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An increase in anthropogenic carbon dioxide is driving oceanic chemical shifts resulting in a long-term global decrease in ocean pH, colloquially termed ocean acidification (OA). Previous studies have demonstrated that OA can have negative physiological consequences for calcifying organisms, especially during early lifehistory stages. However, much of the previous research has focused on static exposure to future OA conditions, rather than variable exposure to elevated pCO2, which is more ecologically relevant for nearshore species. This study examines the effects of OA on embryonic and larval Pacific razor clams (Siliqua patula), a bivalve that produces a concretion during early shell development. Larvae were spawned and cultured over 28 days under three pCO2 treatments: a static high pCO2 of 867 matm, a variable, diel pCO2 of 357 to 867 matm, and an ambient pCO2 of 357 matm. Our results indicate that the calcium carbonate polymorphism of the concretion phase of S. patula was amorphous calcium carbonate which transitioned to vaterite during the advanced D-veliger stage, with a final polymorphic shift to aragonite in adults, suggesting an increased vulnerability to dissolution under OA. However, exposure to elevated pCO2 appeared to accelerate the transition of larval S. patula from the concretion stage of shell development to complete calcification. There was no significant impact of OA exposure to elevated or variable pCO2 conditions on S. patula growth or HSP70 and calmodulin gene expression. This is the first experimental study examining the response of a concretion producing bivalve to future predicted OA conditions and has important implications for experimentation on larval mollusks and bivalve management. [ABSTRACT FROM AUTHOR]

Ocean acidification, a product of CO[subscript 2] absorption by the world's oceans, is largely driven by the anthropogenic combustion of fossil fuels and has already lowered the pH of marine ecosystems. Organisms with calcium carbonate shells and skeletons are especially susceptible to increasing environmental acidity due to reduction in the saturation state of CaCO[subscript 3] that accompanies ocean acidification. Creating a connection between human-mediated changes to our environment and the effect it will have on biota is crucial to establishing an understanding of the potential effects of global climate change. We outline two low-cost laboratory experiments that eloquently mimic the biochemical process of ocean acidification on two timescales, providing educators with hands-on, hypothesis-driven experiments that can easily be conducted in middle and high school biology or environmental science courses.

The Pacific razor clam, Siliqua patula (Sugpiaq: Cingtaataq, Dixon, 1789), is vital to commercial, recreational, and subsistence fisheries across the Pacific Northwest Coast of North America. Despite the species' status as one of the most popular shellfish species harvested in the Pacific Northwest, British Columbia, and Alaska, its larval development has never been fully characterized. Generating a developmental times series, and describing development fully, is crucial for guiding targeted management, developing a mariculture strategy for the species, and providing a more pointed avenue for studies examining the response of S. patula to ocean change. This study presents the first photographic documentation of larval development in S. patula , including the timing of key transitions during embryogenesis and early larval development. Scanning electron microscopy revealed that the larval shell forms via a concretion, a process typically documented in early gastropod development. This novel characterization is pertinent, as it conveys the need for the inclusion of alternative bivalve development processes, such as a concretion, in bivalve research. This study also compared development in S. patula to a global assortment of bivalve species, including two other members of the Pharidae family, determining that the timing to D-veliger and trochophore stages was similar to the majority of bivalves surveyed. While bivalve response to climate change is a topic of great interest, not all species of concern have undergone comprehensive developmental assessments, a requisite benchmark for designing climate change studies that examine early life history sensitivity to such changes. This research supports the use of comprehensive developmental studies as prerequisites for designing climate change experimentation, establishes the necessity of high-magnification and high-resolution scanning electron microscopy within developmental assessments, and provides information about the development of a cornerstone bivalve species. [ABSTRACT FROM AUTHOR]

Populations that span a large geographic range often experience a thermal gradient that can differentially affect the phenotypic response of individuals across the population. Variation in temperature has been shown to affect the final adult size of ectotherms, which is referred to as the temperature-size rule for ectotherms. Body size is a fundamentally important trait, as it can impact physiological performance, fecundity, longevity, and macroecological patterns. Hence, temperature may affect body size across a range, which can in turn influence maintenance of populations and ecological interactions. Here, we test whether biogeographic differences in size (carapace width) exist for a recent invasion of the non-native European green crab, Carcinus maenas, along the west coast of North America. We assembled trapping and temperature data collected from 10 sites along the western North American coast over a 5-year period. We also conducted a literature review of C. maenas size across their native range. Our results indicate that adult body size shows negative correlation with environmental temperature in both the native and invaded ranges, conforming to the temperature-size rule for ectotherms. Given the short time since colonization and lack of evident genetic structure across the invasive range, it may be that phenotypic plasticity in response to environmental temperature is driving this relationship. Forces that shape the phenotypic trajectory of species may play an important role in both invasion dynamics and subsequent ecological impacts., Author(s): Amanda L. Kelley [sup.1] , Catherine E. de Rivera [sup.2] , Edwin D. Grosholz [sup.3] , Gregory M. Ruiz [sup.2] [sup.4] , Sylvia Behrens Yamada [sup.5] , Graham Gillespie […]

The western Arctic Ocean, including its shelves and coastal habitats, has become a focus in ocean acidification research over the past decade as the colder waters of the region and the reduction of sea ice appear to promote the uptake of excess atmospheric CO2. Due to seasonal sea ice coverage, high-frequency monitoring of pH or other carbonate chemistry parameters is typically limited to infrequent ship-based transects during ice-free summers. This approach has failed to capture year-round nearshore carbonate chemistry dynamics which is modulated by biological metabolism in response to abundant allochthonous organic matter to the narrow shelf of the Beaufort Sea and adjacent regions. The coastline of the Beaufort Sea comprises a series of lagoons that account for > 50 % of the land-sea interface. The lagoon ecosystems are novel features that cycle between open and closed phases (i.e., ice-free, and ice covered, respectively). In this study, we collected high-frequency pH, salinity, temperature, and PAR measurements in association with the Beaufort Lagoon Ecosystem LTER for an entire calendar year in Kaktovik Lagoon, Alaska, USA, capturing two open water phases and one closed phase. Hourly pH variability during the open water phases are some of the fastest rates reported, exceeding 0.4 units. Baseline pH varied substantially between open phase 2018 and open phase 2019 with a difference of ~ 0.2 units despite similar hourly rates of change. Salinity-pH relationships were mixed during all three phases displaying no correlation in open 2018, a negative correlation in closed 2018-2019, and positive correlation during open 2019. The high-frequency of pH variability could partially be explained by photosynthesis-respiration cycles as correlation coefficients between daily average pH and PAR were 0.46 and 0.64 for open 2018 and open 2019 phases, respectively. The estimated annual daily average CO2 efflux was 5.9 ± 19.3 mmol m-2 d-1, which is converse to the negative influx of CO2 estimated for the coastal Beaufort Sea despite exhibiting extreme variability. Considering the geomorphic differences in Beaufort Sea lagoons, further investigation is needed to assess if there are periods of the open phase in which all lagoons are sources of carbon to the atmosphere, potentially offsetting the predicted sink capacity of the greater Beaufort Sea. [ABSTRACT FROM AUTHOR]

The commercially available Sea-Bird SeaFET™ provides an accessible way for a broad community of researchers to study ocean acidification and obtain robust measurements of seawater pH via the use of an in situ autonomous sensor. There are pitfalls, however, that have been detailed in previous best practices for sensor care, deployment, and data handling. Here, we took advantage of two distinctly different coastal settings to evaluate the Sea-Bird SeaFET™ and examine the multitude of scenarios in which problems may arise confounding the accuracy of measured pH. High-resolution temporal measurements of pH were obtained during 3- to 5-month field deployments in three separate locations (two in south-central, Alaska, USA, and one British Columbia, CA) spanning a broad range of nearshore temperature and salinity conditions. Both the internal and external electrodes onboard the SeaFET™ were evaluated against robust benchtop measurements for accuracy utilizing either the factory calibration, an in situ single-point calibration, or in situ multi-point calibration. In addition, two sensors deployed in parallel in Kasitsna Bay, AK, USA, were compared for inter-sensor variability in order to quantify other factors contributing to SeaFET™ intrinsic inaccuracies. Based on our results, the multi-point calibration method provided the highest accuracy (< 0.025 difference in pH) of pH when compared against benchtop measurements. Spectral analysis of time series data showed that during spring in Alaskan waters, a range of tidal frequencies dominated pH variability, while seasonal oceanographic conditions were the dominant driver in Canadian waters. Further, it is suggested that spectral analysis performed on initial deployments may be able to act as an a posteriori method to better identify appropriate calibration regimes. Based on this evaluation, we provide a comprehensive assessment of the potential sources of uncertainty associated with accuracy and precision of the SeaFET™ electrodes. [ABSTRACT FROM AUTHOR]

Ocean acidification is expected to have wide-ranging and complicated impacts on organismal physiology, notably metabolism. Effects on metabolism may have numerous consequences at the whole-organism level, in particular costs to growth, locomotion, reproductive output, and homeostasis. Negative effects on these metrics may further cascade up to impact ecosystem structure and function, and thus human society. As such, the study of metabolism in response to ocean acidification is a pivotal research avenue within the study of global ocean change. Here, the metabolic responses of marine species to ocean acidification are reviewed and examined through meta-analysis. We reviewed a total of 44 published studies and used a traditional meta-analysis to identify broad-scale trends in the metabolic responses of species to ocean acidification. Results from this study indicate varied metabolic strategies in response to OA, further complicating our predictive power to forecast ecosystem-level consequences of ongoing CO2 increases. However, strong effects were observed with respect to ontogeny, marine ecosystem, motility, and taxonomic origin, thereby reinforcing the need for a multi-faceted approach to both management of sensitive species and mitigation of future impacts. [ABSTRACT FROM AUTHOR]