Lower Trophic Level Indices of Biological Integrity

and Their Possible CBP Uses

Presentation to the Monitoring and Assessment Subcommittee

May 12, 2004 Meeting by

Claire Buchanan and Jacqueline JohnsonInterstate Commission on the Potomac River Basin

“Lower Trophic Levels”

Phytoplankton

Benthos

SAV Zooplankton

Source to Resource

SourceWater

Quality

LowerTrophicLevels

Resource

Biological Integrity• “the capability of supporting and

maintaining a balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of the natural (minimally impaired) habitat...”

(Karr and Dudley 1981)

• Healthy biological communities are:– more resilient to natural and man-made disruptions – require minimal external support from management

Index Development Steps

• Assess Habitat• Select Metrics• Score Metrics• Score Index • Validate Index

SAV

• Restoration Goals – Not an IBI– May be used like an IBI– “Reference sites” derived from historic

data– Poor water clarity is major stressor

Benthos

Restoration Goals Led to B-IBI•Reference Site Criteria

- No highly developed watersheds, no known point source discharges, and no toxic pollutants

- Low total organic content in sediments- Bottom dissolved oxygen

All records >2 mg DO liter-1 90% records >3 mg DO liter-1 80% records >5 mg DO liter-1

Benthic IBIs• strongly reflect seasonal habitat conditions• communities “meeting goal”:

– high abundance and high diversity of taxa– pollution sensitive species dominate– diverse feeding guilds

IBI Classification Efficiencies (Summer)

Tidal Fresh 66%

Oligohaline 73%

Low Mesohaline 78%

High Mesohaline Sand

82%

High Mesohaline Mud 88%

Polyhaline Sand 97%

Polyhaline Mud 95%

— 5 meets goal— 3

— 1— 2.1— 2.7 marginal

degraded

severely degraded

IBI Scale

Phytoplankton

• Reference Criteria for Samples in All Seasons

– Low phosphorus (PO4)and

– Low nitrogen (DIN) and

– Relatively high light (Secchi depth)

Phytoplankton IBIs

IBI Classification Efficiencies

IBI Scale

5 — 4 3 2 1 —

goodfair-goodfairfair-poorpoor

----

• strongly reflect immediate water quality conditions• reference, or “good,” communities:

- no nuisance algal blooms - associated with high DO and good water clarity- often higher median biomass (consistent good supply)

Spring Summer

Tidal Fresh

69% 78%

Oligohaline

71% 76%

Mesohaline

75% 73%

Polyhaline 84% 81%

Zooplankton

• POLYHALINE Reference Criteria for Summer Samples

– Low phosphorus (PO4)and

– Low nitrogen (DIN) and

– Relatively high light (Secchi depth)

Same as phytoplankton

***

Zooplankton

MESOHALINE Reference Criteria for Summer Samples

• Phytoplankton reference habitat criteria aren’t very effective…

• low DIN and • low PO4 and • low chlorophyll a and • high diatom biomass and • low dinoflagellate biomass (CART analysis)

Zooplankton

IBI Scale

5 — 4 3 2 1 —

goodfair-goodfairfair-poorpoor

----

IBI Classification Efficiencies

Summer

Mesohaline

78%

Polyhaline 88%

• reflect water quality and algal food conditions

• reference, or “good,” communities:

– higher median abundance & biomass, esp. copepods

– more “blooms” (desirable for fish)

– greater diversity (more robust)

Food Availability

Index

Poor: < 5 / liter

Anadromous Fish Spawning & Nursery Areas

(Mesozooplankton liter-1)

Below Minimum: 5 to 15 / liter

Minimum: 15 to 25 / liter

Optimal: > 25 / liter

Upper Bay

PotomacPatuxent

Choptank

Rappahannock

York

James

Analysis Tools at Hand

• SAV Restoration Goals• Benthic Restoration Goals and

IBI• Phytoplankton IBI• Zooplankton IBI, FAI, Habitat

Index

1. Confirm Achievement of Designated Uses

DO, water clarity, and chlorophyll a criteria are protective of designated uses

Criteria attainment doesn’t guarantee achievement of designated uses

Designated Uses

Ex. Potomac Shallow Water Habitats

Water Clarity Criteria Attainment0% 100%

Dry Years Wet Years

SAV Goal

Ex. Potomac Deep Water Habitats

Dissolved Oxygen Criteria Attainment60%

100%

Dry Years Wet Years

3.6 2.1 2.4 3.0 2.1 2.6 1.9

2.4 - - 3.3 1.6 2.2 1.3

Benthic IBI

Ex. Potomac Open Water Habitats

2.0 1.9 2.4

1.8 2.2 2.8

Risk of Algal Blooms100% 0%

Dry Years Wet Years

Phytoplankton IBI

2. Components in Index of Ecosystem Integrity (IEI)

• Ecological Integrity – “sum of balanced, integrated, and

adaptive chemical, physical, and biological data can be equated with ecological integrity”

(Karr and Dudley 1981)

Jordan and Vaas 2000“An Index of ecosystem integrity for Northern Chesapeake Bay” Environmental Science and Policy 3:S59-S88

• DIN• PO4

• Secchi depth• Chlorophyll a• Bluegreen and dinoflagellate biomasses• Ratio of mesozooplankton to microzooplankton• Microzooplankton biomass• Benthic restoration goal values (pre-IBI index)• % DO observations <1 ppm in bottom waters or <5ppm

above pycnocline• % SAV Tier 1 goal achieved• Index of relative proportions of carnivores, planktivores

and benthivores for fish• Number of species in bottom trawl

3. Mechanism for Coupling WQ & Fisheries Models

SourceWater

Quality

LowerTrophicLevels

Resource

WatershedModel

3D WaterQuality Model

EcoPath/EcoSimModel

Model elements Phytoplanktonin common: SAV

BenthosZooplanktonOysters

4. Fisheries Ecosystem Planning

• Habitat, Habitat Requirements and Habitat Management (Element 3)– Assess habitat value using habitat requirements– Produce habitat suitability maps

• Indicators of Ecosystem Health and Biological Reference Points (Element 6)– Use data from long-term monitoring data sets– Evaluate usefulness of existing indicators– Develop a framework in which to use indicators

Summary of Possible CBP Uses

• Confirm Achievement of Designated Uses

• Develop Index of Ecosystem Health

• Provide a Mechanism to Couple WQ and Fisheries Models

• Fisheries Ecosystem Planning

Data Time Line

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

MD_PPCBP_LTBMEPA_EMAP

B-RGIB-IBI_V1B-IBI_V2

CBP_PHYTOPHYTO_INDRGI-PHYTO

P-IBI

CBP_ZOOLSBHI

ZOO_INDRGI-ZOO

Z-IBI

VIMS_STUDYVIMS_STUDY

CB_STUDYMD_ONLYVA_ONLY

CBP_SAV_1CBP_SAV_2

TECH_SYN_V1TECH_SYN_V2

Benthic Programs

Phytoplankton Programs

Zooplankton Programs

First CB Agreement Start LR Data Management Program

Start Plankton QA Program

SAV PROGRAMS

IC SAV GOALS 1989, 1990 & 1993

Acknowledgements

the CBP monitoring programs, past and present

Supported by Interstate Commission on the Potomac River Basin & EPA Chesapeake Bay Program