1

BENTHIC COMMUNITY STRUCTURE AND BIODIVERSITY BENTHIC COMMUNITY STRUCTURE AND BIODIVERSITY FOLLOWING SEWAGE ABATEMENT PROGRAMS IN BOSTON FOLLOWING SEWAGE ABATEMENT PROGRAMS IN BOSTON

HARBOR HARBOR

By

James A. Blake, Nancy J. Maciolek ENSR Marine & Coastal Center, Woods Hole, MA

&Kenneth Keay

Massachusetts Water Resources Authority, Boston, MA

2

Clean-up of Boston HarborClean-up of Boston Harbor

End Sludge disposal (1991) Development of New Sewage Treatment Facilities and

offshore outfall Upgrade Sewage to Secondary Treatment (1997–2000) Transfer Sewage Outfalls from Boston Harbor To

Massachusetts Bay (September 2000) On-going CSO improvement program

3

Benthic Community Monitoring in Boston HarborBenthic Community Monitoring in Boston Harbor

Surveys performed for the MDC as part of the 301(h) Waiver Applications: 1978, 1979, 1982

Formal Monitoring by MWRA began in September 1991

April and August Sampling from 1992−2002

August Sampling continued since 2003

Total of 17 Years of Benthic Monitoring: August/September 1991−2007 and continuing

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Nitrogen Loading and Sewage Abatement in Boston Nitrogen Loading and Sewage Abatement in Boston Harbor Harbor (after Taylor, 2006)(after Taylor, 2006)

PERIOD I PERIOD II PERIOD III PERIOD IV

YEAR 1991 1995 1997–2000 1998 2000

Nitrogen SourcesDeer Island and

Nut Island Outfalls

Deer Island and Nut Island Outfalls Deer Island Outfall Mass Bay Outfall

MILESTONE Sludge dumping ends

New primary treatment at DI

Upgrade to Secondary

Treatment at DI

Nut Island discharge

transferred to Deer Island (Inter-Island

transfer tunnel)

Deer Island Discharge

transferred from Boston Harbor to Mass Bay outfall

5

Benthic Sampling Benthic Sampling Stations in Stations in

Boston HarborBoston Harbor19911991−−20072007

T01: Deer Island Flats

T02: Governor’s Island Flats

T03: Long Island

T04: Dorchester Bay

T05A: President Roads

T06: Peddocks Island

T07: Quincy Bay

T08: Hingham Bay

C019: Inner Harbor CSO

Deer Island

Hingham/Hull Bay

Quincy Bay

Dorchester Bay

Presidents Roads

Little Brewsters

Broad Sound

42°2

3'42

°22'

42°2

1'42

°20'

42°1

9'42

°18'

42°1

7'42

°16'

42°1

5'42

°14'

71°00'71°01'71°02'71°01' 70°59' 70°58' 70°57' 70°56' 70°54' 70°53'70°55'

71°00'71°01'71°02'71°01' 70°59' 70°58' 70°57' 70°56' 70°54' 70°53'70°55'

42°23'42°22'

42°21'42°20'

42°19'42°18'

42°17'42°16'

42°15'42°14'

Kilometers

0 1 2 3

NGrab stations

Boston Harbor Stations

T01

T02

T03

T04T06

T07 T08

T05A

6

Deployment of the Deployment of the Ted Young grab Ted Young grab samplersampler

0.04-m0.04-m22 surface area surface area

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Looking for Evidence of ChangeLooking for Evidence of Change Changes in Faunal Abundance (density of organisms)

Changes in Species Richness (numbers of species)

Changes in Species Composition (i.e., opportunistic or stress-resistant species replaced by others)

Changes in Species Assemblages (community structure; functional groups)

Changes in Species Diversity (H′, ESn, Log-series alpha)

8

Changes in Faunal AbundanceChanges in Faunal Abundance

Boston Harbor

0

2000

4000

6000

8000

10000

12000

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Tota

l Abu

ndan

ce

Mean+/- 1SE

9

Long-term Trends in Species RichnessLong-term Trends in Species Richness

Boston Harbor

05

1015202530354045505560657075

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Num

ber o

f Tax

a

Mean+/- 1SE

10

Long-term Trends in Species Diversity: Long-term Trends in Species Diversity: alphaalpha

Boston Harbor

0123456789

1011121314

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Log-

serie

s Al

pha

Mean+/- 1SE

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Benthic parameters summarized by time periods Benthic parameters summarized by time periods defined by Taylor (2006) defined by Taylor (2006)

ParameterPeriod

I−II III IV1991–1998 1999–2000 2001–2005

Number of Samples n = 192 N = 47 n = 120

Number of Species 32.3 ± 14.3 32.0±12.5 42.3 ± 18.0H′ (base 2) 2.3 ± 0.9 2.8 ± 0.8 2.9 ± 0.8log-series alpha 5.2 ± 2.1 5.9 ± 1.9 7.7 ± 3.0ESn (rarefaction curves ) low high highest

Fauna

higher abundancesof opportunistic species such as Streblospiobenedicti andPolydora cornuta

Feweropportunists,more oligo-chaetes, somespecies from Massachusetts Bay

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Changes to Boston Harbor Benthos in 2005Changes to Boston Harbor Benthos in 2005

Amphipod mats entirely absent in 2005 Shifted from a biologically to physically dominated sediment surface

13

AmpeliscaAmpelisca Abundance: 1991 Abundance: 1991––20072007

Ampelisca spp. Total number sampled by grab at eight Boston Harbor stations each August

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Tota

l Num

ber p

er S

ampl

ing

Date

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Some benthic invertebratesSome benthic invertebrates in Boston Harbor in Boston Harbor

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Tota

l Abu

ndan

ce

Ampelisca spp. Nephtys cornuta Polydora cornuta Aricidea catherinae

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Nephtys Nephtys cornutacornutaAdultsAdults

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Nephtys Nephtys cornutacornutalarvaelarvae

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Amphipod Population Crash in 2005Amphipod Population Crash in 2005– Loss of habitat diversity– Commensurate decline in species richness and

diversity in 2005 and 2006– Populations stayed low in 2006, but slight recovery is

evident in 2007– Long-term reduction in organic loadings– Two unusual spring 2005 Nor’easters contributed to

amphipod population crash – Over-wintering adults swim into the water column in

the spring and the storms are believed to have caught these individuals and swept them away

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Deer Island

Hingham/Hull Bay

Quincy Bay

Dorchester Bay

Presidents Roads

Little Brewsters

Broad Sound

42°2

3'42

°22'

42°2

1'42

°20'

42°1

9'42

°18'

42°1

7'42

°16'

42°1

5'42

°14'

71°00'71°01'71°02'71°01' 70°59' 70°58' 70°57' 70°56' 70°54' 70°53'70°55'

71°00'71°01'71°02'71°01' 70°59' 70°58' 70°57' 70°56' 70°54' 70°53'70°55'

42°23'42°22'

42°21'42°20'

42°19'42°18'

42°17'42°16'

42°15'42°14'

Kilometers

0 1 2 3

NGrab stations

Boston Harbor Stations

T01

T02

T03

T04T06

T07 T08

T05A

Long-Term Results Long-Term Results for Individual Stations for Individual Stations

19911991−−20072007

T01 Deer Island Flats: significant improvement in species diversity and complete change in community structure

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Total Abundance at Station T01 (1991−2005)Total Abundance at Station T01 (1991−2005)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Tota

l Abu

ndan

ce

T01 Mean +/- 1 SE

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Diversity (Diversity (log-series og-series alphaalpha) at Station T01 ) at Station T01 (1991−2006)(1991−2006)

0

12

3

4

5

6

7

8

9

10

11

12

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Log-

serie

s Al

pha

T01 Mean +/- 1 SE

21

22

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PCA-H analysis of T01: 1991–2007PCA-H analysis of T01: 1991–2007

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Euclidean Euclidean Distance Distance BiplotBiplot

Station T01 Deer Island Flats (1991(1991––2007)2007)

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Overall Conclusions Relative to Sewage Overall Conclusions Relative to Sewage Diversion from Boston Harbor to Diversion from Boston Harbor to

Massachusetts BayMassachusetts Bay

Benthic communities in Boston Harbor have improved significantly since the diversion to the new outfall in September 2000

There is no evidence of any adverse impact on the infaunal benthos of Massachusetts Bay or Cape Cod Bay since the new outfall came on-line

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AcknowledgementsAcknowledgementsMassachusetts Water Resources Authority is thanked for

supporting this long-term monitoring program and leading the effort to clean up Boston Harbor

Field programs were successfully led by Isabelle P. Williams & Pamela Neubert

Laboratory analyses were managed by Isabelle Williams and Stacy Doner; important taxonomic contributions have been made by Brigitte Hilbig, Russ Winchell, Gene Ruff, Tim Morris, & Nancy Mountford

Interpretation has been enhanced by contributions from Bob Diaz, Don Rhoads, Gene Gallagher & Roy Kropp