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

4 Nitrogen Loading and Sewage Abatement in Boston Harbor (after Taylor, 2006) PERIOD IPERIOD IIPERIOD IIIPERIOD IV YEAR – Nitrogen Sources Deer Island and Nut Island Outfalls Deer Island OutfallMass 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 Stations in Boston Harbor 1991−2007 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

6 Deployment of the Ted Young grab sampler 0.04-m 2 surface area

7 Looking 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 Abundance

9 Long-term Trends in Species Richness

10 Long-term Trends in Species Diversity: alpha

11 Benthic parameters summarized by time periods defined by Taylor (2006) Parameter Period I−IIIIIIV 1991– – –2005 Number of Samples n = 192N = 47n = 120 Number of Species32.3 ± ± ± 18.0 H′ (base 2)2.3 ± ± ± 0.8 log-series alpha5.2 ± ± ± 3.0 ESn (rarefaction curves ) lowhighhighest Fauna higher abundances of opportunistic species such as Streblospio benedicti and Polydora cornuta Fewer opportunists, more oligo- chaetes, some species from Massachusetts Bay

12 Changes to Boston Harbor Benthos in 2005 Amphipod mats entirely absent in 2005 Shifted from a biologically to physically dominated sediment surface

13 Ampelisca Abundance: 1991–2007

14 Some benthic invertebrates in Boston Harbor

15 Nephtys cornuta Adults

16 Nephtys cornuta larvae

17 Amphipod 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

18 Long-Term Results for Individual Stations 1991−2007 T01 Deer Island Flats: significant improvement in species diversity and complete change in community structure

19 Total Abundance at Station T01 (1991−2005)

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

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23 PCA-H analysis of T01: 1991–2007

24 Euclidean Distance Biplot (1991–2007) Euclidean Distance Biplot Station T01 Deer Island Flats (1991–2007)

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

26 Acknowledgements Massachusetts 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