• Publication date: June 14th, 2021

    Slides: Who is the Chesapeake Bay Program and How Can We Help You Webinar

    This webinar will offer an overview of the partnership and how we work together and discuss what we can offer to you regarding data, access to experts and content (including photos and videos).

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  • Publication date: June 14th, 2021

    Slides: May 2021 Wetlands Webinar

    In this webinar, a panel of experts discussed challenges impacting wetlands and what’s being done to save them.

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  • Publication date: June 14th, 2021

    Slides: April 2021 Native Plants and Pollinators Webinar

    In this webinar a panel of experts discussed the benefits of native plants and pollinators. 

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  • Publication date: June 14th, 2021

    Slides: June 2021 Recreation Webinar

    Our June 2021 monthly webinar discusses what there is to do to recreate throughout the watershed and how you can find it.

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  • Publication date: June 9th, 2021

    Impacts of sea level rise on hypoxia in the Chesapeake Bay: A model intercomparison

    Over the recent years a number of studies have examined the effects of climate change and sea level rise (SLR) on hypoxia in Chesapeake Bay. However, variations in the methodology, the years considered, and the metrics reported made comparisons between these studies difficult. To clarify the effects of SLR on the Bay’s hypoxia, we present an intercomparison between four numerical models following a common methodology. The models share the riverine fluxes, baseline period (1991–1995), and consider the same three scenarios of SLR: an increase in sea level of 0.17 m,
    0.50 m, and 1.00 m (representative of years 2025, 2050 and 2100, respectively). SLR is the sole climate driver considered in these experiments.
    There is considerable agreement between the models in how salinity changes in response to SLR. Salinity increases throughout the Bay and throughout the water column with little seasonality. The changes are amplified with increasing SLR but their spatial distributions remain similar. The models do not suggest an appreciable change with SLR in the top-to-bottom salinity contrast. The model projections for salinity are quantitatively close to those of earlier studies.
    The models agree that SLR, in absence of other drivers of climate change, produces slightly warmer water temperatures in November–January and slightly cooler water temperatures in May– July. The changes are amplified with increasing SLR but their spatial distributions remain similar. The models exhibit some variations in the vertical structure of the changes in temperature (either concentrated in the upper 10 m or more vertically homogeneous). The magnitude of the changes in temperature due to SLR are substantially smaller than those associated with global warming.
    The models agree that SLR decreases dissolved oxygen concentrations (DO) in the upper part of the water column and increases bottom DO at least in parts of the deep channel in May–July. Both negative and positive DO anomalies are amplified by SLR but the seasonal and spatial patterns remain similar. The vertical profiles of DO are uplifted by SLR and this feature accounts quantitatively for the negative DO anomaly of the upper part of the water column. The positive DO anomaly apparent in the bottom layer of the deep channel in the summer cannot be explained by changes in water solubility. Similarly, changes in the advection/diffusion of DO in response to SLR cannot account for the positive bottom DO anomaly. Instead, the models point toward a decrease in bottom-layer respiration as the cause of the positive bottom DO anomaly.
    Focusing on the variables that affect bottom-layer respiration, we find that the slightly cooler water temperatures during summer, combined with the temperature-dependent respiration rates of the models, can account for the decrease in bottom layer respiration. Despite the similarities between the model results, the magnitude and duration of the positive bottom DO anomaly show substantial variations from one model to another. Further examination of the model parameterizations suggest that differences in the temperature sensitivity and the primary production are likely responsible for differences in the magnitude/duration of the positive bottom DO anomaly.
    The hypoxic volume, a metric commonly used in studies of hypoxia, was found to be poor indicator of changes in DO concentrations within the deep channel of the Bay (where hypoxia and anoxia are most prevalent). The boundary of the hypoxic zone (isosurface of DO=2 mg L-1) often lies close to (or lies inside) shallow areas where the models project DO to decrease in response to SLR. In these cases, the hypoxic volume will expand with SLR, regardless of the presence/absence of a positive DO anomaly within the deep channel. The result emphasizes that consistent metrics should be used when comparing model studies of hypoxia.

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  • Publication date: May 13th, 2021

    Microplastic Monitoring & Science Strategy for the Chesapeake Bay

    The Plastic Pollution Action Team (PPAT) was formed at the directive of the CBP Management Board and was charged to develop a preliminary ecological risk assessment model (Appendix C), in addition to a size classification document (Appendix B), and this science strategy. Many of the topics from those first two documents are found in this document to formulate a strategy to address microplastics bay-wide.

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