The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Edward J. Buskey - One of the best experts on this subject based on the ideXlab platform.
-
measuring rna dna ratios in individual Acartia tonsa copepoda
Marine Biology, 2007Co-Authors: Scott B Nunez, Christa L Speekmann, Edward J. BuskeyAbstract:Acartia tonsa Dana is a dominant copepod in coastal waters and is therefore an important link in the food web between microplankton and higher trophic levels. RNA:DNA ratios have been used to describe growth and nutritional condition of field-collected copepods and to show strong correlation between RNA:DNA ratios and group egg production (EP). A method was developed using a sensitive, nucleic acid-specific fluorescent dye, and automated microplate fluorometer to measure DNA, RNA, and the RNA:DNA ratio of individual A. tonsa. DNA, RNA, and RNA:DNA ratios and EP were all significantly higher in copepods fed Thalassiosira sp. compared to starved copepods. There was a general trend toward an increase in RNA:DNA ratios with increase in EP, but due to the high degree of variation in both RNA:DNA ratios and EP among individual copepods there was no significant correlation between RNA:DNA ratios and EP. Significant differences in RNA:DNA ratios between fed (7.2) and starved (3.3) copepods were found after 2 days. This assay may be applied to other species of copepods sampled in the field to provide an index of the health of planktonic food webs.
-
Effects of the red tide dinoflagellate, Karenia brevis, on grazing and fecundity in the copepod Acartia tonsa
Journal of Plankton Research, 2007Co-Authors: C. F. Breier, Edward J. BuskeyAbstract:Among studies of copepod grazers fed harmful algae, decreased grazing and fecundity are the most common results. The causes of decreased grazing (physiological incapacitation, behavioral avoidance or lack of stimulation) and decreased fecundity (toxic versus nutritional effect) vary among studies. This study used a series of controlled laboratory experiments to investigate the cause of decreased grazing and fecundity in the copepod Acartia tonsa fed sole and mixed diets of the harmful alga, Karenia brevis. Copepods fed K. brevis mixed with the nutritionally viable dinoflagellate Peridinium foliaceum had higher ingestion rates and offspring production than copepods fed a sole diet of K. brevis (even when K. brevis was virtually nontoxic). Copepods fed mixtures did not discriminate between P. foliaceum and K. brevis while feeding. The results of this study suggest that K. brevis is not toxic to A. tonsa but lacks some chemical component responsible for stimulating a grazing response in A. tonsa as well as the nutritional requirements for normal offspring production.
-
Turbulence decreases the hydrodynamic predator sensing ability of the calanoid copepod Acartia tonsa
Journal of Plankton Research, 2005Co-Authors: Owen M. Gilbert, Edward J. BuskeyAbstract:The copepod Acartia tonsa is very sensitive to hydrodynamic signals, including those made by approaching predators, and responds with a vigorous escape jump. Whether the presence of moderate turbulence changes this ability to detect hydrodynamic signals was investigated by comparing the response of copepods to velocity gradients created by a siphon flow in turbulent and still water. Turbulence decreased the distance at which A. tonsa initiated escapes from the siphon and increased the capture rate, indicating decreased sensitivity to hydrodynamic signals, but did not trigger unnecessary escape reactions that might produce fatigue.
-
Factors affecting feeding selectivity of visual predators on the copepod Acartia tonsa: locomotion, visibility and escape responses
Hydrobiologia, 1994Co-Authors: Edward J. BuskeyAbstract:Visual predation by fish on copepods involves prey encounter, attack and capture; during any of these processes prey selection can occur. Developmental changes in copepods, including increases in swimming speed, size and image contrast increase the encounter rate and distance at which they can be detected by predators. Copepods compensate for this increase vulnerability with age through diel vertical migration and improved escape capabilities. This study quantifies the changes in swimming speed and movement pattern with developmental stage of the copepod Acartia tonsa, using a video-computer system for motion analysis. Changes in visible size and image contrast with developmental stage were quantified under simulated natural illumination conditions using a video based image analysis system. The escape responses of the naupliar stages of the copepod Acartia tonsa were quantified in response to a stationary pipette sucking in water at a constant speed. Accurate quantification of the parameters that affect feeding selectivity of planktivorous fish will provide the basis for evaluation of their relative importance in future studies.
Ines Lacchetti - One of the best experts on this subject based on the ideXlab platform.
-
standardized methods for acute and semichronic toxicity tests with the copepod Acartia tonsa
Environmental Toxicology and Chemistry, 2012Co-Authors: Gessica Gorbi, Isabella Buttino, Marion Invidia, F. Savorelli, Elisabetta Giacco, Olga Faraponova, Monica Cigar, Tristano Leoni, Ermelinda Prato, Ines LacchettiAbstract:The availability of standardized protocols for both organism culture and bioassay with ecologically relevant species is of great concern in ecotoxicology. Acartia tonsa represents an important, often dominant, member of zooplankton communities and meets all the practical criteria suggested for model species. New standardized procedures for laboratory culturing of the copepod A. tonsa and standardized methods for acute (24- and 48-h) and semichronic (7-d, static-renewal) toxicity tests with the nauplius stage are described. In both cases, eggs are the starting stage, and nauplius immobilization is the endpoint. The methods were the object of an intercomparison test involving nine laboratories, and nickel was the reference toxicant. Relative reproducibility was 24, 25, and 34% for 24-h, 48-h, and 7-d tests, respectively.
-
Short Communication STANDARDIZED METHODS FOR ACUTE AND SEMICHRONIC TOXICITY TESTS WITH THE COPEPOD Acartia tonsa
2012Co-Authors: Gessica Gorbi, Isabella Buttino, Marion Invidia, F. Savorelli, Elisabetta Giacco, Ines LacchettiAbstract:The availability of standardized protocols for both organism culture and bioassay with ecologically relevant species is of great concern in ecotoxicology. Acartia tonsa represents an important, often dominant, member of zooplankton communities and meets all the practical criteria suggested for model species. New standardized procedures for laboratory culturing of the copepod A. tonsa and standardized methods for acute (24and 48-h) and semichronic (7-d, static-renewal) toxicity tests with the nauplius stage are described. In both cases, eggs are the starting stage, and nauplius immobilization is the endpoint. The methods were the object of an intercomparison test involving nine laboratories, and nickel was the reference toxicant. Relative reproducibility was 24, 25, and 34% for 24-h, 48-h, and 7-d tests, respectively. Environ. Toxicol. Chem. 2012;31:2023–2028. # 2012 SETAC Keywords—Acartia tonsa Acute test Semichronic test Standardized methods Interlaboratory test
Peter A. Todd - One of the best experts on this subject based on the ideXlab platform.
-
The effects of suspended sediments on the swimming behavior of the calanoid copepod, Acartia tonsa
Journal of Plankton Research, 2020Co-Authors: Xinlu Liu, Hans Henrik Jakobsen, Genevieve Sew, Peter A. ToddAbstract:Abstract Copepod swimming behavior is governed by chemical and hydro-mechanical cues. The environment of copepods, however, is frequently impacted by anthropogenic activities, in particular increased levels of suspended sediment due to coastal development. To better understand the effects of sediments on copepod behavior, we used video recordings to document free-swimming in Acartia tonsa under five sediment regimes, both with and without food. Results of the video analysis indicate that as sediment concentration increased, jumping increased and swimming paths became more convoluted. In the presence of prey, swimming trajectories became circular, as opposed to without prey, where paths were more erratic and slower. There was a reverse trend at higher sediment concentrations (120 and 200 mg l−1) for net velocity, turning rate and “spread of participation” index, which could indicate a behavioral threshold. Overall, greater motility with increasing sediment concentration suggests that the copepods were trying to transport themselves out of the sediment-affected area. In the absence of food, the energy cost of this behavior may affect the fitness of Acartia tonsa and, consequently, its predators.
Gessica Gorbi - One of the best experts on this subject based on the ideXlab platform.
-
standardized methods for acute and semichronic toxicity tests with the copepod Acartia tonsa
Environmental Toxicology and Chemistry, 2012Co-Authors: Gessica Gorbi, Isabella Buttino, Marion Invidia, F. Savorelli, Elisabetta Giacco, Olga Faraponova, Monica Cigar, Tristano Leoni, Ermelinda Prato, Ines LacchettiAbstract:The availability of standardized protocols for both organism culture and bioassay with ecologically relevant species is of great concern in ecotoxicology. Acartia tonsa represents an important, often dominant, member of zooplankton communities and meets all the practical criteria suggested for model species. New standardized procedures for laboratory culturing of the copepod A. tonsa and standardized methods for acute (24- and 48-h) and semichronic (7-d, static-renewal) toxicity tests with the nauplius stage are described. In both cases, eggs are the starting stage, and nauplius immobilization is the endpoint. The methods were the object of an intercomparison test involving nine laboratories, and nickel was the reference toxicant. Relative reproducibility was 24, 25, and 34% for 24-h, 48-h, and 7-d tests, respectively.
-
Short Communication STANDARDIZED METHODS FOR ACUTE AND SEMICHRONIC TOXICITY TESTS WITH THE COPEPOD Acartia tonsa
2012Co-Authors: Gessica Gorbi, Isabella Buttino, Marion Invidia, F. Savorelli, Elisabetta Giacco, Ines LacchettiAbstract:The availability of standardized protocols for both organism culture and bioassay with ecologically relevant species is of great concern in ecotoxicology. Acartia tonsa represents an important, often dominant, member of zooplankton communities and meets all the practical criteria suggested for model species. New standardized procedures for laboratory culturing of the copepod A. tonsa and standardized methods for acute (24and 48-h) and semichronic (7-d, static-renewal) toxicity tests with the nauplius stage are described. In both cases, eggs are the starting stage, and nauplius immobilization is the endpoint. The methods were the object of an intercomparison test involving nine laboratories, and nickel was the reference toxicant. Relative reproducibility was 24, 25, and 34% for 24-h, 48-h, and 7-d tests, respectively. Environ. Toxicol. Chem. 2012;31:2023–2028. # 2012 SETAC Keywords—Acartia tonsa Acute test Semichronic test Standardized methods Interlaboratory test
Guillaume Drillet - One of the best experts on this subject based on the ideXlab platform.
-
Dealing with the presence of the ciliate Euplotes sp. in cultures of the copepod Acartia tonsa
Aquaculture International, 2013Co-Authors: Guillaume Drillet, Jörg DutzAbstract:Ciliates in live feed cultures can be a pest that lower production yields. This could dramatically affect the management and success of copepod cultures. In this study, we investigated the effect of the ciliate Euplotes sp. on egg production, specific egg production and egg hatching success of Acartia tonsa fed with Rhodomonas salina. We found that at a concentration of 2 cells ml−1, Euplotes sp. had no effect on the production and hatching success of eggs but increased/decreased the mortality/quality of non-subitaneous eggs. Euplotes sp. had a good fatty acid profile containing high proportion of unsaturated fatty acids, but the amount of fatty acids compared to their carbon weight was very low and, therefore, it was considered as a poor food source. We propose a short-term interruption of food supply to copepod cultures in order to mitigate bloom formation of ciliates. This will force copepods to feed on them actively as prey and therefore decrease their long-term negative effects.
-
Do Inactivated Microbial Preparations Improve Life History Traits of the Copepod Acartia tonsa?
Marine Biotechnology, 2011Co-Authors: Guillaume Drillet, Tahina Rabarimanantsoa, Stéphane Frouël, Jacob S. Lamson, Anette M. Christensen, Sandra Kim-tiam, Benni W. HansenAbstract:We have tested a microbial preparation with probiotic effects (PSI; Sorbial A/S DANISCO) on the calanoid copepod Acartia tonsa (Dana) development time and reproduction effectiveness in culture. The hypotheses were that PSI increases the productivity and quality of copepods in culture (increased egg production and hatching success, HS). This was carried out because the use of copepods as live prey in aquaculture could increase the number of fish successfully raised through their entire life cycle. However, the availability of copepods is limited by their difficulty to be effectively raised. Our results show that the addition of PSI to the algal food increased the individual size of the adult females and their egg production. The PSI, together with Rhodomonas salina , also increased the HS of the eggs produced by PSI-treated females. These effects were observed despite that the biochemical analysis of the PSI revealed that it is a nutritionally poor food lacking essential fatty acids, and hence it cannot be used alone to raise copepods but instead as a food additive. This is the first demonstration that the effectiveness of copepod culturing can be improved using microbial preparations as a food additive.
-
influence of storage conditions on viability of quiescent copepod eggs Acartia tonsa dana effects of temperature salinity and anoxia
Aquaculture Research, 2006Co-Authors: Martin Holmstrup, Benni Winding Hansen, Guillaume Drillet, Johannes Overgaard, Thomas Flarup Sørensen, Hans Ramløv, Kirsten EngellsorensenAbstract:Copepods have proven to be an ideal source of live food for the production of marine fish larvae in aquaculture. Therefore, there is a need to develop new methods for production and storage of copepod eggs that can be hatched and used at fish farms. In the present study quiescent eggs of Acartia tonsa were stored for periods up to 35 weeks at different temperatures, salinities and oxygen conditions in a full factorial experiment. None of these storage conditions seemed to induce diapause in eggs even though this has been reported by other authors. The most promising storage conditions were those involving low temperature (<5°C), medium salinity (10-20 ppt) and anoxia. The practical aspects of these results for aquaculture are discussed.
-
Influence of storage conditions on viability of quiescent copepod eggs (Acartia tonsa Dana): effects of temperature, salinity and anoxia
Aquaculture Research, 2006Co-Authors: Martin Holmstrup, Benni Winding Hansen, Guillaume Drillet, Johannes Overgaard, Thomas Flarup Sørensen, Hans Ramløv, Kirsten Engell-sørensenAbstract:Copepods have proven to be an ideal source of live food for the production of marine fish larvae in aquaculture. Therefore, there is a need to develop new methods for production and storage of copepod eggs that can be hatched and used at fish farms. In the present study quiescent eggs of Acartia tonsa were stored for periods up to 35 weeks at different temperatures, salinities and oxygen conditions in a full factorial experiment. None of these storage conditions seemed to induce diapause in eggs even though this has been reported by other authors. The most promising storage conditions were those involving low temperature (
