Environmental Sciences Commons^™

Decadal Variability Of Net Water Flux At The Mediterranean Sea Gibraltar Strait, L. Fenoglio-Marc, A. Mariotti, G. Sannino, B. Meyssignac, A. Carillo, M. V. Struglia, M. Rixen

United States Department of Commerce: Staff Publications

Long-term variability of the net water flux into the Mediterranean Sea at the Gibraltar Strait over the period 1960–2009 is explored based on an approach combining multiple observational datasets and results from a regional climate model simulation. The approach includes deriving Gibraltar net inflow from the application of the Mediterranean Sea water budget equation using observationally based estimates of mass variation, evaporation, precipitation and simulated river discharge and Bosphorus Strait water fluxes. This derivation is compared with results from a simulation using the PROTHEUS regional ocean–atmosphere coupled model considering both individual water cycle terms and overall Gibraltar water flux.

Results …

The Effect Of Soil Surface Litter Residue On Energy And Carbon Fluxes In A Deciduous Forest, T.B. Wilson, T.P. Meyers, J. Kochendorfer, M. C. Anderson, M. Heuer

United States Department of Commerce: Staff Publications

The Atmosphere–Land Exchange Surface Energy (ALEX) balance model is an analytical formulation of the energy and mass transport within the soil and the vegetation canopy used for simulating energy, evapotranspiration, and CO2 fluxes in a wide range of vegetation environments. The objective of this study was to evaluate the ability of ALEX to simulate the effect of soil-surface leaf litter residue on soil heat conduction (G), sensible heat (H), evapotranspiration (ET) (or latent heat (LE) when expressed as rate of energy loss) and CO₂ fluxes in a deciduous forest. The model was evaluated in a deciduous forest in Oak …

Changes In Atmospheric Circulation Patterns Associated With High And Low Rainfall Regimes In The Hawaiian Islands Region On Multiple Time Scales, Henry F. Diaz, Thomas W. Giambelluca

United States Department of Commerce: Staff Publications

We examine a suite of climate variables in the North Pacific associated with different temporal scales of dry and wet episodes in the Hawaiian Islands. The goal is to ascertain whether varying the length in the occurrence of such events from seasonal to multi-decadal results from different ocean–atmosphere circulation patterns over the North Pacific region.We find that as the dryness period lengthens, the spatial scale of the anomalies widens, but the characteristics of the anomalous circulation fields exhibit elements evident at each time scale. At the longest (multi-decadal) time scales during the wet season (November–April), the major anomalous circulation features …

Pacific Cod (Gadus Macrocephalus) As A Paleothermometer: Otolith Oxygen Isotope Reconstruction, Catherine F. West, Stephen Wischniowski, Christopher Johnston

United States Department of Commerce: Staff Publications

Stable isotope studies are increasingly important for understanding past environmental and cultural developments along the North Pacific Rim. In this paper, we present methods for using Pacific cod (Gadus macrocephalus) otoliths as a paleothermometer using a case study from Kodiak Island, Alaska. The results of this study indicate that Pacific cod otoliths record variable paleoenvironmental conditions during the Little Ice Age. The broad distribution of Pacific cod and success in using the otoliths as a paleothermometer makes this method widely applicable to researchers working throughout the northern Pacific Rim.

Immunomodulation In Eastern Oysters, Crassostrea Virginica, Exposed To A Pah-Contaminated, Microphytobenthic Diatom, April N. Croxton, Gary H. Wikfors, Richard D. Schulterbrandt-Gragg

United States Department of Commerce: Staff Publications

The trophic transfer of sediment-associated pollutants is a growing concern in shellfish harvesting areas. Previous studies have examined the role of phytoplankton in the transport of organic contaminants to bivalve species, but little information on microphytobenthic communities and their role as contaminant vectors exists. Polycyclic aromatic hydrocarbons (PAHs) are organic compounds formed during natural and industrial processes; they are termed “persistent organic pollutants” because they are only slowly degraded by natural processes. This study examined the transfer of PAH compounds (naphthalene, pyrene, and benzo(a)pyrene) by a microphytobenthic diatom to the eastern oyster, a commercially important shellfish species, to determine if …

Social Network Correlates Of Food Availability In An Endangered Population Of Killer Whales, Orcinus Orca, Emma A. Foster, Daniel W. Franks, Lesley J. Morrell, Ken C. Balcomb, Kim M. Parsons, Astrid Van Ginneken, Darren P. Croft

United States Department of Commerce: Staff Publications

For the majority of social species, group composition is dynamic, and individuals are interconnected in a heterogeneous social network. Social network structure has far-reaching implications for the ecology of individuals and populations. However, we have little understanding of how ecological variables shape this structure. We used a long-term data set (1984e2007) to examine the relationship between food availability and social network structure in the endangered southern resident killer whales. During the summer months individuals in this population feed primarily on chinook salmon, Oncorhynchus tshawytscha, which show annual variation in abundance. We tested the hypothesis that temporal variation in chinook …

Estimation Of Surface Albedo And Directional Reflectance From Moderate Resolution Imaging Spectroradiometer (Modis) Observations, Tao He, Shunlin Liang, Dongdong Wang, Hongyi Wu, Yunyue Yu, Jindi Wang

United States Department of Commerce: Staff Publications

Land surface albedo is one of the key geophysical variables controlling the surface radiation budget. In recent years, land surface albedo products have been generated using data from various satellites. However, some problems exist in those products due to either the failure of the current retrieving procedures resulting from persistent clouds and/or abrupt surface changes, or the reduced temporal or spatial coverage, which may limit their applications. Rapidly generated albedo products that help reduce the impacts of cloud contamination and improve the capture of events such as ephemeral snow and vegetation growth are in demand.

In this study, we propose …

North American Carbon Program (Nacp) Regional Interim Synthesis: Terrestrial Biospheric Model Intercomparison, D.N. Huntzinger, W.M. Post, Y. Wei, A.M. Michalak, T.O. West, A.R. Jacobson, I.T. Baker, J.M. Chen, K. J. Davis, D.J. Hayes, F.M. Hoffman, A.K. Jain, S. Liu, A.D. Mcguire, R.P. Neilson, Chris Potter, B. Poulter, David T. Price, B.M. Raczka, H.Q. Tian, P. Thornton, E. Tomelleri, N. Viovy, J. Xiao, W. Yuan, N. Zeng, M. Zhao, R. Cook

United States Department of Commerce: Staff Publications

Understanding of carbon exchange between terrestrial ecosystems and the atmosphere can be improved through direct observations and experiments, as well as through modeling activities. Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding to much larger terrestrial regions. Although models vary in their specific goals and approaches, their central role within carbon cycle science is to provide a better understanding of the mechanisms currently controlling carbon exchange. Recently, the North American Carbon Program (NACP) organized several interim-synthesis activities to evaluate and inter-compare models and observations at local to continental scales for the years 2000–2005. …

Coupling Planktonic Ecosystem And Fisheries Food Web Models For A Pelagic Ecosystem: Description And Validation For The Subarctic Pacific, Kelly A. Kearney, Charles Stock, Kerim Aydin, Jorge L. Sarmiento

United States Department of Commerce: Staff Publications

We provide a modeling framework that fully couples a one-dimensional physical mixed layer model, a biogeochemical model, and an upper trophic level fisheries model. For validation purposes, the model has been parameterized for the pelagic Eastern Pacific Subarctic Gyre ecosystem. This paper presents a thorough description of the model itself, as well as an ensemble-based parameterization process that allows the model to incorporate the high level of uncertainty associated with many upper trophic level predator-prey processes. Through a series of model architecture experiments, we demonstrate that the use of a consistent functional response for all predator-prey interactions, as well as …

Arctic Cloud Macrophysical Characteristics From Cloudsat And Calipso, Yinghui Liu, Jeffrey R. Key, Steven A. Ackerman, Gerald G. Mace, Qiuqing Zhang

United States Department of Commerce: Staff Publications

The lidar and radar profiling capabilities of the CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder (CALIPSO) satellites provide opportunities to improve the characterization of cloud properties. An Arctic cloud climatology based on their observations may be fundamentally different from earlier Arctic cloud climatologies based on passive satellite observations, which have limited contrast between the cloud and underlying surface. Specifically, the Radar–Lidar Geometrical Profile product (RL-GEOPROF) provides cloud vertical profiles fromthe combination of active lidar and radar. Based on this data product for the period July 2006 to March 2011, this paper presents a new cloud macrophysical property characteristic analysis for …

Starvation Causes Disturbance In Amino Acid And Fatty Acid Metabolism In Diporeia, Suman Maity, Amber Jannasch, Jiri Adamec, Thomas Nalepa, Tomas O. Höök, Maria S. Sepúlveda

United States Department of Commerce: Staff Publications

The benthic amphipod Diporeia spp. was once the predominant macroinvertebrate in deep, offshore regions of the Laurentian Great Lakes. However, since the early 1990s, Diporeia populations have steadily declined across the area. It has been hypothesized that this decline is due to starvation from increasing competition for food with invasive dreissenid mussels. In order to gain a better understanding of the changes in Diporeia physiology during starvation, we applied two-dimensional gas chromatography coupled with time of flight mass spectrometry (GCXGC/TOF-MS) for investigating the responses in Diporeia metabolome during starvation. We starved Diporeia for 60 days and collected five organisms every …

Health Status, Infection And Disease In California Sea Lions (Zalophus Californianus) Studied Using A Canine Microarray Platform And Machine-Learning Approaches, Annalaura Mancia, James C. Ryan, Robert W. Chapman, Qingzhong Wu, Gregory W. Warr, Frances M.D. Gulland, Frances M. Van Dolah

United States Department of Commerce: Staff Publications

Conservation biologists face many challenges in assessing health, immune status and infectious diseases in protected species. These challenges include unpredictable sample populations, diverse genetic and environmental backgrounds of the animals, as well as the practical, legal and ethical issues involved in experimentation. The use of whole genome scale transcriptomics with animal samples obtained in a minimally invasive manner is an approach that shows promise for health assessment. In this study we assessed the utility of a microarray to identify changes in gene expression predictive of health status by interrogating blood samples from California sea lions (Zalophus californianus) in …

Disease Will Limit Future Food Supply From The Global Crustacean Fishery And Aquaculture Sectors, G.D. Stentiford, D.M. Neil, E.J. Peeler, J.D. Shields, H.J. Small, T.W. Flegel, J.M. Vlak, B. Jones, F. Morado, S. Moss, J. Lotz, L. Bartholomay, D.C. Behringer, C. Hauton, D.V. Lightner

United States Department of Commerce: Staff Publications

Seafood is a highly traded food commodity. Farmed and captured crustaceans contribute a significant proportion with annual production exceeding 10 M metric tonnes with first sale value of $40bn. The sector is dominated by farmed tropical marine shrimp, the fastest growing sector of the global aquaculture industry. It is significant in supporting rural livelihoods and alleviating poverty in producing nations within Asia and Latin America while forming an increasing contribution to aquatic food supply in more developed countries. Nations with marine borders often also support important marine fisheries for crustaceans that are regionally traded as live animals and commodity products. …

The Development Of A New Optical Total Suspended Matter Algorithm For The Chesapeake Bay, Michael Ondrusek, Eric Stengel, Christopher Kinkade, Ronald Vogel, Phillip Keegstra, Craig Hunter, Chunai Kim

United States Department of Commerce: Staff Publications

Sediment loading is one of the primary threats to the health of the Chesapeake Bay.We have developed a high resolution (250 m) ocean color satellite tool to monitor sediment concentrations in the Bay. In situ optical and sediment sampling is used to develop a total suspended matter (TSM) algorithm for the Chesapeake Bay. The Coastal Optical Characterization Experiment (COCE) is part of an ongoing effort to optically characterize processes and to develop regional remote sensing ocean color algorithms in the coastalwaters. The goal is to characterize sediment concentrations and to develop a tool to track plumes cascading down the Bay …

Groundwater Pumping And Spatial Externalities In Agriculture, Lisa Pfeiffer, C.-Y. Cynthia Lin

United States Department of Commerce: Staff Publications

We investigate the behavior of farmers who share an underground aquifer. In the case where seepage may occur the resource is nonexclusive, giving rise to a spatial externality whereby pumping by one user affects others nearby. Theoretically, these externalities are potentially important causes of welfare loss. Using a unique spatial data set of groundwater users in western Kansas, we are able to empirically measure the physical and behavioral effects of groundwater pumping by neighbors. To address the simultaneity of neighbors’ pumping, we use the neighbors’ permitted water allocation as an instrument for their pumping. We estimate that 2.5% of the …

Comparison Of Methods For The Detection Of Coliphages In Recreational Water At Two California, United States Beaches, Roberto A. Rodríguez, David C. Love, Jill R. Stewart, Julianne Tajuba, Jacqueline Knee, Jerold W. Dickerson Jr., Laura F. Webster, Mark D. Sobsey

United States Department of Commerce: Staff Publications

Methods for detection of two fecal indicator viruses, F+ and somatic coliphages, were evaluated for application to recreational marine water. Marine water samples were collected during the summer of 2007 in Southern California, United States from transects along Avalon Beach (n = 186 samples) and Doheny Beach (n = 101 samples). Coliphage detection methods included EPA method 1601 – two-step enrichment (ENR), EPA method 1602 – single agar layer (SAL), and variations of ENR. Variations included comparison of two incubation times (overnight and 5-h incubation) and two final detection steps (lysis zone assay and a rapid latex agglutination …

Water Properties In Chesapeake Bay From Modis-Aqua Measurements, Seunghyun Son, Menghua Wang

United States Department of Commerce: Staff Publications

This study evaluates the performance of ocean color products derived from measurements of the Moderate Resolution Imaging Spectro-radiometer (MODIS) on the satellite Aqua using the standard near-infrared (NIR) and the shortwave infrared (SWIR)-based atmospheric correction algorithms in the Chesapeake Bay. The MODIS-Aquaderived normalized water-leaving radiances, nL_w(λ), and chlorophyll-a (Chl-a) data are comparedwith in situ radiometric measurements fromtheNASA SeaWiFS Bio-opticalArchive and Storage System(SeaBASS) database and Chl-a data from the Chesapeake Bay Water Quality Database. Results show that, using the NIR-SWIR combined ocean color data processing, improved nL_w(λ) and Chl-a data products can be produced in …

View Angle Effects On Modis Snow Mapping In Forests, Qinchuan Xin, Curtis E. Woodcock, Jicheng Liu, Bin Tan, Rae A. Melloh, Robert E. Davis

United States Department of Commerce: Staff Publications

Binary snow maps and fractional snow cover data are provided routinely from MODIS (Moderate Resolution Imaging Spectroradiometer). This paper investigates how the wide observation angles of MODIS influence the current snow mapping algorithm in forested areas. Theoretical modeling results indicate that large view zenith angles (VZA) can lead to underestimation of fractional snow cover (FSC) by reducing the amount of the ground surface that is viewable through forest canopies, and by increasing uncertainties during the gridding of MODIS data. At the end of the MODIS scan line, the total modeled error can be as much as 50% for FSC. Empirical …

Prototype For Monitoring And Forecasting Fall Foliage Coloration In Real Time From Satellite Data, Xiaoyang Zhang, Mitchell D. Goldberg, Yunyue Yu

United States Department of Commerce: Staff Publications

While determining vegetation phenology from the time series of historical satellite data has been widely investigated throughout the last decade, little effort has been devoted to real-time monitoring and shortterm forecasting. The latter is more important for numerical weather modeling, ecosystem forecasting, forest and crop management, and health risk warning. In this study we developed a prototype approach for the real-time monitoring and short-term forecasting of fall foliage status (including low coloration, moderate coloration, near-peak coloration, peak coloration, and post-peak coloration) using temporal satellite observations. The algorithm combined the climatology of vegetation phenology and temporally available satellite observations to establish …

Validation Of The Goes-R Abi Flood And Standing Water Algorithm Using Gauging Station Measurements And Interpretation Maps, Rui Zhang, Donglian Sun, Yunyue Yu, Anthony Stefanidis, Mitchell D. Goldberg

United States Department of Commerce: Staff Publications

Validation is an important task in the development of satellite remote sensing products. Strategies for validation vary depending on the nature of the products. The validation process of the flood and standing water product (FSW) for the Geostationary Operational Environmental Satellite - R series (GOES-R) is presented in this paper. A major challenge in the validation of the FSW product is the lack of ground truth flood maps and similar reference products from other satellite systems and other sources. To overcome this limitation, a two-level validation scheme for the FSW product is developed using the Moderate-resolution Imaging Spectroradiometer (MODIS) data …

Prototype For Monitoring And Forecasting Fall Foliage Coloration In Real Time From Satellite Data, Xiaoyang Zhang, Mitchell D. Goldberg, Yunyue Yu

United States Department of Commerce: Staff Publications

While determining vegetation phenology from the time series of historical satellite data has been widely investigated throughout the last decade, little effort has been devoted to real-time monitoring and shortterm forecasting. The latter is more important for numerical weather modeling, ecosystem forecasting, forest and crop management, and health risk warning. In this study we developed a prototype approach for the real-time monitoring and short-term forecasting of fall foliage status (including low coloration, moderate coloration, near-peak coloration, peak coloration, and post-peak coloration) using temporal satellite observations. The algorithm combined the climatology of vegetation phenology and temporally available satellite observations to establish …

Validation Of The Goes-R Abi Flood And Standing Water Algorithm Using Gauging Station Measurements And Interpretation Maps, Rui Zhang, Donglian Sun, Yunyue Yu, Anthony Stefanidis, Mitchell D. Goldberg

United States Department of Commerce: Staff Publications

Validation is an important task in the development of satellite remote sensing products. Strategies for validation vary depending on the nature of the products. The validation process of the flood and standing water product (FSW) for the Geostationary Operational Environmental Satellite - R series (GOES-R) is presented in this paper. Amajor challenge in the validation of the FSWproduct is the lack of ground truth floodmaps and similar reference products from other satellite systems and other sources. To overcome this limitation, a two-level validation scheme for the FSW product is developed using the Moderate-resolution Imaging Spectroradiometer (MODIS) data as a proxy. …

Land Surface Temperature Product Validation Using Noaa's Surface Climate Observation Networks—Scaling Methodology For The Visible Infrared Imager Radiometer Suite (Viirs), Pierre C. Guillevic, Jeffrey L. Privette, Benoit Coudert, Michael A. Palecki, Jerome Demarty, Catherine Ottlé, John A. Augustine

United States Department of Commerce: Staff Publications

NOAA will soon use the new Visible Infrared Imager Radiometer Suite (VIIRS) on the Joint Polar Satellite System (JPSS) as its primary polar-orbiting satellite imager. Employing a near real-time processing system, NOAA will generate a series of Environmental Data Records (EDRs) from VIIRS data. For example, the VIIRS Land Surface Temperature (LST) EDR will estimate the surface skin temperature over all global land areas and provide key information for monitoring Earth surface energy and water fluxes. Because both VIIRS and its processing algorithms are new, NOAA is conducting a rigorous calibration and validation program to understand and improve product quality. …

Mercury In The Gulf Of Mexico: Sources To Receptors, Reed Harris, Curtis Pollman, William Landing, David Evans, Donald Axelrad, David Hutchinson, Steven L. Morey, Darren Rumbold, Dmitry Dukhovskoy, Douglas H. Adams, Krish Vijayaraghavan, Christopher Holmes, R. Dwight Atkinson, Tom Myers, Elsie Sunderland

United States Department of Commerce: Staff Publications

Gulf of Mexico (Gulf) fisheries account for 41% of the U.S. marine recreational fish catch and 16% of the nation's marine commercial fish landings. Mercury (Hg) concentrations are elevated in some fish species in the Gulf, including king mackerel, sharks, and tilefish. All five Gulf states have fish consumption advisories based on Hg. Per-capita fish consumption in the Gulf region is elevated compared to the U.S. national average, and recreational fishers in the region have a potential for greater MeHg exposure due to the higher levels of fish consumption. Atmospheric we Hg deposition is estimated to be higher in the …

Pharmaceuticals And Personal Care Products (Ppcps) In Treated Wastewater Discharges Into Charleston Harbor, South Carolina, Melanie Lea Hedgespeth, Yelena Sapozhnikova, Paul Pennington, Allan Clum, Andy Fairey, Edward Wirth

United States Department of Commerce: Staff Publications

This study assessed seasonal and regional trends of pharmaceuticals and personal care products (PPCPs) detected in monthly samples from two local wastewater treatment plants (WWTPs) in Charleston, South Carolina, USA, over the period of one year. Surface water of Charleston Harbor was also analyzed to examine environmental distribution in an estuarine ecosystem. Of the 19 compounds examined, 11 were quantified in wastewater influent, 9 in effluent, and 7 in surface water. Aqueous concentrations of many PPCPs were reduced by >86% in wastewater effluent compared with influent, though some compounds showed low removal and greater effluent concentrations compared with influent (e.g. …

Corrigendum To “Recent Changes In Primary Production And Phytoplankton In The Offshore Region Of Southeastern Lake Michigan” [J. Great Lakes Res. 36 (Supplement 3) (2010) 20–29], G. Fahnenstiel, Steven A. Pothoven, H. Vanderploeg, D. Klarer, T. F. Nalepa, D. Scavia

United States Department of Commerce: Staff Publications

The authors regret that there is an error on the labels of two figures that were published in the paper referenced above. For Figs. 5b, c, and d and 7b and c the y-axes have the wrong labels.

The following are the correct y-axis labels: Fig. 5b — the y-axis should range from 0 to 5, Fig. 5c — the y-axis should range from 0 to 2, Fig. 5d — the y-axis label should range from 0 to 3, Fig. 7b — the y-axis should range from 0 to 40, and for Fig. 7c — the y-axis should range from …

Seasonal Zooplankton Dynamics In Lake Michigan: Disentangling Impacts Of Resource Limitation, Ecosystem Engineering, And Predation During A Critical Ecosystem Transition, Henry A. Vanderploeg, Steven A. Pothoven, Gary L. Fahnenstiel, Joann F. Cavaletto, James R. Liebig, Craig A. Stow, Thomas F. Nalepa, Charles P. Madenjian, David B. Bunnell

United States Department of Commerce: Staff Publications

We examined seasonal dynamics of zooplankton at an offshore station in Lake Michigan from 1994 to 2003 and 2007 to 2008. This period saw variable weather, declines in planktivorous fish abundance, the introduction and expansion of dreissenid mussels, and a slow decline in total phosphorus concentrations. After the major expansion of mussels into deep water (2007–2008), chlorophyll in spring declined sharply, Secchi depth increased markedly in all seasons, and planktivorous fish biomass declined to record-low levels. Overlaying these dramatic ecosystem-level changes, the zooplankton community exhibited complex seasonal dynamics between 1994–2003 and 2007–2008. Phenology of the zooplankton maximum was affected by …

Characterization Of Turbidity In Florida’S Lake Okeechobee And Caloosahatchee And St. Lucie Estuaries Using Modis-Aqua Measurements, Menghua Wang, Carl J. Nim, Seunghyun Son, Wei Shi

United States Department of Commerce: Staff Publications

This paper describes the use of ocean color remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to characterize turbidity in Lake Okeechobee and its primary drainage basins, the Caloosahatchee and St. Lucie estuaries from 2002 to 2010. Drainage modification and agricultural development in southern Florida transport sediments and nutrients from watershed agricultural areas to Lake Okeechobee. As a result of development around Lake Okeechobee and the estuaries that are connected to Lake Okeechobee, estuarine conditions have also been adversely impacted, resulting in salinity and nutrient fluctuations. The measurement of water turbidity in lacustrine and …

Effect Of Fires On Soil Organic Carbon Pool And Mineralization In A Northeastern China Wetland, Hongmei Zhao, Daniel Q. Tong, Qianxin Lin, Xianguo Lu, Guoping Wang

United States Department of Commerce: Staff Publications

Fire occurs frequently over wetland, but little is known of its impact on soil carbon variations and carbon mineralization, process that are potentially important in global carbon cycle. To investigate this issue, we have designed and implemented a two-year field campaign to quality the effects of fire seasonality and frequency on soil carbon abundance and carbon mineralization in a wetland of the Sanjiang Plain in Northeastern China. A total of 4 burning experiments were conducted over 12 wetland plots from autumn 2007 to spring 2009. Our results show that after burning soil organic carbon (OC) increased in the burned soils …

Spatial Variation In Rna:Dna Ratios Of Diporeia Spp. In The Great Lakes Region, Daniel J. Ryan, Maria S. Sepúlveda, Thomas F. Nalepa, Tomas O. Höök

United States Department of Commerce: Staff Publications

Over the past two decades, Diporeia in all of the Laurentian Great Lakes, except Superior, have declined dramatically. These declines have seemingly coincided with expansion of invasive Dreissena polymorpha and D. bugensis, however the exact mechanisms underlying decreasing Diporeia densities are obscure. We explored the use of RNA:DNA (R/D) ratios as a conditional index for Diporeia by experimentally demonstrating that Diporeia R/D responds to periods of starvation. Moreover, during 2008–2009 we collected Diporeia from throughout the Great Lakes and Cayuga Lake (New York, USA), and used R/D ratios to index condition of these in situ collected animals. We evaluated …