Sex differences in biochemical composition, energy content and allocation to reproductive effort in the brooding sea star Leptasterias polaris

Abstract

ABSTRACT:We assessed sex differences in reproductive investment of the brooding sea star Leptasterias polaris (in the northern Gulf of St. Lawrence, eastern Canada) by examining the biochemical composition and energetic content of the principal body components in 3 contrasting periods: just before spawning, after spawning and after brooding. The reproductive effort for a standard sea star with an underwater mass of 10 g (equivalent to 8.2 cm in radius) was similar for both sexes (15.1 kJ in males and 12.2 kJ in females). However, the sexes differed in how energy was allocated for reproduction. The energy loss due to gamete release was almost 4-fold greater for males (15.1 kJ) than females (4.1 kJ). The major reproductive expenditure in females came from maintenance costs during the prolonged brooding period (8.1 kJ). For the body wall and stomach, lipid, protein and energy contents were similar for males and females over the spawning and brooding periods. The ratio of males to females in the population was 1:1 in smaller size classes but was about 2:1 for individuals measuring >11 cm in radius. This is possibly explained by slower somatic growth of females due to the repeated use of energetic reserves and lack of feeding during the 5 to 6 mo brooding period. The replenishment of body wall carbohydrates in males during the winter (not observed in females) suggests that males feed during this period.KEY WORDS: Sea star · Leptasterias polaris · Brooding · Proximate biochemical composition · Reproductive effort · Gulf of St. Lawrence Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 283: [179][180][181][182][183][184][185][186][187][188][189][190] 2004 Comparisons of energy reserves before and after reproduction will reflect the energetic costs of reproduction (Doughty & Shine 1997).Asteroids show 3 types of larval development: pelagic planktotrophic larvae, pelagic lecithotrophic larvae, or lecithotrophic development of embryos brooded by the females (Thorson 1946, 1950, Mileikovsky 1971, Lawrence & Herrera 2000. Brooding is often considered a response to limited food resources and is more common in small asteroids: the small size may mean that they cannot produce sufficient gametes to ensure successful external fertilisation (Menge 1974). An alternative hypothesis is that the small size of brooders optimises brood number relative to female body size (Strathmann & Strathman 1982, Strathmann 1985. This suggests that brooding is an unlikely strategy for large animals because the relative surface area for brooding decreases with increasing body size. Brooding may reduce parental fitness by limiting mobility and increasing vulnerability to predators (Strathmann 1985, Bosch & Slattery 1999. This limited mobility may also prevent or reduce feeding, leading to the use of somatic reserves (Chia 1969, Nimitz 1971, Menge 1974, 1975, Harrold & Pearse 1980, Hendler & Franz 1982, Jangoux 1982, Doughty & Shine 1997. Whereas reproductive investment is limited to the period of game...

Sex‐specific differences in gonopore and gonadal growth trajectories in the brooding sea urchin, Abatus cavernosus (Spatangoida)

“…However, more energy is probably necessary to produce large yolky eggs than spermatozoa. A similar tradeoff between mass and energy content, resulting in sex‐specific differences, has been observed in other species of brooding echinoderms (Gil, Reartes, Mutti, Tolosano, & Zaixso, ; Gil & Zaixso, ; McClintock & Pearse, ; Raymond, Himmelman, & Guderley, ). Relatively low ovarian mass could also be a consequence of producing large eggs, since the size of the brood mass is limited by the capacity of the brood chamber (Gil et al, ).…”

Reproductive biology and energetics of the brooding sea star Anasterias antarctica (Echinodermata: Asteroidea) in the Beagle Channel, Tierra del Fuego, Argentina

“…3a) when all males were sexually mature. GI maximum values reported here were lower than those reported for Neosmilaster georgianus (Bosch & Slattery, 1999) and similar to those reported for Leptasterias polaris (Raymond et al, 2004). This difference in the synchronicity between sexes would be interpreted as a consequence of highly differential energetic costs of reproduction of A. antarctica at high latitudes, which imposes only to females a biannual cycle.…”

“…In species with direct development, reproductive effort differs between sexes. Normally, males invest more energy to gametes production than females, but females face the additional cost of incubating embryos (Raymond, Himmelman & Guderley, 2004;Gillespie & McClintock, 2007;Pérez et al, 2015). The pyloric caeca work as a reserve of energy, located inside the arms and the size and concentration of lipid are indicative of the energy reserves of the individual (Lawrence, 1987a).…”

Brood chamber isolation during salinity stress in two estuarine mollusk species: from a protective nursery to a dangerous prison

“…Such incubation by the female is generally considered to be protective (Gillespie & McClintock 2007). Such physical maternal protection of the spawned egg mass is apparently an evolved, complex, and expensive mechanism (Chaparro & Thompson 1998, Brante et al 2003, Raymond et al 2004. Retaining embryos and larvae in such enclosures reduces the predation risks to which they would be exposed during a pelagic larval phase (Pechenik 1978, Rumrill 1990) and can also isolate the offspring from physical stresses, as might be caused, for example, by substantial changes in humidity, pH, dissolved oxygen, osmotic concentration, or salinity (see reviews by Clutton-Brock 1991, Morritt & Spicer 1996, Surbida ABSTRACT: Faced with environmental stress, the females of many marine invertebrate species can isolate their brood chambers from the external environment for prolonged periods.…”