Food intake, growth, and reproduction as affected by day length and food availability in the pond snail Lymnaea stagnalis*

Abstract

Abstract:With the aim of integrating the physiology and evolutionary ecology of Lymnaea stagnalis (Linnaeus, 1758), we studied the effects of day length and food availability on the energy budget. Snails were assigned to two different photoperiods and three levels of food availability. The snails were kept individually, and food consumption, growth, and egg production were measured for about 2 months. Snails could nearly compensate for a one-day starvation period by increasing the rate of food-intake. However, food-intake rates did not increase further after a starvation period of 2 days. Growth was well described by the Von Bertalanffy growth equation. The ultimate size of snails kept under medium-day conditions (MD; light:dark = 12:12 h) was not affected by food availability. By contrast, the ultimate size of snails kept under long-day conditions (LD; light:dark = 16:8 h) depended on food availability; those fed the lowest quantities grow the least. Dry-weight densities (dry weight/wet weight) of MD snails were considerably above those of LD snails. In MD snails, food availability did not appreciably affect dry-weight density. By contrast, in LD snails, dry-weight density decreased with decreasing food availability. The reproductive output of LD snails declined with declining food availability, but was 2 to 4 times that of MD snails. The difference in reproductive output was largely accounted for by the difference in stored energy, i.e. dry-weight density. To gauge the extent to which the conclusions from our laboratory work applied to free-living snails, a field study was conducted. The wild-caught snails' dry-weight density was also lowest in long-day conditions when most eggs were laid. However, the dry-weight densities during medium and short days were lower than the dry-weight densities of laboratory animals under LD conditions. Thus, in the field, snails stored less energy than in the laboratory.

Effects of age, size, and mating history on sex role decision of a simultaneous hermaphrodite

“…In addition, we measured water temperature in the ditches during sampling and noted the photoperiod because both these factors have been shown to affect the reproduction of L. stagnalis (e.g., Dogterom et al 1984 ; Ter Maat et al 2007 , 2012 ). Also, we recorded reproductive activity, that is, presence of egg masses and pairs that were copulating.…”

Reproductive strategies in hermaphroditic gastropods: conceptual and empirical approaches

“…In contrast to gonochorists, which need at least a generation to alter their sex allocation in terms of sex ratio, simultaneous hermaphrodites are known for their flexible adjustment of sex allocation depending on various factors. In hermaphroditic gastropods, various abiotic or biotic factors influencing sex allocation are known: mating group size and density (Sprenger et al 2011), rearing condition (Locher and Baur 2000b;Koene and Ter Maat 2004;Koene et al 2008), mating opportunity (Locher and Baur 2000a;Karlsson 2001;Hoffer et al 2012;Lange et al 2012), age (Hermann et al 2009;Sprenger et al 2009), body size (Angeloni 2003;Chaine and Angeloni 2005;Ter Maat et al 2007), parasitic infection (reviewed in Jordaens et al 2007), food availability (Adamo and Chase 1991;Locher and Baur 2002), O 2 contents and cleanness of environment (Ter Maat et al 1983), light cycle (Ter Maat et al 2012), and temperature (Dogterom et al 1984). However, because most studies only investigate the change in allocation towards one sex function, not both simultaneously (Schärer 2009) or growth , the exact mechanism and fitness consequences of the flexible altering of sex allocation remain to be tested.…”

The effect of light on induced egg laying in the simultaneous hermaphrodite Lymnaea stagnalis

“…Egg masses can be laid at a frequency of more than one mass per week, and such masses typically contain between 50 and 150 eggs depending on the individual's body size as well as the time since the last egg mass was laid (Ter Maat, Lodder & Wilbrink, 1983). Decreases in egg laying are caused by short light periods (Bohlken & Joosse, 1982;Ter Maat et al, 2007), frequent mating (Van Duivenboden, Pieneman & Ter Maat, 1985;Koene, Brouwer & Hoffer, 2009) and low temperatures (Vianey-Liaud, 1981;Dogterom et al, 1984). Egg laying completely ceases when food supply is very low (Bohlken et al, 1986;Ter Maat et al, 2007), at old age (Janse, Wildering & Popelier, 1989) and in dirty water (Ter Maat et al, 1983).…”