scholarly journals Transgenerational plasticity and the capacity to adapt to low salinity in the eastern oyster, Crassostrea virginica

2021 ◽  
Vol 288 (1951) ◽  
pp. 20203118
Author(s):  
Joanna S. Griffiths ◽  
Kevin M. Johnson ◽  
Kyle A. Sirovy ◽  
Mark S. Yeats ◽  
Francis T. C. Pan ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Crassostrea Virginica ◽  
Salinity Tolerance ◽  
Eastern Oyster ◽  
Important Species ◽  
Transgenerational Plasticity ◽  
Low Salinity ◽  
Breeding Grounds ◽  
Commercially Important ◽  
Local Hydrology

Salinity conditions in oyster breeding grounds in the Gulf of Mexico are expected to drastically change due to increased precipitation from climate change and anthropogenic changes to local hydrology. We determined the capacity of the eastern oyster, Crassostrea virginica , to adapt via standing genetic variation or acclimate through transgenerational plasticity (TGP). We outplanted oysters to either a low- or medium-salinity site in Louisiana for 2 years. We then crossed adult parents using a North Carolina II breeding design, and measured body size and survival of larvae 5 dpf raised under low or ambient salinity. We found that TGP is unlikely to significantly contribute to low-salinity tolerance since we did not observe increased growth or survival in offspring reared in low salinity when their parents were also acclimated at a low-salinity site. However, we detected genetic variation for body size, with an estimated heritability of 0.68 ± 0.25 (95% CI). This suggests there is ample genetic variation for this trait to evolve, and that evolutionary adaptation is a possible mechanism through which oysters will persist with future declines in salinity. The results of this experiment provide valuable insights into successfully breeding low-salinity tolerance in this commercially important species.

Evolutionary Change in the Eastern Oyster, Crassostrea Virginica, Following Low Salinity Exposure

2021 ◽  
Author(s):  
Joanna S Griffiths ◽  
Kevin M Johnson ◽  
Morgan W Kelly
Keyword(s):  
Genetic Variation ◽  
Crassostrea Virginica ◽  
Larval Stage ◽  
Genetic Load ◽  
Early Life History ◽  
Eastern Oyster ◽  
Evolutionary Change ◽  
Low Salinity ◽  
Multiple Loci ◽  
Breeding Grounds

Synopsis The presence of standing genetic variation will play a role in determining a population's capacity to adapt to environmentally relevant stressors. In the Gulf of Mexico, extreme climatic events and anthropogenic changes to local hydrology will expose productive oyster breeding grounds to stressful low salinity conditions. We identified genetic variation for performance under low salinity (due to the combined effects of low salinity and genetic load) using a single-generation selection experiment on larvae from two populations of the eastern oyster, Crassostrea virginica. We used pool-sequencing to test for allele frequency differences at 152 salinity-associated genes for larval families pre- and post-low salinity exposure. Our results have implications for how evolutionary change occurs during early life history stages at environmentally relevant salinities. Consistent with observations of high genetic load observed in oysters, we demonstrate evidence for purging of deleterious alleles at the larval stage in C. virginica. In addition, we observe increases in allele frequencies at multiple loci, suggesting that natural selection for low salinity performance at the larval stage can act as a filter for genotypes found in adult populations.

scholarly journals Heritability of acute low salinity survival in the Eastern oyster (Crassostrea virginica)

Aquaculture ◽  
2020 ◽  
Vol 529 ◽  
pp. 735649
Author(s):  
Alexandra J. McCarty ◽  
K. McFarland ◽  
J. Small ◽  
S.K. Allen ◽  
L.V. Plough
Keyword(s):  
Crassostrea Virginica ◽  
Eastern Oyster ◽  
Low Salinity

scholarly journals Sublethal Effects of Crude Oil and Chemical Dispersants on Multiple Life History Stages of the Eastern Oyster, Crassostrea virginica

2020 ◽  
Vol 8 (10) ◽  
pp. 808
Author(s):  
Sara M. Garcia ◽  
Kevin T. Du Clos ◽  
Olivia H. Hawkins ◽  
Brad J. Gemmell
Keyword(s):  
Life History ◽  
Crude Oil ◽  
Crassostrea Virginica ◽  
Sublethal Effects ◽  
Oil Pollution ◽  
Eastern Oyster ◽  
Clearance Rates ◽  
Important Species ◽  
Life History Stages ◽  
Oil Exposure

The eastern oyster Crassostrea virginica is an ecologically and economically important species that is vulnerable to oil pollution. We assessed sublethal effects of soluble fractions of crude oil alone (WAF) and crude oil in combination with Corexit 9500 dispersant (CEWAF) on oysters at three life history stages. Veliger swimming, pediveliger settlement, and adult clearance rates were quantified after 24 h exposures to the contaminants. Veliger swimming speeds were not significantly impacted by 24 h exposures to WAF or CEWAF. A larger proportion of veligers were inactive following WAF and CEWAF exposure as compared to the control, but the effect was greater for pediveligers, and pediveliger settlement in the highest concentration CEWAF treatment decreased by 50% compared to controls. Thus, pediveligers may be particularly vulnerable to oil exposure. In the adults, we found significant clearance rates reductions that persisted 33 days after acute exposure to CEWAF. Knowledge of sublethal effects of oil and dispersant at multiple life history stages aids understanding of how this important species will respond to an oil spill.

scholarly journals Synergistic Effects of Temperature and Salinity on the Gene Expression and Physiology of Crassostrea virginica

2019 ◽  
Vol 59 (2) ◽  
pp. 306-319 ◽  
Author(s):  
H R Jones ◽  
K M Johnson ◽  
M W Kelly
Keyword(s):  
Climate Change ◽  
Crassostrea Virginica ◽  
Synergistic Effects ◽  
Gill Tissue ◽  
Eastern Oyster ◽  
Comparative Transcriptomics ◽  
Functional Enrichment ◽  
Low Salinity ◽  
Hypoosmotic Stress

Abstract The eastern oyster, Crassostrea virginica, forms reefs that provide critical services to the surrounding ecosystem. These reefs are at risk from climate change, in part because altered rainfall patterns may amplify local fluctuations in salinity, impacting oyster recruitment, survival, and growth. As in other marine organisms, warming water temperatures might interact with these changes in salinity to synergistically influence oyster physiology. In this study, we used comparative transcriptomics, measurements of physiology, and a field assessment to investigate what phenotypic changes C. virginica uses to cope with combined temperature and salinity stress in the Gulf of Mexico. Oysters from a historically low salinity site (Sister Lake, LA) were exposed to fully crossed temperature (20°C and 30°C) and salinity (25, 15, and 7 PSU) treatments. Using comparative transcriptomics on oyster gill tissue, we identified a greater number of genes that were differentially expressed (DE) in response to low salinity at warmer temperatures. Functional enrichment analysis showed low overlap between genes DE in response to thermal stress compared with hypoosmotic stress and identified enrichment for gene ontologies associated with cell adhesion, transmembrane transport, and microtubule-based process. Experiments also showed that oysters changed their physiology at elevated temperatures and lowered salinity, with significantly increased respiration rates between 20°C and 30°C. However, despite the higher energetic demands, oysters did not increase their feeding rate. To investigate transcriptional differences between populations in situ, we collected gill tissue from three locations and two time points across the Louisiana Gulf coast and used quantitative PCR to measure the expression levels of seven target genes. We found an upregulation of genes that function in osmolyte transport, oxidative stress mediation, apoptosis, and protein synthesis at our low salinity site and sampling time point. In summary, oysters altered their phenotype more in response to low salinity at higher temperatures as evidenced by a higher number of DE genes during laboratory exposure, increased respiration (higher energetic demands), and in situ differential expression by season and location. These synergistic effects of hypoosmotic stress and increased temperature suggest that climate change will exacerbate the negative effects of low salinity exposure on eastern oysters.

scholarly journals Regulation of sperm motility in Eastern oyster (Crassostrea virginica) spawning naturally in seawater with low salinity

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0243569
Author(s):  
Zoe G. Nichols ◽  
Scott Rikard ◽  
Sayyed Mohammad Hadi Alavi ◽  
William C. Walton ◽  
Ian A. E. Butts
Keyword(s):  
Crassostrea Virginica ◽  
Sperm Motility ◽  
Eastern Oyster ◽  
Fertilization Success ◽  
Channel Blockers ◽  
Physiological Mechanisms ◽  
Ambient Seawater ◽  
Low Salinity ◽  
Oyster Aquaculture ◽  
Term Storage

Oyster aquaculture is expanding worldwide, where many farms rely on seed produced by artificial spawning. As sperm motility and velocity are key determinants for fertilization success, understanding the regulation of sperm motility and identifying optimal environmental conditions can increase fertility and seed production. In the present study, we investigated the physiological mechanisms regulating sperm motility in Eastern oyster,Crassostrea virginica. Sperm motility was activated in ambient seawater with salinity 4–32 PSU with highest motility and velocity observed at 12–24 PSU. In artificial seawater (ASW) with salinity of 20 PSU, sperm motility was activated at pH 6.5–10.5 with the highest motility and velocity recorded at pH 7.5–10.0. Sperm motility was inhibited or totally suppressed in Na+, K+, Ca2+, and Mg2+-free ASW at 20 PSU. Applications of K+(500 μM glybenclamide and 10–50 mM 4-aminopyridine), Ca2+(1–50 μM mibefradil and 10–200 μM verapamil), or Na+(0.2–2.0 mM amiloride) channel blockers into ASW at 20 PSU inhibited or suppressed sperm motility and velocity. Chelating extracellular Ca2+ions by 3.0 and 3.5 mM EGTA resulted in a significant reduction and full suppression of sperm motility by 4 to 6 min post-activation. These results suggest that extracellular K+, Ca2+, and Na+ions are involved in regulation of ionic-dependent sperm motility in Eastern oyster. A comparison with other bivalve species typically spawning at higher salinities or in full-strength seawater shows that ionic regulation of sperm motility is physiologically conserved in bivalves. Elucidating sperm regulation inC.virginicahas implications to develop artificial reproduction, sperm short-term storage, or cryopreservation protocols, and to better predict how changes in the ocean will impact oyster spawning dynamics.

Effects of resuspension of eastern oyster Crassostrea virginica biodeposits on phytoplankton community structure

2020 ◽  
Vol 640 ◽  
pp. 79-105
Author(s):  
ET Porter ◽  
E Robins ◽  
S Davis ◽  
R Lacouture ◽  
JC Cornwell
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Crassostrea Virginica ◽  
Skeletonema Costatum ◽  
Eastern Oyster ◽  
Energy Dissipation Rate ◽  
Negative Effects ◽  
Cell Densities ◽  
Sediment Bottom ◽  
Nitrite Nitrate

Anthropogenic disturbances in the Chesapeake Bay (USA) have depleted eastern oyster Crassostrea virginica abundance and altered the estuary’s environment and water quality. Efforts to rehabilitate oyster populations are underway; however, the effect of oyster biodeposits on water quality and plankton community structure are not clear. In July 2017, we used 6 shear turbulence resuspension mesocosms (STURMs) to determine differences in plankton composition with and without the daily addition of oyster biodeposits to a muddy sediment bottom. STURM systems had a volume-weighted root mean square turbulent velocity of 1.08 cm s-1, energy dissipation rate of ~0.08 cm2 s-3, and bottom shear stress of ~0.36-0.51 Pa during mixing-on periods during 4 wk of tidal resuspension. Phytoplankton increased their chlorophyll a content in their cells in response to low light in tanks with biodeposits. The diatom Skeletonema costatum bloomed and had significantly longer chains in tanks without biodeposits. These tanks also had significantly lower concentrations of total suspended solids, zooplankton carbon, and nitrite +nitrate, and higher phytoplankton carbon concentrations. Results suggest that the absence of biodeposit resuspension initiates nitrogen uptake for diatom reproduction, increasing the cell densities of S. costatum. The low abundance of the zooplankton population in non-biodeposit tanks suggests an inability of zooplankton to graze on S. costatum and negative effects of S. costatum on zooplankton. A high abundance of the copepod Acartia tonsa in biodeposit tanks may have reduced S. costatum chain length. Oyster biodeposit addition and resuspension efficiently transferred phytoplankton carbon to zooplankton carbon, thus supporting the food web in the estuary.

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