ALBERT

Description: To determine the effects of changing temperatures and carbonate levels on Northern California's bull kelp populations, we collected sporophylls from mature bull kelp individuals in Point Arena, CA. At the Bodega Marine Laboratory, we released spores from field-collected bull kelp, and cultured microscopic gametophytes in a common garden experiment with a fully factorial design crossing modern conditions (11.63 ± 0.54°C and pH 7.93 ± 0.26) with observed extreme climate conditions (15.56 ± 0.83°C and 7.64 ± 0.32 pH). In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2022) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2023-09-06.

Description: The effects of climate change, including ocean acidification and ocean heatwaves, on biological communities in estuaries are often uncertain. Part of the uncertainty is due to the complex suite of environmental factors in addition to acidification and warming that influence the growth of shells and skeletons of many estuarine organisms. The goal of this study was to document spatial and temporal variation in water column properties and to measure the in situ effects on larval and recently settled stages of ecologically important Olympia oysters (Ostrea lurida) and commercially important Pacific oysters (Crassostrea gigas) in a low‐inflow estuary with a Mediterranean climate in Northern California. Our results reveal that seasonal inputs of upwelled or riverine water create important and predictable gradients of carbonate system parameters, temperature, salinity, dissolved oxygen (DO), and other variables that influence oyster performance, and that the influence of these gradients is contingent upon the location in the estuary as well as seasonal timing. During upwelling events (dry season), temperature, carbonate chemistry, and DO had the greatest impact on oyster performance. During runoff events (wet season), gradients in salinity, nutrient concentrations, and total alkalinity driven by river discharge were comparatively more important. These results suggest that the spatial importance of carbonate chemistry and temperature are seasonally variable and are two of several other factors that determine oyster performance. We use these results to discuss future impacts on oysters given projected regional changes in the frequency and magnitude of upwelling and precipitation‐driven runoff events.

Description: Understanding how climate change may influence ecosystems depends substantially on its effects on foundation species, such as the ecologically important giant kelp (Macrocystis pyrifera). Despite its broad distribution along strong temperature and pH gradients and strong barriers to dispersal, the potential for local adaptation to climate change variables among kelp populations remains poorly understood. We assessed this potential by exposing giant kelp early life stages from genetically disparate populations in Chile and California to current and projected temperature and pH levels in common garden experiments. We observed high resistance at the haploid life stage to elevated temperatures with developmental failure appearing at the egg and sporophyte production stages among Chilean and high-latitude California populations, suggesting a greater vulnerability to climate- or ENSO-driven warming events. Additionally, populations that experience low pH events via strong upwelling, internal waves, or estuarine processes, produced more eggs per female under experimental low-pH conditions, which could increase fertilization success. These results enhance our ability to predict population extinctions and ecosystem range shifts under projected declines in ocean pH and increases in ocean temperature.