2018
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FluoRAS Sensor - Online organic matter for optimising recirculating aquaculture systems

År: 2018

FluoRAS Sensor - Online organic matter for optimising recirculating aquaculture systems

Hambly, A. & Stedmon, C. 2018 In : Research Ideas and Outcomes. 4, e23957

Publication: Research - peer-reviewJournal article – Annual report year: 2018

FluorRAS will develop a sensor that can save recycled fish farms 30% per year in water and energy consumption for water treatment, as well as optimize nitrogen removal. The sensor will be developed in a partnership between engineers (Krüger A / S) and researchers (DTU), and the product will be made available to the entire sector through Danish Aquaculture. Global aquaculture production is expected to double within the next 15 years. Recycling technology has a great potential for supporting environmentally and economically sustainable production. However, the technology has some challenges in balancing both the maintenance of necessary water quality and water treatment costs. Loss of production due to poor water quality is expensive and can be avoided with correct sensor systems. Accumulation of dissolved organic matter and nutrients in the water reduce the effectiveness of UV treatment, is a source of nutrition for opportunistic pathogens, and reduces the effectiveness of the biofilter's removing ammonia. Modern recycling systems are therefore dependent on a network of online sensors that monitor and respond to changes in water quality, but currently there is a need for a sensor to monitor the accumulation of organic matter. FluoRAS aims to fill this gap in technology by developing an online fluorescence sensor. The sensor is based on non-destructive, online optical technology that does not require chemicals and can run continuously.
Original languageEnglish
Article numbere23957
JournalResearch Ideas and Outcomes
Volume4
ISSN2367-7163
DOIs
StatePublished - 2018

 

Effects of Salinity, Commercial Salts, and Water Type on Cultivation of the Cryptophyte Microalgae Rhodomonas salina and the Calanoid Copepod Acartia tonsa

År: 2018

Effects of Salinity, Commercial Salts, and Water Type on Cultivation of the Cryptophyte Microalgae Rhodomonas salina and the Calanoid Copepod Acartia tonsa

Jepsen, P. M., Thoisen, C. V., Carron-Cabaret, T., Pinyol Gallemi, A., Nielsen, S. L. & Hansen, B. W. 2018 In : Journal of the World Aquaculture Society.

Publication: Research - peer-reviewJournal article – Annual report year: 2018

Marine aquaculture facilities positioned far from the sea need access to seawater (SW); hence, commercial salts are often the chosen solution. In marine hatcheries, most fish larvae require live feed (zooplankton) that are in turn fed with microalgae. The objective of this research was to investigate the applicability of commercial salts and clarify the potential effects on the cultivation of the microalga Rhodomonas salina and the copepod Acartia tonsa. Three commercial salts were tested, Red Sea Salt (RS), Red Sea – Coral Pro Salt (CP), and Blue Treasure Salt. R. salina was cultured at salinities of 10, 20, and 30 psu resulting in equal growth rates at salinities 20 and 30 in SW and RS mixed with deionized (DI) water. The optimum salinity for R. salina was 29 psu. For A. tonsa eggs, we observed highest hatching success in 30 psu with CP or RS mixed with DI water. The egg hatching success was not affected by salinities 15–40 and optimal hatching was obtained at 27 psu. Results confirm it was possible to use commercial salts for rearing of both R. salina and A. tonsa, widening the application of these species for aquaculture facilities without access to SW.
Original languageEnglish
JournalJournal of the World Aquaculture Society
ISSN0893-8849
DOIs
StateAccepted/In press - 2018

 

Både laks og ørred er vilde med nyt gydestryg

År: 2018

Både laks og ørred er vilde med nyt gydestryg

Nielsen, J. & Sivebæk, F. 2018 .

Publication: CommunicationInternet publication – Annual report year: 2018

Original languageDanish
Publication date2018
Source/PublisherFiskepleje.dk
StatePublished - 2018

 

Tracking anguillid eels: five decades of telemetry-based research

År: 2018

Tracking anguillid eels: five decades of telemetry-based research

Beguer-Pon, M., Dodson, J. J., Castonguay, M., Jellyman, D., Aarestrup, K. & Tsukamoto, K. 2018 In : Marine and Freshwater Research. 69, 2, p. 199-219

Publication: Research - peer-reviewJournal article – Annual report year: 2018

Advances in telemetry technologies have provided new opportunities to reveal the often-cryptic spatial ecology of anguillid eels. Herein we review 105 studies published between 1972 and 2016 that used a variety of telemetry technologies to study the movements of eels in a variety of habitats. Eight anguillid species have been tracked in three main geographical locations: Western Europe, the north-eastern part of North America and Australasia. Telemetry has proven to be an effective method for determining patterns of yellow eel movements in continental waters. It has also been used extensively to investigate the migratory behaviour of maturing eels as they leave fresh water to reach the sea. Among recent findings is the observation that downstream migration in continental waters is quite discontinuous, characterised by extended stopovers. Reconstructed migration routes in the open ocean obtained from satellite tags have provided indications of spawning areas, extensive vertical migrations and initial clues about the orientation mechanisms at sea. Telemetry studies have also revealed apparent evidence of predation by marine mammals and fish at sea, suggesting a significant natural source of mortality during the eel spawning migration. Finally, we discuss some limitations of telemetry technology and future directions, as well as associated challenges, to the developing field of eel spatial ecology.
Original languageEnglish
JournalMarine and Freshwater Research
Volume69
Issue number2
Pages (from-to)199-219
ISSN1323-1650
DOIs
StatePublished - 2018

 

Environmental calcium and variation in yolk sac size influence swimming performance in larval lake sturgeon (Acipenser fulvescens)

År: 2018

Environmental calcium and variation in yolk sac size influence swimming performance in larval lake sturgeon (Acipenser fulvescens)

Deslauriers, D., Svendsen, J. C., Genz, J., Wall, A. J., Baktoft, H., Enders, E. C. & Anderson, W. G. 2018 In : Journal of Experimental Biology. jeb.164533

Publication: Research - peer-reviewJournal article – Annual report year: 2018

In many animal species, performance in the early life stages strongly affects recruitment to the adult population; however, factors that influence early life history stages are often the least understood. This is particularly relevant for lake sturgeon, Acipenser fulvescens, living in areas where environmental calcium concentrations are declining, partly due to anthropogenic activity. As calcium is important for muscle contraction and fatigue resistance, declining calcium levels could constrain swimming performance. Similarly, swimming performance could be influenced by variation in yolk sac volume, because the yolk sac is likely to affect drag forces during swimming. Testing swimming performance of larval A. fulvescens reared in four different calcium treatments spanning the range of 4-132 mg l-1 [Ca2+], this study found no treatment effects on the sprint swimming speed. A novel test of volitional swimming performance, however, revealed reduced swimming performance in the low calcium environment. Specifically, volitionally swimming larvae covered a shorter distance before swimming cessation in the low calcium environment compared to the other treatments. Moreover, sprint swimming speed in larvae with a large yolk sac was significantly slower than in larvae with a small yolk sac, regardless of body length variation. Thus, elevated maternal allocation (i.e., more yolk) was associated with reduced swimming performance. Data suggest that larvae in low calcium environments or with a large yolk sac exhibit reduced swimming performance and could be more susceptible to predation or premature downstream drift. Our study reveals how environmental factors and phenotypic variation influence locomotor performance in a larval fish.
Original languageEnglish
Article numberjeb.164533
JournalJournal of Experimental Biology
ISSN0022-0949
DOIs
StateAccepted/In press - 2018

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Transgenerational interactions between pesticide exposure and warming in a vector mosquito

År: 2018

Transgenerational interactions between pesticide exposure and warming in a vector mosquito

Tran, T. T., Janssens, L., Dinh, K. V. & Stoks, R. 2018 In : Evolutionary Applications (Online).

Publication: Research - peer-reviewJournal article – Annual report year: 2018

While transgenerational plasticity may buffer ectotherms to warming and pesticides separately, it remains unknown how combined exposure to warming and pesticides in the parental generation shapes the vulnerability to these stressors in the offspring. We studied the transgenerational effects of single and combined exposure to warming (4°C increase) and the pesticide chlorpyrifos on life history traits of the vector mosquito Culex pipiens. Parental exposure to a single stressor, either warming or the pesticide, had negative effects on the offspring: both parental exposure to warming and to the pesticide resulted in an overall lower offspring survival, and a delayed offspring metamorphosis. Parental exposure to a single stressor did, however, not alter the vulnerability of the offspring to the same stressor in terms of survival. Parental pesticide exposure resulted in larger offspring when the offspring experienced the same stressor as the parents. Within both the parental and offspring generations, warming made the pesticide more toxic in terms of survival. Yet, this synergism disappeared in the offspring of parents exposed to both stressors simultaneously because in this condition the pesticide was already more lethal at the lower temperature. Our results indicate that transgenerational effects will not increase the ability of this vector species to deal with pesticides in a warming world. Bifactorial transgenerational experiments are crucial to understand the combined impact of warming and pesticides across generations, hence to assess the efficacy of vector control in a warming world
Original languageEnglish
JournalEvolutionary Applications (Online)
ISSN1752-4563
DOIs
StateAccepted/In press - 2018

 

Tilskud til udsætning af flodkrebs i søer

År: 2018

Tilskud til udsætning af flodkrebs i søer

Berg, S. 2018 .

Publication: CommunicationInternet publication – Annual report year: 2018

Original languageDanish
Publication date2018
Source/PublisherFiskepleje.dk
StatePublished - 2018

 

Opgang af laks i Ribe Å i 2017

År: 2018

Opgang af laks i Ribe Å i 2017

Jepsen, N., Koed, A. & Sivebæk, F. 2018 .

Publication: CommunicationInternet publication – Annual report year: 2018

Original languageDanish
Publication date2018
Source/PublisherFiskepleje.dk
StatePublished - 2018

2017
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Assessing and mitigating of bottom trawling. Final BENTHIS project Report (Benthic Ecosystem Fisheries Impact Study)

År: 2017

Assessing and mitigating of bottom trawling. Final BENTHIS project Report (Benthic Ecosystem Fisheries Impact Study)

Rijnsdorp, A. D., Eigaard, O. R., Kenny, A., Hiddink, J. G., Hamon, K., Piet, G. J., Sala, A., Nielsen, J. R., Polet, H., Laffargue, P., Zengin, M. & Gregersen, Ó. 2017 28 p.

Publication: ResearchReport – Annual report year: 2018

BENTHIS developed the scientific basis to quantify the impact of bottom trawling on the seafloor and the benthic ecosystem. Based on insight in how fishing gear affects the seafloor, an assessment framework was developed that provide indicators of impact and seafloor status on a continuous scale that can be applied in the context of the MSFD. The mechanistic approach allows us to set reference values of impact (status) to estimate the proportion of a region or habitat where the impact is below (status is above) the threshold. The methodology combines estimates of trawling intensity with the depth to which the fishing gear penetrates into the sea bed (penetration profile) and the sensitivity of the habitat. Habitat sensitivity is estimated from the longevity composition of the benthic community that is related to the recovery rate. The mortality imposed by trawling was shown to be related to penetration depth of the fishing gear. The framework was applied to explore which fisheries had the greatest impact and which habitats were impacted the most. Fishers concentrate their activities in only a part of their total fishing area. These core fishing grounds are characterised by a relative low status (high impact). Additional fishing in these core grounds have only a small impact. In the peripheral areas where fishing intensity is low, additional fishing will have a much larger impact. Hence, shifting trawling activities from the core fishing grounds to the peripheral areas will increase the overall impact. Shifting activities from the peripheral grounds to the core will reduce the overall impact. This asymmetry provides the possibility to reduce the impact at a minimal cost. It was shown that implementing a habitat credit management system can provide incentives to reduce fishing in peripheral areas at minimal cost. In collaboration with the fishing industry and gear manufacturers, technological innovations were studied to reduce the impact of trawling. Promising results were obtained showing that (semi-) pelagic otter doors can be applied to reduce bottom impact and at the same time reduce the fuel cost without affecting the catch rate of the target species. Replacing mechanical stimulation by tickler chains with electrical stimulation In the beam trawl fishery for sole, reduced footprint and penetration depth as well as the fuel cost. Electrical stimulation is also a promising innovation to reduce the bycatch and bottom contact in the beam trawl fishery for brown shrimps. Sea trials to replace bottom trawls with pots were inconclusive. Results suggest that creels may offer an alternative for small Nephrops fishers in the Kattegat. In waters off Greece, the catch rates were very low. Sea trials with the blue mussel fishery showed that fishers could reduce their footprint by deploying acoustic equipment to detect mussel concentrations that allow the fishers to more precisely target the mussel beds and hence reduce fishing in areas with low mussel density. A review of the various case studies carried out in BENTHIS revealed the critical success factors for implementing technological innovations to mitigate trawling impact. While economic investment theory predict that economic profitability should lead to investment in innovative gears, it appeared that many other factors play a role in the successful uptake of new technology such as social, regulatory, technological and environmental factors. For the successful development and implementation of gear innovations, collaboration between fishers, gear manufacturers, policy makers, scientist and society is important
Original languageEnglish
Number of pages28
StatePublished - 2017

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glmmTMB balances speed and flexibility among packages for Zero-inflated Generalized Linear Mixed Modeling

År: 2017

glmmTMB balances speed and flexibility among packages for Zero-inflated Generalized Linear Mixed Modeling

Brooks, M. E., Kristensen, K., van Benthem, K. J., Magnusson, A., Berg, C. W., Nielsen, A., Skaug, H. J., Machler, M. & Bolker, B. M. 2017 In : R Journal. 9, 2, p. 378-400

Publication: Research - peer-reviewJournal article – Annual report year: 2017

Count data can be analyzed using generalized linear mixed models when observations are correlated in ways that require random effects. However, count data are often zero-inflated, containing more zeros than would be expected from the typical error distributions. We present a new package, glmmTMB, and compare it to other R packages that fit zero-inflated mixed models. The glmmTMB package fits many types of GLMMs and extensions, including models with continuously distributed responses, but here we focus on count responses. glmmTMB is faster than glmmADMB, MCMCglmm, and brms, and more flexible than INLA and mgcv for zero-inflated modeling. One unique feature of glmmTMB (among packages that fit zero-inflated mixed models) is its ability to estimate the Conway-Maxwell-Poisson distribution parameterized by the mean. Overall, its most appealing features for new users may be the combination of speed, flexibility, and its interface's similarity to lme4.
Original languageEnglish
JournalR Journal
Volume9
Issue number2
Pages (from-to)378-400
StatePublished - 2017


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22 FEBRUAR 2018