92 research outputs found

    The fate of the Arctic seaweed Fucus distichus under climate change : an ecological niche modeling approach

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    Rising temperatures are predicted to melt all perennial ice cover in the Arctic by the end of this century, thus opening up suitable habitat for temperate and subarctic species. Canopy‐forming seaweeds provide an ideal system to predict the potential impact of climate‐change on rocky‐shore ecosystems, given their direct dependence on temperature and their key role in the ecological system. Our primary objective was to predict the climate‐change induced range‐shift of Fucus distichus, the dominant canopy‐forming macroalga in the Arctic and subarctic rocky intertidal. More specifically, we asked: which Arctic/subarctic and cold‐temperate shores of the northern hemisphere will display the greatest distributional change of F. distichus and how will this affect niche overlap with seaweeds from temperate regions? We used the program MAXENT to develop correlative ecological niche models with dominant range‐limiting factors and 169 occurrence records. Using three climate‐change scenarios, we projected habitat suitability of F. distichus – and its niche overlap with three dominant temperate macroalgae – until year 2200. Maximum sea surface temperature was identified as the most important factor in limiting the fundamental niche of F. distichus. Rising temperatures were predicted to have low impact on the species' southern distribution limits, but to shift its northern distribution limits poleward into the high Arctic. In cold‐temperate to subarctic regions, new areas of niche overlap were predicted between F. distichus and intertidal macroalgae immigrating from the south. While climate‐change threatens intertidal seaweeds in warm‐temperate regions, seaweed meadows will likely flourish in the Arctic intertidal. Although this enriches biodiversity and opens up new seaweed‐harvesting grounds, it will also trigger unpredictable changes in the structure and functioning of the Arctic intertidal ecosystem

    Mapping Marine Macroalgae along the Norwegian Coast Using Hyperspectral UAV Imaging and Convolutional Nets for Semantic Segmentation

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    Marine macroalgae form underwater "blue forests" with several important functions. Hyperspectral imaging from unmanned aerial vehicles provides a rich set of spectral and spatial data that can be used to map the distribution of such macroalgae. Results from a study using 81 annotated hyper-spectral images from the Norwegian coast are presented. A U-net convolutional network was used for classification, and accuracies for all macroalgae classes were above 90%, indicating the potential of the method as an accurate tool for blue forest monitoring

    Pre-zygotic isolation in the macroalgal genus Fucus from four contact zones spanning 100-10 000 years : a tale of reinforcement?

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    Hybrid zones provide an ideal natural experiment to study the selective forces driving evolution of reproductive barriers and speciation. If hybrid offspring are less fit than the parental species, pre-zygotic isolating barriers can evolve and strengthen in response to selection against the hybrids (reinforcement). Four contact zones between the intertidal macroalgae Fucus serratus (Fs) and Fucus distichus (Fd), characterized by varying times of sympatry and order of species introduction provide an opportunity to investigate reinforcement. We examined patterns of hybridization and reproductive isolation between Fs and Fd in: (i) northern Norway (consisting of two natural sites, 10 000 years old), (ii) the Kattegat near Denmark (Fd introduced, nineteenth century) and (iii) Iceland (Fs introduced, nineteenth century). Using 10 microsatellites and chloroplast DNA, we showed that hybridization and introgression decreased with increasing duration of sympatry. The two younger contact zones revealed 13 and 24% hybrids and several F(1) individuals, in contrast to the older contact zone with 2–3% hybrids and an absence of F(1)s. Cross-fertilization experiments revealed that the reduction in hybridization in the oldest zone is consistent with increased gametic incompatibility

    Live discrimination of Calanus glacialis and C. finmarchicus females : can we trust phenological differences?

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    Author's accepted version (post-print).This is a post-peer-review, pre-copyedit version of an article published in Marine Biology. The final authenticated version is available online at: http://dx.doi.org/10.1007/s00227-014-2419-5
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