skip to main content

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: The impact of oyster aquaculture on the estuarine carbonate system
Many studies have examined the vulnerability of calcifying organisms, such as the eastern oyster (Crassostrea virginica), to externally forced ocean acidification, but the opposite interaction whereby oysters alter their local carbonate conditions has received far less attention. We present an exploratory model for isolating the impact that net calcification and respiration of aquacultured eastern oysters can have on calcite and aragonite saturation states, in the context of varying temperature, ocean-estuary mixing, and air-sea gas exchange. We apply the model to the Damariscotta River Estuary in Maine which has experienced rapid expansion of oyster aquaculture in the last decade. Our model uses oyster shell growth over the summer season and a previously derived relationship between net calcification and respiration to quantify impacts of net oyster calcification and gross metabolism on carbonate saturation states in open tidal waters. Under 2018 industry size and climate conditions, we estimate that oysters can lower carbonate saturation states by up to 5% (i.e., 0.17 and 0.11 units on calcite and aragonite saturation states, respectively) per day in late summer, with an average of 3% over the growing season. Perturbations from temperature and air-sea exchange are similar in magnitude. Under 2050 climate conditions and 2018 industry size, calcite saturation state will decrease by up to an additional 0.54 units. If the industry expands 3-fold by 2050, the calcite and aragonite saturation states may decrease by 0.73 and 0.47 units, respectively, on average for the latter half of the growing season when compared to 2018 climate conditions and industry size. Collectively, our results indicate that dense aggregations of oysters can have a significant role on estuarine carbonate chemistry.  more » « less
Award ID(s):
2018851
PAR ID:
10438618
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Elementa
Date Published:
Journal Name:
Elementa: Science of the Anthropocene
Volume:
10
Issue:
1
ISSN:
2325-1026
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ( , Geochemistry, Geophysics, Geosystems)
    Abstract

    Ocean acidification is predicted to impair marine calcifiers' abilities to produce shells and skeletons. We conducted laboratory experiments investigating the impacts of CO2‐induced ocean acidification (pCO2 = 478–519, 734–835, 8,980–9,567; Ωcalcite = 7.3–5.7, 5.6–4.3, 0.6–0.7) on calcification rates of two estuarine calcifiers involved in a classic predator‐prey model system: adultPanopeus herbstii(Atlantic mud crab) and juvenileCrassostrea virginica(eastern oyster). Both oyster and crab calcification rates significantly decreased at the highestpCO2level. Notably, however, oysters maintained positive net calcification rates in the highest pCO2treatment that was undersaturated with respect to calcite, while mud crabs exhibited net dissolution (i.e., net loss of shell mass) in calcite‐undersaturated conditions. Secondary electron imaging of oyster shells revealed minor microstructural alterations in the moderate‐pCO2treatment, and major microstructural and macrostructural changes (including shell dissolution, delamination of periostracum) in the high‐pCO2treatment. These results underscore the threat that ocean acidification poses for marine organisms that produce calcium carbonate shells, illustrate the strong biological control that some marine calcifiers exert over their shell‐building process, and shows that ocean acidification differentially impacts the crab and oyster species involved in this classical predator‐prey model system.

     
    more » « less
  2. ; ( , Proceedings American Geophysical Union)
    Telesca, L (Ed.)
    Rapid environmental changes are predicted to impact shellfish abundance and their commercial value. The Eastern Oyster, Crassostrea virginica, a key foundation species with high environmental and commercial value has dramatically declined due to climate and anthropogenic impacts over the last century. Our current understanding of oyster vulnerability mostly stems from laboratory-based experiments but lacks studies in natural systems. Here, we investigated how shell production and composition of C. virginica are affected by natural salinity gradients under different temperature regimes. We studied variations in oyster shell shape, production, structure, composition, and organic matrix content in oysters from a temperate, Hudson River (NY), and subtropical, Galveston Bay (TX), estuary. parameters such as weight, area, density, chalk production, and organic matrix to see how the shells varied based on salinity and temperature. Our findings showed that Eastern oysters produced shells with higher chalk content under calcification-limiting environments (i.e., low temperature and low salinity). In comparison, shells with lower chalk content were produced in high predation environments (i.e., high temperatures and salinity). Temperate oyster's shell structure preferentially favored chemical protection against dissolution while subtropical oysters preferentially favored mechanical protection against predation. Oyster’s shell showed a strong capacity for protective responses under calcification- and predation-controlled environments. 
    more » « less
  3. ; ; ( , Gulf and Caribbean Research)

    Oyster reefs provide crucial ecosystem services, but their populations are declining worldwide. Oyster reef restoration efforts are underway in many regions, including the Gulf Coast of the United States, where the intertidal oyster populations of the eastern oyster, Crassostrea virginica, have experienced significant declines. A novel method of restoration aimed at decreasing oyster mortality from predators through induction of predatory defenses has been implemented in coastal Alabama. The first step in this novel oyster reef restoration method is the deployment of a base layer of uninhabited oyster shells directly on the sediment prior to the introduction of live oysters. This study evaluated the impacts of the first step of this novel method of restoration, construction of the reef structure, on local sediment physicochemical characteristics. Results indicate that the vertical structure of the oyster reef affects sediment grain size and physicochemical properties. After 47 days, sediment pH increased from 8.29 ± 0.04 to 8.86 ± 0.03 with a concomitant increase in calcium carbonate from 0.509 ± 0.021 % to 0.818 ± 0.112 %. Despite many positive geochemical effects of oyster reef restoration being mediated by the presence of live oysters, the increased pH and calcium carbonate demonstrated herein represent more ideal conditions for oyster growth and survivability, potentially increasing the long-term efficacy of oyster reef restoration via this method.

     
    more » « less
  4. ; ; ; ( , Biogeosciences)
    Abstract. The net ecosystem productivity (NEP) of two seagrassmeadows within one of the largest seagrass ecosystems in the world, FloridaBay, was assessed using direct measurements over consecutive diel cyclesduring a short study in the fall of 2018. We report significant differencesbetween NEP determined by dissolved inorganic carbon (NEPDIC) and bydissolved oxygen (NEPDO), likely driven by differences in air–water gasexchange and contrasting responses to variations in light intensity. We alsoacknowledge the impact of advective exchange on metabolic calculations ofNEP and net ecosystem calcification (NEC) using the “open-water” approachand attempt to quantify this effect. In this first direct determination ofNEPDIC in seagrass, we found that both seagrass ecosystems were netheterotrophic, on average, despite large differences in seagrass netabove-ground primary productivity. NEC was also negative, indicating thatboth sites were net dissolving carbonate minerals. We suggest that acombination of carbonate dissolution and respiration in sediments exceededseagrass primary production and calcification, supporting our negative NEPand NEC measurements. However, given the limited spatial (two sites) andtemporal (8 d) extent of this study, our results may not berepresentative of Florida Bay as a whole and may be season-specific. Theresults of this study highlight the need for better temporal resolution,accurate carbonate chemistry accounting, and an improved understanding ofphysical mixing processes in future seagrass metabolism studies. 
    more » « less
  5. ; ; ( , Integrative and Comparative Biology)
    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.

     
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email