Ecological Risks in the
Caloosahatchee Estuary:
A Conceptual Model Developed
through the Southwest Florida
Feasibility Study
Darren Rumbold, Ph. D
Professor of Marine Science
Depart. of Marine and Ecological Sciences
Coastal Watershed Institute
Florida Gulf Coast University
Southwest Florida Feasibility Study (SWFFS)
Purpose and Relationship to Comprehensive
Everglades Restoration Plan (CERP) and Critical
Projects
The Restudy recommended a
separate Comprehensive
watershed study for Southwest
Florida with the following
purposes
• Health of aquatic ecosystems
• Water flows
• Water quality (including appropriate
pollution reduction targets)
• Water supply (Lower West Coast Water
Supply Plan)
• Flood damage reduction
• Wildlife and biological diversity
• Natural habitat
• Recreation (opportunity)
Barnes, 2005
Benefits of Developing Conceptual Models?
• The process of creating a conceptual model is a
powerful learning tool.
• Conceptual models are easily modified as knowledge
increases.
• Conceptual models highlight what is known and not
known and can be used to plan future work.
• Conceptual models can be a powerful communication
tool. They provide an explicit expression of the
assumptions and understanding of a system for
others to evaluate.
• Conceptual models provide a framework for prediction
and are the template for generating more risk
hypotheses.
Barnes, 2005
Drivers
• Sea Level Rise
• Water Management
• Land Use &
Management
• Maintaining Navigation
Stressors
• Altered Estuarine
Salinity
• Altered Hydrology
• Input & Elevated Levels
of Nutrients, Dissolved
Organics & Toxins
• Boating & Fishing
Pressure
• Physical Alteration to
Estuary
Altered Salinity Regime
• While estuarine species are generally well
adapted to cope with varying salinity
conditions, larger shifts and timing of
freshwater discharges can be a problem.
– impacts the community structure and function of
phytoplankton, submerged aquatic vegetation
(SAV), macroalgae, benthos- particularly oysters
and fisheries
• Secondary, or indirect, effects on manatee
demographics and wading bird community
structure
Important to Clearly Identify and
Communicate Cascading Adverse Effects
• Primary, or direct, effects:
– occur when a stressor acts directly on the
assessment endpoint and causes an adverse
response
• Secondary, or indirect, effects:
– occur when the entity’s response becomes a
stressor to another entity
– are often a series of effects among a diversity of
organisms and processes that cascade through
the ecosystem
– may have greater ecological significance than
primary effect
Increased Nutrients &
Contaminants
• Biostimulants, e.g., inorganic and
organic nutrients, influence growth and
community structure of phytoplankton,
macroalgae, and microbes.
– Indirect effects on SAV, zooplankton, fish
and other aquatic organisms from: 1) light
attenuation, 2) altered dissolved oxygen
concentrations, and 3) biotoxins
• which, in turn, can have cascading effects on
manatee, dolphins and wading bird community
structure
Cloern 2001, Marine Ecology Progress Series
Table 1. Summary of findings of water quality assessments in the Caloosahatchee
Estuary, San Carlos Bay, Pine Island Sound and Matlacha Pass.
Waterbody
Upper
Caloosahatchee
(WBID 3240C)
Middle
Caloosahatchee
(WBID 3240B)
Lower
Caloosahatchee
(WBID 3240A)
Doering and
Chamberlain,
1998a
Chl a>11 ug/L
TP>state
median
TN>state
median
DO<WQS
Color rel. high
Chl a>11 ug/L
TN > state
median
TN>state
median
Janicki
Environ. Inc.,
2002b
Chl a>ref. site,
IWR
TN>ref. site
TP>historic, ref.
site
DO<historic, ref.
site, IWR
Turbidity>histori
c
Chl a>ref. site,
IWR
TN>ref. site
TP>ref. site
DO<ref. site,
IWR
Turbidity>ref.
site
Chl a>ref. site,
IWR
TN>ref. site
TP>historic, ref.
site
DO<historic, ref.
site, IWR
Turbidity>histori
c
FDEP,
2002; 2003c
Impaired for:
Chl a,
DO, coliform
Impaired for:
Chl a,
DO,
copper,
coliform
Impaired for:
Chl a,
DO,
copper,
lead,
biology
ERD, 2003d
Strong
gradient with
decreasing
conc. of most
constituents
with
increasing
dist. from
S79;
Chl a>11 ug/L
DO<WQS
Spike in
downstream
gradient in
ammonia,
TKN, TN and
Chl a.
Chl a>11 ug/L
Mean
DO>WQS
Janicki Environ
Inc., 2003e
Tetra Tech, Inc., 2004f
Unaccept. based
on informal IWR:
Chl a,
DO, coliform;
trend of declining
WQ in
BOD, TSS,
nutrients, secchi
depth
Decreasing trends in DO,
increasing trends in
turbidity, potassium and
TN;
Improvements in TP;
Water of Concern: Fecal
Coliform, DO, unionized
ammonia (tribs), nutrients,
iron, copper, conductance
(tribs)
Unaccept. based
on informal IWR:
Chl a,
DO, coliform;
trend of declining
WQ in
BOD, TSS,
nutrients, secchi
depth
Decreasing trends in DO,
increasing trends in
turbidity, BOD, TSS;
mixed trends in TP; Water
of Concern: Fecal
Coliform, DO, unionized
ammonia (tribs), nutrients,
iron, copper
Unaccept. based
on informal IWR:
Chl a,
DO, coliform;
trend of declining
WQ in
BOD, TSS,
nutrients, secchi
depth
Decreasing trends in DO,
increasing trends in
turbidity, TSS,
nitrite+nitrate, BOD, TP,
and fecal coliform; mixed
trends with TNand TKN,
Water of Concern: Fecal
Coliform, DO, nutrients,
iron, copper, conductance
(tribs)
Table 1. Continued.
Waterbody
Doering and
Chamberlain,
1998a
Janicki
Environ.
Inc.,
2002b
FDEP,
2002;
2003c
ERD,
2003d
San Carlos
Bay (WBID
2065H)
Chl a rel. low
TN>state
median
DO rel. high
Turbidity rel.
low; TSS >
state median
Pine Island
Sound
(WBID
2065E and G)
Chl a rel. low
TN>statewide
median
DO rel. high
TSS>state
median
Matlacha Pass
(WBID
2065F)
Chl a rel. low
TN>state
median
DO rel. high
not
assessed
No listed
impairment
not
assessed
SW coast
not assessed
not
assessed
Mercury
not
assessed
not
assessed
not
assessed
No listed
impairment
Impaired
for:
bacteria (in
shellfish)
Chl a<11
ug/L
Mean
DO>WQS
not
assessed
Janicki
Environ Inc.,
2003e
Tetra Tech, Inc.,
2004f
Assessed under
Matlacha Pass
DO, turbidity trends
not assessed;
Accept. based
on informal
IWR;
exceedances in
ammonia and
DO at some
stations
Accept. based
on informal
IWR;
improving
trends in secchi
depth and TN
Decreasing trends in
DO; Water of
Concern: Fecal
Coliform, DO
(Sanibel), nutrients
(St James City)
Decreasing trends in
DO, increasing trends
in turbidity
Water of Concern:
Fecal Coliform, DO
(Gator Slough)
Water of Concern:
nutrients
Increased Nutrients &
Contaminants
• Toxicants, both metals and organics (e.g.,
pesticides, pharmaceuticals and personal
care products) could be having insidious
effects on individuals (e.g.,
immunosuppression, behavior, etc.)
populations and community structure.
– Loss or contamination of prey can have
indirect effects on fish and wildlife
predators (e.g., sharks, dolphins, birds), as
well as human consumers
Input parameters might include:
water-column BOD, COD; sediment oxygen demand;
adsorption coeff., particle-size distribution, settling coeff.;
rates of nitrification, denitrification, mineralization and fixation;
reaeration rate (SA/vol., temp., turbulence, stratification,
algal growth, photosynthesis, respiration, settling rates;
light avail. (note, inter-dependence).
WQ PERFORMANCE MEASURE
Parameter
;
causal, response or both
WQS;
Component
specific
Basin
e.g., C43,
Tidal Caloosahatchee,
Estero, and BCB
Loading model
Process model,
Target
Constraint
Inflow v. outflow
concentration
e.g., ECOlab
loads
Empirical model,
TSS; Turbidity
DOC / DOM;
TN (NOx + TKN);
TP, SRP
Historical-based,
e.g., natural systems, OFW, etc.
e.g., regression
Reference site,
BMP effectiveness
as % reduction
Process model,
e.g., ECOlab
Fraction of
Freshwater
Method,
i.e., mass balance
Input parameters will include:
Land use
Soils
Topography
Land use-specific event mean conc.
Land use-sp. runoff coefficient
Many other simplifying assump.
Empirical model,
e.g., regression
e.g., 10K Island,
25th - 75th percentile
for a given salinity regime
Dissolved Oxygen;
Chl-a;
Color; Clarity / PAR
Coordinate w/
Natural
Systems Group
Eco-resource,
e.g., SAV, oysters, redfish; sawgrass
Habitat Units,
NEED TO CONNECT THE DOTs
Output Scale ???
Instantaneous minimum ---Seasonal means
Point - River segment - Spatially explicit
e.g., acres, lbs,
Catch per unit effort
Cloern 2001, Marine Ecology Progress Series
Simultaneous Effects of Multiple Stressors
“The presence of multiple stressors may either increase or dampen the temporal
and spatial variability seen in aquatic systems, depending on the interactions
among stressors and the influence of background environmental conditions and
sensitive species on the expression of stressor effects.” (Breitburg et al. 1999)
Breitburg et al. 1999
Barnes, 2005
Take Home Message
• Many people invested an incredible amount
of time and energy in the SWFFS developing
decision-support products such as the
conceptual model
• Although those products should serve as a
strong foundation, they can be improved
upon and expanded, especially the predictive
models linking stressors with eco-resources
• We are not under the same constraints as
SWFFS and so can develop an analysis plan
for research to fill data gaps, particularly on
simultaneous effects of multiple stressors
and indirect effects