Effects of dietary essential fatty acids on reproduction rates of a subtropical calanoid copepod, Acartia erythraea 

Abstract

To understand the role of food quality in planktonic trophic interactions and marine copepod reproduction, we conducted laboratory experiments to investigate the effect of different prey with specific fatty acid profiles on the reproduction of Acartia erythraea. Copepod egg production rates and hatching success were assessed using a mixed diet combining Dunaliella sp. (containing no long-chain polyunsaturated fatty acids, PUFAs) with the diatom Thalassiosira weissflogii (high eicosapentaenoic acid, EPA), the dinoflagellate Prorocentrum dentatum (high docosahexaenoic acid, DHA), the cryptophyte Rhodomonas sp. (moderate EPA and DHA) or the ciliate Strombidium sulcatum (high nitrogen), respectively. Copepods fed a mono-diet of Dunaliella sp. were used as controls. The results showed that a food mixture with dinoflagellates provided the highest egg production rate and hatching success. The bacterivorous ciliate was not a good prey for copepod reproduction because of the deficit in fatty acid composition, despite its low C:N ratio. Generalized additive models indicated that food quality (ingested PUFAs) was important for egg production in addition to food quantity. Among PUFAs, DHA was the most important specific fatty acid based on its high partial correlation coefficient for egg production rate. Egg hatching success was significantly correlated with the percentage of the 3 major ω3 unsaturated fatty acids (alpha-linolenic acid ALA, EPA and DHA) in diets.KEY WORDS: Food quality · Essential fatty acids · DHA · EPA · Copepods · Acartia · Egg production rate · Egg hatching Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 455: [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110] 2012 gen, indicative of low concentrations of proteins in the food (Checkley 1980). According to the theory of stoichiometry, ciliates should be a good food item for copepods because ciliates generally have a low C:N ratio compared to most phytoplankton. For example, the development of copepods can be enhanced by a diet containing ciliates (Stoecker & Capuzzo 1990). However, stoichiometric ratios are too simple as predictors and sometimes fail to represent the nutritional quality of food in terms of supporting copepod reproduction. It is believed that the reproductive success of copepods also depends on a balance of macronutrients, such as amino acids, sterols and essential fatty acids (Ederington et al. 1995, Kleppel et al. 1998, Guisande et al. 2000, Hassett 2004). The biochemical composition of ciliates can vary significantly depending on their food source, which makes the importance of ciliates for copepod reproduction uncertain (Broglio et al. 2003).Polyunsaturated fatty acids (PUFAs) are indispensable nutrients that are involved in various key processes of marine copepods such as development and reproduction (Sargent & Falk-Petersen 1988), primarily because PUFAs are the major components of phospholipids that play important roles in cell membrane structure a...

Predator‐induced morphological defences in two invasive dreissenid mussels: implications for species replacement

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