Primary Production in the Delta: Then and Now

Cloern, James E.; Robinson, April; Richey, Amy; Grenier, Letitia; Grossinger, Robin M.; Boyer, Katharyn E.; Burau, Jon R.; Canuel, Elizabeth A.; DeGeorge, John F.; Drexler, Judith Z.; Enright, Chris; Howe, Emily; Kneib, R. T.; Mueller–Solger, Anke; Naiman, Robert J.; Pinckney, James L.; Safran, Samuel M.; Schoellhamer, David H.; Simenstad, Charles A.

doi:10.15447/sfews.2016v14iss3art1

Cited by 16 publications

(17 citation statements)

References 10 publications

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“…Habitat alteration, introductions of invasive species (e.g. filter feeders such as clams), flow alterations, and increased water diversions for human use (Cloern et al., 2016; Jassby, Cloern, & Cole, 2002; Tockner & Stanford, 2002) have altered the composition and quantity of POM within the Delta for almost a century. Concurrent with the physical and chemical changes to Delta habitats, populations of native fish species have also declined (Mac Nally et al., 2010; Moyle, Katz, & Quiñones, 2011; Sommer et al., 2007).…”

Section: Methodsmentioning

confidence: 99%

Dynamic river processes drive variability in particulate organic matter over fine spatiotemporal scales

et al. 2020

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1. We sampled freshwater suspended particulate organic matter (POM) to determine its carbon and nitrogen stable isotope composition and collected co-located water chemistry data in California's Sacramento-San Joaquin Delta from sites on the Mokelumne and Cosumnes rivers. A 10-km 2 area was sampled across 12 sites and divided among three habitat types (i.e. riverine, slackwater/slough, and off-channel), 34 times between November 2016 and July 2017. Here, we describe the variability in water quality and POM variables, and assess factors associated with that variability using dimensional reduction and linear modelling within the context of our habitat types. 2. The stable isotope composition of freshwater POM and water chemistry variables differed significantly across small areas (<10 km) and short time frames (weekly). Hydrological connectivity amongst sites was found to be an important factor in the isotopic and elemental composition of POM. 3. During periods of low hydrological connectivity, in situ dynamics were strongly associated with differentiation of POM in different habitats. Discharge (16-433 m 3 /s) and water temperature (8-30°C) were the variables most associated with variations in the composition of POM. Slackwater sites showed the greatest variability in POM composition, which may be symptomatic of longer water residence times, increased cycling rates of nutrients and organic matter, or a combination of the two. 4. Variability in POM stable isotope composition demonstrates that caution should be exercised when interpreting analyses that assume a static POM stable isotope composition based on two-end member mixing. Unconstrained variability in space or time could confound interpretations of models and data. Moving forward, conceptual and numerical models for river ecosystems that emphasise temporally heterogeneous lateral exchange amongst habitat patches should be prioritised when considering restoration efforts and monitoring outcomes.

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Section: Methodsmentioning

confidence: 99%

Dynamic river processes drive variability in particulate organic matter over fine spatiotemporal scales

et al. 2020

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“…Since the majority of research on estuarine food webs in the estuary has focused on pelagic habitat, our discussion of historical periods is also pelagicfocused. Given that systematic scientific data collection did not begin until the mid-20th century, our characterizations of early food web processes are limited and speculative, but new work on the historical landscapes of the Delta-Suisun region (Whipple et al 2012;Robinson et al 2014) provides an increasingly solid basis for such speculation, and efforts are underway to estimate historic primary production Cloern et al 2016). …”

Section: Conceptual Frameworkmentioning

confidence: 99%

“…Hypotheses about primary production in the historical landscapes are currently being addressed Cloern et al 2016). Many of the small deadend sloughs in the tidal wetlands were likely very productive, especially if their length exceeded the tidal excursion (Geyer and Signell 1992) so that long residence time allowed for accumulation of biomass.…”

Section: Pre-gold Rush Era (< Ca 1850)mentioning

confidence: 99%

Food Webs of the Delta, Suisun Bay, and Suisun Marsh: An Update on Current Understanding and Possibilities for Management

Brown¹,

Kimmerer²,

Conrad³

et al. 2016

SFEWS

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This paper reviews and highlights recent research findings on food web processes since an earlier review by . We conduct this review within a conceptual framework of the DeltaSuisun food web, which includes both temporal and spatial components. The temporal component of our framework is based on knowledge that the landscape has changed markedly from historical conditions. The spatial component of our framework acknowledges that the food web is not spatially static; it varies regionally and across habitat types within regions. The review highlights the idea of a changing baseline with respect to food web function. New research also indicates that interactions between habitat-specific food webs vary across the current landscape. For example, based on early work in the south Delta, the food web associated with submerged aquatic vegetation was thought to provide little support to species of concern; however, data from other regions of the estuary suggest that this conceptual model may not apply across the entire region. Habitat restoration has been proposed as a method of re-establishing historic food web processes to support species of concern. Benefits are likely for species that directly access such restored habitats, but are less clear for pelagic species. Several topics require attention to further improve the knowledge of food webs needed to support effective management, including: (1) synthesis of factors responsible for low pelagic biomass; (2) monitoring and research on effects of harmful algal blooms; (3) broadening the scope of long-term monitoring; (4) determining benefits of tidal wetland restoration to species of concern, including evaluations of interactions of habitat-specific food webs; and (5) interdisciplinary analysis and synthesis. The only certainty is that food webs will continue to change in response to the changes in the physical environment and new species invasions.

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“…Similar to other estuaries around the world, the historic floodplains and wetlands of San Francisco Estuary, California, USA (hereinafter SFE) have been largely reclaimed for agriculture and urban development [23,24]. Within the upper SFE, over 90% of freshwater wetland habitats have been lost since the 1800’s and replaced with leveed channels and deep open waters, that have little to no connectivity to former floodplain habitats [25,26]. This extensive landscape transformation, along with other changes such as the introduction of invasive species, increase in contaminant inputs, and alteration of freshwater flows to the SFE have contributed to the steep decline of multiple native fish species over the past two decades [27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Role of freshwater floodplain-tidal slough complex in the persistence of the endangered delta smelt

Mahardja¹,

Hobbs

Ikemiyagi³

et al. 2019

PLoS ONE

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Seasonal floodplain wetland is one of the most variable and diverse habitats found in coastal ecosystems, yet it is also one of the most highly altered by humans. The Yolo Bypass, the primary floodplain of the Sacramento River in California’s Central Valley, USA, has been shown to provide various benefits to native fishes when inundated. However, the Yolo Bypass exists as a tidal dead-end slough during dry periods and its value to native fishes has been less studied in this state. During the recent drought (2012–2016), we found higher abundance of the endangered Delta Smelt (Hypomesus transpacificus), than the previous 14 years of fish monitoring within the Yolo Bypass. Meanwhile, Delta Smelt abundance elsewhere in the estuary was at record lows during this time. To determine the value of the Yolo Bypass as a nursery habitat for Delta Smelt, we compared growth, hatch dates, and diets of juvenile Delta Smelt collected within the Yolo Bypass with fish collected among other putative nursery habitats in the San Francisco Estuary between 2010 and 2016. Our results indicated that when compared to other areas of the estuary, fish in the Yolo Bypass spawned earlier, and offspring experienced both higher quality feeding conditions and growth rates. The occurrence of healthy juvenile Delta Smelt in the Yolo Bypass suggested that the region may have acted as a refuge for the species during the drought years of 2012–2016. However, our results also demonstrated that no single region provided the best rearing habitat for juvenile Delta Smelt. It will likely require a mosaic of habitats that incorporates floodplain-tidal sloughs in order to promote the resilience of this declining estuarine fish species.

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Primary Production in the Delta: Then and Now

Cited by 16 publications

References 10 publications

Dynamic river processes drive variability in particulate organic matter over fine spatiotemporal scales

Dynamic river processes drive variability in particulate organic matter over fine spatiotemporal scales

Food Webs of the Delta, Suisun Bay, and Suisun Marsh: An Update on Current Understanding and Possibilities for Management

Role of freshwater floodplain-tidal slough complex in the persistence of the endangered delta smelt

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