Modeling the effect of water quality on the recreational shellfishing cultural ecosystem service of Buzzards Bay, Massachusetts.

Estuaries provide significant cultural ecosystem services, including recreation and tourism. Disruptions of estuarine biogeochemical processes resulting from environmental degradation could interrupt the flow of these services, reducing benefits and diminishing the welfare of local communities. This study focused on recreational shellfishing in Buzzards Bay, Massachusetts (41.55°N, 70.80°W). Relationships among measures of recreational shellfishing, estuarine water quality, and local socioeconomic conditions were tested to understand how the benefits of cultural ecosystem services to local communities might be affected by declining water quality. Transferring estimated economic benefits from an analysis of nearby municipalities, the study finds that increases in Chl a during the 24-year period were associated with losses in recreational shellfishing benefits of $0.08-0.67 million per decade. The approach presented here suggests a more broadly applicable framework for assessing the impacts of changes in coastal ecosystem water quality on the welfare of local communities.

Changes in Ocean Heat, Carbon Content, and Ventilation: A Review of the First Decade of GO-SHIP Global Repeat Hydrography.

Global ship-based programs, with highly accurate, full water column physical and biogeochemical observations repeated decadally since the 1970s, provide a crucial resource for documenting ocean change. The ocean, a central component of Earth's climate system, is taking up most of Earth's excess anthropogenic heat, with about 19% of this excess in the abyssal ocean beneath 2,000 m, dominated by Southern Ocean warming. The ocean also has taken up about 27% of anthropogenic carbon, resulting in acidification of the upper ocean. Increased stratification has resulted in a decline in oxygen and increase in nutrients in the Northern Hemisphere thermocline and an expansion of tropical oxygen minimum zones. Southern Hemisphere thermocline oxygen increased in the 2000s owing to stronger wind forcing and ventilation. The most recent decade of global hydrography has mapped dissolved organic carbon, a large, bioactive reservoir, for the first time and quantified its contribution to export production (∼20%) and deep-ocean oxygen utilization. Ship-based measurements also show that vertical diffusivity increases from a minimum in the thermocline to a maximum within the bottom 1,500 m, shifting our physical paradigm of the ocean's overturning circulation.

The North Atlantic spring phytoplankton bloom and Sverdrup's critical depth hypothesis.

More than 50 years ago, Harald Sverdrup developed a simple model for the necessary conditions leading to the spring bloom of phytoplankton. Although this model has been used extensively across a variety of aquatic ecosystems, its application requires knowledge of community compensation irradiance (IC), the light level where photosynthetic and ecosystem community loss processes balance. However, reported IC values have varied by an order of magnitude. Here, IC estimates are determined using satellite and hydrographic data sets consistent with the assumptions in Sverdrup's 1953 critical depth hypothesis. Retrieved values of IC are approximately uniform throughout much of the North Atlantic with a mean value of 1.3 mol photons meter-2 day-1. These community-based IC determinations are roughly twice typical values found for phytoplankton alone indicating that phytoplankton account for approximately one-half of community ecosystem losses. This work also suggests that important aspects of heterotrophic community dynamics can be assessed using satellite observations.