Entity

Time filter

Source Type


Hixson S.M.,Ryerson University | Sharma B.,University of Toronto | Sharma B.,A+ Network | Kainz M.J.,WasserCluster Biologische Station Lunz | And 2 more authors.
Environmental Reviews | Year: 2015

Long-chain polyunsaturated fatty acids (LC-PUFA) are critical for the health of aquatic and terrestrial organisms; therefore, understanding the production, distribution, and abundance of these compounds is imperative. Although the dynamics of LC-PUFA production and distribution in aquatic environments has been well documented, a systematic and comprehensive comparison to LC-PUFA in terrestrial environments has not been rigorously investigated. Here we use a data synthesis approach to compare and contrast fatty acid profiles of 369 aquatic and terrestrial organisms. Habitat and trophic level were interacting factors that determined the proportion of individual omega-3 (n-3) or omega-6 (n-6) PUFA in aquatic and terrestrial organisms. Higher total n-3 content compared with n-6 PUFA and a strong prevalence of the n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) characterized aquatic versus terrestrial organisms. Conversely, terrestrial organisms had higher linoleic acid (LNA) and alpha-linolenic acid (ALA) contents than aquatic organisms; however, the ratio of ALA:LNA was higher in aquatic organisms. The EPA + DHA content was higher in aquatic animals than terrestrial organisms, and increased from algae to invertebrates to vertebrates in the aquatic environment. An analysis of covariance (ANCOVA) revealed that fatty acid composition was highly dependent on the interaction between habitat and trophic level. We conclude that freshwater ecosystems provide an essential service through the production of n-3 LC-PUFA that are required to maintain the health of terrestrial organisms including humans. © 2015 Published by NRC Research Press.


Koussoroplis A.-M.,WasserCluster Biologische Station Lunz | Koussoroplis A.-M.,University of Potsdam | Nussbaumer J.,WasserCluster Biologische Station Lunz | Arts M.T.,National Water Research Institute | And 3 more authors.
Limnology and Oceanography | Year: 2014

We investigated the effects of temperature (4°C, 8°C, and 12°C) on structural and storage dynamics, as measured by changes in fatty acids (FA) associated with cell membrane phospholipids (PL) and triacylglycerols (TAG), respectively, as well as on body weight and survival of a freshwater calanoid copepod (Eudiaptomus gracilis) during fasting (10 d) and refeeding (10 d) with two algae of differing nutritional quality (Cryptomonas ozolinii and Scenedesmus obliquus). Fasting led to 50% loss in body weight, a near total depletion of TAG, and a drastic decrease of the polyunsaturated FA (PUFA) in TAG and PL, indicating their preferential utilization and alterations in membrane function, respectively. Higher temperatures accelerated the decrease of body weight and of PUFA in PL and TAG, and decreased survival. After 10 d of refeeding, copepods partially recovered their initial lipid stores and cell membrane composition. The effects of food quality were temperature dependent: Cryptomonas promoted better recovery (i.e., return to or close to the levels at the beginning of the experiment) of both body weight and TAG at only the two higher temperatures (8°C and 12°C), whereas no recovery was observed at 4°C. Higher temperatures and refeeding on Cryptomonas also had a positive, but minor, influence on the recovery of membrane FA composition. Survival differed among treatments but was lowest at the intermediate temperature (8°C) for both diets. We conclude that temperature changes on the order of 4-8°C significantly influence TAG and PL during fasting periods and interact with food quality to determine the extent of recovery in copepod lipids. © 2014, by the Association for the Sciences of Limnology and Oceanography, Inc.


McMeans B.C.,WasserCluster Biologische Station Lunz | McMeans B.C.,University of Guelph | Koussoroplis A.-M.,WasserCluster Biologische Station Lunz | Koussoroplis A.-M.,University of Potsdam | And 2 more authors.
Journal of Plankton Research | Year: 2015

We experimentally show that Daphnia magna can use terrestrial-derived dissolved organic matter (t-DOM) to support growth and reproduction when alternative food sources are limiting or absent. Unlike previous studies, we restricted available food to limiting algae (0.1 mg C L-1 of Scenedesmus obliquus, provided to all treatments) and bacteria (conditions were not sterile) by excluding heterotrophic protists and running our experiment in darkness to prevent algal growth. Daphnia receiving 10 mg t-DOC L21 leached from either beech (Fagus sylvatica, t-DOMbeech) or hazel leaves (Corylus maxima, t-DOMhazel) had significantly higher juvenile growth rates and deposited larger clutch sizes across a range of realistic temperatures (15, 20, 25%deg;C) than Daphnia receiving no t-DOM, which failed to deposit eggs. Growth rates of t-DOM-supplied Daphnia were similar (0.10+0.01 d-1) and clutch sizes were low (>2 eggs female-1) across temperatures. Our experimental leachate additions mimic fresh t-DOM inputs in natural systems (e.g. during runoff or precipitation) and suggest that t-DOM and t-DOM-supported bacteria can supplement Daphnia growth and reproduction across a range of temperatures even when algae are strongly limiting. Low growth and reproduction rates, however, indicate that t-DOM based resources are unlikely to sustain Daphnia populations independently from sufficient algal contributions. © The Author 2015.


Murray D.S.,WasserCluster Biologische Station Lunz | Hager H.,WasserCluster Biologische Station Lunz | Tocher D.R.,University of Stirling | Kainz M.J.,WasserCluster Biologische Station Lunz
Comparative Biochemistry and Physiology Part - B: Biochemistry and Molecular Biology | Year: 2015

The aim of this 14-month feeding study was to investigate the effects of dietary docosahexaenoic acid (DHA) on tissue fatty acid composition, DHA retention, and DHA content per biomass accrual in muscle tissues of Arctic charr (Salvelinus alpinus). A control feed, formulated with a relatively high DHA inclusion level (F1), was compared with feeds containing gradually reduced amounts of DHA (Feeds F2, F3, and F4). Arctic charr were randomly distributed among 12 tanks and fed one of the feeds in triplicate. The DHA content within muscle tissues of fish fed diets F1 and F2 was generally higher compared to fish fed diets F3 and F4. However, there was an interaction between dietary DHA treatment and season, which resulted in fish muscle tissues having similar DHA contents irrespective of dietary supply during specific sampling periods. Although diets F3 and F4 contained ~4-fold less DHA compared to diets F1 and F2, the retention of DHA in dorsal and ventral muscle tissue was up to 5-fold higher relative to the diet content in fish fed diets F3 and F4. However, the difference among treatments was dependent on the month sampled. In addition, younger fish retained DHA more efficiently compared to older fish. DHA (μg DHA/g/day) accrual in muscle tissue was independent of somatic growth, and there was no difference among treatments. The results suggested that dietary DHA may be essential throughout the life cycle of Arctic charr and that the DHA content of muscle tissues was influenced by diet and metabolic/physiological factors, such as specific DHA retention during the entire growth cycle Finally, this long-term feeding study in Arctic charr indicated a non-linear function in DHA retention in dorsal and ventral muscle tissues throughout the life cycle, which varied in its relationship to dietary DHA. © 2014 Elsevier Inc.


Murray D.S.,WasserCluster Biologische Station Lunz | Hager H.,WasserCluster Biologische Station Lunz | Tocher D.R.,University of Stirling | Kainz M.J.,WasserCluster Biologische Station Lunz
Aquaculture | Year: 2014

The aim of this 15-month feeding study was to investigate the effects of more sustainable feeds on specific growth rate, fatty acid composition and metabolism of Arctic charr (Salvelinus alpinus). A control feed, formulated with fish meal and fish oil (F1), was compared with feeds where the marine ingredients were increasingly replaced by pumpkin kernel cake and rapeseed oil (feeds F2, F3, and F4). Arctic charr were randomly distributed into 12 tanks and fed one of the feeds in triplicate. The biomass of fish fed F1 and F2 diets was significantly higher compared to fish fed with diet F4 which was the highest replacement level. However, the dorsal and ventral muscle tissues had very similar total saturated, monounsaturated, and polyunsaturated fatty acid (PUFA) contents, irrespective of dietary supply. Although diets F3 and F4 contained 6-fold less fish oil than diets F1 and F2, fish fed diets F3 and F4 retained only 2-fold less highly desired omega-3 (n-3) long-chain (LC)-PUFA in their dorsal and ventral muscle tissues. Incubating isolated hepatocytes with 14C-labelled α-linolenic acid (18:3n-3) provided evidence that Arctic charr can bioconvert this essential dietary PUFA to n-3 LC-PUFA, including docosahexaenoic acid. The results suggested that tissue fatty acid compositions in Arctic charr are dependent, not only on dietary fatty acid supply, but also on their ability for endogenous synthesis of n-3 LC-PUFA. Finally, this long-term feeding study indicated that feeds containing pumpkinseed press cake and rapeseed oil produced fish with largely similar fatty acid composition to fish fed diets containing higher contents of fish meal and fish oil. © 2014 Elsevier B.V.

Discover hidden collaborations