Surface distribution of brachyuran megalopae and ichthyoplankton in the Columbia River plume during transition from downwelling to upwelling conditions

In the California Current coastal boundary zone, the spring transition between downwelling and upwelling conditions, along with the fluctuating structure of the Columbia River plume, creates highly dynamic interactions. In this study, we investigated whether the surface distribution of brachyuran larvae and ichthyoplankton would track the dynamics of the Columbia River plume. By happenstance, the cruise period coincided with the spring transition from downwelling to sustained upwelling conditions in 2010, a year when the transition was delayed and Columbia River flow was substantially higher than average. We used time series of wind and freshwater input to evaluate the influence of physical forcing on oceanographic patterns, and sampled hydrography and surface plankton concentrations within a 182 km(2) grid off Willapa Bay, WA. Additionally, two longer transects, one cross-shelf and the other along-shore, were made to discern the extent of plume influence on larval crab and fish abundance. We found that plume waters that were trapped in a northward-flowing coastal-boundary current during downwelling conditions were advected offshore after several days of upwelling-favorable winds. Neustonic collections of brachyuran larvae and ichthyoplankton varied in response to this large seaward advective event. Megalopae of cancrid crabs exhibited patterns of both offshore transport (Cancer oregonensis/productus) and nearshore retention (C. magister). Additionally, abundant numbers of large juvenile widow (Sebastes entomelas) and yellowtail (S. flavidus) rockfish of a size appropriate for settlement were sampled during a period when ocean conditions favored high recruitment success. These results demonstrated that the response of planktonic crab larvae and ichthyoplankton to large-scale advection varied by species, with larger and more vagile fish exhibiting less evidence of passive transport than smaller crab larvae. Importantly, portions of the planktonic fish and crab community were able to maintain nearshore distributions in favorable settlement habitat, despite physical advection offshore. Published by Elsevier Ltd.Keywords: Crab megalopae, Neuston, Juvenile fishes, California Current, Upwelling, Columbia River plum

Coastal Upwelling Supplies Oxygen-Depleted Water to the Columbia River Estuary

Low dissolved oxygen (DO) is a common feature of many estuarine and shallow-water environments, and is often attributed to anthropogenic nutrient enrichment from terrestrial-fluvial pathways. However, recent events in the U.S. Pacific Northwest have highlighted that wind-forced upwelling can cause naturally occurring low DO water to move onto the continental shelf, leading to mortalities of benthic fish and invertebrates. Coastal estuaries in the Pacific Northwest are strongly linked to ocean forcings, and here we report observations on the spatial and temporal patterns of oxygen concentration in the Columbia River estuary. Hydrographic measurements were made from transect (spatial survey) or anchor station (temporal survey) deployments over a variety of wind stresses and tidal states during the upwelling seasons of 2006 through 2008. During this period, biologically stressful levels of dissolved oxygen were observed to enter the Columbia River estuary from oceanic sources, with minimum values close to the hypoxic threshold of 2.0 mg L−1. Riverine water was consistently normoxic. Upwelling wind stress controlled the timing and magnitude of low DO events, while tidal-modulated estuarine circulation patterns influenced the spatial extent and duration of exposure to low DO water. Strong upwelling during neap tides produced the largest impact on the estuary. The observed oxygen concentrations likely had deleterious behavioral and physiological consequences for migrating juvenile salmon and benthic crabs. Based on a wind-forced supply mechanism, low DO events are probably common to the Columbia River and other regional estuaries and if conditions on the shelf deteriorate further, as observations and models predict, Pacific Northwest estuarine habitats could experience a decrease in environmental quality

Impacts of algal blooms and microcystins in fish on small-scale fishers in Winam Gulf, Lake Victoria: implications for health and livelihood

Lake Victoria, bordered by Kenya, Tanzania, and Uganda, provides one of the largest freshwater fisheries in the world and supports millions in small-scale fishing communities. Historical environmental change, including population growth, nutrient loading, introduced invasive species, and rising temperatures, has resulted in eutrophication and persistent cyanobacterial harmful algae blooms (cyanoHABs) over recent decades, particularly in the shallower gulfs, bays, and inlets. CyanoHABs impact fisheries and food web dynamics and compromise food and water security for nearshore fisher populations. In this study, we examine the socialecological impact of freshwater blooms on fisher health in one of these eutrophic regions, Winam Gulf in Lake Victoria. CyanoHABs persist for months and produce microcystins and hepatotoxins at levels unsafe for human health. We assessed potential risk and contribution of microcystin exposure through fish consumption, in addition to exposure through water source, and conducted 400 fisher and 400 household surveys. Average microcystin concentrations exceeded the World Health Organization (WHO) guideline for drinking water consistently during the long dry season, and cyanobacterial cell counts surpassed WHO standards for recreational risk in 84% of samples. Hazard quotients for fish consumed by young children were 5 to 10 times higher than permissible levels. In addition, fishers chronicled profound ecosystem changes with direct impact on livelihood, fisheries, and water quality with 77.4% reporting a decline in profit or catch, 83.1% reporting adverse impacts of cyanoHABs on fish in the lake, and 98.2% reporting indicators of declining water quality in the lake overall. Through the application of a social-ecological lens to a public health model, we identified spheres of influence that modify how fishers experience HABs related stressors and risks to provide a starting point at which to identify sustainable strategies to improve food and water security and livelihood for the millions in nearshore communities

Protocols for Monitoring Habitat Restoration Projects in the Lower Columbia River and Estuary

Protocols for monitoring salmon habitat restoration projects are essential for the U.S. Army Corps of Engineers' environmental efforts in the Columbia River estuary. This manual provides state-of-the science data collection and analysis methods for landscape features, water quality, and fish species composition, among others

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2009

This is the sixth annual report of a seven-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the lower Columbia River and estuary (LCRE). The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers Portland District (USACE) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), the Columbia River Estuary Study Taskforce (CREST), and the University of Washington. The goal of the Cumulative Effects Study is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the 235-km-long LCRE. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2009, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tidegate replacement vs. culvert replacement vs. dike breach)

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2006

This report is the third annual report of a six-year project to evaluate the cumulative effects of habitat restoration action in the Columbia River Estuary (CRE). The project is being conducted for the U.S. Army Corps of Engineers (Corps) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory, the Pt. Adams Biological Field Station of the National Marine Fisheries Service, and the Columbia River Estuary Study Taskforce. Measurement of the cumulative effects of ecological restoration projects in the Columbia River estuary is a formidable task because of the size and complexity of the estuarine landscape and the meta-populations of salmonids in the Columbia River basin. Despite the challenges presented by this system, developing and implementing appropriate indicators and methods to measure cumulative effects is the best way to enable estuary managers to track the overall effectiveness of investments in estuarine restoration projects. This project is developing methods to quantify the cumulative effects of multiple restoration activities in the CRE. The overall objectives of the 2006 study were to continue to develop techniques to assess cumulative effects, refine the standard monitoring protocols, and initiate development of an adaptive management system for Corps of Engineers’ habitat restoration monitoring efforts in the CRE. (The adaptive management effort will be reported at a later date.) Field studies during 2006 were conducted in tidal freshwater at Kandoll Farm on the lower Grays River and tidal brackish water at Vera Slough on Youngs Bay. Within each of area, we sampled one natural reference site and one restoration site. We addressed the overall objectives with field work in 2006 that, coupled with previous field data, had specific objectives and resulted in some important findings that are summarized here by chapter in this report. Each chapter of the report contains data on particular monitored variables for pre- and post-restoration conditions at both the Kandoll and Vera study areas

Red Waters of Myrionecta rubra are Biogeochemical Hotspots for the Columbia River Estuary with Impacts on Primary/Secondary Productions and Nutrient Cycles

The localized impact of blooms of the mixotrophic ciliate Myrionecta rubra in the Columbia River estuary during 2007-2010 was evaluated with biogeochemical, light microscopy, physiological, and molecular data. M. rubra affected surrounding estuarine nutrient cycles, as indicated by high and low concentrations of organic nutrients and inorganic nitrogen, respectively, associated with red waters. M. rubra blooms also altered the energy transfer pattern in patches of the estuarine water that contain the ciliate by creating areas characterized by high primary production and elevated levels of fresh autochthonous particulate organic matter, therefore shifting the trophic status in emergent red water areas of the estuary from net heterotrophy towards autotrophy. The pelagic estuarine bacterial community structure was unaffected by M. rubra abundance, but red waters of the ciliate do offer a possible link between autotrophic and heterotrophic processes since they were associated with elevated dissolved organic matter and showed a tendency for enhanced microbial secondary production. Taken together, these findings suggest that M. rubra red waters are biogeochemical hotspots of the Columbia River estuary.Keywords: Myrionecta rubra, Biogeochemical cycles, Red waters, Mesodinium rubrum, Columbia River estuar

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2007

The goal of this multi-year study (2004-2010) is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the lower Columbia River and estuary. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. Field research in 2005, 2006, and 2007 involved intensive, comparative studies paired by habitat type (tidal swamp vs. marsh), trajectory (restoration vs. reference site), and restoration action (tide gate vs. culvert vs. dike breach). The field work established two kinds of monitoring indicators for eventual cumulative effects analysis: core and higher-order indicators. Management implications of limitations and applications of site-specific effectiveness monitoring and cumulative effects analysis were identified

Recruitment Constraints in Singapore's Fluted Giant Clam (Tridacna squamosa) Populations - A Dispersal Model Approach

10.1371/journal.pone.0058819PLoS ONE83