Egg boon fatty acids reveal effects of a climatic event on a marine food web

Abstract

Flow of essential fatty acids (EFAs) through food webs is critical for the health of individual animals, populations, and communities. Planktonic eggs may play a central role in marine systems because they are highly concentrated in EFAs, superabundant, and consumed by a variety of species. Previous research suggests that egg fatty acid composition should not be useful for trophodynamic studies because it should be tightly regulated to meet the nutritional needs of embryos. Eight years of sampling the egg boon of the teleost fish red drum (Sciaenops ocellatus) provided the opportunity to test the hypothesis that extreme climatic events differentially alter abundances of prey populations and, ultimately, egg fatty acid composition. Fatty acid composition of eggs varied significantly among years and three major patterns of interannual variation (principal components) paralleled trends in the Palmer Drought Severity Index. Each of the first three principal components was related to abundances of particular prey (blue crabs, filter‐feeding fishes, and brown shrimp, respectively) during the spring and summer. Summer abundances of blue crab and brown shrimp were most strongly correlated with bay salinity 12–14 months earlier. Summer abundances of filter‐feeding fishes were most strongly correlated with bay salinity 0–1 month earlier. The delayed responses of crustacean abundances to variations in bay salinity likely operate through variability in recruitment. The fast connection for filter‐feeding fishes suggests a behavioral response to changing environmental conditions. The analyses revealed changes in trophodynamic flow that were associated with the phases of the climatic event. EFA content of eggs increased during drought years then decreased in the recovery years, indicating the potential for downstream effects on reproductive output, offspring viability, and tissue composition of egg consumers. Generally, nutrients move from intermediate sized consumers to a larger, higher order consumer (adult red drum). Then, trophic flow reverses when the egg boon is exploited by smaller planktivores. The analysis also revealed climate‐related shifts in the degree of benthic‐pelagic coupling and pelagic recycling that were mediated by the egg boons. This study demonstrates that egg boons can be a useful subject for investigations of trophodynamics in marine ecosystems.

Climate change‐induced deprivation of dietary essential fatty acids can reduce growth and mitochondrial efficiency of wild juvenile salmon

“…This suggests that dietary EPA and ALA were not retained in the salmon tissues, but instead likely used for the synthesis of DHA by fish in both dietary treatments (Kainz et al, 2006). Besides internal synthesis of DHA (Murray et al, 2014;Taipale et al, 2018) individuals also could attain high DHA via dietary retention before the experiment and through the maternal provisioning of eggs from which they hatched (Fuiman, 2018). Despite a higher bioaccumulation factor, the DHA content was lower in both muscle and brain tissues n − 3 of the salmon fed on the n − 3 LC-PUFA-deprived diet.…”

“…An important but poorly understood consequence of climate change is the reduced availability of omega-3 long-chain polyunsaturated fatty acids (n − 3 LC-PUFA), eicosapentaenoic acid (EPA, 20:5 n − 3) and docosahexaenoic acid (DHA, 22:6 n − 3), in aquatic food webs (Fuiman, 2018;Hixson & Arts, 2016;Taipale et al, 2018). This issue is especially pressing in temperate headwater streams vulnerable to rapid decrease of these micronutrients because increasing temperature (Hixson & Arts, 2016) and frequency of extreme weather events, such as torrential rains (Kanno et al, 2014;Woodward et al, 2015).…”

Biochemical Composition and Energy Strategy Along the Reproductive Cycle of Female Octopus vulgaris in Galician Waters (NW Spain)

“…Regarding seasonality, the increment in the PUFA content during summer and autumn and a higher DHA/EPA ratio in autumn with both patterns mostly observed in the digestive gland, could be explained by changes in the diet that would be lately detected in the FA profile as shown in other cases (e.g., Hardy and Keay, 1972;Tir et al, 2015;Fuiman, 2018). Apart from the season, we observed other time-related variations associated to the sampled year, particularly in 2004 and 2005, when differences were mainly apparent in the FA profile of the digestive gland.…”

Dynamics of diet-egg transfer of fatty acids in the teleost fish, red drum ( Sciaenops ocellatus )

“…Batch-spawning fishes that continue to feed during spawning periods largely depend on recent diets for nutrients that are deposited in eggs [3,4], which provides an opportunity to understand trophic flow of FA through egg boons. A recent field study, for example, reported substantial interannual variation in FA composition of eggs of a batch-spawning marine fish and demonstrated that this variation was associated with climate-driven changes in prey availability [5].…”