31
Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande Harmony Lu REU Project Summer 2010

Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

  • Upload
    ima

  • View
    50

  • Download
    7

Embed Size (px)

DESCRIPTION

Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande. Harmony Lu REU Project Summer 2010. Background. River Continuum Concept to Network Hypothesis gradient of change from headwaters to mouth of hydrological properties - PowerPoint PPT Presentation

Citation preview

Page 1: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Effects of the Rio Salado Confluence on Benthic Substrate

in the Rio Grande

Harmony LuREU Project

Summer 2010

Page 2: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Background

River Continuum Concept

to Network Hypothesis- gradient of change from

headwaters to mouth of hydrological properties

- biological communities also change to match the local conditions

- discontinuities in these gradients occur, instead view the river as a network

Page 3: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

BackgroundFlood events in an intermittent stream

Page 4: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Research Questions

• Are there observable effects from the confluence of an intermittent stream, the Rio Salado, on the main channel, the Rio Grande?

• Do these effects alter the local habitat?

Page 5: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Possible lasting effects of an intermittent tributary

- focus on substrate variation in the main channel water energy determines particle carriage/deposition tributary carries sediment into main channel

- benthic substrate important habitat characteristic

Page 6: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Background

Rio Grande– major water source for agriculture,

domestic use, natural habitats (riparian areas)

– also is a habitat itself for many species– sandy-bottomed with wide floodplain

Page 7: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

BackgroundInvertebrate communities are useful

biological indicators in freshwater- commonly studied- many are sedentary and provide

assessment of localized effects- are important parts of river communities

Page 8: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Research Site

Sevilleta National Wildlife Refuge

Page 9: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Research Site

Page 10: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Procedure 1– mapping

• 11 transects from the west bank to the east bank

• 4 samples along each transect

• at each site, 3 measurements:1. % cobble2. depth3. sediment sample taken

for texture analysis

Page 11: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Procedure 2– invertebrate sampling

• 2 sets of samples taken (Day 1: June 4+6, Day 2: June 23)

• 7 sites along the west bank• Data from each site (3

types):– sediment texture– water characteristics– invertebrate community

Page 12: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Invertebrate Sampling Sites

Page 13: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Procedure – invert collection

• Invertebrate sampling:- sediment core sampling

4 cores of the top 1 cm of benthic substrate

• samples preserved in 70% ethanol

Page 14: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Procedure – sample analysis• Sediment

– hydrometer soil texture analysis used to assess % composition

• Invertebrate– invertebrates separated

from debris/sediment– identified to Order or

Family using dissecting microscopeDay Site Chironomidae Simuliidae Tricorythidae Baetidae Leptoceridae Hempitera Odonata Cladocera

1 1 5 12 0 0 0 0 0 01 2 3 7 0 0 1 0 0 01 3 11 14 0 3 0 0 0 01 4 17 653 0 0 0 0 0 0

Page 15: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Results and Discussion

• Confluence map• Invertebrate community• Environmental influence on

invertebrate community• Lasting effects of the confluence

Page 16: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Confluence Depth Map

Rio Salado

Page 17: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Confluence Cobble Cover Map

Rio Salado

bubble size indicates % cobble cover

Page 18: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Invertebrate Data

Page 19: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Invertebrate Community Data

(Global R): 0.536p: 0.001

Similarity of communities – positioning around confluence

Multidimensional Scaling (MDS)

• multivariate – can look at community as a whole• each site’s community data viewed as a matrix• calculated a similarity between all of the matrices• plot similarity in multidimensional space• compress to 2D plot with meaningless axis

Bottom line:relative distance is keycloseness implies similarity

Page 20: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Invertebrate Community Data

(Global R): 0.536p: 0.001

Temporal Changes – succession of species over the summer

Page 21: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Correlation between environment and biological

communities

Correlation Variables

0.330 gravel, vv fine sand + silt

0.330 gravel, vv fine sand + silt,v fine sand

0.321 gravel, vv fine sand + silt

- water characteristics: showed very small variation between sites- sediment texture: much higher variation between sites- BEST analysis: compares environmental information (soil texture) to biological information (community)

- % gravel and % vv fine sand + silt explain most of the variation in biological communities

Page 22: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

MDSsize indicates relative % gravel

size indicates relative % vv fine sand + silt

Page 23: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Confluence Sand Map

Rio Salado

bubble size indicates % sand (by mass)

Page 24: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Confluence Gravel Map

Rio Salado

bubble size indicates % gravel (by mass)

Page 25: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Rio Salado

Confluence vv fine sand and silt Map

bubble size indicates % (by mass)gravel

silt

vv fine sand

Page 26: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Matching up to observations

Rio Salado

Page 27: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Conclusions• Invertebrate communities changed through

time• Variation in invertebrate communities could

be correlated with substrate qualities• The main channel around the confluence

shows high variation in substrate quality• Patterns of substrate quality match

observations of tributary inputs• Implications that tributary has lasting

influence on habitat quality of main channel

Page 28: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Further Research

• Intermittent streams as sources of disturbance that change throughout the year

• Interannual variation of precipitation and flow rates of intermittent tributaries

• Variability in the benthic substrate of the Rio Grande overall (temporal and spatial)

Page 29: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Acknowledgements

Ayesha Burdett, Jennifer Johnson

Sevilleta LTER REU 2010 students (Christopher Shepard, Shayla Burnett, Amanda Labrado, Ricardo Duran, Cynthia Malone, Ileana Betancourt, Melissa Shaginoff, Mitch Nakai, Natasha Ribeiro, Amanda Liebrecht, Antonio Nevarez, Elida Iniguez)

Brenda Nieto

National Science Foundation

Sevilleta National Wildlife Refuge & LTER

Page 30: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

ReferencesBenda, L., N.L. Poff, D. Miller, T. Dunne, G. Reeves, G. Pess, M. Pollock. (2004). The Network Dynamics

Hypothesis: How Channel Networks Structure Riverine Habitats. BioScience. 54: 413-427.Best, J.L. (1988). Sediment transport and bed morphology at river channel confluences. Sedimentology. 35:

481-498.Burdett, A, R. Bixby. (2008). Effects of nutrient availability on periphyton growth and diversity in the Middle

Rio Grande: top-down and bottom-up factors. Middle Rio Grande Endangered Species Collaborative Program Annual Report. 1-53.

Duan, X., Z. Wang, M. Xu, K. Zhang. (2009). Effect of streambed sediment on benthic ecology. International Journal of Sediment Research. 24: 325–338.

Gensler, G. R. Oad, K. Kinzli. (2009). Irrigation System Modernization: Case Study of the MiddleRio Grande Valley. Journal of Irrigation and Drainage Engineering. 169-176.Kiffney, P.M., C.M. Greene, J.E. Hall, and J.R. Davies. (2006). Tributary streams create spatial discontinuities

in habitat, biological productivity, and diversity in mainstem rivers. Can. J. Fish. Aquat. Sci. 63: 2518–2530.

Palmer, M.A., H.L. Menniger, E. Bernhardt. (2010). River restoration, habitat heterogeneity and biodiversity: a failure of theory or practice? Freshwater Biology. 55: 205–222.

Rice, S.P., M.T. Greenwood, C.B. Joyce. (2001). Macroinvertebrate community changes at coarse sediment recruitment points along two gravel bed rivers. Water Resources Research. 37: 2793–2803.

Rice, S.P., R.I. Ferguson, T.B. Hoey. (2006). Tributary control of physical heterogeneity and biological diversity at river confluences. Can. J. Fish. Aquat. Sci. 63: 2553–2566.

Svendsen, K.M., C. E. Renshaw, F.J. Magilligan, K.H. Nislow, J.M. Kaste. (2009). Flow and sediment regimes at tributary junctions on a regulated river: impact on sediment residence time and benthic macroinvertebrate communities. Hydrol. Process. 23: 284–296.

Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R. Sedell, C.E. Cushing. (1980). The River Continuum Concept. Can. J. Fish. Aquat. Sci. 37: 130-137.

Page 31: Effects of the Rio Salado Confluence on Benthic Substrate in the Rio Grande

Questions?