Prolonged exposure to low dissolved oxygen affects early development and swimming behaviour in the gastropod Nassarius festivus (Nassariidae)

Limiting factors to encapsulation: the combined effects of dissolved protein and oxygen availability on embryonic growth and survival of species with contrasting feeding strategies

“…The oxy-conformer strategy observed in this species, and also in C. coquimbensis, has been observed in other marine gastropods (Kushins and Mangum, 1971;Raghunathan and Ayyakkannu, 1992;Cheung, 1997). However, although it had been described that low levels of oxygen conditions may affect the consumption efficiency of marine invertebrate larvae (Widdows et al, 1989;Wang and Widdows, 1991;Chan et al, 2008), we did not find evidence of this for embryos of C. fornicata feeding on dissolved albumen. Moreover, embryos of C. coquimbensis did not show differences in the number of embryos cannibalised (survival percentage) between normoxia and hypoxia, which is reinforcing the idea of no impact on food intake.…”

“…This effect can be explained by a decrease in the capacity to catch, ingest and process the food under hypoxia (Das and Stickle, 1991;Sobral and Widdows, 1997;Brante and Hughes, 2001). A similar effect on growth rate was observed in larvae of the marine gastropods Mytilus edulis and Nassarius festivus exposed to hypoxia, which seems to be related to decreasing ciliary activity at low levels of oxygen (Wang and Widdows, 1991;Chan et al, 2008). Therefore, the impact of hypoxia on embryo performance may follow two different ways with different predictions: (1) a decrease in metabolic rate at hypoxia may be interpreted as a low demand for additional food or energy.…”

Differences in the timing of cardio-respiratory development determine whether marine gastropod embryos survive or die in hypoxia

“…Comparisons with previous studies where isolated gastropod eggs or embryos were exposed to chronic hypoxia show a general concordance with the impacts on growth, development and survival that we observed in L. obtusata (but see discussion of velum plasticity below). Only around 1 in 10 eggs of the slipper limpet, Crepidula fornicata, survived a 3 day exposure to an environmental P O2 of 3.2 kPa (Brante et al, 2008) and no embryos of the nassarid Nassarius festivus hatched successfully when cultured in seawater of P O2 of just less than 1 kPa (Chan et al, 2008). It should be noted that both these P O2 values are considerably lower than we used in our study.…”

“…This plasticity takes the form of hypertrophy -an increase in the volume of an organ due to the enlargement of its cells rather than an increase in cell number. Paradoxically, the only other study investigating the influence of reduced P O2 (∼11.5 kPa) on gastropod velum plasticity reported a reduction in velum size in terms of both absolute size (length) and when size was standardised relative to the size of the shell (Chan et al, 2008) in the dogwhelk, N. festivus. Swimming behaviour and dispersal velocities were also lower in snails reared in hypoxic compared with normoxic conditions, suggesting that the locomotory function of the velum was impaired by hypoxia.…”

“…While the survival of the encapsulated slipper limpet, C. coquimbensis, was not significantly affected by exposure to P O2 of ∼11.5 kPa (Brante et al, 2008), Brante et al (2009) later found that aerobic metabolism of embryos of this species and the related C. fornicata decreased significantly at P O2 <12 kPa. Similarly, development, hatching and shell secretion of the encapsulated muricid snail Chorus giganteus were all compromised by culture in seawater of P O2 ∼10 kPa (Cancino et al, 2003(Cancino et al, , 2011 and embryonic development of N. festivus was significantly delayed when cultured at a P O2 of ∼7.6 kPa (Chan et al, 2008).…”