Data from: Batch spawning facilitates transfer of an essential nutrient from diet to eggs in a marine fish

Fatty acid composition of eggs affects development, growth, and ecological performance of fish embryos and larvae, with potential consequences for recruitment success. Essential fatty acids in eggs derive from the maternal diet, and the time between ingestion and deposition in eggs is ecologically important but unknown. We examined the dynamics of diet-egg transfer of arachidonic acid (ARA) in the batch-spawning fish, red drum (Sciaenops ocellatus), by measuring ARA concentrations in eggs after a single diet shift and during a period of irregular variations in diet. ARA concentrations in eggs changed within 2-16 days of a diet shift. The rate of change was proportional to the magnitude of the shift, with no evidence of equilibration. These results are not consistent with eggs being assembled entirely from accumulated body stores. The immediate source of ARA in eggs appears to be the recent diet. We propose that batch spawning produces rapid diet-egg transfer of ARA because it removes large amounts of fatty acids from the body and prevents equilibration. The immediacy of the diet-egg connection suggests that spawning migration combined with short-interval batch spawning may have evolved to take advantage of nutrients critical for offspring survival that are available at the spawning site.

鱼卵的脂肪酸组成可影响鱼类胚胎与仔鱼的发育、生长及生态表现，进而对种群补充成功率产生潜在影响。鱼卵中的必需脂肪酸源自母体日粮，而日粮摄入至脂肪酸沉积至鱼卵的时间间隔在生态学层面具有重要意义，但目前该时长尚未明确。本研究以分批产卵鱼类红鼓鱼（Sciaenops ocellatus）为研究对象，通过单次日粮转换后以及日粮出现不规则波动期间测定鱼卵内的花生四烯酸（ARA）浓度，探究了ARA从日粮向鱼卵转移的动态过程。结果表明，日粮转换后的2至16天内，鱼卵中的ARA浓度即发生改变；其变化速率与日粮转换的幅度呈正比，且未观测到平衡稳态出现的相关证据。上述结果与“鱼卵完全由体内积累的储备物质合成”的假说并不一致，由此可见，鱼卵中ARA的直接来源似乎为母体近期摄入的日粮。研究人员据此提出，分批产卵模式可快速完成ARA从日粮到鱼卵的转移，因为该产卵过程会将大量脂肪酸从母体体内排出，从而阻止平衡稳态的建立。日粮与鱼卵间的直接关联表明，产卵洄游结合短间隔分批产卵的繁殖策略，可能是为了利用产卵场中可获取的、对子代存活至关重要的营养物质而演化形成的。