Impact of Environment and Ontogeny on Relative Fecundity and Egg Quality of Female Oysters (Crassostrea virginica) from Four Sites in Northern Chesapeake Bay

Abstract

Resource allocation to reproduction is a primary physiological concern for individuals, and can vary with age, environment, or a combination of both factors. In this study we quantified the impact of environment and individual age on the reproductive output of female oysters Crassostrea virginica. We determined the relative fecundity, egg total lipid content, and overall and omega-3/omega-6 (ω3/ω6) fatty acid signatures (FAS) of eggs spawned by female oysters over a 2-year period (n = 32 and n = 64). Variation was quantified spatially and ontogenetically by sampling young and old oyster populations from two rivers in Chesapeake Bay, totaling four collection sites. During Year 1, when oysters underwent oogenesis in different locations, overall and ω3/ω6 egg FAS varied significantly by river, with no significant differences observed in the FAS of oysters by age in Year 1. In Year 2, when oysters from different sites underwent oogenesis in a single location, no significant differences in the overall egg FAS or ω3/ω6 egg FAS by river or age were observed. These findings suggest that oysters integrate environment into their reproductive output, but that time spent growing at a specific location (in this case, represented by oyster age) plays a relatively minor role in the biochemical composition of oyster eggs. These results have consequences for our understanding of how resources are allocated from the female oyster to eggs and, more generally, the impact of environment and ontogeny on reproductive physiology.

Fatty acid composition and N2 solubility in triacylglycerol-rich adipose tissue: the likely importance of intact molecular structure

“…A total of 72 FA were identified using gas chromatography; however, our analysis included only the FA found in concentrations >1.0 mol% (Glandon et al, 2016). The mean concentrations by taxonomic group of these 30 FA can be found in Tables S2 ( present study) and S3 (comparative data from the literature).…”

Using reproductive potential to assess oyster population sustainability

“…This emphasis is largely because we lack information on fecundity, its drivers (e.g. food or water quality), or larval dispersal and survival for many of these marine invertebrates (Hobday et al 2001; Mroch III et al 2012; Glandon et al 2016). As a result, when required for management, stock assessments, or restoration and conservation planning, models often assume constant environmental conditions and life history characteristics (e.g.…”

“…regular recruitment; Hobday et al 2001). This assumption fails to account for the high variation in fecundity or recruitment documented across many species and environments (Hughes et al 2000; Hobday et al 2001; Lester et al 2007; Jack & Wing 2010; Glandon et al 2016). Recent restoration seeks to develop self‐sustaining populations, and this inherently requires better understanding of early life history.…”

“…salinity and temperature) and food availability remain the dominant conditions affecting reproduction and reproductive potential (i.e. Shumway 1996; Glandon et al 2016). As sessile filter‐feeders, small changes in these environmental conditions can have magnified effects on life history development (Hofmann et al 1992; Lowe et al 2017).…”

“…Along the Atlantic coast of the United States estimates of fecundity showed an exponential increase with shell height, but significant variation by season and location (i.e. Cox & Mann 1992; Mann & Evans 1998; Mroch III et al 2012; Glandon et al 2016). No such estimates exist for oysters located along the northern Gulf of Mexico coast and we lack explicit understanding of how environmental conditions may influence fecundity or reproductive potential.…”