The present experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the ramshorn snail, Marisa cornuarietis, in order to identify suitable husbandry conditions for maintaining multi-generation populations in the laboratory for use in ecotoxicological testing. In this paper we focus on the effects of a combination of food types and feeding frequencies (i.e., the frequency with which the snails were offered food) on juvenile growth and survival at different temperatures. Offspring produced in the laboratory by wild specimens of M. cornuarietis, from Puerto Rico, were used to test the effects of three types of food (lettuce, alginate with fish food, alginate with snail mix) fed at three frequencies (given ad libitum on 4/4, 2/4, or 1/4 d) on juvenile survival and growth. The 4-d feeding regimens were repeated four times, giving a total of 16 d for the experiments. The experiments were conducted at two temperatures (22° and 25°C) under a 12 h light:12 h dark photoperiod. Juvenile growth rates increased with increasing feeding frequency for all food types. The most rapid growth rates occurred in the high-frequency lettuce treatments and the slowest growth rates in the low-frequency lettuce and alginate with snail mix treatments. Juvenile snails grew faster at 25° than at 22°C, and mortality was about twice as high at the lower temperature. Growth rates were used to provide a rough estimate of time to maturity, which was determined to take about twice as long at 22° than at 25°C. The results showed that lettuce is the best food if supplied in abundance, but effects on growth are very dependent on feeding frequency and temperature. We conclude that 25°C is a more appropriate temperature for maintaining populations than 22°C, that lettuce provides a suitable food source, and that food should be supplied continuously for husbandry and toxicity testing of populations of M. cornuarietis.

中文翻译：

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食物类型、摄食频率和温度对 Marisacornuarietis（软体动物：腹足类动物）幼鱼存活和生长的影响

本实验是一项大型研究的一部分，该研究旨在调查饲养参数对 ramshorn 蜗牛 Marisacornuarietis 生活史的影响，以确定合适的饲养条件，以在实验室中维持多代种群用于生态毒理学测试. 在本文中，我们关注食物类型和喂食频率（即为蜗牛提供食物的频率）的组合对不同温度下幼鱼生长和存活的影响。来自波多黎各的 M.cornuarietis 野生标本在实验室中产生的后代被用来测试三种食物（生菜、海藻与鱼食、海藻与蜗牛混合）以三种频率（随意给4/4、2/4 或 1/4 d) 对幼鱼的存活和生长。4 d 喂养方案重复4 次，实验共16 d。实验在两个温度（22°C 和 25°C）和 12 小时光照：12 ​​小时黑暗光周期下进行。幼鱼的生长速度随着所有食物类型的喂食频率的增加而增加。高频生菜处理的生长速度最快，低频生菜和藻酸盐与蜗牛混合处理的生长速度最慢。幼蜗牛在 25°C 下比在 22°C 下生长得更快，并且在较低温度下死亡率大约是其两倍。生长率用于粗略估计成熟时间，确定在 22°C 下所需的时间大约是 25°C 下的两倍。结果表明，如果供应充足，生菜是最好的食物，但对生长的影响很大程度上取决于喂食频率和温度。我们得出的结论是，25°C 是比 22°C 更适合维持种群的温度，生菜提供了合适的食物来源，并且应该持续供应食物用于 M.cornuarietis 种群的养殖和毒性测试。