Does Puget Sound have a long-term memory?

More than a decade of high-resolution, full-water column data collected by profiling UW ORCA/NANOOS moorings in several Puget Sound Basins are used to investigate interannual variability of near-surface and deep water properties. Although there are no significant trends in temperature, salinity, density and dissolved oxygen spanning the last decade, measurements show steady and relatively strong trends in these variables over periods of 3 to 5 years in both South Sound near bottom waters and in south Hood Canal deep water. For example, the annual minimum density in south Hood Canal deep water increased four years in a row from 2006 to 2009, then this trend reversed for three years. In Carr Inlet the annual maximum deep temperature increased five years in a row from 2011 to 2015, with deep salinity following a similar trend. As these trends are significantly longer than expected flushing and residence times (\u3c year), this hints at potential interannual dynamical feedbacks, longer-term system “memory”, and/or similar trends in ocean and atmospheric forcing. Using archived National Data Buoy Center, National Weather Service and UW Atmospheric Sciences data we explore and report on potential factors contributing to these trends

Patterns and variability in ocean acidification conditions in Puget Sound and the Strait of Juan de Fuca

The Washington Ocean Acidification Center is working with NOAA and other partners to increase understanding of ocean acidification dynamics and spatial variability in the Salish Sea, and how these correlate with planktonic responses. These data are critical for assessing water quality, areas with higher or lower OA stress, and to understand effects on the food web. Two main strategies are employed; seasonal ship cruises provide spatial coverage and the ability to collect plankton, while mooring buoys provide information on mechanisms and the range of variation due to the high-resolution and constant coverage they provide. Results show a strong degree of depth, seasonal, and spatial variation in pH and aragonite saturation state. In general, the lowest pH and aragonite saturation state values are at depth, particularly in stratified areas, though this can shift during seasonal localized upwelling, e.g., Southern Hood Canal, and in mixed water columns, e.g., the Main Basin. Seasonal patterns are spatially diverse, with stratified areas exhibiting strong vertical gradients with depth during summer and more homogenous conditions during winter; well-mixed areas show less variation year-round. This implies that species encounter quite different OA conditions in various parts of the Salish Sea between the seasons. Mooring CO2 data reveal higher variation during late fall through early spring at sites within the Salish Sea, due to winter mixing of stratified waters, yet the reverse pattern off the Washington coast, due to summer upwelling. In both cases, these mechanisms (winter mixing and summer upwelling) operate across a gradient, bringing relatively deeper lower pH / aragonite saturation state waters in contact with surface waters with higher values. Such changes in the spatial and depth distribution of corrosive conditions have broad implications for sensitive marine life

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012

The eastern tropical North Pacific (ETNP) is a large region of anoxic water that hosts widespread water column N loss (denitrification). There is some disagreement about the long‐term trends of denitrification and anoxia and long‐term studies of water column denitrification within the anoxic zone are lacking. In this study, we compared ETNP water column nitrite, N*, and O2 data along the same transect for four studies ranging from 1972 to 2012. Anoxic water volume increased, and low‐oxygen conditions expanded into shallower isopycnals from 1972 to 2012. A geochemical marker for cumulative N loss indicates that denitrification was highest in 2012 and the upper oxygen‐deficient zone (ODZ) experienced the most change. Oxygen and N loss changes in the world's largest ODZ for 2012 could not be explained by the Pacific Decadal Oscillation, and decreased O2 in supply currents and increased wind‐driven upwelling are likely mechanisms contributing to increased N loss and anoxia

Reconstructing carbonate chemistry in deep waters of the southern Salish Sea

Through survey cruises and moored time-series, we have observed the dynamic carbon cycle in various sub-basins of the southern Salish Sea since 2008. Areas of Puget Sound with restricted circulation, such as Hood Canal, may experience conditions of high pCO2, low pH, and low aragonite saturation state in deep waters throughout the year. Historically, the highest pCO2 and lowest pH and aragonite saturation states have been observed in early fall in Hood Canal. Upwelling of dense, nutrient- and CO2-rich but oxygen-poor water along the coast provides the marine source for Puget Sound’s deep waters. We have previously estimated that marine waters entering Puget Sound via the Strait of Juan de Fuca are now corrosive 95% of the time, representing a 26% increase in frequency since the preindustrial era. Both river inputs and intense primary production in surface waters drive remineralization of organic matter in deep waters of Puget Sound basins, contributing to the exacerbation of corrosive conditions in waters below the stratified and productive surface waters. In addition, we estimate that regionally enhanced atmospheric CO2 content may result in an increased uptake of CO2 in the region. Empirical relationships for reconstructing carbonate chemistry within Puget Sound have been created based on calibration data sets from coastal surveys, individual Puget Sound cruises, individual basins within Puget Sound, and the full Puget Sound data set (2008–2014). Here we compare their efficacy in reconstructing the evolution of carbonate system variables through seasons and across years on a profiling mooring in Hood Canal. In 2015 many features of the seasonal carbon cycle were accelerated relative to earlier years, as a result of the influence of the NE Pacific warm water anomaly. In southern Hood Canal, we saw the lowest estimated pH and aragonite saturation values in deep waters observed to date in Washington marine environments

Attribution of corrosive bottom-water conditions to ocean acidification and other estuarine drivers in Puget Sound: an updated analysis

Providing specific attribution of observed changes in biogeochemical signals to specific process drivers is notoriously challenging in coastal and estuarine ecosystems, with natural variability often substantially larger than an anthropogenic signal of interest, such as ocean acidification (OA). In 2010, we estimated that anthropogenic OA was responsible for 24–49% of the added corrosiveness observed in the bottom waters of southern Hood Canal, relative to conditions naturally present in CO2-rich upwelling water, with the remaining 51–74% due to respiration processes. For these purposes, “added corrosiveness” referred to the contribution of additional dissolved CO2 from uptake of anthropogenic CO2 (i.e. anthropogenic OA) or respiration within Hood Canal to undersaturation of aragonite beyond that in the upwelled source waters. Here we expand this analysis to encompass five cruise data sets for Hood Canal (2008–2011). We also determine the CO2 variability of marine source waters coming into Puget Sound using moored time-series in combination with empirical relationships developed for coastal waters, as well as the impact of different transport-time scenarios within the basin on our attribution estimates