A modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae

Abstract

modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae. e ICES Journal of Marine Science, 61: 596e616. A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food.Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations.In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg qualityegrowth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts.

The Pacific oyster, Crassostrea gigas, shows negative correlation to naturally elevated carbon dioxide levels: Implications for near‐term ocean acidification effects

“…Additionally, Rumrill (1990) noted that fertilization failure, adverse hydrography, substrate limitation, and predation are the most important determinants of the success of natural populations of meroplankton, such as larval oysters. Recent biochemical studies of oyster larvae indicate the importance of food quality and quantity in conjunction with sensitivity to fluctuating salinity and temperature (Hofmann et al 2004). Increased food availability and quality generally improved tolerance of C. gigas larvae to salinity and temperature variability in these modeling studies.…”

Vertical swimming behavior influences the dispersal of simulated oyster larvae in a coupled particle-tracking and hydrodynamic model of Chesapeake Bay

“…It did not include biological processes (production, growth, mortality) that are well articulated in 1 and 2D individually based models of oyster larvae (e.g. Dekshenieks et al 1997, Hofmann et al 2004). Instead of focusing on biological processes like egg production, larval growth, and predation mortality, we isolated the influence of physical conditions and organism behavior on the 3D spatial trajectories of particles to determine if larval swimming behavior could influence dispersal distance, encounter with suitable habitat, and subpopulation connectivity.…”

Bivalve larvae transport and connectivity within the Ahe atoll lagoon (Tuamotu Archipelago), with application to pearl oyster aquaculture management

“…Larvae were expected to die due to predation and food deprivation (Eckman, 1996), but the good agreement between simulations and observations seemed to suggest that natural mortality could be very low in Ahe atoll, or that most mortality occur in the first 2 days of larval life. Indeed, mortality rates is highest in early life stages in the first couple of days (Pechenik, 1999) and in the last stages, due to higher predation and likely longer periods of starvation (Hofmann et al, 2004). Here; these early stages were not taken into account since capture and census in the field yielded larvae already 1-2 days old.…”