U.S. Department of the Interior

U.S. Geological Survey

Near Shore Biological SaDuring Fluctuating and SReleases in September aOctober 2005B. Ralston1, M. Lauretta2, T. Kennedy1, GCMRC1 and SW

August 2, 2006
Introduction & Background

 Temperature and available habita

parameters associated with fish gsurvivorship

 Lees Ferry trout – Korman et al. 200

 Growth response to Sunday steady flow Changes in abundance with changes in 

and base flow

 Native fish – Gorman and Stone 199

Childs 2001, Korman et al 2004 
Purpose

Determine if physical and biologiccollected under minor fluctuations data collected under steady releasWater temperature & other abiotiBenthic composition & densityPlankton composition & densityFish composition and abundanc
Methods

• Trip dates S

22-Oct 7, 20

• 12 Paired sa

each trip

•Backwate•Shoreline

100 seconds

Backwater area
Hydrology

Collection 

Dates

Maximum 

Releases (ft3/s)

Minimum 

Releases (ft3/s)

R

Sept. 4 - 16, 

2005

9310 6690 2

Sept 22 – Oct 

7, 2005

9010 8040 9

Trip 1 
Results – Physical parameters

Fluctuating BW

Steady BW

19.5

± 0.5 s.e.

18.4

± 0.4 s.e.

9.7 ± 0.2 s.e

9.2 ± 0.1 s.e

FluctuatShorelin

Surface water temp (°C)

18.1

± 0.3 s

Dissolve Oxygen(mg/L)

9.5 ± 0.1 
Results – Physical parameters

Fluctuating BW

Steady BW

21.6 

± 2.4 s.e.

5.6

± 0.4 s.e.

0.04 0.02

FluctuaShoreli

Turbidity (NTU)

25.3

± 3.3 s

Velocity (m/s) 0.13 
Physical parameter conclus

 No statistical difference between flows within h Temperatures declined between trips

 Possibly due to changes in day length/sola

 Shoreline and backwater temperatures differed 

shorelines significantly colder (t-test p<0.05)

 Shoreline velocities varied between trips

 Associated with stage elevation of sample 

 Turbidity decreased between trips

 Spates from Paria, LCR during first trip
Results – Backwater Phytoplan

Backwater phytoplankton

0

1000200030004000500060007000

Achnanthes

Biddulphia

Ceratium

Chlamydomonas

Chroomonas

Cladophora

Cocconeis

Cruceginia

Cryptomonas

Cyclotella

Cymbella

Diatoma

Dinobryon

Elakathorix

Fragilaria

Glenodinium

Gomphonema

Gyrosigma

Merismopedia Navic

Os

Species

# / liter
Results – Shoreline Phytoplank

Shoreline Phytoplankton

0

500

10001500200025003000

Achnanth es

Biddulphia

Ceratium

Chlamydomonas

Chroomonas

Cladophora

Cocconeis

Cruceginia

Cryptom onas

Cyclotella

Cym bella

Diatoma

Dinobryon

Elakathorix

Fragilaria

Glenodinium

Gomphonema

Gyrosigma

Merismopedia

Navicula

Oscillatori

Rhoico

S

Species

# / liter
Phytoplankton conclusions

 Plankton densities were significantly d

between trips in both habitats (t-test p<

 Associated with antecedent flows & 

inputs

 Plankton densities between habitats w

significantly different during either flow
Results – Backwater Macroinve

Backwater Macroinvertebrate Density during Va

0

500

1000150020002500

ANN

AMISC

MITE

CASE

CHIL

CHIP

CYCL

DET

GAM

GAS

HYD

HYDL

NEM

NZM

SIML

S

Family

Density (# / sq m)
Results – Shoreline Macroinve

Shoreline Macroinvertebrate Density during Varie

0

200400600800

100012001400

ANN

AMISC

MITE

CHIL

CHIP

DIPL

GAM

GAS

HYD

HYDL

NEM

NZM

SIML

SIMP

Family

Density (# / sq. m)
Macroinvertebrate conclusi

 Total Macroinvertebrate densities were 

significantly different between trips in 

 Total Macroinvertebrate densities betw

also did not differ significantly between 

 Observed changes in densities may 

turbidity during first trip and antececonditions. 
Backwater fish abundance

Backwater Seining Catch-per-unit-effo

0.00.20.40.60.81.01.2

BBH

BHS

CCF

CRP

FHM

FMS

HBC

PKF

Species

CPUE (fish/m2)
Shoreline Fish Abundance

Shoreline Electrofishing Catch-per-unit-effo

0.0000.0020.0040.0060.0080.0100.0120.0140.016

BBH

BHS

CCF

CRP

FHM

FMS

HBC

PKF

RBT

Species

CPUE (fish/s)

FS
Fish Abundance conclusion

 Mean Catch effort for all fish did not di

flows except for Bluehead Suckers.

 Bluehead sucker catch effort increased dur

trip in backwaters (t-test(1-tailed) p<0.05).

 Differences in catch effort may be asso

turbidity values during first trip and fisflushed into mainstem.
Overall Conclusions

 Biological and physical paramete

were comparable between flows

 Temperatures varied between habita Plankton densities varied between t

 Limited conclusions can be made 

physical and biological variables

 Antecedent conditions  Local weather  Time between treatments likely too s

 Recommend studying in lab situa