Spatial and temporal patterns in food web accumulation
Spatial and temporal patterns in food web accumulation of Hg Project Update RMP Exposure and Effects Work Group May 12, 2008 Draft data - do not cite or quote
Workplan: Specific questions to address 1. Where is mercury entering the Bay food web? 2. What habitats, conditions, or factors help to identify hotspots of food web accumulation in Bay margins? 3. Are there interannual trends in Me. Hg bioaccumulation resulting from wetland margin restoration activities? 4. What are the best biomonitoring tools for characterizing hotspots of Me. Hg bioaccumulation? Draft data - do not cite or quote
General approach • Spatial analysis – Stratified random design – Identify hotspots based on conceptual model • • • Seasonal trend evaluation Interannual trend detection Field sampling for Hg isotopes and for DGT study Draft data - do not cite or quote
Allocation of effort • Total of 62 sampling events per year to evaluate spatial, seasonal, and interannual patterns Type Events Total Events % per Events Over 3 Sampling Sites Year per Years Budget Spatial 36 108 73% Interannual 8 1 8 24 17% Seasonal 2 9 18 54 10% 62 186 Draft data - do not cite or quote
Spatial survey design - hypothesis testing Hydrology: Site Type Open Shoreline Enclosed Total Number High Hg Wetland NA NA 6/yr Low Hg Wetland NA NA 6/yr Hg Source Area 6/yr 12/yr Other 6/yr 12/yr Total number sites 36/yr Draft data - do not cite or quote Draft data – do not cite or quote
Spatial survey sites chosen probabilistically • Same GRTS method as Status and Trends Program • What types of conditions Bay-wide higher Hg • Stratified sampling scheme • Even if all our hypotheses are wrong, we are still characterizing conditions and identifying hotspots Bay-wide Draft data - do not cite or quote Draft data – do not cite or quote
How separating different site types? Hydrology: Site Type Open Shoreline Enclosed Total Number High Hg Wetland NA NA 6/yr Low Hg Wetland NA NA 6/yr Hg Source Area 6/yr 12/yr Other 6/yr 12/yr Total number sites 36/yr Draft data - do not cite or quote
Map of areas to be sampled GIS based on morphology, size, depth -Strata 1: Open Shorelines -Strata 2: Enclosed areas and creeks Draft data - do not cite or quote Draft data – do not cite or quote
Identifying Hg source areas Hydrology: Site Type Open Shoreline Enclosed Total Number High Hg Wetland NA NA 6/yr Low Hg Wetland NA NA 6/yr Hg Source Area 6/yr 12/yr Other 6/yr 12/yr Total number sites 36/yr Draft data - do not cite or quote
Source site selection • Mining sources – Creeks draining probable source mines • POTW discharges – Feedback from RB NPDES Permitting Staff • Creeks draining urban/industrial areas – Feedback from BASMAA • Industrial areas with high sediment THg • Total of about 50 sites Draft data - do not cite or quote
Wetland site selection Hydrology: Site Type Open Water Embayment Total Number High Hg Wetland NA NA 6/yr Low Hg Wetland NA NA 6/yr Hg Source Area 6/yr 12/yr Other 6/yr 12/yr Total number sites 36/yr Draft data - do not cite or quote
Wetland site selection • Oversight by Josh Collins and Letitia Grenier • Based on GRTS sampling performed for SBMP and CRAM • Stratified based on: • relative wetland elevation and age • Is wetland hypothesized to be high or low in bioavailable Hg Draft data - do not cite or quote Draft data – do not cite or quote
Results of site selection Draft data - do not cite or quote
Non-wetland site selection Years 1 - 3 Draft data - do not cite or quote Draft data – do not cite or quote
Wetland site selection Years 1 -3 Draft data – do not cite or quote Draft data - do not cite or quote
Source site selection Years 1 -3 Draft data - do not cite or quote Draft data – do not cite or quote
All sites Year One Draft data - do not cite or quote Draft data – do not cite or quote
Source Sites Year One Draft data - do not cite or quote Draft data – do not cite or quote
Enclosed vs. Open shoreline Year One Draft data - do not cite or quote Draft data – do not cite or quote
All sites Year Two (does not include wetlands) Draft data - do not cite or quote Draft data – do not cite or quote
Coordination and Collaboration • University of Michigan – RMP Hg stable isotope study (Joel Blum, Gretchen Gehrke) – Hg isotope sites characterize specific sources • Urban runoff, mining, waste water, atmospheric deposition • Sites will be chosen from small fish source sites after probabilistic site selection is complete • Sediment Hg and isotope analysis Draft data - do not cite or quote
Coordination and Collaboration • Trent University – Diffusive Gradient in Thinfilm devices (Holger Hintelmann) – Just completing analyses of the pilot study data (2007) – Year 1 - validation • 15 small fish sites varying in chemistry and expected bioaccumulation • Will overlap with mercury isotope sites – Year 2 – process studies • • Source sites of interest including fishless locations Gradient studies Likely include SPL sites (e. g. , Z 4 LA) Report available February 2010 – Addition of water column DOC as correlate Draft data - do not cite or quote
Discussion points • How select sites for DGT and Hg isotope in year one Draft data - do not cite or quote
END OF TALK • REST IS ANCILLARY MATERIAL IN EVENT OF DISCUSSION Draft data - do not cite or quote
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Sediment Me. Hg may be correlated with topsmelt Hg • Topsmelt 2006 data • RMP and Calfed sediment data within 1. 5 km disk of fish • R 2 = 0. 61 Draft data - do not cite or quote
Trend analysis – a multiple station BACI design Draft data - do not cite or quote Draft data – do not cite or quote
Trend Sampling Locations Hamilton Benicia Park China Camp Control Point Isabel Impact (Restoration) Oakland Middle Harbor Candlestick Point Eden Landing Bird Island/ Steinberger Slough Newark Slough Alviso Slough Draft data - do not cite or quote Draft data – do not cite or quote
Trend Sampling Locations Hamilton Benicia Park China Camp Control Point Isabel Impact (Restoration) Oakland Middle Harbor Candlestick Point Eden Landing Bird Island/ Steinberger Slough Newark Slough Alviso Slough Draft data - do not cite or quote Draft data – do not cite or quote
Monthly sampling locations Additional North Bay Station Sampled by USFWS Martin Luther King Shoreline Draft data - do not cite or quote Draft data – do not cite or quote
MLK Shoreline Location Draft data - do not cite or quote Draft data – do not cite or quote
Collection of additional parameters • Aimed at better understanding mechanisms for spatial variation in bioavailable Hg • GIS spatial parameters • Sediment parameters Draft data - do not cite or quote
Sediment parameters • Sediment parameters: redox, TON, grain size, total and methyl Hg • Samples at subset of 20 Sites Draft data - do not cite or quote
Sediment Me. Hg: < 1 ng/g 1 – 2 ng/g > 2 ng/g Draft data - do not cite or quote
Annual monitoring of trend stations Draft data - do not cite or quote
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