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- Cervin, Linnea, et al.
(författare)
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Multiple stressors and data deficient populations; a comparative life-history approach sheds new light on the extinction risk of the highly vulnerable Baltic harbour porpoises (Phocoena phocoena).
- 2020
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Ingår i: Environment international. - : Elsevier BV. - 1873-6750 .- 0160-4120. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- Many endangered marine mammal populations are difficult to study, spread out over large areas, and capturing them for branding and research purposes would be unethical. Yet, they are in urgent need for assessment and conservation actions. We suggest collecting data from other more abundant populations of the same species, with careful consideration of body size, age at sexual maturity, and ecological conditions to produce scientifically sound best approximations of vital rates of data deficient endangered populations. The genetically distinct Baltic Sea harbour porpoise population amounts to about 500 animals and is classified as 'Critically Endangered' according to the IUCN red list. Data deficiency on nearly all demographic parameters have precluded systematic investigations of the relative importance of stressors affecting population viability. We took a comparative life history approach and investigated the phenotypic plasticity in somatic and demographic vital rates of seven larger, well studied North Atlantic harbour porpoise populations, enabling us to approximate the missing pieces of the life history of the Baltic population. We parameterized a stochastic, individual-based population model, and performed a population viability analysis for a range of biologically realistic parameter values and scenarios of environmental stressors. The baseline scenario was based on the most representative samples of healthy harbour porpoise populations and challenged with three different levels of bycatches. Due to high levels of endocrine disruptive contaminants observed in Baltic harbour porpoises, we also investigated the effect of a possible reduction in fecundity. Subsequently, the combined effects of bycatches and reduced fecundity were investigated in terms of population growth rate and quasi-extinction risk. The Baltic harbour porpoise population is viable in the baseline scenario without anthropogenic stressors. However, even the lowest estimated bycatch level of 7 individuals per year will lead to a population collapse to ≤50 animals with high probability (0.4-1.0) over the next century, assuming an intermediate or low (<73%) fecundity. Adult survival is of critical importance and mitigation of fishery impacts and reduction of anthropogenic disturbances in the identified main breeding areas are recommended.
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- Cervin, Nicholas, et al.
(författare)
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Lightweight and strong cellulose materials made from aqueous foams stabilized by NanoFibrillated Cellulose (NFC)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A novel, lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified NanoFibrillated Cellulose (NFC). This material differs from other particle stabilized foams in that we use renewable cellulose as stabilizing particle. Confocal microscopy and high speed video imaging show that the long-term stability of the wet foams can be attributed to the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface which prevent the air bubbles from collapsing or coalescing. This can be achieved at solids content around 1 % by weight. Careful removal of the water results in a cellulose-based material with a porosity of 98 % and a density of 30 mg cm-3. These porous cellulose materials have a higher Young’s modulus than other cellulose materials made by freeze drying and a compressive energy absorption of 56 kJ m-3 at 80 % strain. Measurement with the aid of an autoporosimeter revealed that most pores are in the range of 300 to 500 μm.
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- Tchang Cervin, Nicholas, 1982-, et al.
(författare)
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Lightweight and Strong Cellulose Materials Made from Aqueous Foams Stabilized by Nanofibrillated Cellulose
- 2013
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 14:2, s. 503-511
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Tidskriftsartikel (refereegranskat)abstract
- A lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified nanofibrillated cellulose (NFC). This material differs from other dry, particle stabilized foams in that renewable cellulose is used as stabilizing particles. Confocal microscopy and high speed video imaging show that the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface prevent the air bubbles from collapsing or coalescing. Stable wet foams can be achieved at solids content around 1% by weight. Careful removal of the water results in a cellulose-based material with a porosity of 98% and a density of 30 mg cm(-3). These porous cellulose materials have a higher Young's modulus than porous cellulose materials made from freeze-drying, at comparable densities, and have a compressive energy absorption of 56 kJ m(-3) at 80% strain. Measurement with the aid of an autoporosimeter revealed that most pores are in the range of 300 to 500 mu m.
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- Ulfsson, Vigge, et al.
(författare)
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Investigation of Spatiotemporal Patterns of Harbour Porpoise (Phocoena phocoena) Strandings in Swedish Waters for Improved Monitoring and Management
- 2024
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Ingår i: OCEANS-SWITZERLAND. - : MDPI. - 2673-1924. ; 5:2, s. 166-180
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Tidskriftsartikel (refereegranskat)abstract
- Harbour porpoises (Phocoena phocoena) are the only cetacean residents found year-round in Swedish waters and they are exposed to numerous natural and anthropogenic threats. Since the in situ monitoring of cetaceans can be difficult, invasive and often expensive, investigation of stranding patterns and examination of stranded animals can be used as a cost-effective source of data to study these elusive animals. The aim of this study was to investigate the spatiotemporal patterns of harbour porpoise stranding reports and the possible underlying causes in Swedish waters over a ten-year period (2014-2023). Additionally, the Swedish stranding network plays a key role in the collection of stranded carcasses for health and disease surveillance, and geographic coverage of the network also was analysed. When making spatial comparisons, the ten-year period was divided into two five-year blocks. Data on 854 stranded harbour porpoises were analysed from the coasts of the Skagerrak, Kattegat, and Baltic Seas. Both significant spatial and temporal patterns could be identified. Strandings peaked in July through September and hotspots occurred along most of the Swedish west coast, with the most frequent hotspots located around & Ouml;resund and especially the area around the Kullen peninsula. The spatial patterns of strandings found in this study are consistent with data on porpoise abundance, prey abundance, and gillnet fisheries' efforts. The latter is known to be one of the primary causes of porpoise mortality. Furthermore, the coverage of the Swedish stranding network increased between the two periods, likely reflecting an increased awareness of the carcass-based surveillance program, and gaps requiring network expansion efforts were identified. These results also provide baseline data to enable the continued monitoring of stranding trends, as changes may indicate changes in population distribution, size or mortality rates.
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