# Presentation: 035762

## Invertebrate Communities

- Florida Fish and Wildlife Conservation Commission

-     as Tools for Establishing
-         Minimum Flows and Levels
-                         in  Florida Streams

**Notes:**
Purpose of presentation is to justify use of aquatic invertebrate communities as a tool for setting minimum flows and levels in Florida streams.

## Florida’s Minimum Flows and Levels Statute (373.042 FS)

- Defines MFLs as “the limit at which further withdrawals would be significantly harmful to the water resources or ecology of the area.”

-  Calculated using “best available information.”

-   Charges water management districts with
-    establishing MFLs for water bodies within
-    their boundaries.

**Notes:**
In recognition of the need to manage water resources for all users and environmental concerns, the Florida Legislature created the state’s 5 water management districts, and included in the founding legislation a statute to establish minimum flows and levels in Florida water bodies.  The legislation defines minimum flows as “.........”, but, significantly, did not define the term “significant harm”.

A primary intent of the statute is that consumptive use permits will not be issued once levels decline to the established minima.

The legislation charged the water management districts with setting MFLs, and directed them to use the “best available information” in doing so.  Unfortunately, in many cases, there has not been a lot of information out there, and one of our goals is to rectify that situation.

## The Role of FWC in the Determining

-  Minimum Flows and Levels

-  Charged with protecting biological integrity
-    of fish and wildlife communities in
-    aquatic ecosystems.

-  Present role is to advise and provide data.

-   Developing science to enable us to provide
-    “best available information” and propose
-    specific flow regimes in specific systems.

**Notes:**
The FFWCC was not given a role in establishing MFLs by the legislature, but as the agency charged with protecting the state’s fish and wildlife resources, we believe we are mandated to play a substantial role.  Currently we comment on MFLs set by WMDs and we provide them with biological data that supports our concerns.

However, as we focusing more on the issue, we are beginning to develop the science that will allow us to propose specific flow regimes is specific systems.

## Invertebrate Instream Flow Group

-  Working Definition of  “Significant Harm”

-    _Organismal_: measured deviation in species
-    composition, population densities, or
-    relative abundance of species outside the
-    range of natural and seasonal variability.

-  Two Components

-   _Habitat_:  measured deviation of the areal
-   extent or density of habitat outside the
-   range of natural and seasonal variation.

**Notes:**
Of prime importance to us is the development of a definition of “significant harm” that ensures the ability to sustain ecological integrity in stream ecosystems by protecting native biodiversity and the ecological processes that maintain that diversity.  Our group in Gainesville has developed the working definition that you see here.  This definition has two components – one organism-based and one habitat-based.  Both components define significant harm as deviations outside the range of natural and seasonal variability. 

## The Role of Invertebrates in Freshwater Ecosystems

_**Food Web**_:  Essential to the transfer of energy from primary producers to tertiary consumers.

-   _**Ecosystem Processes**_:  Metabolic activities
-    vital to decomposition and nutrient cycling.

-   _**Ecological Indicators**_:  Invertebrate
-    community structure is indicative of past
-    and present habitat conditions and overall
-    environmental health.

**Notes:**
Invertebrates are among the most important of the biological components of stream ecosystems.  Their position in the food web is pivotal – they concentrate the products of photosynthesis for shipment up the food chain.  Most of my fishery biologist friends view them as fish food, but they are also critical to the diets of many amphibian, reptile, bird, and mammal species.

The feeding and digestive activities of Invertebrates is critical to decomposition and nutrient cycling in stream ecosystems,and, to stream ecologists, 
The structure of invertebrate communities is an important indicator of habitat and overall ecosystem health.

## Why Use Invertebrate Communities?

-  _**Sessile**_**:  **unable to escape disturbance;
-   community structure reflective of
-   prevailing environmental conditions.
_**                **_

-  _**Long-lived**_**:**  life cycles usually one year or
-   more; given suitable environmental conditions,
-   communities survive at a location indefinitely.

-  _**Flow sensitive**_**:**  invertebrate communities
-   require greater current velocities than fish
-   communities.

-  _**Easily sampled**_**:  **habitat-specific, quantitative.

**Notes:**
Why are we focusing on invertebrate communities in our MFL work?  Invertebrate communities are sessile.  Unlike fish or other animal communities, invertebrates cannot escape changing environmental conditions, hence their structure reflects ambient environmental conditions.

## Flow Sensitive Invertebrates

## Objectives

- Document existing (baseline) structure of invertebrate assemblages for the Santa Fe, Withlacoochee, and Ichetucknee Rivers.
- Assemble a database suitable for comparison with future data collections.
- Determine flow sensitive invertebrate taxa and their responses to changes in flow.

## Objectives

- Integrate biological and physical data to develop habitat suitability curves.
- Utilize methods of “Instream Flow Incremental Methodology” (IFIM) and Physical Habitat Simulation (PHABSIM) to  quantify habitat availability as a function of discharge.
- Determine optimum flow conditions to maintain suitable lotic habitats for invertebrate communities.