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المؤلفون: Jeffrey T. Wright, Christopher J. T. Mabin, Cayne Layton, Masayuki Tatsumi, Victor Shelamoff, Matthew J. Cameron, Craig R. Johnson
المصدر: Journal of Phycology. 58:92-104
مصطلحات موضوعية: 0106 biological sciences, Abiotic component, Gametophyte, biology, Zoospore, Reproduction, 010604 marine biology & hydrobiology, Kelp, Sporophyte, Ecklonia, Plant Science, Aquatic Science, Ecklonia radiata, Phaeophyta, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Density dependence, Botany, Seasons, 14. Life underwater, Ecosystem
الوصف: The kelp, Ecklonia radiata, is an abundant subtidal ecosystem engineer in southern Australia. Density-dependent changes in the abiotic environment engineered by Ecklonia may feedback to affect reproduction and subsequent recruitment. Here, we examined: 1) how the reproductive capacity of Ecklonia individuals in the field (zoospores released · mm-2 reproductive tissue) varied with adult density and time, and 2) how the recruitment of microscopic gametophytes and sporophytes was influenced by zoospore density at two times. Zoospore production did not vary with adult density, with only one month out of ten sampled over a 2-y period showing a significant effect of density. However, zoospore production varied hugely over time, being generally highest in mid-autumn and lowest in mid-late summer. There were strong effects of initial zoospore density on gametophyte and sporophyte recruitment with both a minimum and an optimum zoospore density for sporophyte recruitment, but these varied in time. Almost no sporophytes developed when initial zoospore density was 335 · mm-2 in spring and >261 · mm-2 in winter and was zero at very high zoospore densities. These findings suggest that although adult Ecklonia density does not affect per-capita zoospore production, because there is a minimum zoospore density for sporophyte production, a decline in population-level output could feedback to impact recruitment.
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المؤلفون: Christopher J. T. Mabin, Jeffrey T. Wright, Craig R. Johnson
المصدر: Marine Ecology Progress Series. 614:1-19
مصطلحات موضوعية: 0106 biological sciences, Abiotic component, Photoinhibition, Ecology, biology, 010604 marine biology & hydrobiology, Kelp, Climate change, Aquatic Science, Photosynthetic efficiency, biology.organism_classification, Photosynthesis, 01 natural sciences, Relative growth rate, Macrocystis pyrifera, Ecology, Evolution, Behavior and Systematics
الوصف: Climate change is characterised by multiple abiotic forcings acting simultaneously on biotic systems. In marine systems, temperature appears to drive much of the observed change in biotic communities subject to climate change, but this may reflect the focus of most studies only on temperature without consideration of other environmental variables affected by climate change. The giant kelp Macrocystis pyrifera was once abundant in eastern Tasmania, forming extensive habitats of ecological and economic importance, but recent extensive population decline has occurred. Southerly incursion of warm oligotrophic East Australian Current (EAC) water has increased in frequency and intensity into this region, which has warmed ~4 times the global average, and the warming trend is predicted to continue. This study investigated the single and combined effects of temperature, light, and nitrate availability on the physiology of juvenile M. pyrifera sporophytes in a laboratory experiment. Determination of relative growth rate, photosystem II characteristics, pigments, elemental chemistry, and nucleic acid characteristics over 28 d showed that all experimental factors affected sporeling physiology. Temperature and light drove much of the observed variation related to performance characteristics, and rapid deterioration of kelp tissue was a consequence of temperature stress (high temperature), photoinhibition (high light), and low light, accompanied by impaired photosynthetic efficiency and increased RNA concentration, presumably associated with production of photoprotective proteins. Surprisingly, higher relative growth rates were observed in low-nitrate treatments. These findings suggest that negative effects of temperature on M. pyrifera populations will be mediated by local variation in light and nutrient conditions.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::098d918450910f898d49b16140331506
https://doi.org/10.3354/meps12900 -
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المؤلفون: Christopher J. T. Mabin, Jeffrey T. Wright, Craig R. Johnson
المصدر: Journal of phycology. 55(2)
مصطلحات موضوعية: 0106 biological sciences, Gametophyte, Male, Life Cycle Stages, Photoinhibition, biology, Ecology, 010604 marine biology & hydrobiology, Effects of global warming on oceans, Acclimatization, Climate Change, Kelp, Sporophyte, Plant Science, Aquatic Science, Ecklonia radiata, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Kelp forest, Temperate climate, Animals, Female, Ecosystem
الوصف: Temperate kelp forests (Laminarians) are threatened by temperature stress due to ocean warming and photoinhibition due to increased light associated with canopy loss. However, the potential for evolutionary adaptation in kelp to rapid climate change is not well known. This study examined family‐level variation in physiological and photosynthetic traits in the early life‐cycle stages of the ecologically important Australasian kelp Ecklonia radiata and the response of E. radiata families to different temperature and light environments using a family × environment design. There was strong family‐level variation in traits relating to morphology (surface area measures, branch length, branch count) and photosynthetic performance (Fv/Fm) in both haploid (gametophyte) and diploid (sporophyte) stages of the life‐cycle. Additionally, the presence of family × environment interactions showed that offspring from different families respond differently to temperature and light in the branch length of male gametophytes and oogonia surface area of female gametophytes. Negative responses to high temperatures were stronger for females vs. males. Our findings suggest E. radiata may be able to respond adaptively to climate change but studies partitioning the narrow vs. broad sense components of heritable variation are needed to establish the evolutionary potential of E. radiata to adapt under climate change.
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مصطلحات موضوعية: Ecology, biology, Radiata, Kelp, Sporophyte, Aquatic Science, Ecklonia radiata, biology.organism_classification, Kelp forest, Marine Biology & Hydrobiology, Sea surface temperature, Nutrient, Habitat, Ecology, Evolution, Behavior and Systematics
الوصف: Increasing ocean temperatures are a threat to kelp forests in several regions of the world. In this study, we examined how changes in ocean temperature and associated nitrate concentrations driven by the strengthening of the East Australian Current (EAC) will influence the morphology, reproduction and development of the widespread kelp Ecklonia radiata in southeastern Australia. E. radiata morphology and reproduction were examined at sites in New South Wales (NSW) and Tasmania, where sea surface temperature differs by ~5°C, and a laboratory experiment was conducted to test the interactive effects of temperature and nutrients on E. radiata development. E. radiata size and amount of reproductive tissue were generally greater in the cooler waters of Tasmania compared to NSW. Importantly, one morphological trait (lamina length) was a strong predictor of the amount of reproductive tissue, suggesting that morphological changes in response to increased temperature may influence reproductive capacity in E. radiata . Growth of gametophytes was optimum between 15 and 22°C and decreased by >50% above 22°C. Microscopic sporophytes were also largest between 15 and 22°C, but no sporophytes developed above 22°C, highlighting a potentially critical upper temperature threshold for E. radiata in Tasmania. Lower nitrate concentration had no effect on E. radiata gametophytes and sporophytes. Given forecast increases in ocean temperature of between 2 and 3°C in southeastern Australia by 2100, these findings suggest that E. radiata is likely to be affected by a strengthening EAC and highlight the susceptibility of the development and growth of early life-cycle stages to these changes.
وصف الملف: application/pdf
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::defaff4ae2797b4dcdca2454ea482acc
https://hdl.handle.net/10453/27473
