| 1. |
- Bejarano, Sonia, et al.
(författare)
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The shape of success in a turbulent world : wave exposure filtering of coral reef herbivory
- 2017
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 31:6, s. 1312-1324
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Forskningsöversikt (refereegranskat)abstract
- While environmental filters are well-known factors influencing community assembly, the extent to which these modify species functions, and entire ecosystem processes, is poorly understood. Focusing on a high-diversity system, we ask whether environmental filtering has ecosystem-wide effects beyond community assembly. We characterise a coral reef herbivorous fish community for swimming performance based on ten functional traits derived from fish morphology. We then investigate whether wave exposure modifies the functional make-up of herbivory, and the absolute and relative feeding frequency of distinct feeding functional groups. Herbivorous fish species conformed to either laterally compressed or fusiform body plans, which differ in their morphological design to minimise drag. High wave exposure selectively limited the feeding function of the deepest body shapes with highest caudal thrust efficiency, and favoured fusiform bodies irrespective of pectoral fin shape. Traditionally recognised herbivore feeding functional groups (i.e. grazers-detritivores and scrapers-small excavators) differed in swimming performance, and in their capacity to feed consistently across levels of wave exposure. We therefore emphasise the distinctness of their ecological niche and functional complementarity. Species within the same feeding functional group also had contrasting responses to wave exposure. We thereby reveal a further ecological dimension of niche partitioning, and reiterate the risk of assuming functional redundancy among species with a common feeding mode. Contrasting responses of species within feeding functional roles (i.e. response diversity) allowed the preservation of critical trophic functions throughout the gradient (e.g. macroalgal browsing), and likely explained why overall levels of herbivory were robust to filtering. Whether ecosystem functioning will remain robust under the additive effects of environmental stress and human-induced disturbances remains to be tested.
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| 2. |
- Chan, Phoebe, et al.
(författare)
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Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios
- 2011
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Ingår i: Journal of Geophysical Research-Biogeosciences. - 0148-0227. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- Arctic Ocean freshening can exert a controlling influence on global climate, triggering strong feedbacks on ocean-atmospheric processes and affecting the global cycling of the world's oceans. Glacier-fed ocean currents such as the Alaska Coastal Current are important sources of freshwater for the Bering Sea shelf, and may also influence the Arctic Ocean freshwater budget. Instrumental data indicate a multiyear freshening episode of the Alaska Coastal Current in the early 21st century. It is uncertain whether this freshening is part of natural multidecadal climate variability or a unique feature of anthropogenically induced warming. In order to answer this, a better understanding of past variations in the Alaska Coastal Current is needed. However, continuous long-term high-resolution observations of the Alaska Coastal Current have only been available for the last 2 decades. In this study, specimens of the long-lived crustose coralline alga Clathromorphum nereostratum were collected within the pathway of the Alaska Coastal Current and utilized as archives of past temperature and salinity. Results indicate that coralline algal Mg/Ca ratios provide a 60 year record of sea surface temperatures and track changes of the Pacific Decadal Oscillation, a pattern of decadal-to-multidecadal ocean-atmosphere climate variability centered over the North Pacific. Algal Ba/Ca ratios (used as indicators of coastal freshwater runoff) are inversely correlated to instrumentally measured Alaska Coastal Current salinity and record the period of freshening from 2001 to 2006. Similar multiyear freshening events are not evident in the earlier portion of the 60 year Ba/Ca record. This suggests that the 21st century freshening of the Alaska Coastal Current is a unique feature related to increasing glacial melt and precipitation on mainland Alaska.
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| 3. |
- Gelcich, Stefan, et al.
(författare)
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Navigating transformations in governance of Chilean marine coastal resources
- 2010
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 107:39, s. 16794-16799
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Tidskriftsartikel (refereegranskat)abstract
- Marine ecosystems are in decline. New transformational changes in governance are urgently required to cope with overfishing, pollution, global changes, and other drivers of degradation. Here we explore social, political, and ecological aspects of a transformation in governance of Chile's coastal marine resources, from 1980 to today. Critical elements in the initial preparatory phase of the transformation were (i) recognition of the depletion of resource stocks, (ii) scientific knowledge on the ecology and resilience of targeted species and their role in ecosystem dynamics, and (iii) demonstration-scale experimental trials, building on smaller-scale scientific experiments, which identified new management pathways. The trials improved cooperation among scientists and fishers, integrating knowledge and establishing trust. Political turbulence and resource stock collapse provided a window of opportunity that triggered the transformation, supported by new enabling legislation. Essential elements to navigate this transformation were the ability to network knowledge from the local level to influence the decision-making processes at the national level, and a preexisting social network of fishers that provided political leverage through a national confederation of artisanal fishing collectives. The resultant governance scheme includes a revolutionary national system of marine tenure that allocates user rights and responsibilities to fisher collectives. Although fine tuning is necessary to build resilience of this new regime, this transformation has improved the sustainability of the interconnected social-ecological system. Our analysis of how this transformation unfolded provides insights into how the Chilean system could be further developed and identifies generalized pathways for improved governance of marine resources around the world.
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| 4. |
- Nyström, Magnus, et al.
(författare)
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Steering feedbacks toward healthier marine ecosystems
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Marine ecosystem decline is accelerating. At some point degradation may pass a tipping point beyond which ecosystems become trapped in alternative degraded states, as a result of changes in critical feedbacks. Self-reinforcing feedbacks pose a major challenge for managers and policy-makers seeking remedial actions to curb the marine crisis. Here we synthesize the dynamics of critical feedbacks of the degraded states in five socio-economically important marine ecosystems; coral reefs, kelp forests, seagrass beds, shallow unvegetated soft-bottom habitats, and coastal pelagic food webs. A better understanding of the way human actions influence the strength and direction of feedbacks, how different feedbacks interact and at what scales they operate, is crucial for successful implementation of marine ecosystem management. We advocate a critical-feedback management approach that ventures beyond traditionally discipline boundaries, as an essential element of marine ecosystem management.
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| 5. |
- Peña, Viviana, et al.
(författare)
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Lithothamnion (Hapalidiales, Rhodophyta) in the changing Arctic and Subarctic : DNA sequencing of type and recent specimens provides a systematics foundation*
- 2021
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Ingår i: European journal of phycology. - : Taylor & Francis. - 0967-0262 .- 1469-4433. ; 56:4, s. 468-493
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Tidskriftsartikel (refereegranskat)abstract
- Coralline red algae in the non-geniculate genera Clathromorphum, Phymatolithon and Lithothamnion are important benthic ecosystem engineers in the photic zone of the Arctic and Subarctic. In these regions, the systematics and biogeography of Clathromorphum and Phymatolithon have mostly been resolved whereas Lithothamnion has not, until now. Seventy-three specific and infraspecific names were given to Arctic and Subarctic Lithothamnion specimens in the late 19th and early 20th century by Frans R. Kjellman and Mikael H. Foslie. DNA sequences from 36 type specimens, five historical specimens, and an extensive sampling of recent collections resulted in the recognition of four Arctic and Subarctic Lithothamnion species, L. glaciale, L. lemoineae, L. soriferum and L. tophiforme. Three genes were sequenced, two plastid-encoded, rbcL and psbA, and the mitochondrial encoded COI-5P; rbcL and COI-5P segregated L. glaciale from L. tophiforme but psbA did not. Partial rbcL sequences obtained from type collections enabled us to correctly apply the earliest available names and to correctly place the remainder in synonymy. We were unable to sequence another 22 type specimens, but all of these are more recent names than those that are now applied. It is difficult to identify these species solely on morpho-anatomy as they can all occur as encrusting corallines or as maerl (rhodoliths). We demonstrate the importance of sequencing historical type specimens by showing that the recently proposed North-east Atlantic L. erinaceum is a synonym of one of the earliest published Arctic species of Lithothamnion, L. soriferum, itself incorrectly placed in synonymy under L. tophiforme based on morpho-anatomy. Based on sequenced specimens, we update the distributions and ecology of these species.
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| 6. |
- Rasher, Douglas B., et al.
(författare)
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Keystone predators govern the pathway and pace of climate impacts in a subarctic marine ecosystem
- 2020
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 369:6509, s. 1351-1355
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Tidskriftsartikel (refereegranskat)abstract
- Predator loss and climate change are hallmarks of the Anthropocene yet their interactive effects are largely unknown. Here, we show that massive calcareous reefs, built slowly by the alga Clathromorphum nereostratum over centuries to millennia, are now declining because of the emerging interplay between these two processes. Such reefs, the structural base of Aleutian kelp forests, are rapidly eroding because of overgrazing by herbivores. Historical reconstructions and experiments reveal that overgrazing was initiated by the loss of sea otters, Enhydra lutris (which gave rise to herbivores capable of causing bioerosion), and then accelerated with ocean warming and acidification (which increased per capita lethal grazing by 34 to 60% compared with preindustrial times). Thus, keystone predators can mediate the ways in which climate effects emerge in nature and the pace with which they alter ecosystems.
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