Warm water temperature regimes in eelgrass beds (Z. marina and Z. japonica) of Padilla Bay, WA

Padilla Bay, WA has over 3300 hectares of eelgrass with vast areas of intermixed beds of the native Zostera marina and non-native Zostera japonica. Water temperature is thought to be one of the primary influences on eelgrass distribution, and long term monitoring shows that temperatures in Padilla Bay have increased substantially (mean increase \u3e2°C) from 2011 through 2016. We were interested to see if changes in eelgrass distribution were correlated with the changes we observed in water temperature in Padilla Bay, however, our long term temperature monitoring station is located in a shallow channel within the eelgrass beds. Because of this sensor placement, we first needed to determine if these data were representative of temperatures experienced by eelgrass on the vegetated flats. To test this, we deployed 45 temperature loggers throughout the intertidal and subtidal distribution of Z. marina and Z. japonica. We found that temperatures recorded at our long term monitoring site greatly underestimated the high temperatures experienced by the intertidal eelgrass. In Padilla Bay, Zostera marina was exposed to temperatures above 8°C, the optimal temperature reported for Z. marina growth in the PNW, for over 90% of the time during the peak growing season (March – Sept.). Furthermore, Z. marina experienced extended periods of time above 15°C, temperatures thought to cause stress to local plants. Despite these elevated temperatures, Z. marina remain robust, suggesting that Z. marina in Padilla Bay may have a higher tolerance for warmer water temperatures than other beds in the PNW or may be living near the upper limits of tolerance for PNW plants. This study characterizes – on a fine spatial scale – the duration and intensity of temperatures extremes that eelgrass experience in shallow systems and ultimately provides insight into the health and performance of eelgrass in a warmer future ocean

The Effects of Ocean Acidity and Elevated Temperature on Bacterioplankton Community Structure and Metabolism

By the end of the 21st century, mean sea surface temperatures are expected to increase 4?C, while atmospheric CO2 concentrations are predicted to triple causing seawater to become acidic. These compounding effects will undoubtedly have major consequences for the organisms and processes in the oceans. Bacterioplankton play a vital role in the marine carbon cycle and the oceans’ ability to sequester CO2. We utilized pCO2 perturbation experiments to investigate the effects of ocean acidity and elevated temperature on bacterioplankton community structure and metabolism. Terminal-restriction fragment length polymorphism (T-RFLP) of small subunit ribosomal (SSU) genes revealed that bacterioplankton incubated in lower pH conditions exhibited a reduction of species richness, evenness, and overall diversity, relative to those incubated in ambient pH conditions. Non-metric multidimensional scaling (MDS) of T-RFLP data resulted in clustering by pH suggesting that pH influenced the structure of these communities. Shifts in the dominant members of bacterioplankton communities incubated under different pH were observed in both T-RFLP and SSU clone library analyses. Both ambient and low pH communities were dominated by Gammaproteobacteria and Alphaproteobacteria, although abundance of Alphaproteobacteria increased in communities incubated at lower pH. This was expressed by the gamma to alpha ratio dropping from ~9 to 4, respectively. In general, the representative taxa from these two classes were distinctly different between the treatments, with a few taxa found to be persistent in both treatments. Changes in the structure of bacterioplankton communities coincided with significant changes to their overall metabolism. Bacterial production rates decreased, while bacterial respiration increased under lower pH conditions. This study highlights the ability of bacterioplankton communities to respond to ocean acidification both structurally and metabolically, which may have significant implications for their ecological function in the marine carbon cycle and the ocean’s response to global climate change

Mapping eelgrass (Zostera sp.) habitat in Padilla Bay, WA, using an unmanned aerial system (UAS)

Eelgrass (Zostera marina) monitoring and restoration is important to commercial and ecological management in the Salish Sea. In the southern Salish Sea (Puget Sound, WA), eelgrass distribution overall has not changed in acreage but local eelgrass habitats have declined whereas others have increased. Additionally, coexistence with non-native dwarf eelgrass (Z. japonica) motivates tracking the spatial patterns of change in distribution of both Zostera species on a seasonal and interannual basis. Past efforts to map eelgrass communities have involved the use of satellite imagery and imagery acquired from manned aircraft. Imagery acquired using these platforms typically has a spatial resolution ranging from ~30m to ~1 m. UAS technology offers a new approach to obtain imagery with a spatial resolution of a few centimeters, at very low cost and the image acquisition can be carefully timed to take advantage of low tides. The Padilla Bay National Estuarine Research Reserve (PBNERR) includes one of the largest expanses of eelgrass on the west coast, which has been monitored long-term along permanent transects for Z. marina and Z. japonica coverage, shoot density, and biomass. This provides an ideal setting for the evaluation of alternative methods for mapping eelgrass communities using UAS technology. During the summer of 2017, we collected imagery from a 200 m by 2500 m transect overlapping the permanent plots that make up the PBNERR long-term monitoring transect. We collected imagery using both a multirotor and fixed-wing UAS and two different camera systems with different spectral and spatial resolutions. Here we discuss the logistical challenges of conducting these surveys and present preliminary results of our image classification efforts

Rapid deterioration of sediment surface ecosystems in Bellingham Bay as indicated by benthic foraminifera

Benthic foraminifera, shelled protists, are valuable tools for monitoring environmental conditions of the sediment surface in nearshore marine and estuarine to marsh settings. This study analyzed 64 sediment samples from Bellingham Bay (June 1997, 2006 and 2010) and 18 samples from Boundary Bay, Birch Bay and Neptune Beach (June 2006 and 2010), provided by the Washington State Department of Ecology. Thirty five taxa were identified, dominated by three calcareous and one agglutinate species. In Bellingham Bay, benthic foraminiferal diversity and density deteriorated strikingly between 1996 and 2006, most notably in the middle of the bay. Many of these bay-center sites yielded no foraminifera at all, and the situation did not improve in 2010. The samples from Boundary Bay to Neptune Beach generally demonstrated higher diversity; however decreases in both diversity and density are also recorded from 1996 to 2006. Correlations with six metal contaminants and with total polycyclic aromatic hydrocarbons showed a negative trend but R2 values are low. This corroborates the findings from benthic invertebrate faunas from the same sites by Weakland et al. (2013). Bottom water dissolved oxygen levels and pH data from the central part of Bellingham Bay indicate hypoxia and high levels of acidification. We infer that either combinations of organic pollutants or eutrophication have impacted the benthic biota

Variability in water column respiration in Salish Sea waters and implications for coastal and ocean acidification

Water column respiration is a key driver of carbon cycling, ocean acidification, and oxygen dynamics in marine ecosystems. However, empirical estimates of the range and variability of respiration and its relative contribution to ocean acidification are seldom measured. In 2014, we began measuring respiration rates at multiple sites in the central Salish Sea (San Juan Islands, Bellingham Bay) and then initiated routine monitoring of water column respiration at multiple sites in Padilla Bay National Estuarine Research Reserve (NERR). Measurements in Padilla Bay were integrated into the well-established NERR System Wide Monitoring Program (SWMP). Our investigation revealed that 1) rates of respiration vary seasonally and appear to be associated with changes in organic matter supply and, to a lesser extent, temperature, and 2) incoming deeper waters of marine origin are characterized by relatively low rates of respiration (i.e. ~5ugO2/L/h). To further explore underlying mechanisms, we conducted a series of manipulative experiments to investigate the direct effect of increasing ocean temperature and organic matter supply on rates of respiration. These experiments revealed that respiration can more than triple in response to increases in organic carbon supply and that this response may be influenced by seasonal changes in the export of organic matter and detritus from the extensive eelgrass meadows of Padilla Bay. Our field sampling and manipulative experiments have produced empirical estimates of respiration that can be included in models and projections of water quality and ocean acidification for the Puget Sound, and provide insight into the response of inland marine waters of the Pacific Northwest to a warmer, more acidified ocean

Temperature Regulation of Bacterial Production, Respiration, and Growth Efficiency in a Temperate Salt-marsh Estuary

There is consensus that temperature plays a major role in shaping microbial activity, but there are still questions as to how temperature influences different aspects of bacterioplankton carbon metabolism under different environmental conditions. We examined the temperature dependence of bacterioplankton carbon metabolism, whether this temperature dependence changes at different temperatures, and whether the relationship between temperature and carbon metabolism varies among estuarine sub-systems differing in their degree of enrichment. Two years of intensive sampling in a temperate estuary (Monie Bay, Chesapeake Bay, USA) revealed significant differences in the temperature dependence of bacterial production (BP) and respiration (BR), which drove a strong negative temperature response of bacterial growth efficiency (BGE). Accordingly, BGE was lower in summer (\u3c 0.2) and higher in winter (\u3e 0.5). For all measured metabolic processes, the most pronounced temperature response was observed at lower temperatures, with Q10 values generally 2-fold greater than in warmer waters. Despite significant differences in resource availability, both the temperature dependence and magnitude of BR and bacterioplankton carbon consumption (BCC) were remarkably similar among the 4 estuarine sub-systems. Although temperature dependencies of BP and BGE were also similar, their magnitude differed significantly, with highest values in the nutrient-enriched sub-system and lowest in the open bay. This pattern in carbon metabolism among sub- systems was present throughout the year and was confirmed by temperature manipulation experiments, suggesting the temperature effects on BP and BGE did not override the influence of resource availability. We conclude that temperature is the dominant factor regulating seasonality of BR and BCC in this system, whereas BP and BGE are influenced by both temperature and organic matter quality, with variation in the relative importance of each of these factors throughout the year

Variability in Protist Grazing and Growth on Different Marine Synechococcus Isolates

Grazing mortality of the marine phytoplankton Synechococcus is dominated by planktonic protists, yet rates of consumption and factors regulating grazer-Synechococcus interactions are poorly understood. One aspect of predator-prey interactions for which little is known are the mechanisms by which Synechococcus avoids or resists predation and, in turn, how this relates to the ability of Synechococcus to support growth of protist grazer populations. Grazing experiments conducted with the raptorial dinoflagellate Oxyrrhis marina and phylogenetically diverse Synechococcus isolates (strains WH8102, CC9605, CC9311, and CC9902) revealed marked differences in grazing rates-specifically that WH8102 was grazed at significantly lower rates than all other isolates. Additional experiments using the heterotrophic nanoflagellate Goniomonas pacifica and the filter-feeding tintinnid ciliate Eutintinnis sp. revealed that this pattern in grazing susceptibility among the isolates transcended feeding guilds and grazer taxon. Synechococcus cell size, elemental ratios, and motility were not able to explain differences in grazing rates, indicating that other features play a primary role in grazing resistance. Growth of heterotrophic protists was poorly coupled to prey ingestion and was influenced by the strain of Synechococcus being consumed. Although Synechococcus was generally a poor-quality food source, it tended to support higher growth and survival of G. pacifica and O. marina relative to Eutintinnis sp., indicating that suitability of Synechococcus varies among grazer taxa and may be a more suitable food source for the smaller protist grazers. This work has developed tractable model systems for further studies of grazer-Synechococcus interactions in marine microbial food webs

Providing modeling tools on extreme events of climate change to Puget Sound managers

As climate change becomes a reality for the management of Puget Sound, water resource and fisheries managers should consider incorporating predictions and outcomes of future climate drivers into their long-range plans and daily operations. Modeling tools that focus on climate impacts and predictions show that extreme events are more often responsible for large impacts than the long-term press of climate change. Working with water resource and fisheries managers in the Dungeness and Skagit watersheds, this project uses outputs of existing climate and estuarine models to define thresholds and metrics associated with extreme climate-driven events that are of importance to the resource managers. Managers from the Dungeness and Skagit basins were brought together to assist with defining information needs for sustainable fish habitat and human water uses. The resource managers participating in the project include municipal waste water treatment operators and planners, fisheries managers, agricultural practitioners and conservation district staff, flood control specialists, and others. The information needs identified by the planners, based on the climate model outputs, include better predictions for low stream flows, stream temperature, extent of salinity intrusion into tidal rivers, and timing of extreme events that fall outside the historical norm. The project is developing a decision-support system to meet these needs. The metrics used to drive the decision-support system are derived from model outputs, driven by resource management needs. The information needs, metrics derived from existing models, and the draft decision-support system will be presented. The research team also seeks to use the project to define improved communication pathways between the scientific community and local managers

Changing seasonal transitions within the zooplankton community in the Padilla Bay National Estuarine Research Reserve.

The importance of zooplankton as an indicator of ecosystem health and climate change is widely accepted, but remains an understudied component of many estuarine ecosystems. In 2008, we initiated a monthly zooplankton monitoring program at the Padilla Bay National Estuarine Research Reserve (NERR) to explore temporal and spatial patterns in abundance and community composition. Samples were collected at two sites located in channels draining eelgrass covered flats, and a third located in deep (20 m) water well beyond the subtidal edge of the eelgrass beds. Water quality parameters (i.e. temperature, salinity) and nutrient concentrations were also measured at each of these sites. Analysis of these data over an 8 year period reveal tremendous seasonal, interannual and spatial variability in community composition. Strong seasonal transitions of the dominant plankton groups (copepods, copepod nauplii, and larvaceans) at the deep water site were found. However, these patterns were disrupted in 2014 when Padilla Bay and the greater regional area experienced its highest temperatures, lowest salinities, and a positive PDO index. Despite these co-occurring anomalies, paired measures of water quality parameters were not good predictors of abundance or shifting community composition. Accordingly, we explore the effect of time lags and integrating water quality parameters over multiple temporal scales to help identify what regulates zooplankton communities in Padilla Bay NERR. Additionally, we explore the phenological shifts of the spring and fall peaks in zooplankton abundance in relation to changing environmental factors and the impact theses shifts may have on the food web and larval recruitment in Padilla Bay