coralline algae are global palaeothermometers with bi-weekly resolution
2008
Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 72:3, s. 771-779
Tidskriftsartikel (refereegranskat) abstract
High resolution palaeoclimate data are required for the Holocene to resolve differences recorded by current proxies. The pole to pole distribution of rhodoliths (coralline algae) with their annual and sub-annual calcite bands make these attractive candidates for such a role. These bands contain climate information in the form of elemental traces. In situ temperature (IST) was recorded at two rhodolith beds for 1.5 years. The concentrations of MgCO3 and SrCO3 (mol %) deposited in Lithothamion glaciale and Phymatolithon calcareum over this 18- month period were determined using electron and ion microprobes. Highly significant linear relationships exist between Mg, Sr and IST as well as sea surface temperature. Calibration between Mg concentration and IST was used to obtain a 2-year temperature profile from a subfossil rhodolith thallus indicating half the seasonal peak-to-peak temperature amplitude earlier during the Holocene than the present day. Both slow-growing species (<200 mu m year(-1)) allowed sampling resolutions of 23 year-1 which is equivalent to I reading every 2 weeks. Sub-monthly Mg and Sr records in rhodoliths make them unique globally distributed palaeothermometers which may help refine regional climate histories during the Holocene.
6.
Schoenrock, Kathryn M., et al.
(författare)
Biodiversity of Kelp Forests and Coralline Algae Habitats in Southwestern Greenland
2018
Ingår i: Diversity. - : MDPI. - 1424-2818. ; 10:4
Tidskriftsartikel (refereegranskat) abstract
All marine communities in Greenland are experiencing rapid environmental change, and to understand the effects on those structured by seaweeds, baseline records are vital. The kelp and coralline algae habitats along Greenland's coastlines are rarely studied, and we fill this knowledge gap for the area around Nuuk, west Greenland. Using subtidal swath surveys, photo-quadrats, and grab samples, we characterised the diversity of floral and faunal assemblages in kelp forests and coralline algae beds. The most abundant herbivore assemblages and the most diverse communities occur in the interstitial habitats of rhodolith beds. In kelp forests, species diversity is higher in epi-benthic (photo-quadrat) and mid-water (swath) surveys. These habitats are not mutually exclusive; Agarum clathratum is prominent in coralline algal habitats, while crustose coralline algae cover the bedrock under kelp holdfasts. Overall, the suite of surveys used capture the diverse communities within kelp forests and coralline algae in Greenland and their differing role in the life history of the inhabitants. Furthermore, coralline algae beds are an important carbonate store, with CaCO3 concentrations ranging from 28.06 to 103.73 gm(-3). Our research sets the baseline for continued investigations and monitoring of these important habitats and their supported fisheries.
7.
Schoenrock, Kathryn M., et al.
(författare)
Influences of salinity on the physiology and distribution of the Arctic coralline algae, Lithothamnion glaciale (Corallinales, Rhodophyta)
2018
Ingår i: Journal of Phycology. - : Wiley-Blackwell. - 0022-3646 .- 1529-8817. ; 54:5, s. 690-702
Tidskriftsartikel (refereegranskat) abstract
In Greenland, free-living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthabsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured insitu during summers of 2015 and 2016, and annual patterns of productivity in L.glaciale were monitored in laboratory-based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold-room measurements indicate that both L.glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 +/- 0.17 or 0.002 +/- 0.023mol CaCO3.g(-1).h(-1) and -0.007 +/- 0.003 or -0.004 +/- 0.001mg O-2.L-1.h(-1) in each species respectively. Mesocosm experiments indicate L.glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L.glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 +/- 1.73mg.d(-1) of biomass through summer. These results indicate high freshwater input to the Godthabsfjord region may drive the low abundance of L.glaciale, and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.
8.
Bach, Lydia L., et al.
(författare)
In situ Response of Tropical Coralline Algae to a Novel Thermal Regime
2017
Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 4
Tidskriftsartikel (refereegranskat) abstract
Coralline algae provide important ecosystem services. In situ observations of how they respond to different environmental conditions can help us to understand (i) their ability to adapt to their local environment and (0 their capacity to acclimatize to a novel thermal regime. Here, individuals of the tropical coralline algae, Lithophyllum kotschyanum, were translocated on a coral reef from thermally stable areas to areas characterized by natural temperature variability. Changes in their photosynthetic efficiency were determined using pulse amplitude modulation (PAM) chlorophyll fluorescence. Despite an initial stress response, algae exposed to increases in thermal variation recovered within 24 hours, indicating a rapid, short-term acclimatization capacity. Algae naturally inhabiting thermally variable areas of the reef showed no change in photosynthetic efficiency throughout the study suggesting longer-term adaptation to living in a variable environment also occurs. However, coralline algae living in thermally stable reef areas were abundant and marginally larger, suggesting physiological trade-offs are used to survive in variable environments. Thus, our results suggest that while coralline algae can survive in environmentally variable conditions, there may be structural and ecosystem costs.
9.
Claverie, Thomas, et al.
(författare)
Spawning aggregations and mass movements in subtidal Onchidoris bilamellata (Mollusca Opisthobranchia)
2008
Ingår i: Journal of the Marine Biological Association of the United Kingdom. - : Cambridge University Press. - 0025-3154 .- 1469-7769. ; 88:1, s. 157-159
Tidskriftsartikel (refereegranskat) abstract
Little is known about spawning aggregations in subtidal populations of the nudibranch Onchidoris bilamellata. We provide photographic evidence of the spawning aggregations and associated spawning migrations or mass movements whose occurrence was debated.
10.
Hennige, S. J., et al.
(författare)
The potential for coral reef establishment through free-living stabilization
2017
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
Tidskriftsartikel (refereegranskat) abstract
Corals thrive in a variety of environments, from low wave and tidal energy lagoons, to high energy tidal reef flats, but remain dependent upon suitable substrate. Herein we reviewed the phenomenon of free-living corals (coralliths), examined whether they have the capacity to create their own stable habitat in otherwise uninhabitable, poor substrate environments through 'free-living stabilization', and explore their potential ecological role on coral reefs. This stabilization could be achieved by coral settlement and survival on mobile substrate, with subsequent growth into free-living coralliths until a critical mass is reached that prevents further movement. This allows for secondary reef colonization by other coral species. To preliminarily test this hypothesis we provide evidence that the potential to support secondary coral colonisation increases with corallith size. Due to the limited diversity of corallith species observed here and in the literature, and the lack of physiological differences exhibited by coralliths here to static controls, it seems likely that only a small selection of coral species have the ability to form coralliths, and the potential to create their own stable habitat.
