Marine heatwaves are increasingly affecting marine ecosystems, with cascading impacts on coastal economies, communities, and food systems. Studies of heatwaves provide crucial insights into potential ecosystem shifts under future climate change and put fisheries social- ecological systems through “stress tests” that expose both vulnerabilities and resilience. The 2014– 16 Northeast Pacific heatwave was the strongest and longest marine heatwave on record and resulted in profound ecological changes that impacted fisheries, fisheries management, and human livelihoods. Here, we synthesize the impacts of the 2014– 2016 marine heatwave on US and Canada West Coast fisheries and extract key lessons for preparing global fisheries science, management, and industries for the future. We set the stage with a brief review of the impacts of the heatwave on marine ecosystems and the first systematic analysis of the economic

Despite increasing recognition of the need for more diverse and equitable representation in the sciences, it is unclear whether measurable progress has been made. Here, we examine trends in authorship in coral reef science from 1,677 articles published over the past 16 years (2003–2018) and find that while representation of authors that are women (from 18 to 33%) and from non-OECD nations (from 4 to 13%) have increased over time, progress is slow in achieving more equitable representation. For example, at the current rate, it would take over two decades for female representation to reach 50%. Given that there are more coral reef non-OECD countries, at the current rate, truly equitable representation of non-OECD countries would take even longer. OECD nations also continue to dominate authorship contributions in coral reef science (89%), in research conducted in both OECD (63%) and non-OECD nations (68%). We identify systemic issues that remain prevalent in coral reef science (i.e., parachute science, gender bias) that likely contribute to observed trends. We provide recommendations to address systemic biases in research to foster a more inclusive global science community. Adoption of these recommendations will lead to more creative, innovative, and impactful scientific approaches urgently needed for coral reefs and contribute to environmental justice efforts.

Oxygen decline poses increasing risks to global shelf communities. This study was conducted to measure species oxygen exposures in situ and to assess risks of low oxygen based on the hypothesis that species risk varies spatially and is dependent on the interaction of shelf oxygen dynamics with habitat pattern, species mobility, and tolerance to low oxygen. Here, we report concomitant observations of oxygen, depth, and habitat for the most common benthic and epibenthic megafauna on the southern California shelf (30-125 m). The study was conducted when oxygen concentrations were the lowest observed within the previous 30 years off southern California (2012-2014), yet hypoxic conditions (<1.42 ml l(-1)) were not observed. No significant oxygen exposure differences were observed among highly mobile, mobile, and sessile species due to the dynamic nature of the oxycline. Habitat affinities for the most abundant benthic megafauna (53 taxa) were discriminated among four different habitats. Highly mobile rockfish (Sebastidae) exhibited distributions suggesting less tolerance to low oxygen than most other taxa. Given the mosaic of consolidated and coarse-grained habitats that rockfish prefer, the onset of hypoxic conditions near the shelf break (similar to 90-120m) would likely compress local rockfish populations into less favourable habitat in a non-linear fashion.

The market squid Doryteuthis opalescens deposits embryo capsules onto the continental shelf from Baja California to southern Alaska, yet little is known about the environment of embryo habitat. This study provides a baseline of environmental data and insights on factors underlying site selection for embryo deposition off southern California, and defines current essential embryo habitat using (1) remotely operated vehicle-supported surveys of benthos and environmental variables, (2) SCUBA surveys, and (3) bottom measurements of T, S, pH, and O-2. Here, embryo habitat is defined using embryo capsule density, capsule bed area, consistent bed footprint, and association with [O-2] and pH (pCO(2)) on the shelf. Spatial variation in embryo capsule density and location appears dependent on environmental conditions, whereas the temporal pattern of year-round spawning is not. Embryos require [O-2] greater than 160 mu mol and pH(T) greater than 7.8. Temperature does not appear to be limiting (range: 9.9 degrees C-15.5 degrees C). Dense embryo beds were observed infrequently, whereas low-density cryptic aggregations were common. Observations of dense embryo aggregation in response to shoaling of low [O-2] and pH indicate habitat compression. Essential embryo habitat likely expands and contracts in space and time directly with regional occurrence of appropriate O-2 and pH exposure. Embryo habitat will likely be at future risk of compression given secular trends of deoxygenation and acidification within the Southern California Bight. Increasingly localized and dense spawning may become more common, resulting in potentially important changes in market squid ecology and management.

The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5-7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.

Assessing the impacts of anthropogenic ocean acidification requires knowledge of present-day and future environmental conditions. Here, we present a simple model for upwelling margins that projects anthropogenic acidification trajectories by combining high-temporal-resolution sensor data, hydrographic surveys for source water characterization, empirical relationships of the CO2 system, and the atmospheric CO2 record. This model characterizes CO2 variability on timescales ranging from hours (e.g., tidal) to months (e.g., seasonal), bridging a critical knowledge gap in ocean acidification research. The amount of anthropogenic carbon in a given water mass is dependent on the age; therefore a density–age relationship was derived for the study region and then combined with the 2013 Intergovernmental Panel on Climate Change CO2 emission scenarios to add density-dependent anthropogenic carbon to the sensor time series. The model was applied to time series from autonomous pH sensors deployed in the surf zone, kelp forest, submarine canyon edge, and shelf break in the upper 100 m of the Southern California Bight. All habitats were within 5 km of one another, and exhibited unique, habitat-specific CO2 variability signatures and acidification trajectories, demonstrating the importance of making projections in the context of habitat-specific CO2 signatures. In general, both the mean and range of pCO2 increase in the future, with the greatest increase in both magnitude and range occurring in the deeper habitats due to reduced buffering capacity. On the other hand, the saturation state of aragonite (ΩAr) decreased in both magnitude and range. This approach can be applied to the entire California Current System, and upwelling margins in general, where sensor and complementary hydrographic data are available.

Spawning market squid lay embryo capsules on the seafloor of the continental shelf of the California Current System (CCS), where ocean acidification, deoxygenation and intensified upwelling lower the pH and [O2]. Squid statolith geochemistry has been shown to reflect the squid’s environment (e.g., seawater temperature and elemental concentration). We used real-world environmental levels of pH and [O2] observed on squid-embryo beds to test in the laboratory whether or not squid statolith geochemistry reflects environmental pH and [O2]. We asked whether pH and [O2] levels might affect the incorporation of element ratios (B:Ca, Mg:Ca, Sr:Ca, Ba:Ca, Pb:Ca, U:Ca) into squid embryonic statoliths as (1) individual elements and/or (2) multivariate elemental signatures, and consider future applications as proxies for pH and [O2] exposure. Embryo exposure to high and low pH and [O2] alone and together during development over four weeks only moderately affected elemental concentrations of the statoliths, and uranium was an important element driving these differences. Uranium:Ca was eight-times higher in statoliths exposed to low pHT (7.57–7.58) and low [O2] (79–82 µmol·kg−1) than those exposed to higher ambient pHT (7.92–7.94) and [O2] (241–243 µmol·kg−1). In a separate experiment, exposure to low pHT (7.55–7.56) or low [O2] (83–86 µmol·kg−1) yielded elevated U:Ca and Sr:Ca in the low [O2] treatment only. We found capsular effects on multiple elements in statoliths of all treatments. The multivariate elemental signatures of embryonic statoliths were distinct among capsules, but did not reflect environmental factors (pH and/or [O2]). We show that statoliths of squid embryos developing inside capsules have the potential to reflect environmental pH and [O2], but that these “signals” are generated in concert with the physiological effects of the capsules and embryos themselves.

Natural variation and changing climate in coastal oceans subject meroplanktonic organisms to broad ranges of pH and oxygen ([O2]) levels. In controlled‐laboratory experiments we explored the interactive effects of pH, [O2], and semidiurnal pH fluctuations on the survivorship, development, and size of early life stages of two mytilid mussels, Mytilus californianus and M. galloprovincialis. Survivorship of larvae was unaffected by low pH, low [O2], or semidiurnal fluctuations for both mytilid species. Low pH (<7.6) resulted in delayed transition from the trochophore to veliger stage, but this effect of low pH was absent when incorporating semidiurnal fluctuations in both species. Also at low pH, larval shells were smaller and had greater variance; this effect was absent when semidiurnal fluctuations of 0.3 units were incorporated at low pH for M. galloprovincialis but not for M. californianus. Low [O2] in combination with low pH had no effect on larval development and size, indicating that early life stages of mytilid mussels are largely tolerant to a broad range of [O2] reflective of their environment (80–260 μmol kg−1). The role of pH variability should be recognized as an important feature in coastal oceans that has the capacity to modulate the effects of ocean acidification on biological responses.

As the field of ocean acidification has grown, researchers have increasingly turned to laboratory experiments to understand the impacts of increased CO2 on marine organisms. However, other changes such as ocean warming and deoxygenation are occurring concurrently with the increasing CO2 concentrations, complicating the understanding of the impacts of anthropogenic changes on organisms. This experimental aquarium design allows for independent regulation of CO2 concentration, O2 levels, and temperature in a controlled environment to study the impacts of multiple stressors. The system has the flexibility for a wide range of treatment chemistry, seawater volumes, and study organisms. Control of the seawater chemistry is achieved by equilibration of a chosen gas mixture with seawater using a Liqui-Cel® membrane contactor. Included as examples, two experiments performed using the system have shown control of CO2 at values between approximately 500 and 1400 μatm and O2 at values from 80 to 240 μmol kg−1. Temperature has been maintained to 0.5 °C or better in the range of 10–17 °C. On a weeklong timescale, the system has achieved variability in pH of less than 0.007 pH units and in oxygen concentration of less than 3.5 μmol kg−1. Longer experiments, over a month in duration, have been completed with control to better than 0.08 pH units and 13 μmol kg−1 O2. The ability to study the impacts of multiple stressors in the laboratory simultaneously, as well as independently, will be an important part of understanding the response of marine organisms to a high-CO2 world.

Marine mammal-sport fishery interactions in Southern California waters are often observed but far less studied than marine mammal interactions with commercial fisheries (Hanan and Read 1989, Beeson and Hanan 1996, NMFS 1997). Older studies (Fiscus and Baines 1968, Miller et al. 1983) show that sea lions rarely interact with fishing activities in and near Santa Monica Bay while, in later investigations, California sea lions (Zalophus californianus) are reported to negatively affect sport fishing (Beeson and Hanan 1996). Previous to our study, no information was reported on interactions between fishermen and other species of marine mammals, except for Miller et al. (1983). The abundance of marine mammals and sport fishermen makes Santa Monica Bay an excellent area to further investigate marine mammal-sport fishery interactions, to compare results with previous findings, and to provide information for future conservation and management decisions linked with the creation of a Marine Protected Area in Santa Monica Bay. The most common marine mammals known to inhabit and feed in the bay year-round include the California sea lion, the bottlenose dolphin (Tursiops truncatus), the short-beaked common dolphin (Delphinus delphis) and the longbeaked common dolphin (D. capensis) (Bearzi 2005a). A survey of sport fishermen was conducted during 1998–1999 to gather general information on the type of interactions existing between marine mammals and fishermen activities and how marine mammals affect sport fishery in Santa Monica Bay. Of 90 interviewed sport fishermen, 30 were selected for the survey in Marina del Rey and Redondo Beach harbors during February–June 2000. The fishermen selected were required to have fished year-round and to have made at least 20 fishing trips per year in Santa Monica Bay (Point Vicente 33u 459 N 118 249 W to Point Dume 33u 599 N 118 489 W, up to 20 km offshore). Further, the fishermen were chosen from both charter boats (n 5 18) and private vessels (n 5 12); this was different from previous investigations where those interviewed were exclusively on charter boats (Miller et al. 1983, Beeson and Hanan 1996). Information about Sport Fishermen and Their Catches Of the selected fishermen, 87% stated they spent 1–3 days per month fishing in the bay and 80% preferred fishing during the summer months (June–August). Most (67%) fished less than 10 km from shore, of which 43% were within 1–5 km and only one fisherman at less than 1 km from shore. In 1998, 38% of the fishermen reported catching mostly ‘‘bass’’ (the term bass is generally used by local fishermen to include any fish species similar to a rockfish) and 36% reported catching mostly yellowtail, Seriola lalandi. In 1999, 47% of the fishermen reported catching ‘‘bass’’ most abundantly while only 13% reported catching yellowtail. Interactions with Marine Mammals All the fishermen observed dolphins in 1998 and 1999. Virtually all (97%) stated that dolphins – generally recognized as ‘‘common dolphins’’ never interfered with their fishing operations; one fisherman reported one Bull. Southern California Acad. Sci. 106(3), 2007, pp. 215–217 E Southern California Academy of Sciences, 2007