Explore the vast range of titles available.

Global change is leading to warming, acidification, and oxygen loss in the ocean. In the Southern California Bight, an eastern boundary upwelling system, these stressors are exacerbated by the localized discharge of anthropogenically enhanced nutrients from a coastal population of 23 million people. Here, we use simulations with a high-resolution, physical–biogeochemical model to quantify the link between terrestrial and atmospheric nutrients, organic matter, and carbon inputs and biogeochemical change in the coastal waters of the Southern California Bight. The model is forced by large-scale climatic drivers and a reconstruction of local inputs via rivers, wastewater outfalls, and atmospheric deposition; it captures the fine scales of ocean circulation along the shelf; and it is validated against a large collection of physical and biogeochemical observations. Local land-based and atmospheric inputs, enhanced by anthropogenic sources, drive a 79% increase in phytoplankton biomass, a 23% increase in primary production, and a nearly 44% increase in subsurface respiration rates along the coast in summer, reshaping the biogeochemistry of the Southern California Bight. Seasonal reductions in subsurface oxygen, pH, and aragonite saturation state, by up to 50 mmol m−3, 0.09, and 0.47, respectively, rival or exceed the global open-ocean oxygen loss and acidification since the preindustrial period. The biological effects of these changes on local fisheries, proliferation of harmful algal blooms, water clarity, and submerged aquatic vegetation have yet to be fully explored.

Children may be at higher risk for swimming-associated illness following exposure to fecally-contaminated recreational waters. We analyzed a pooled data set of over 80,000 beachgoers from 13 beach sites across the United States to compare risks associated with the fecal indicator bacteria Enterococcus spp. (measured by colony forming units, CFU and quantitative polymerase chain reaction cell equivalents, qPCR CE) for different age groups across different exposures, sites and health endpoints. Sites were categorized according to the predominant type of fecal contamination (human or non-human). Swimming exposures of varying intensity were considered according to degree of contact and time spent in the water. Health endpoints included gastrointestinal and respiratory symptoms and skin rashes. Logistic regression models were used to analyze the risk of illness as a function of fecal contamination in water as measured by Enterococcus spp. among the exposed groups. Non-swimmers (those who did not enter the water) were excluded from the models to reduce bias and facilitate comparison across groups. Gastrointestinal symptoms were the most sensitive health endpoint and strongest associations were observed with Enterococcus qPCR CE at sites impacted by human fecal contamination. Under several exposure scenarios, associations between illness and Enterococcus spp. levels were significantly higher among children compared to adolescents and adults. Respiratory symptoms were also associated with Enterococcus spp. exposures among young children at sites affected by human fecal sources, although small sample sizes resulted in imprecise estimates for these associations. Under many exposure scenarios, children were at higher risk of illness associated with exposure to fecal contamination as measured by the indicator bacteria Enterococcus spp. The source of fecal contamination and the intensity of swimming exposure were also important factors affecting the association between Enterococcus spp. and swimming-associated illness.

In 2007, the US west coast shellfish industry began to feel the effects of unprecedented levels of larval mortality in commercial hatcheries producing the Pacific oysterCrassostrea gigas. Subsequently, researchers at Whiskey Creek Shellfish Hatchery, working with academic and government scientists, showed a high correlation between aragonite saturation state (Ωarag) of inflowing seawater and survival of larval groups, clearly linking increased CO₂ to hatchery failures. This work led the Pacific Coast Shellfish Growers Association (PCSGA) to instrument shellfish hatcheries and coastal waters, establishing a monitoring network in collaboration with university researchers and the US Integrated Ocean Observing System. Analytical developments, such as the ability to monitor Ωaragin real time, have greatly improved the industry's understanding of carbonate chemistry and its variability and informed the development of commercial-scale water treatment systems. These treatment systems have generally proven effective, resulting in billions of additional oyster larvae supplied to Pacific Northwest oyster growers. However, significant challenges remain, and a multifaceted approach, including selective breeding of oyster stocks, expansion of hatchery capacity, continued monitoring of coastal water chemistry, and improved understanding of biological responses will all be essential to the survival of the US west coast shellfish industry.

Microplastic particles (MPs) are ubiquitous across a wide range of aquatic habitats but determining an appropriate level of risk management is hindered by a poor understanding of environmental risk. Here, we introduce a risk management framework for aquatic ecosystems that identifies four critical management thresholds, ranging from low regulatory concern to the highest level of concern where pollution control measures could be introduced to mitigate environmental emissions. The four thresholds were derived using a species sensitivity distribution (SSD) approach and the best available data from the peer-reviewed literature. This included a total of 290 data points extracted from 21 peer-reviewed microplastic toxicity studies meeting a minimal set of pre-defined quality criteria. The meta-analysis resulted in the development of critical thresholds for two effects mechanisms: food dilution with thresholds ranging from ~ 0.5 to 35 particles/L, and tissue translocation with thresholds ranging from ~ 60 to 4100 particles/L. This project was completed within an expert working group, which assigned high confidence to the management framework and associated analytical approach for developing thresholds, and very low to high confidence in the numerical thresholds. Consequently, several research recommendations are presented, which would strengthen confidence in quantifying threshold values for use in risk assessment and management. These recommendations include a need for high quality toxicity tests, and for an improved understanding of the mechanisms of action to better establish links to ecologically relevant adverse effects.

[This corrects the article DOI: 10.1371/journal.pone.0266749.].

Microplastics are pervasive in the aqueous environment, having been reported in air, lakes, ocean, drinking water, sediment, snow, animals, and even humans [1–4]. Since plastic pollution was first documented in the marine environment in the 1970’s [5], production has increased more than 10-fold [6], and inputs into the environment are expected to triple over the next ~ 20 years [7]. Since plastic degrades over extremely long timescales [8] and is ingested, inhaled, or absorbed throughout the food chain from microscopic organisms to humans [9–11], contamination is causing increasing concern for environmental managers. [...]was identifying prevalence of microplastics in the environment and the sources that lead to that contamination, with the first exemplary monitoring in the state conducted in San Francisco Bay [36, 37]. [...]visual microscopy might be used for particles larger than ~ 500 μm, Raman spectroscopy for particles larger than ~ 5 μm and electron microscopy for even smaller particles, each requiring different protocols and encompassing substantial cost differences [35]. [...]some techniques allow for estimation of the total mass of polymers (e.g. pyrolysis-gas chromatography/mass spectrometry) without providing detailed information about the particles’ sizes or shapes, while others can quantify particle counts in addition to these other parameters (e.g., Raman and infrared spectroscopy) [52].

Interpreting the vulnerability of pelagic calcifiers to ocean acidification (OA) is enhanced by understanding of their critical thresholds and how these thresholds are modified by other climate change stressors (e.g. warming). To address this need, we undertook a three-part data synthesis for pteropods, one of the calcifying zooplankton group. We conducted the first meta-analysis and threshold analysis of literature characterizing pteropod responses to OA and warming by synthetizing dataset comprising of 2097 datapoints. Meta-analysis revealed the extent to which responses among studies conducted on differing life stages and disparate geographies could be integrated into a common analysis. The results demonstrated reduced calcification, growth, development and survival to OA with increased magnitude of sensitivity in the early life stages, under prolonged duration, and with the concurrent exposure of OA and warming, but not species-specific sensitivity. Second, breakpoint analyses identified OA thresholds for several endpoints: dissolution (mild and severe), calcification, egg development, shell growth, and survival. Finally, consensus by a panel of pteropod experts was used to verify thresholds and assign confidence scores for five endpoints with sufficient signal:noise ratio to develop life-stage specific, duration-dependent thresholds. The range of aragonite saturation state from 1.5 to 0.9 provides a risk range from early warning to lethal impacts, thus providing rigorous basis for vulnerability assessments to guide climate change management responses, including evaluation of the efficacy of local pollution management. In addition, meta-analyses with OA and warming shows increased vulnerability in two pteropod processes, i.e. shell dissolution and survival, and thus pointing towards increased threshold sensitivity under combined stressor effect.

Microplastics have been documented in drinking water, but their effects on human health from ingestion, or the concentrations at which those effects begin to manifest, are not established. Here, we report on the outcome of a virtual expert workshop conducted between October 2020 and October 2021 in which a comprehensive review of mammalian hazard studies was conducted. A key objective of this assessment was to evaluate the feasibility and confidence in deriving a human health-based threshold value to inform development of the State of California’s monitoring and management strategy for microplastics in drinking water. A tiered approach was adopted to evaluate the quality and reliability of studies identified from a review of the peer-reviewed scientific literature. A total of 41 in vitro and 31 in vivo studies using mammals were identified and subjected to a Tier 1 screening and prioritization exercise, which was based on an evaluation of how each of the studies addressed various quality criteria. Prioritized studies were identified largely based on their application and reporting of dose–response relationships. Given that methods for extrapolating between in vitro and in vivo systems are currently lacking, only oral exposure in vivo studies were identified as fit-for-purpose within the context of this workshop. Twelve mammalian toxicity studies were prioritized and subjected to a Tier 2 qualitative evaluation by external experts. Of the 12 studies, 7 report adverse effects on male and female reproductive systems, while 5 reported effects on various other physiological endpoints. It is notable that the majority of studies (83%) subjected to Tier 2 evaluation report results from exposure to a single polymer type (polystyrene spheres), representing a size range of 0.040 to 20 µm. No single study met all desired quality criteria, but collectively toxicological effects with respect to biomarkers of inflammation and oxidative stress represented a consistent trend. While it was possible to derive a conservative screening level to inform monitoring activities, it was not possible to extrapolate a human–health-based threshold value for microplastics, which is largely due to concerns regarding the relative quality and reliability of current data, but also due to the inability to extrapolate data from studies using monodisperse plastic particles, such as polystyrene spheres to an environmentally relevant exposure of microplastics. Nevertheless, a conservative screening level value was used to estimate a volume of drinking water (1000 L) that could be used to support monitoring activities and improve our overall understanding of exposure in California’s drinking water. In order to increase confidence in our ability to derive a human–health-based threshold value in the future, several research recommendations are provided, with an emphasis towards strengthening how toxicity studies should be conducted in the future and an improved understanding of human exposure to microplastics, insights critically important to better inform future risk assessments. Graphical abstract

The Second National Workshop on Environmental DNA was held on September 12–15, 2022, at the Southern California Coastal Water Research Project (SCCWRP) in Southern California and was focused on transitioning eDNA from research to management applications. The Workshop was attended by 150 people in‐person and an additional 200 more online. Workshop attendees represented a broad cross‐section of disciplines and backgrounds, including research scientists, state, and federal agencies, and those in the environmental management sector. This diverse collection of attendees assembled with the goal of achieving cross‐sector collaboration and working together to identify the necessary next steps to move eDNA methods into the management application mainstream. The Workshop structure included a Training Day oriented towards environmental managers and those new to eDNA science, to facilitate a common ground for discussions on subsequent days. The Plenary Day focused on case studies about eDNA applications and culminated with a roundtable panel discussion with local, state, and federal agency representatives on eDNA method readiness and the road to method adoption. Among the key takeaways from the Workshop was bridging the communication gap between researchers and managers because scientists often focus on technical details and the unknowns, giving the impression that eDNA science is not yet mature, whereas managers want to hear consensus statements about readiness and a roadmap for method adoption, including standard operating procedures, lab accreditation, and unified sequence libraries. This outcome was a clear directive for many scientists in attendance that it is time to stop letting perfect be the enemy of good and to focus future efforts on method harmonization and a national strategy towards method adoption. The Workshop concluded with a working session of invited participants to identify key priorities and needs to achieve the goals highlighted in the Workshop discussions. This is an invited commentary on the Second National Workshop on Environmental DNA, which was held on September 12–15, 2022, at the Southern California Coastal Water Research Project (SCCWRP), and was focused on transitioning eDNA from research to management applications. The Workshop's goal was to achieve cross‐sector collaboration and work together to identify the necessary next steps to move eDNA methods into the management application mainstream.

There are numerous reasons to conduct scientific research within protected areas, but research activities may also negatively impact organisms and habitats, and thus conflict with a protected area's conservation goals. We developed a quantitative ecological decision-support framework that estimates these potential impacts so managers can weigh costs and benefits of proposed research projects and make informed permitting decisions. The framework generates quantitative estimates of the ecological impacts of the project and the cumulative impacts of the proposed project and all other projects in the protected area, and then compares the estimated cumulative impacts of all projects with policy-based acceptable impact thresholds. We use a series of simplified equations (models) to assess the impacts of proposed research to: a) the population of any targeted species, b) the major ecological assemblages that make up the community, and c) the physical habitat that supports protected area biota. These models consider both targeted and incidental impacts to the ecosystem and include consideration of the vulnerability of targeted species, assemblages, and habitats, based on their recovery time and ecological role. We parameterized the models for a wide variety of potential research activities that regularly occur in the study area using a combination of literature review and expert judgment with a precautionary approach to uncertainty. We also conducted sensitivity analyses to examine the relationships between model input parameters and estimated impacts to understand the dominant drivers of the ecological impact estimates. Although the decision-support framework was designed for and adopted by the California Department of Fish and Wildlife for permitting scientific studies in the state-wide network of marine protected areas (MPAs), the framework can readily be adapted for terrestrial and freshwater protected areas.