Signatures of Restoration and Management Changes in the Water Quality of a Central California Estuary

Gee, Alison K.; Wasson, Kerstin; Shaw, Susan L.; Haskins, John

doi:10.1007/s12237-010-9276-3

Cited by 5 publications

(4 citation statements)

References 48 publications

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“…The estuary is part of several protected areas. All tidal lands below the mean high water (MHW) mark are part of the Monterey Bay National Marine Sanctuary (Gee et al, 2010) and adjacent lands are mostly protected open space including the 704 ha Elkhorn Slough National Estuarine Research Reserve. The 10-km main channel of the Slough is bordered by extensive intertidal salt marshes and mudflats, and several shallow water impoundments are associated with water control structures that restrict tidal exchange beneath railroad tracks along the eastern border of the estuary.…”

Section: Study Sitementioning

confidence: 99%

“…To ensure that historical differences in interpolation maps were a function of data differences rather than variogram methodology, the spherical kriging method was used for all timepoints. We also applied data from monthly water quality sampling collected by a volunteer-based monitoring program at a network of (~26) stations across Elkhorn Slough since 1988 (Ritter et al, 2008;Gee et al, 2010). Monthly nitrate data from the sites were averaged during the period 1990 to 2010 and mapped using ordinary kriging for comparison to spatial patterns of the isoscape and stoichioscape maps.…”

Section: Isoscape and Stoichioscape Mappingmentioning

confidence: 99%

“…), within 48 hours, or frozen for later analysis in accordance with standard methods (Gee et al, 2010;NOAA National Estuarine Research Reserve System, 2017). Three of the high-resolution sediment cores were collected at the same locations as water quality monitoring sites.…”

mentioning

confidence: 99%

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Use of historical isoscapes to develop an estuarine nutrient baseline

Champlin,

Woolfolk,

Oczkowski

et al. 2023

Front. Mar. Sci.

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Coastal eutrophication is a prevalent threat to the healthy functioning of ecosystems globally. While degraded water quality can be detected by monitoring oxygen, nutrient concentrations, and algal abundance, establishing regulatory guidelines is complicated by a lack of baseline data (e.g., pre-Anthropocene). We use historical carbon and nitrogen isoscapes over ~300 years from sediment cores to reconstruct spatial and temporal changes in nutrient dynamics for a central California estuary, Elkhorn Slough, where development and agriculture dramatically enhanced nutrient inputs over the past century. We found strong contrasts between current sediment stable isotopes and those from the recent past, demonstrating shifts exceeding those in previously studied eutrophic estuaries and substantial increases in nutrient inputs. Comparisons of contemporary with historical isoscapes also revealed that nitrogen sources shifted from a historical marine-terrestrial gradient with higher δ15N near the inlet to amplified denitrification at the head and mouth of the modern estuary driven by increased N inputs. Geospatial analysis of historical data suggests that an increase in fertilizer application – rather than population growth or increases in the extent of cultivated land – is chiefly responsible for increasing nutrient loads during the 20th century. This study demonstrates the ability of isotopic and stoichiometric maps to provide important perspectives on long-term shifts and spatial patterns of nutrients that can be used to improve management of nutrient pollution.

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Section: Study Sitementioning

confidence: 99%

Section: Isoscape and Stoichioscape Mappingmentioning

confidence: 99%

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Use of historical isoscapes to develop an estuarine nutrient baseline

Champlin,

Woolfolk,

Oczkowski

et al. 2023

Front. Mar. Sci.

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“…In 1997, the south culvert broke open and resulted in an increase in tidal range. The Elkhorn Slough National Estuarine Research Reserve (ESNERR) found a significant decrease in nitrate (NO3) within the system (samples were taken in the middle of the wetland) from before and after this accidental restoration took place (Gee et al 2010). This change in hydrology decreased nutrients in the system due to greater tidal exchange, and created a 100' vegetated buffer between adjacent agricultural fields and the high-water edge of the wetland.…”

Section: Study Area and Study Systemmentioning

confidence: 99%

Temporal and Spatial Impacts of Water Control Structures on the Benthic Infaunal Community of a Tidally Restricted Wetland in Elkhorn Slough, CA

Mann

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North Azevedo Pond in Elkhorn Slough, CA is a partially tidally restricted wetland that underwent an experimental ponding manipulation which increased inundation and tidal mixing within the system. This wetland has two spatially significant infaunal microsystems, south and north. Benthic cores taken before and after the manipulation showed that both the south and north infaunal communities remained dominated by the same major taxa, respectively. Both systems, however, experienced species shifts following the ponding manipulation. In the South, the non-native bivalve, Gemma gemma, declined from an average of 19,103 to 385 individuals (m 2)-1 whereas the native clam, Nutricola tantilla, increased from an average of 128 to 26,154 individuals (m 2)-1. In the north, Capitella teleta declined from an average of 15,256 to 1,667 individuals (m 2)-1 , while Pseudopolydora kempi, increased from a mean of 7,436 to 38,077 individuals (m 2)-1. Overall, the hydrographic manipulations were successful in improving water quality by increasing ponding and creating more complex infaunal communities than those present prior to the ponding manipulation. v ACKNOWLEDGMENTS I want to thank the Benthic Lab for sharing their data sets to supplement my own data collection. I want to thank all the taxonomists whom enabled me to power through identifying all of my critters. Thank you to my two interns, Imani and Enio, for their hard work ethic and taxonomic prowess. Lastly, thank you to all the folks at ESNERR and ESF for helping me carry out my thesis project with data, background information, and access to my study site. Crucial funding for this thesis came from San Jose State University, CCR, and Myers Ocean Trust. Thank you to my committee members especially John Oliver for his refreshingly unconventional style of advising. I am inspired by his vast knowledge of the natural world, and I hope to know even a little bit of what he knows by the end of my lifetime. This thesis would not have been possible without my unofficial advisor, Kamille Hammerstrom. I will never forget her kindness, patience, and willingness always to set aside time to help me with any aspect of my thesis. Most importantly, I'd like to thank my family. Mom, it means so much to me that you have always shown me unwavering love and support towards me. Katherine, Carolyn, and Evelyn, you are all so dear to me, and I am grateful for the love and respect you give me. Lastly, thank you Corey, for being there for me through the last haul of my thesis, and for keeping me focused at the task at hand. vii TABLE OF CONTENTS LIST OF TABLES .

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