To develop more accurate global carbon (C) budgets and to better inform management of human activities in the ocean, we need high-resolution estimates of marine C stocks. Here we quantify global marine sedimentary C stocks at a 1-km resolution, and find that marine sediments store 2322 (2239–2391) Pg C in the top 1 m (nearly twice that of terrestrial soils). Sediments in abyss/basin zones account for 79% of the global marine sediment C stock, and 49% of that stock is within the 200-mile Exclusive Economic Zones of countries. Currently, only ∼2% of sediment C stocks are located in highly to fully protected areas that prevent the disturbance of the seafloor. Our results show that marine sediments represent a large and globally important C sink. However, the lack of protection for marine C stocks makes them highly vulnerable to human disturbances that can lead to their remineralization to CO2, further aggravating climate change impacts.

The Alaskan Matanuska‐Susitna Basin (MSB) provides habitat for all five Pacific salmon species, and their large seasonal spawning runs are important both ecologically and economically. However, the encroachment of human development through urbanization and extractive industries poses a serious risk to salmon habitat in the MSB. Using systematic conservation planning techniques, different methods of incorporating anthropogenic risks were assessed to determine how to conserve salmon habitat in the area cost‐effectively. The consequences of four distinct conservation scenarios were quantified: no consideration either of urbanization or extractive industries (‘Risk ignored’ scenario); accounting for the risk of urbanization, and avoiding conservation in all areas rich in fossil fuels (‘Urbanization accounted, all extraction avoided’ scenario); accounting for urbanization and oil and gas development, but avoiding conservation in coal‐rich areas (‘Urbanization accounted, coal areas avoided’ scenario); and accounting for all anthropogenic risks to habitat, and allowing conservation in oil, gas, or coal‐rich areas (‘All risks accounted’ scenario). To compare conservation success and resilience, the impacts of these risks were estimated using Monte Carlo simulations. The final cost of each solution was then divided by the number of conservation targets met to determine a return on investment. Results from scenarios that avoided all extractive activities, or only coal, suggest that conservation targets cannot be met simply by avoiding areas rich in fossil fuels, and these scenarios resulted in lower returns on investment than those in which risks from extraction were incorporated into the solution. By developing a method for setting priorities that are economically based, this study provides a method for local managers and conservation groups to identify conservation opportunities in MSB river basins.

In the United States, the Clean Water Act (CWA) establishes water quality standards important for maintaining healthy freshwater ecosystems. Within the CWA framework, states define their own water quality criteria, leading to a potential fragmentation of standards between states. This fragmentation can influence the management of shared water resources and produce spillover effects of pollutants crossing state lines and other political boundaries. We used numerical simulations to test the null prediction of no difference in impairment between watersheds that cross political boundaries (i.e. state lines, national or coastal borders, hereafter termed “transboundary”) and watersheds that cross no boundaries (hereafter “internal”). We found that transboundary watersheds are more likely to be impaired than internal watersheds. Further, we examined possible causes for this relationship based on both geographic and sociopolitical drivers. Though geographic variables such as human-modified land cover and the amount of upstream catchment area are associated with watershed impairment, the number and type of agencies managing land within a watershed better explained the different impairment levels between transboundary and internal watersheds. Watersheds primarily consisting of public lands are less impaired than watersheds consisting of private lands. Similarly, watersheds primarily managed by federal agencies are less impaired than state-managed watersheds. Our results highlight the importance of considering Integrated Watershed Management strategies for water resources within a fragmented policy framework.

This chapter deals with the impact of parthenium weed (Parthenium hysterophorus) on the environment, more specifically, the negative impact of the weed on soil properties, and the above- and below-ground community biodiversity, including fauna, flora and microorganisms. Also, the chapter comprehensively examines the negative impact of parthenium weed on insect pollinators and shows how the weed can: (i) alter nutrient cycling; (ii) reduce plant species diversity and abundance; (iii) change vegetation structure; and (iv) alter the assemblage of other organisms such as invertebrates, amphibians, reptiles, birds and mammals. Although some key gaps with regard to determining the impacts of parthenium weed on biodiversity have been detected, there is sufficient evidence to conclude that parthenium weed is having a dramatic impact on biodiversity and ecosystem function throughout its introduced range in Africa, Asia and Australia.

No abstract