HABITAT SUITABILITY INDEX MODEL FOR HABITAT SUITABILITY INDEX MODEL FOR

THE AMERICAN OYSTER, THE AMERICAN OYSTER, Crassostrea Crassostrea

virginicavirginica: IMPLICATIONS FOR : IMPLICATIONS FOR

RESTORATION AND ENHANCEMENT OF RESTORATION AND ENHANCEMENT OF

OYSTERS IN SW FLORIDA ESTUARIESOYSTERS IN SW FLORIDA ESTUARIES

Aswani K. Volety, Aswani K. Volety,

Florida Gulf Coast University Florida Gulf Coast University

Tomma Barnes, Tomma Barnes,

South Florida Water Management DistrictSouth Florida Water Management District

Leonard Pearlstine, Frank Mazzotti, Leonard Pearlstine, Frank Mazzotti,

University of FloridaUniversity of FloridaDo not

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RationaleRationale

• SW Florida is one of the fastest growing areas in the United States

• Watershed development and water management practices to accommodate development

• Interruption of sheet flow, water releases regulated through weirs

• Impact to water quality and salinity

• Altered flow regimeDo not

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RationaleRationale

• Caloosahatchee Estuary in SW Florida exhibiting impaired ecological health – hydrological alteration, agricultural land use, development, marinas

• Watershed management typified by large freshwater releases during wet (rainy) summer months and little or no releases during dry winter months

• FW releases from Lake Okeechobee for flood control and agricultural uses

• Water runoff and freshwater releases typically occur during summer, followed by storm water runoff depressing the salinities for extended periodsDo n

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RationaleRationale

• Information related to optimal timing, duration, frequency and quantity of FW releases into the Caloosahatchee River is lacking.

• Better communication between the resource managers and scientists in adjusting the FW flows to enhance and sustain oyster reefs in SW Florida estuaries is required.

• Ties in with the greater Everglades Restoration.

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Why Oysters?Why Oysters?

• Life History is typical of other estuarine

organisms

• Sessile, easy to monitor

• Ecologically important

• Has a well established linkage to stressors

of management interest

• Important fishery in Gulf of Mexico

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Need for a new HSI model?Need for a new HSI model?

• Oysters are physiologically adapted to local

environment (latitude and local conditions).

• Model needs to be optimized based on local

conditions and important factors.

• Adaptive management – policy decisions

• Identification of areas of restoration potential

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Project ObjectiveProject Objective

• Identify key factors (stressors) responsible for

success or failure of oyster reefs.

• Develop a Habitat Suitability Index (HSI)

model for oysters using Caloosahatchee estuary

as a model system.

• Portray spatially and temporally, each stressor

metric in the Caloosahatchee estuary and

incorporate it into a GIS to facilitate policy

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Study SiteStudy Site

Courtesy: SFWMD

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MethodsMethods

• Salinity, temperature, DO from sampling events

and continuous data recorders

• Flow Data from South Florida Water

Management District (in cubic feet per second )

• Perkinsus marinus infection prevalence and

intensity, juvenile growth, spat recruitment,

gonadal condition, and substrate maps.

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Current StudyCurrent Study

• Larval Component Index

• Presence of suitable cultch material

• Appropriate salinity mean

• Presence of other oysters/Spat recruitment

• Adult Component Index.

• Density of adult living oysters

• Historic mean water salinity

• Frequency of killing floods

• Mean intensity of disease, Perkinsus marinus.Do not

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HSI modelHSI model

Eastern Oyster Larval Component Index =

(Settlementw * Salinityw * Temperaturew * Floww)

Eastern Oyster Adult Component Index =

(Floww * Salinityw * Temperaturew * Disease / Predationw* Oyster

densityw * Frequency of Killing Floodsw)

Where Settlement = (Substratew * Recruitmentw) and

Flow = frequency of killing floods

HSI summer = (LarvaeComponentIndexw * AdultComponentIndexw)

HSI not summer = (AdultComponentIndex)

W = weight, 1/number of variables.

Weights can be different, but sum of weights must be equal to one.

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HSI Curves

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Modeling InterfaceModeling Interface

• Spatial display of model outcomes

• Edit component weights

• Review alternative outcomes

• Review overall index values and the

contribution of each component

•Spatially evaluate differences between

alternatives

•Report Habitat Units

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Basic SimulationBasic Simulation

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Data input Data input –– HSI calculationHSI calculation

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ReRe--weight weight -- SimulationSimulation

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Compare ResultsCompare Results

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Zoom Zoom --inin

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• Preferred flow frequency distribution for the Caloosahatchee

Estuary (est05) based on providing a full range of salinity along

its longitudinal axis that is supportive of naturally occurring

estuarine biota

• Existing conditions (2000RD) – land use

• Future conditions without any Comprehensive Everglades

Restoration Plan (CERP) projects (2050RD) – land use

Model Scenarios

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2000RD 2050RD

EST05

1982 flow data

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• A GIS integrated HSI model was created.

• Currently we are field testing the model using

existing data.

• Model has to be optimized for local conditions.

• Model will be valuable for making policy

decisions.

SummarySummary

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