assessments 2 : what the biota can tell us about watershed condition k.e. limburg lecture notes

Assessments 2:

What the biota can tell us about watershed condition

K.E. Limburg lecture notes

26 March, 2002

Outline

1. Intro: a brief glimpse at a defining moment for KL

2. What we mean by “watershed health”

3. Biotic assessments – common methods

Biotic assessments – an introduction through a study by KL and colleagues in the Hudson River watershed

Research project:

“Larval fish use of tributaries of the Hudson” – R.E. Schmidt and K.E. Limburg

Goal: to quantify “larval fish flux” from tributaries to the mainstem – connecting the system pieces

Initial hypotheses:

1. Spawning would proceed from south to north (temperature effect)

2. More production in smaller streams

3. Anthropogenic effects might be important

Studied 16 tribs, in 4 “reaches” of the estuary: 1st to 9th order

• sampled weekly for 15 weeks in spring

• 4 teams sampled during same 48 hr period – synoptic survey

• collected fish larvae, measured flow, DO, pH

Some streams were sublime

Some had obvious problems!

Some streams were just mysterious at the time!

Methods

Dusk sampling…

“proto-GIS”

Method of quantifying land use

Results

Ln(1

+(#

fish/

m3 )

)

Strong spatial patterns

Tribs warmed up more or less simultaneously – we did not see a south-to-north trend in fish production

Size of stream did not appear to matter in this study

Land use type, in particular, land in urban and suburban uses, did!!

Main points:

Verified by other studies in other places

Watershed Health• How does land use change affect the ecological structure and function of a watershed?

• How can environmental change be linked to land use and economic change?

• What is/should be the role of watershed health and monitoring in designing policy?

• How does tributary health affect the larger ecosystem?

Ecosystem (and hence, watershed) health, qu’est-ce que c’est? - a concept that’s been around a long time, currently enjoying a comeback

• maintenance of “biotic integrity”

• resistance and/or resilience of systems in the face of disturbance

• absence of factors that degrade ecological population, community, and ecosystem structure and function

Waterways and water bodies are often good sites for assessing “watershed health”

-- why?

Low Human influence High

Met

ric B

Met

ric A

Ecosystem indicators of anthropogenic disturbance should ideally be sensitive to these factors, and not confounded by natural ones

(or at least possible to tease out the differences)

Federal, state, local agencies have really espoused this concept

So have many non-profit organizations

Possible to enlist the help of many volunteers (e.g., FL-LOWPA, Hudson R. Basin Watch)

US EPA

EPA Bioindicators homepage:

http://www.epa.gov/bioindicators/index.html

US EPA

US EPA

US EPA

US EPA

Assessing watershed health with biotic indicators:

The idea: organisms and ecosystems integrate and reflect the insults (or lack thereof) resulting from watershed-level processes

Some techniques have proven robust after 25+ years of testing; others in development

Indicators of ecosystem health can (should?) evaluate changes at levels of

•Population•Community/habitat•Whole-system

Metrics may not all be additive, although many schemes designed that way

1. Taxonomic soundness and easily recognized2. Cosmopolitan distribution3. Numerical abundance4. Low genetic and ecological variability5. Large body size6. Limited mobility and relatively long-life history7. Ecological characteristics are well known8. Suitable for use in laboratory studies

Ideal indicator species characteristics

(Resh and Rosenberg, 1993)

Uses fish community characteristics to assess aquatic health: includes for example

• Species richness & abundance• Total biomass (and distribution)• Ratio of native spp to introduced• Functional role ID (generalists vs specialists, detritivores, piscivores, etc)• Condition & health indices

Example: Index of Biotic Integrity (IBI)

IBI’s originally worked out for Ohio streams (James Karr and colleagues)

- in general, these are region-specific

- therefore, IBI’s must be calibrated to a given region

- for northern Mid-Atlantic drainages, a calibration study for a regional IBI will soon be published (Daniels et al., Transactions of the American Fisheries Society)

Other taxonomic can also be used as indicators of watershed condition – most, but not all, work is done in streams:

• benthic macroinvertebrates

• periphyton

• macrophytes (aquatic and wetland)

• birds (some work in PA and Southeast)

NY State biotic assessment website:

http://www.dec.state.ny.us/website/dow/stream/index.htm

This site is specifically for rapid bio-assessments using stream macroinvertebrates – contains a pictorial key and verbal descriptions

Pro’s and con’s of indicators