Seasonal Diversity and Abundance of Larval and

Juvenile Fishes in The Upper Barataria Estuary

Sean Jackson

Introduction Barataria Estuary

• 1.7 million hectares• Diverse Habitats

– Freshwater swamps– Salt marshes

IntroductionStudy location

IntroductionUpper Barataria Estuary

• Land Use– 41.5% forested

wetlands – 38.0% agricultural

lands– 5.2% urban land

Study Area• Upper Barataria Estuary

– Large river floodplain• Leveed from Mississippi river

• No annual flood pulse

– Precipitation only water source• Wind can influence water level

• Major Water Bodies– Bayou’s Chevreuil and Citamon – St. James Canal– Lac des Allemands

IntroductionHabitat Description

• Canal Habitats– Dredged straight channel – High banks

• Bayou Habitats– Meandering curves– Low banks

Large River Floodplain Ecology

• Floodplain Ecology– Hydrology driving force

• Flood Pulse– Habitat access– Flush nutrients into system– Homogenize water quality

IntroductionLarge River Floodplain Ecology

• Flood Pulse Concept – Predictable annual flood pulse – Spawning and nursery habitat – Timing and duration important – Atchafalaya River Basin

• Low Flow Recruitment Hypothesis– No predictable annual flood pulse– Opportunistic use of floodplain– Brazos River floodplain

IntroductionLarge River Floodplain Ecology

• Water Types– Brown

• Well mixed, high DO

– Green• Stratified, high/low DO

– Black• Low turbidity, low DO

– Tea colored• High turbidity, Low DO

IntroductionFish Reproduction

• Successful Fish Reproduction– Cues

• Photoperiod (day length)• Temperature

– Environmental requirements• Access to spawning habitat• Acceptable water quality

IntroductionFish Reproduction

• Quality Nursery Habitat– Food availability– Water quality

• Dissolved oxygen– Normoxic = >2.0 mg/L– Hypoxic = < 2.0 mg/L

• Specific conductance

IntroductionFish Reproduction

PeriodicDorosoma spp.

OpportunisticGambusia spp.

EquilibriumLepomis spp.

Small BodiedRapid Maturation

Low FecundityShort Brood Period

Long Spawning Season

Large Egg SizeHigh Parental Care

Long Spawning SeasonIntermediate Fecundity

Citation?

IntroductionEcosystem Health

• V-O-R model– Vigor – production– Organization – structure or diversity– Resilience – maintain or rebuild

• Environmental Indicators – Water quality– Fisheries catch– Habitat diversity / availability

Purpose

• Describe distribution and abundance of larval and juvenile fishes in the upper Barataria Estuary

Predictions

• Natural bayou habitats will support higher levels of fish reproduction than dredged canal habitats

Specific objectives • Determine spawning period for each

taxonomic group of fish collected in the upper Barataria Estuary

• Compare relative abundance between canal and bayou habitats for all species and for each taxonomic group during their spawning period.

• Compare water quality data between canal and bayou habitats.

• Determine the relationship between larval fish abundance and water quality

IntroductionSite Locations

12

34567

Methods

• Weekly Collections– 9 February 2007 – 25 September 2007– 4 Bayou sites and 3 Canal sites– Three traps per site

Methods

• Light traps– Powered by

chemical light stick

– 500µm nitex mesh screen

– Sample edge of waterways

– Samples kept on ice

Methods

• Light traps – Set two hours before sunset– Pick up 2.5 hours after official sunset

• Water Quality– Temperature, DO, Conductivity, and Water

Color

• Vegetation

1

2

3

x1

x2

x3

Canal (XC)

6

5

4

7

Bayou (XB)

x4

x5

x6

x7

Experimental Design

N= 3 N= 4

Methods

• Samples processed within 24 hours• Fish placed in 70% alcohol solution • Fish identified, counted, and photographed• CPUE = number per hour

MethodsData Analysis

• All analysis performed at genus level– Log transformed if needed

• Analysis of variance (ANOVA)– CPUE, temperature, dissolved oxygen, and specific

conductance between habitats

• Regression Analysis– Determine relationship b/t CPUE and environmental

variables

• Principal Components Analysis (PCA)– Water quality variables and habitat types– Habitat types and CPUE for each fish genera and

developmental stage

ResultsFish

• 4,110 larval and juvenile fish collected• 11 Families, 15 genera represented

ResultsFish

ResultsWater Quality

• Water Temperature– No difference between habitats

• Specific Conductance– Higher in canal habitat than bayou habitat (P =

<0.0001, α = 0.05)

• Dissolved Oxygen– Higher in canal habitat than bayou habitat (P =

<0.0001, α = 0.05)

ResultsWater Quality

• Hypoxic Waters• Canal - solid

– 15% of trips

• Bayou - dashed– 62% of trips– 54 day period

ResultsWater Quality

• Water Color• Sediment laden

= black• Mixed = gray• Tea = open• No green or

black water

ResultsWater Quality

Floodplain inundation

ResultsWater Quality PCA

• PC1 (x-axis) and PC2 (y-axis) account for 86.4% of variation

Variable PC1 PC2

Temperature (°C) -0.199 0.971

Dissolved Oxygen (mg/L) 0.684 0.234

Specific Conductance (µS) 0.702 0.048

Results Vegetation

• Submerged Aquatic Vegetation– Coontail - Ceratophyllum demersum – Hydrilla - Hydrilla verticillata *– Fanwort - Cabomba caroliniana

• Floating Aquatic Vegetation– Salvinia - Salvinia minima *– Water hyacinth - Eichhoria crassipes *– Water lettuce - Pistia stratiotes *

ResultsVegetation

• No vegetation at canal sites 1 and 2

ResultsLarval Fish

• 2,164 Larval fish collected

ResultsLarval Fish

Species Collection Period N Temperature DO Specific Conductance

Dorosoma spp. 3/17/07 – 7/21/07 76* 25.7 ± 0.3 2.8 ± 0.19* 249 ± 7.7*

Ictiobus spp. 3/7/07 – 3/29/07 972* 20.8 ± 0.7 2.5 ± 0.36* 221 ± 6.5*

Lepomis spp. 3/29/07 – 9/5/07 1,050* 27.6 ± 0.2 2.9 ± 0.18* 223 ± 7.0*

Pomoxis spp. 3/17/07 – 3/29/07 64 22.2 ± 0.6 1.9 ± 0.22* 228 ± 7.8*

• Rare Larvae– Cyprinus carpio N=2

ResultsLarval Fish

ResultsLarval Fish

Normoxic (black) VS Hypoxic (open) Collections

Results Larval Dorosoma spp.

• Greatest CPUE - 17 March 2007 • Canal VS Bayou

– CPUE was greater in canal habitat

Percentage of spent and not-spent females collected in Bayou Chevreuil

0

20

40

60

80

100

11/14/2005 2/4/2006 4/27/2006 7/18/2006 10/8/2006

%

Non-spent Spent

3/28/06

7/31/06

Larval Dorosoma spp.

• CPUE / Water Quality– Weakly negatively correlated to

temperature (P=0.0011, R2=0.093) – No correlation with specific conductance– No correlation with dissolved oxygen

Results Larval Ictiobus spp.

• Greatest CPUE - 17 March 2007 • Canal VS Bayou

– CPUE was greater in canal habitat

• CPUE / Water Quality– No correlations

ResultsLarval Ictiobus spp.

Results Larval Lepomis spp.

• Greatest CPUE - 31 May 2007 • Canal VS Bayou

– CPUE was greater in canal habitat

• CPUE / Water Quality– No correlation with temperature– Weakly positively correlated with specific

conductance (P=0.0005, R2=0.0813)– Weakly positively correlated with dissolved

oxygen (P=<0.0001, R2=0.1264)

ResultsLarval Lepomis spp.

ResultsLarval Lepomis spp.

ResultsLarval Lepomis spp.

Results Larval Pomoxis spp.

• Greatest CPUE - 17 March 2007 • Canal VS Bayou

– CPUE not different– No larvae collected at sites 1 and 3

• CPUE / Water Quality– No correlation with temperature– Weakly negatively correlated with specific

conductance (P=0.013, R2=0.282)– No correlation with dissolved oxygen

ResultsLarval Pomoxis spp.

0

1.1

2.2

3.3

March 17 March 23 March 29

Mea

n (±

SD

) Ca

tch

Per

Un

it E

ffo

rt

ResultsJuvenile Fish

• 1,936 Juvenile fish collected

ResultsJuvenile Fish

Species Collection Date N Temperature DO

Specific Conductance

Gambusia affinis 3/29/07 – 9/25/07 1,689 27.6 ± 0.22 2.8 ± 0.17* 218.2 ± 6.9*Heterandria formosa

4/12/07 – 9/5/07 84* 27.7 ± 0.24 2.9 ± 0.19* 221.0 ± 7.3*

Lepomis spp. 5/13/07 – 9/25/07 84 28.5 ± 0.20 2.7 ± 0.20* 194.2 ± 7.4*

ResultsJuvenile Fish

Species Collection date N Collection Sites

Lepisosteus oculatus 5/19/2007 – 6/20/2007 8 4, 5, 6, 7

Anchoa mitchilli 5/31/2007 – 6/20/2007 6 1, 2, 3

Notemigonus crysoleucas 8/16/2007 1 7

Ictalurus punctatus 5/13/2007 – 6/15/2007 5 1, 2, 6

Poecilia latipinna 6/7/2007 – 9/5/2007 27 1, 3, 4, 5, 6, 7

Menidia beryllina 5/31/2007 – 6/7/2007 6 2

Syngnathus scovelli 6/7/2007 1 3

Pomoxis spp. 4/12/2007 – 5/19/2007 3 1, 3, 7

Elassoma zonatum 4/18/2007 – 7/12/2007 13 1, 3, 5, 6, 7

ResultsJuvenile Fish

ResultsJuvenile Fish

Normoxic (black) VS Hypoxic (open) Collections

Results Juvenile Gambusia affinis

• Greatest CPUE - 21 July 2007 • Canal VS Bayou

– CPUE not different

• CPUE / Water Quality– Weakly positively correlated with temperature

(P = 0.0012, R² = 0.067)– Weakly negatively correlated with specific

conductance (P = 0.0086, R² = 0.045)– No correlation with dissolved oxygen

ResultsJuvenile Gambusia affinis

Results Juvenile Heterandria formosa

• Greatest CPUE - 2 May 2007• Canal VS Bayou

– CPUE greater in bayou habitat

• CPUE / Water Quality – No correlations

• CPUE / Lunar Illumination– Greater at illuminations of ≥75%– Weakly positively correlated with lunar

illumination (P = 0.0049, R² = 0.362)

Results Juvenile Heterandria formosa

Results Juvenile Lepomis spp.

• Greatest CPUE - 13 May 2007 • Canal VS Bayou

– CPUE not different

• CPUE / Water Quality – Weakly negatively correlated to temperature

(P=0.0019, R2=0.08) – No correlation with specific conductance– No correlation with dissolved oxygen

Results Juvenile Lepomis spp.

ResultsLarval and Juvenile PCA

• PC I (x-axis) and PC II (y-axis) account for 42.1% of the variation

Species PC1 PC2

Dorosoma spp. -0.517 -0.406

Ictiobus spp. -0.643 -0.074

Gambusia affinis 0.291 -0.087

Heterandria formosa 0.267 -0.017

Lepomis spp. larvae 0.084 -0.693

Lepomis spp. juveniles 0.195 -0.558

Pomoxis spp. -0.343 0.176

Periodic

Equilibrium

Opportunistic

Results

Results

Conclusions Spawning / Collection Period

• Similar to expected• Tidal Influence

– Menidia beryllina – Anchoa mitchilli

Conclusions Absent Species

• Absent Species– Amia calva – Bowfin or Choupic– Ameiurus spp. – Bullhead– Aphredoderus sayanus – Pirate Perch– Fundulus chrysotus – Golden Topminnow– Morone spp. – Yellow Bass– Micropterus salmoides – Largemouth Bass

• Possible causes– No reproduction– Not present in littoral zone– Not vulnerable to sampling gear – Size (opening = 3.2 ± 0.5mm)

Conclusions Upper Barataria Estuary Hydrology

• No Predictable Flood Pulse– Lack of reproductive cue– Limit access to floodplain habitat

• Lack of Flushing– Chronic hypoxia

• Barrier to Fish Movement– Small diversions– Gulf Intracoastal Waterway

Conclusions Upper Barataria Estuary Hydrology

Conclusions Upper Barataria Estuary Fish Reproduction

• Periodic strategists– Prefer canal habitat– No difference b/t hypoxic / normoxic waters– May prefer lotic habitat

• Equilibrium strategists– Prefer canal habitat– Prefer normoxic waters– Extended reproductive period

• Spawn during optimal environmental conditions

• Opportunistic strategists – Common in both habitats– Adapted to hypoxic waters– Exploit shallow edge habitat– High reproduction rate

Conclusions Upper Barataria Estuary Fish Reproduction

• Effects of Altered Hydrology– Non-opportunistic species prefer dredged canal habitats– Lepomis spp. / Bayou Habitat

• Abundant spawning habitat • Little larval production

– May conform to Low Flow Recruitment Hypothesis– May affect all components of V-O-R model

Conclusions Upper Barataria Estuary Ecosystem Health

• Vigor – Reduction of fisheries production

• Loss of habitat• Chronic hypoxia

• Organization– Shift in species composition– Reduction of diversity

• Resilience – Loss of river connectivity – Slow repopulation after environmental stress

Recommendations

• Restore Mississippi River Connection– River water flushing

NOT

Research Suggestions

• Fixed continuous water quality data recorders

• Fish reproduction and recruitment– Quarterly electrofishing surveys at fixed

sites in different habitats– Multiple year light trap and push net

monitoring of larval and juvenile fish

Questions?

Larval FishPreflexion larvae

Postflexion larvae

Early juvenile

Fully formed fins

Larval Fish Identification

Postanal myomeres Preanal myomeres

18 10

Melanophores Swim bladder pigmentation

Genus: Lepomis