Coastal Watersheds: The Lateral Link to Estuaries. Fred Holland & Denise Sanger

Transcription

1 Coastal Watersheds: The Lateral Link to Estuaries Fred Holland & Denise Sanger

2 Estuarine Gradients

3 Upland Creek

4 Saltmarsh Creeks

5 Objectives of Talk Provide the scientific underpinnings linking watershed characteristics and estuarine water quality (at the scale of tidal creeks). Document that tidal creek ecosystems are at great risk to land cover alterations.

6 Complex food webs Refuge and nursery habitat Primary hydrologic link to uplands Preferred sites for development

7 Land Use Change in Horlbeck Creek

8 Reference Developed

9 Myrtle Beach Georgetown Charleston Beaufort

10 Measured Parameters Watershed Characteristics Drainage basin area, land cover and impervious cover Physical/Chemical Water quality: salinity, temperature, DO, ph Sediment characteristics & contamination Fecal coliform bacteria Macrobenthos & Nekton Population and community level properties

11 Wando River Forested Watershed Interstate Interstate

12 Suburban Watershed James Island High School

13 Industrial Watershed Urban Watershed

14 Impervious Cover Urban Criteria Suburban Criteria Impervious Surface Coverage (%) Impervious Surface Coverage (%) BF DP FT LH LI LC RT BL CC HB MC PC YC NM SM VR DL KP SH Forested Suburban Urban/Industrial

15 Human Population Density Population (People/Hectare) r 2 =0.52 p < Percent Impervious Cover

16 Salinity (ppt) Salinity (ppt) Forested Forested Urban/ Urban/ Industrial Industrial Sub Suburban urban Forested Forested Urban/ Urban/ Industrial Industrial Sub Suburban urban Salinity Salinity Summer Summer Winter Winter DL DL KP KP SH SH NM NM VR VR BL BL CC CC MC MC PC PC SM SM YC YC BF BF DP DP FT FT HB HB LH LH LC LC LI LI RT RT DL DL KP KP SH SH VR VR SM SM NM NM BF BF FT FT LH LH LI LI LC LC RT RT DP DP MC MC BL BL CC CC YC YC PC PC HB HB

17 Dissolved Oxygen 160 Summer Winter % Saturation 0 Sub- urban Forested Urban/ Industrial Sub- urban Forested Urban/ Industrial Dissolved Oxygen (% Saturation) Dissolved Oxygen (% Saturation) BF DP FT HB LH LC LI RT BL CC MC PC SM YC NM VR DL KP SH BF DP FT LH LC LI RT BL CC HB MC PC YC NM SM VR DL KP SH

18 Pore Water Ammonia and Benthic Chlorophyll a NH NH + 4 (µmol/l) mol/l) Forested Sub- urban Sub- urban Urban/ Industrial Chlorophyll a (mg/m 2 ) Forested Urban/ Industrial

19 Fecal Coliforms vs. Impervious Cover 6 5 Log of Fecal Coliform r 2 = 0.35 p = Impervious Cover (%)

20 Chemical Contamination r 2 =0.52 p < Log ERMQ Cal 95 Val 00 Cal Percent Impervious Cover

21 Macrobenthic Indicators Summer 1994 Winter Stress-Sensitive Sensitive Taxa Relative Abundance (%) Stress-Indicative Taxa Forested Sub- urban Sub- urban Urban/ Industrial Forested Urban/ Industrial

22 Stress-Tolerant Taxa (%) Stress-Tolerant Taxa r 2 =0.16 p = Cal 94 Val 95 Val 00 Cal Percent Impervious Cover

23 For Ind Urb Sub Fish and Crustaceans 120 Grass Shrimp Spot Abundance (#/m 2 ) Abundance (#/m 2 ) Abundance (#/m 2 ) For Sub Ind Urb For Sub Ind Urb 12 Penaeid Shrimp Mummichog Abundance (#/m 2 ) For Sub Ind Urb

24 Penaeoid Shrimp (Log abundance) Penaeoid Shrimp r 2 =0.36 p = Cal 94 Val 95 Val Percent Impervious Cover

25 Conceptual Model of Linkages Stressor Exposure Response Human Population Density Altered Land Cover Increased Impervious Surface Increased Pollution Loadings Physical-Chemical Environment Altered Hydrography Change in Salinity Sediment Characteristics Chemical Contaminants Increased Bacterial Load Living Resources Altered Abundance Few Sensitive Taxa Altered Food Webs Shellfish Bed Closures 15%Impervious Surface 30% Impervious Surface

26 Management Conclusions Imperviousness is an important indicator of watershed condition for the lateral gradient. Development alters physical, chemical, and biological properties of lateral tidal creeks. Biological properties (e.g., benthic communities) had value in assessing tidal creek condition. Tidal creeks respond to changes in watershed properties on times scales of years to decades.

27 RECOMMENDATIONS Plan green developments: Limit alterations to freshwater inflow require vegetated buffers. build bridges not causeways. utilizing grassy swales. Minimize amount of impervious cover. Maximize open space and vegetation. Develop guidance for environmental friendly living. Scale of development Engineered vs non-structured controls Maintain septic systems/holding ponds Control pet feces

28 RECOMMENDATIONS Develop incentives and guidance to encourage land conservation and stewardship. Land trusts, reserves, sanctuaries Monitor tidal creeks to assess the effectiveness of management actions.

29 Green Planning and Infrastructure Encourage Cluster Development

30 Green Planning and Infrastructure Utilize Grassy Swales

31 Acceptable Buffer Unacceptable Buffer

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