Thomas Allan Rayner
Roskilde University
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Featured researches published by Thomas Allan Rayner.
Aquaculture International | 2016
Benni Winding Hansen; Elisa Blanda; Guillaume Drillet; Jacob Kring Højgaard; Mohamed-Sofiane Mahjoub; Thomas Allan Rayner
It is well established in Denmark to rear calanoid copepods in outdoor tanks for use as live feed during turbot (Scophthalmus maximus) larval production. However, the copepod assemblages, composed of a mixture of all development stages and therefore body sizes, vary over time and do not always match the larval needs. When turbot larvae reach metamorphosis and are transferred indoor for weaning, the outdoor tank sediments may reveal vast amounts of copepod eggs undergoing dormancy. Here, we report a copepod species succession firstly among Centropages hamatus and then Acartia spp. both with resting eggs as part of their life cycles as a result of two different nutrients treatments and a control. We found a tendency to a higher egg production and indeed more eggs in the sediment of nutrient amended tanks. In fact close to 5 million eggs per square meter, making up to 400 million eggs per tank was found in the sediment after one production. Instead of discarding the sediment between production batches, we propose to collect it and generate an egg bank. These eggs can be stored for months to a year, however, according to the results, a large loss rate occurred, which could be potentially decreased by the optimization of storage conditions. Those procedures will enable hatchery managers to apply newly hatched copepod nauplii exactly when the turbot larvae start feeding which would potentially solve the, often occurring, mismatch between the time of start-feeding turbot larvae and actual available prey field.
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology | 2017
Thomas Allan Rayner; Niels Jørgensen; Guillaume Drillet; Benni Winding Hansen
Changes in free amino acids (FAA) were investigated in the potentially important live feed and neritic copepod species Acartia tonsa during naupliar development. Total content of FAA in A. tonsa nauplii was around 17% of dry weight at first development stage, and declined to 6% for later stages. Relative to body-volume and biomass, the FAA content indicated possible volume-dependent changes. However, changes in FAA with osmolytic activity could not account for this decline in FAA content, but suggests that the decline reflected degradation of residual FAAs from the embryonic stage. Glutamic acid revealed the largest change in relative abundance during naupliar development and declined from 29.0% at first nauplius stage to 7.1% at later stages. The high FAA pool in early naupliar stages may be necessary for naupliar development due to an absence of feeding at first development stages. The high FAA content in early nauplii indicates that A. tonsa is a valuable source for nutritional energy for first-feeding fish larvae and should be further exploited for aquaculture purposes. Enhancements to FAA abundances in nauplii through manipulation of maternal diets could be of future interest, as copepod nauplii can contain a substantial pool of FAAs at first development stage.
Journal of Applied Aquaculture | 2018
Jacob Kring Højgaard; Thomas Allan Rayner; Christina K. Jensen; Julia L. Overton; Benni Winding Hansen
ABSTRACT Egg hatching and nauplii success from three euryhaline calanoid copepod species at low salinities suggest a promising alternative initial live feed for pikeperch (Sander lucioperca L.) to the conventional live feed. Acartia bifilosa and Eurytemora affinis are viable candidates with egg hatching down to zero salinity, and Acartia tonsa nauplii survive up to 2 h at zero salinity after transfer from low-salinity seawater. When offered A. tonsa and Artemia, pikeperch larvae equally consumed both prey types. We suggest that euryhaline copepods can be a supplement to or even a substitute for the normal live feed currently used as larval feed for pikeperch.
Aquaculture | 2015
Thomas Allan Rayner; Niels Jørgensen; Elisa Blanda; Cheng-Han Wu; Cheng-Chein Huang; John Mortensen; Jiang-Shiou Hwang; Benni Winding Hansen
Journal of Applied Phycology | 2016
Minh Thi Thuy Vu; Claire Douëtte; Thomas Allan Rayner; Christina Vinum Thoisen; Søren Laurentius Nielsen; Benni Winding Hansen
Journal of Experimental Marine Biology and Ecology | 2015
Hans Henrik Jakobsen; Elisa Blanda; Peter A. Staehr; Jacob K. Højgård; Thomas Allan Rayner; Morten Foldager Pedersen; Per Meyer Jepsen; Benni Winding Hansen
Aquaculture | 2015
Elisa Blanda; Guillaume Drillet; Cheng-Chien Huang; Jiang-Shiou Hwang; Hans Henrik Jakobsen; Thomas Allan Rayner; Huei-Meei Su; Cheng-Han Wu; Benni Winding Hansen
Journal of Plankton Research | 2017
Thomas Allan Rayner; Jiang-Shiou Hwang; Benni Winding Hansen
Journal of Plankton Research | 2017
Thomas Allan Rayner; Jiang-Shiou Hwang; Benni Winding Hansen
Aquaculture Research | 2017
Thomas Allan Rayner; Jacob Kring Højgaard; Benni Winding Hansen; Jiang-Shiou Hwang