Russian River Estuary Management

Jessica Martini-LambPrincipal Environmental Specialist

jessicam@scwa.ca.gov

www.sonomacountywater.org

The Influence of an Intermittently Closed, Northern California Estuary on

the Feeding Ecology of Juvenile Steelhead (Oncorhynchus mykiss)

Erin Seghesio

Study ObjectiveTo determine over time and range, the distribution, composition and relative abundances of potential steelhead prey items and diet before and during a freshwater lagoon conversion.

Lower Reach: Highly saline, cooler temperatureMiddle Reach: Brackish, with three layersUpper Reach: Fresh water, very warm temperatures (22 degree)

Lower Reach: Highly saline, cooler temperature

Middle Reach: Brackish, with three layers

Upper Reach: Fresh water, very warm temperatures (22 degree)

Empirical Data Questions?

1. What are steelhead primary prey taxa?

2. Does steelhead prey vary by location (from freshwater to more saline)

3. Is there a response of primary salmonid prey to a closure?

Methods: Salmonid Diet Sampling -Beach seined-Gastric lavaged-12 sites-Monthly-Jun-Oct 2010

Methods: Invertebrate SamplingMonthly:Sampled 6 locations: June-Early SeptemberSampled 3 locations: June-October

Invertebrate sampling: Benthic Core-Taken along the shoreline -5 replicates per site

Invertebrate sampling: Nearshore Epibenthic Hauls-Pulled 10m perpendicular to the shoreline -5 replicates per site

Invertebrate sampling: Thalweg Epibenthic Sled-Towed from boat in the middle of the channel for 15 meters -5 replicates per site

Invertebrate sampling: Insect Fallout Trap and Zooplankton Vertical net haulsNot going to be covered today because zooplankton was not found in the diets and adult insects in very small quantities

2010 Estuary Closures

6/1/2010

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Aver

age

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ly W

ater

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ght (

feet

)

2010 Estuary Closures and Seining Dates

6/1/2010

6/6/2010

6/11/2

010

6/16/2010

6/21/2

010

6/26/2010

7/1/2010

7/6/2010

7/11/2010

7/16/2

010

7/21/2010

7/26/2

010

7/31/2

010

8/5/2010

8/10/2010

8/15/2

010

8/20/2010

8/25/2

010

8/30/2

010

9/4/2010

9/9/2010

9/14/2010

9/19/2

010

9/24/2010

9/29/2

010

10/4/2010

10/9/2010

10/14/2010

10/19/2010

10/24/2010

10/29/20100

1

2

3

4

5

6

7

8

Aver

age

Dai

ly W

ater

Hei

ght (

feet

)

2010 Estuary Closures, Seining and Invertebrate Sampling Dates

6/1/2010

6/6/2010

6/11/2

010

6/16/2010

6/21/2

010

6/26/2010

7/1/2010

7/6/2010

7/11/2010

7/16/2

010

7/21/2010

7/26/2

010

7/31/2

010

8/5/2010

8/10/2010

8/15/2

010

8/20/2010

8/25/2

010

8/30/2

010

9/4/2010

9/9/2010

9/14/2010

9/19/2

010

9/24/2010

9/29/2

010

10/4/2010

10/9/2010

10/14/2010

10/19/2010

10/24/2010

10/29/20100

1

2

3

4

5

6

7

8

Aver

age

Dai

ly W

ater

Hei

ght (

feet

)

Empirical Data Questions?

1. What are steelhead primary prey taxa?

2. Does steelhead prey vary by location (from freshwater to more saline)

3. Is there a response of primary salmonid prey to a closure?

Steelhead feeding primarily on epibenthic taxa

Eogam

marus c

onfer

vicolu

s

Americo

rophiu

m spini

corne

Gnorim

osph

aerom

a ins

ulare

Ephem

eropte

ra ny

mph

Chiron

omida

e pup

a

Neomys

is merc

edis

juv-ad

ult

Chiron

omida

e larv

a

Hydrob

iidae

adult

Nereidi

dae

Corixid

ae ad

ult0

5

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30

Inde

x of

Rel

ativ

e Im

porta

nce

(%)

Index of Relative Importance factors in:• Amount (numerical)• Weight (gravimetric)• Frequency of Occurrence

Some separation between reaches

ANOSIM: R=0.309, p=0.1%

FreshwaterBrackish/Slightly Salty

Empirical Data Questions?

1. What are steelhead primary prey taxa?

2. Does steelhead prey vary by location (from freshwater to more saline)

3. Is there a response of primary salmonid prey to a closure?

Benthic Core: Taxa did not move with closureJu

ne

July

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st

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ber

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ober

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Den

sity

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Shaded= Closed

Difference in species assemblages

ANOSIM R=0.527 p=0.1%

Nearshore Epibenthic Net: More motile organisms showed more movement with closure

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Thalweg Epibenthic Sled: Sites differences Ju

ne July

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st

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Shaded=Closed

Empirical data findings-Steelhead are feeding primarily on epibenthic organisms.

-Although the highest density of common prey taxa were found in benthic core samples, the greatest diversity was in the epibenthic sampling.

-The more motile organisms are able to move into the newly flooded habitat during the short closures.

-Invertebrate assemblages varied by reach in response to salinity.

Empirical data findings-Steelhead are feeding primarily on epibenthic organisms.

-Although the highest density of common prey taxa were found in benthic core samples, the greatest diversity was in the epibenthic sampling.

-The more motile organisms are able to move into the newly flooded habitat during the short closures.

-Invertebrate assemblages varied by reach in response to salinity.

Empirical data findings- Steelhead are feeding primarily on epibenthic organisms.

-Although the highest density of common prey taxa were found in benthic core samples, the greatest diversity was in the epibenthic sampling.

-The more motile organisms are able to move into the newly flooded habitat during the short closures.

-Invertebrate assemblages varied by reach in response to salinity.

Empirical data findings-Steelhead are feeding primarily on epibenthic organisms.

-Although the highest density of common prey taxa were found in benthic core samples, the greatest diversity was in the epibenthic sampling

-The more motile organisms are able to move into the newly flooded habitat during the short closures.

-Invertebrate assemblages varied by reach in response to salinity.

Steelhead growthTemperaturePrey QualityCompetition

Consumption RatePrey Abundance

Question?

Q: Is steelhead growth going to be affected by an extended closure?

A: There was not an extended closure to sample

So we must model!

Wisconsin Bioenergetics Model (Hanson et. al 1997)

Consumption = Waste + Metabolism + GrowthAn energy balance equation

TemperatureBody massPrey Energy (J)Prey Composition

Metabolic Costs

Waste Loses

Growth

Consumption

Consumption= p* Cmax P-value: proportion of theoretical maximum

consumption

Diet composed of mostly lower caloric valued organisms

Gnorimosph-aeroma insulare

Corixidae (water boatman)

Americorophium spinicorne

Neomysis mercedis

Eogammarus confervicolus

Ephemeroptera nymph

Pictures from Jeff Cordell

Chironomidae Adult

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 250

0.005

0.01

0.015

0.02

0.025

0.03

0.035

Temperature

Grow

th (g

/g*d

)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 250

0.01

0.02

0.03

0.04

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Temperature

Grow

th (g

/g*d

)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 250

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

Temperature

Grow

th (g

/g/d

)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 250

0.005

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0.015

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Temperature

Grow

th (g

/g*d

)

76% Cmax

62% Cmax

48% Cmax

20g2800 J/g

20g5000 J/g

120g2800 J/g

120g5000 J/g

The change in daily growth rate in response to temperature and feeding rates

Review of primary model findings• The more you eat the more you grow!

• Smaller fish are able to grow at a faster rate than larger fish, under the same circumstances.

• Steelhead can better buffer the stresses of increasing temperature and continue to grow by having at least one of the following:

1. Consuming higher quality prey2. Consuming more prey3. Being smaller

• Worst Case Scenario: 120g steelhead feeding at 48% of maximum consumption starts seeing no growth at 18°C

To overcome warmer temperature potentially associated with closure • Find refuge

• Feed on higher quality prey

• Increase consumption rate

Final Conclusions

• Steelhead are feeding primarily on lower calorie epibenthic organisms

• Although the highest density of common prey taxa were found in benthic core samples, the species were not able to move up the shoreline during the short closures

• Higher quality prey organisms do exist in estuary

• Higher prey energy values/greater consumption or finding refuge may allow steelhead to withstand warmer temperatures longer

Pescadero Creek Estuary J. Martin 1995 and M. Robinson 1993 studied fish diets and invertebrate populations

• Estuary went completely anoxic before converting to freshwater lagoon

• Killed significant amount of invertebrate population• Steelhead decreased stomach fullness factors and

growth rate

• Freshwater lagoon• Less diversity but greater abundances of invertebrate• Steelhead shifted diet from epibenthic crustaceans and

mysids to freshwater dependent nymphs and midges

Can be expected that steelhead in RR would make similar shift in diet

Flooded habitat created by closurePrevious research:-Shallow water habitat-Increase growth rate-Spatial segregation -Alleviate competition-Absence of predators -Increase in invertebrate production

The water quality during and after a closure is going to determine if the estuary/freshwater lagoon will be beneficial for steelhead

My final thought

Thank you!Seghesio608@gmail.com

Field Support- Marshall Olin and Sonoma County Water Agency Staff

Lab and Data Support - Beth Armbrust, Claire Levy, Lia Stamatiou, Jeff Cordell, Jason Toft, Alex Ulmke, Ricky Tran and Wetlab Ecosystem Team

Committee Members- Charles “Si” Simenstad (PI), David Beauchamp, and Jeff Cordell (University of Washington)