Elizabeth A. Del Rosario*, Paul A. Montagna, Evan L. Turner. Department of Physical and Environmental Science, Harte Research Institute for Gulf of Mexico ...
Ecosystem Response to Freshwater Inflow: Determining a Link Between Freshwater Pumping Regimes and Ecological Benefit Elizabeth A. Del Rosario*, Paul A. Montagna, Evan L. Turner Department of Physical and Environmental Science, Harte Research Institute for Gulf of Mexico Studies, Texas A&M University - Corpus Christi, TX 78412
METHODS
INTRODUCTION WATER RESOURCE ALLOCATIONS
The Nueces River System has been subject to adaptive management since dam construction:
RESULTS HYDROLOGY BIOLOGICAL RESPONSE
STUDY SITE - TEXAS - NUECES ESTUARY - RINCON BAYOU
• Wesley E. Seale Dam • Built on the Nueces River in 1958 • Reduced inflow into Rincon Bayou by 99% • Choke Canyon Dam • Built on the Frio River in 1982 • Reduced remaining inflow into Rincon Bayou by an additional 55%
Decreased inflow has: • Increased salinity in Rincon Bayou - Nueces Estuary Depiction of links between estuaries and catchments (from Yoskowitz and Montagna 2009) • Resulted in a reverse estuary (higher salinities upstream) • Disturbed hydrology • Increased salinity, decreased nutrients input, low dissolved oxygen, etc. • Caused loss of species biodiversity and critical habitat
Texas Law Requires Environmental Flows for Bays and Estuaries • 2001 Agreed Operating Order - The City of Corpus Christi, Texas: 1. Reconstructed the Nueces River Overflow Channel to Rincon Bayou (Fig. 4) 2. Construct a pipeline to convey 3,000 ac-ft per month to the Nueces Delta (Fig 2.) 3. Implement an on-going monitoring and assessment program Figure 1. Main Map: Rincon Bayou study area and data collection sites. Inset Maps: a) State of Texas with the Nueces Basin highlighted. b) Location of Choke Canyon Reservoir and Lake Corpus Christi within the Nueces Basin.
DATA SOURCES
SAMPLING
http://sanpatwater.com/
(RBP) http://www.mysoutex.com http://sanpatwater.com/
• Benthic macrofauna biomass, abundance and community structure was measured: • Sediment cores covering an area of 35.4 cm2 • Animals extracted using a 0.5mm mesh sieve • Animals enumerated and dried at 50 ̊C for 24 hours then weighed for biomass
Data was obtained from the following sources and analyzed using Microsoft Excel and SAS programing software. Station Name
Hydrological Parameter
Station C
Salinity, Depth, Temperature
Interval
Date Range
Continuous Sept. 2009 - Montagna Stations Discrete Dec. 2015 HRI TAMUCC (psu, m, °C)
Rincon Bayou Daily total Sept. 2009 Pumped Inflow Pipeline (Acre-ft/day) Dec. 2015 USGS Rincon Natural Inflow Channel Gage and Discharge NUDE2 SALT03
www.cbbep.org
NUDEWX
Salinity
Agency
Mean daily rate (f3 /sec)
Nueces River Authority (NRA)
United States Sept. 2009 Geological Survey Dec. 2015 (USGS)
Every 15 May 2009 minitues (psu) Dec. 2015
Computed Daily total at Jan. 2014 Cumulative Rain midnight (cm) Dec. 2015 Fall (ccrf)
Conrad Blucher Institute for Surveying and Science (CBI)
EQUATIONS
𝑏𝑖𝑛 𝑐 𝐵𝑖𝑜𝑖𝑛𝑑𝑖𝑐𝑎𝑡𝑜𝑟 = 𝑎 × exp −0.5 × log 𝑏
www.nueces-ra.org
www.mysoutex.com
• Analyze hydrology data • Pumped inflow (RBP) and natural inflow (gage) • Salinity in upper delta vs. Nueces Bay • Salinity, depth, and temperature (Station C) • Analyze benthic macrofauna data (Stations C, F and G) • Correlate to hydrology data using indicator species • Create prediction graphs: • Salinity from inflow • Depth from inflow
ACKNOWLEDGMENTS I would like to thank the HRI Ecosystems and Modeling Group for their work in sample collection, sorting, species identification, etc. which made this research possible. DISCLAIMER: This material is based upon work supported in part by the National Oceanic and Atmospheric Administration, Educational Partnership Program, U.S. Department of Commerce, under Agreement No. NA11SEC4810001. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration.
Figure 7. Relationship between hydrographical variables (salinity, temperature, depth) with (left) biomass and (right) abundance for Chironomidae larvae.
Streblospio benedicti
Website
Not available online
http://www.nueces-ra.org/CP/CITY/rincon/
http://nwis.waterdata.usgs.gov http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1188
Chironomidae Larvae
http://www.cbi.tamucc.edu/dnr/station
2
𝐼𝑛𝑓𝑙𝑜𝑤 = 𝑎 ∗ 𝑒−𝑏∗𝑠𝑎𝑙𝑖𝑛𝑖𝑡𝑦
CONCLUSION Streblospio benedicti (top) Brackish indicator Pioneer species indicative of disturbed environments Chironomidae larvae (bottom) Freshwater indicator Indicative of poor water quality Figure 8. Species composition at Station C in Rincon Bayou with inflow rates. Low dissolved oxygen Nov. 2013 to Dec. 2015. Biomass (top), abundance (bottom)
OBJECTIVES www.cbbep.org www.cbbep.org
Figure 6. Relationship between hydrographical variables (salinity, temperature, depth) with (left) biomass and (right) abundance for Strebiospio benedicti.
Indicator Species
Figure 5. Estuarine condition. Difference in salinity downstream (SALT03) minus upstream (NUDE2). Width of gray bars indicate pumping duration.
• Rincon Bayou is still a reverse estuary and occasionally exhibits hypersaline conditions (Fig. 5). • Salinity can fluctuate from fresh to hypersaline, and hypersaline to fresh in very short time periods due to flooding event created by pumping: • Unstable disturbed ecosystem with low diversity and high fluctuations of benthic macrofauna indicator species abundance and biomass (Fig. 8). • Recommendations to improve the ecology of Rincon Bayou at Station C: • Optimum salinity for biomass is 1 to 15 psu; 1 to 14 psu for abundance (Fig. 6 - 7). • To achieve targets salinity range inflows of at least 1.02 x 10-3 m3/s are required. • Optimum water depth is 0.05 m to 0.2 m (Fig. 6 - 7). • To improve ecological stability, inflows should be a continuous trickle, not a flood.
Streblospio benedicti
Chironomidae Larvae
Variables
Biomass Parameters
X
Y
BINS
a peak
psu
g/m2
5
0.670
0.529
°C
g/m2
5
0.594
m
g/m2
5
psu
g/m2
°C m
Abundance Parameters
Variables
b c skewness optimal x
X
Y
BINS
a peak
b c skewness optimal x
14.136
psu
n/m2
5
10.361
0.770
13.487
0.493
14.834
°C
n/m2
10
9.406
1.015
18.150
0.559
0.620
0.122
m
n/m2
5
9.477
2.182
0.124
12
1.439
0.972
1.810
psu
n/m2
10
12.736
2.098
1.352
g/m2
6
1.479
0.420
15.320
°C
n/m2
6
10.729
0.798
15.550
g/m2
6
1.442
0.850
0.083
m
n/m2
8
11.337
1.003
0.093
REFERENCES Montagna, P.A., L. Adams, C. Chaloupka, E. DelRosario, A. Gordon, M. Herdener, R.D. Kalke, T.A. Palmer, and E.L. Turner. 2015. Effects of Pumped Flows into Rincon Bayou on Water Quality and Benthic Macrofauna. Final Report to the Coastal Bend Bays & Estuaries Program for Project # 1417. Harte Research Institute, Texas A&M University-Corpus Christi, Corpus Christi, Texas, 46 pp. Full report available online: http://www.cbbep.org/manager/wp-content/uploads/CBBEP-1417-Final-Report.pdf Yoskowitz, D.W. and P.A. Montagna. 2009. Socio-economic Factors that Impact the Desire to Protect Freshwater Flow in the Rio Grande, USA. In: Brebbia, C.A. and E. Tiezzi (eds.), Ecosystems and Sustainable Development VII, WIT Press, Southampton, UK, pp. 547-558.
