Mecklenburg County Land Use & Environmental Services Agency; 2

Transcription

1 3/28/216 CHALLENGES FACING BENTHIC MACROINVERTEBRATE COMMUNITIES IN URBAN STREAMS: A REVIEW OF BENTHIC MACROINVERTEBRATE DATA FROM STREAMS IN CHARLOTTE, NORTH CAROLINA Anthony J. Roux 1,2, Sandra Clinton 3, and Jing Deng 3 1 Mecklenburg County Land Use & Environmental Services Agency; 2 Program in Infrastructure and Environmental Systems - University of North Carolina Charlotte 3 Department of Geography and Earth Sciences - University of North Carolina Charlotte Introduction Urban streams are subjected to numerous stresses which present significant challenges to urban benthic macroinvertebrate communities in maintaining diversity and function including climate conditions, storm water intensity and volume, storm water pollutants, illicit discharges, erosion from new construction, and wastewater collection system failures This study examines the influence of land use changes over time on the benthic macroinvertebrate community by: Examining how the benthic macroinvertebrate community diversity is impacted by changes in (IC) Examining how species traits are impacted by changes in % IC 1

2 3/28/216 Introduction - Benthic Macroinvertebrates Benthic macroinvertebrates include all organisms that live on or in the stream bottom that are large enough to see without a microscope and do not have a backbone The majority of the benthic organisms are aquatic insects Other benthic organisms include worms and leeches, clams and mussels, snails, and crayfish Benthic macroinvertebrates are useful as biological water quality indicators E Mayfly P Stonefly T Caddisfly EPT Taxa Photo by Eric Fleek NCDWR Introduction Species Traits Species traits - characteristics unique to each species reflecting their position in the stream ecosystem. Species traits have been used to characterize the functional composition of benthic macroinvertebrate communities and have been used to predict changes of both species and species assemblages within a biological community along environmental gradients in terms of traits that are sensitive to local environmental conditions. Trait categories include: Life History rate of development, adult life span Mobility crawling rate, swimming ability, flying strength Morphology shape, size, respiration strategy Ecology feeding, thermal, habit preferences 2

3 3/28/216 Benthic Macroinvertebrate Sampling Techniques Collect benthic macroinvertebrates using Standard Qualitative Method developed by North Carolina Division of Water Resources Biological Assessment Unit Identify benthic macroinvertebrates to lowest possible taxa level Compare benthic macroinvertebrate function over time using species trait analysis Study Sites 16 stream watersheds that span a gradient of : Low (<2 %; green) Low-Mid (2-%; yellow) High-Mid (-7%; orange) High (>7%; black) Monitored annually since 1994* 3

4 Population per Square Mile Population per Square Mile 3/28/216 GIS - Classification Table Organized the data processing steps into ArcGIS workflow, Major steps for data processing include: Reclassify land use raster layers based on the categories in the table Re-project the raster data layers to ensure projection consistency between land use raster layers and watershed boundary layer Counting the number of cells for each land use category that fall within corresponding watershed and sub-watershed Calculate land use percentages based on the newly generated table from ArcGIS Workflow Demo GIS Maps Population Density Clarke Creek Gar Creek Clear Creek West Branch 1 Rocky R Goose Creek Population Density McDowell Creek McAlpine Creek McMullen Creek Upper Little Sugar Cr Briar Creek 4

5 3/28/216 Results Land Use Changes Low IC Streams: Gar Creek % IC changed from 6 to 13.7% from 1994 to 214 Other Low IC stream change from 1.3 to 24.% Changes in Low IC Watersheds MC MY13A MY1B MY8 MY1 Results Land Use Changes Low-Mid IC Streams: Goose Creek % IC changed from 11.9 to 38.7% from 1994 to 214 Other Low-Mid IC stream change from 11. to 2% Changes in Low-Mid IC Watersheds MY9 MY7B MY13

6 3/28/216 Results Land Use Changes High-Mid IC Streams: Upper McDowell Creek (MC2A1) % IC changed from 11.2 to 74.2% from 1994 to 214 Other High-Mid IC stream change from 1.9 to 6.9% Changes in High- Mid IC Watersheds MC3E MC4 MC2 MC2A1 Results Land Use Changes High IC Streams: Upper Little Sugar Creek % IC changed from 79. to 97.8% from 1994 to 214 Other High IC stream change from.8 to 96.8% Changes in High IC Watersheds MC38 MC33 MC42 MC29A1 6

7 3/28/216 Challenges to Benthic Macroinvertebrate Communities As a watershed develops, the % impervious cover increases Storm runoff flow and intensity increase Stream channel damage occurs Stream bank erosion and channel incision negatively impact fish and benthic macroinvertebrate communities Challenges: Storm Water Runoff Increase in storm water runoff volume and intensity Streambank erosion and channel incision Stream channel sedimentation and habitat destruction Pollutants such as heavy metals, pesticides, herbicides, fertilizers, and petroleum hydrocarbons 7

8 3/28/216 Challenges: Erosion From New Construction Increase in Turbidity Stream channel sedimentation and habitat destruction Pollutants such as petroleum hydrocarbons, nutrients, legacy land pollutants (agriculture, industrial) Challenges: Leaking/Broken Sewer lines Sewage to stream Fecal Coliform Bacteria Organic material (increase BOD, COD) Miscellaneous pollutants including heavy metals, solvents, detergents, and toxic chemicals 8

9 EPT EPT Taxa Taxa Richness 3/28/216 Challenges: Miscellaneous Discharges Illicit Discharges Industrial Poor Housekeeping Accidental Spills Mobile Car Washers Challenges: Climate/Drought (Gar Creek Example) Droughts impacted the flow volume and stream depth in Gar Creek altering the benthic macroinvertebrate community Droughts impacted Clear Creek to lesser degree as the flow and depth not as impacted as seen in Gar Creek (due to larger watershed size) McMullen Creek already stressed when droughts hit 3 3 EPT - Gar, Clear & McMullen Creeks Drought Drought Gar Clear McMullen 9

10 EPT Taxa Richness EPT Taxa Richness 3/28/216 Changes in EPT Taxa Richness Over Time EPT-Gar, Reedy, McDowell, McMullen Cr MC MY13 MC2A1 MC42 Gar and McDowell Creeks showed declines in EPT taxa richness over time while Reedy Creek showed a slight increase in EPT taxa richness since 28 Very little change in EPT taxa richness occurred in the already stressed McMullen Creek Impact of Impervious Cover on EPT Taxa in Charlotte-Mecklenburg Urban Streams 3 Impact of Impervious Cover on EPT Taxa in Charlotte-Mecklenburg Urban Streams R² = EPT Taxa Richness declines with increasing Multiple points at same % IC indicate some other environmental factor controlling distribution 1

11 EPT Taxa Richness EPT Taxa Richness 3/28/216 Response of EPT Taxa Richness in Low IC Watersheds to Changes in % Impervious Cover Over Time EPT Richness beginning to decline with increases in % IC Decline in EPT Richness appears to begin around 1 % IC Changes in Low IC Watersheds MC MY13A MY1B MY8 MY1 EPT Taxa Richness Response to : Low IC Watersheds MY8 MC MY1 MY1B MY13A Response of EPT Taxa Richness in Low-Mid IC Watersheds to Changes in % Impervious Cover Over Time Changes in Low-Mid IC Watersheds MY9 MY7B MY13 EPT Taxa Richness Response to : Low-Mid IC Watersheds EPT Richness decline with increases in % IC Multiple points at same % IC indicate some other environmental factor controlling distribution MY9 MY7B MY13 11

12 EPT Taxa Richness EPT Taxa Richness 3/28/216 Response of EPT Taxa Richness in High-Mid IC Watersheds to Changes in % Impervious Cover Over Time Changes in High-Mid IC Watersheds MC3E MC4 MC2 MC2A1 EPT Taxa Richness Response to : High-Mid IC Watersheds EPT Richness decline with increases in % IC Multiple points at same % IC indicate some other environmental factor controlling distribution %$ Impervious Area MC3E MC4 MC2 MC2A1 Changes in High IC Watersheds Response of EPT Taxa Richness in High IC Watersheds to Changes in % Impervious Cover Over Time MC38 MC33 MC42 MC29A1 EPT Taxa Richness Response to : High IC Watersheds EPT Richness decline with increases in % IC Multiple points at same % IC indicate some other environmental factor controlling distribution MC38 MC33 MC42 MC29A1 12

13 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: Low IC Watersheds % EPT Trophic Groups vs. for Low IC Watersheds EPT s drop out of the community around 1 to 11 % IC Species Trait Response to Changes in Trophic Groups: Low IC Watersheds % EPT Trophic Groups vs. for Low IC Watersheds EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component 13

14 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: Low IC Watersheds % EPT Trophic Groups vs. for Low IC Watersheds Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component EPT Herbivores become a more important component above 11 % IC Species Trait Response to Changes in Trophic Groups: Low IC Watersheds % EPT Trophic Groups vs. for Low IC Watersheds Collecterfilterer Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterer also become increasingly more important with increasing IC 14

15 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: Low IC Watersheds % EPT Trophic Groups vs. for Low IC Watersheds Collectorgatherer Collecterfilterer Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterers also become increasingly more important with increasing IC EPT Collector-gatherers are co-dominant with Collector-filterers Species Trait Response to Changes in Trophic Groups: Low-Mid IC Watersheds % EPT Trophic Groups vs. for Low-Mid IC Watersheds EPT s drop out of the community around 1 to 11 % IC 1

16 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: Low-Mid IC Watersheds 12 % EPT Trophic Groups vs. for Low-Mid IC Watersheds EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community Species Trait Response to Changes in Trophic Groups: Low-Mid IC Watersheds 6 % EPT Trophic Groups vs. for Low-Mid IC Watersheds 4 Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC 16

17 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: Low-Mid IC Watersheds % EPT Trophic Groups vs. for Low-Mid IC Watersheds Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterers also become increasingly more important with increasing IC Species Trait Response to Changes in Trophic Groups: Low-Mid IC Watersheds 7 % EPT Trophic Groups vs. for Low-Mid IC Watersheds Collecterfilterer Collectorgatherer Collecterfilterer Herbivore EPT s drop out of the community around 1 to 11 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterers also become increasingly more important with increasing IC EPT Collector-gatherers become co-dominant with Collector-filterers and Herbivores with increasing IC 17

18 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: High-Mid IC Watersheds % EPT Trophic Group vs. for High-Mid IC Watersheds EPT s drop out of the community around 1 % IC Species Trait Response to Changes in Trophic Groups: High-Mid IC Watersheds 2 % EPT Trophic Group vs. for High-Mid IC Watersheds EPT s drop out of the community around 1 % IC EPT s are a minor component of the community 18

19 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: High-Mid IC Watersheds 6 % EPT Trophic Group vs. for High-Mid IC Watersheds Herbivore EPT s drop out of the community around 1 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC Species Trait Response to Changes in Trophic Groups: High-Mid IC Watersheds 7 % EPT Trophic Group vs. for High-Mid IC Watersheds Collecterfilterer Herbivore EPT s drop out of the community around 1 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterers also become increasingly more important with increasing IC 19

20 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: High-Mid IC Watersheds 7 % EPT Trophic Group vs. for High-Mid IC Watersheds Collectorgatherer Collecterfilterer Herbivore EPT s drop out of the community around 1 % IC EPT s are a minor component of the community EPT Herbivores become a more important component above 11 % IC EPT Collector-filterers also become increasingly more important with increasing IC EPT Collector-gatherers become co-dominant with Collector-filterers and Herbivores with increasing IC Species Trait Response to Changes in Trophic Groups: High IC Watersheds 3 % EPT Trophic Group vs. for High IC Watersheds EPT s drop out of the community around 1% IC 2

21 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: High IC Watersheds 3 % EPT Trophic Group vs. for High IC Watersheds EPT s drop out of the community around 1% IC EPT s not present in the community at high % IC Species Trait Response to Changes in Trophic Groups: High IC Watersheds 4 4 % EPT Trophic Group vs. for High IC Watersheds Herbivore EPT s drop out of the community around 1% IC EPT s not present in the community at high % IC EPT Herbivores become an important component above % IC 21

22 % Trophic Group % Trophic Group 3/28/216 Species Trait Response to Changes in Trophic Groups: High IC Watersheds 7 % EPT Trophic Group vs. for High IC Watersheds Herbivore EPT s drop out of the community around 1% IC EPT s not present in the community at high % IC EPT Herbivores become an important component above % IC EPT Collector-filterers become a dominant part of the community above % IC Species Trait Response to Changes in Trophic Groups: High IC Watersheds 7 % EPT Trophic Group vs. for High IC Watersheds Collecterfilterer Collectorgatherer Collecterfilterer Herbivore EPT s drop out of the community around 1% IC EPT s not present in the community at high % IC EPT Herbivores become an important component above % IC EPT Collector-filterers become a dominant part of the community above % IC EPT Collector-gathers are similar in importance to herbivores but less dominant than Collector-filterers 22

23 3/28/216 Stream Restoration as a Watershed Management Tool Stream restoration is an attempt to restore damaged stream channels to a more natural condition It has been assumed by many that by simply recreating a more natural channel that the benthic macroinvertebrate community in the stream will recover to resemble the community found in an undisturbed stream. Several shortcomings to this approach: Not addressing the storm water volume and intensity in the watershed, especially above the restored segment Not reconnecting the floodplain with the stream Not restoring the riparian zone beyond the top of bank Conclusion Overall, there was a decrease in EPT richness in each of these streams over the past 2 years % impervious cover is a good indicator of benthic macroinvertebrate community health with community diversity declining with increasing impervious cover, a condition directly associated with urban development Climate conditions impact benthic macroinvertebrate communities as illustrated by the response of Gar Creek to two droughts that occurred in the Piedmont between 22 and 29 Flashiness of the urban stream storm water hydrograph creates an environment that is generally homogenous reducing habitat diversity and, in turn, reduces benthic macroinvertebrate community diversity. Evaluation of species traits can provide information regarding the overall health of the stream ecosystem. Data sets covering longer periods of time are important in order to better understand how environmental factors such as land use changes and climate interact with stream health in addition to understanding stream restoration success. 23

24 3/28/216 Acknowledgements Mecklenburg County Water Quality Bioassessment Team Charlotte-Mecklenburg Storm Water Services David Buetow Taxonomist Members of the Clinton lab at UNCC Little Sugar Creek Westfield Mecklenburg County SWS Questions? 24