Assessing Linkages between Nearshore Habitat and Estuarine Fish Communities in the Chesapeake Bay

1. Assessing Linkages between Nearshore Habitat and Estuarine Fish Communities in the Chesapeake Bay Donna Marie Bilkovic*, Carl H. Hershner, Kirk J. Havens, Marcia R. Berman, David Stanhope and Lyle Varnell Center for Coastal Resources Management Virginia Institute of Marine Science

2. Estuarine Indicator Research Programs in the United States ASC Atlantic Slope Consortium (ASC) Research Institutes involved include: Pennsylvania State, Smithsonian Environmental Research Center, East Carolina University andVirginia Institute of Marine Science

3. Stated GOAL of the Atlantic Slope Consortium “Our suite of indicators will produce integrated assessments of the condition, health and sustainability of aquatic ecosystems based on ecological and socioeconomic information compiled at the scale of estuarine segments and small watersheds, with clear linkages and connections to larger scales”. Brooks et.al., 2001 website: www.asc.psu.edu

4. Can nearshore habitat be linked with fish community integrity, and are these accurate indicators of aquatic ecosystem health? • Study Objectives • Develop and test fish community metrics that assess the health of shallow-water estuarine systems in the Mid-Atlantic • Assess relationships among shoreline condition, subtidal habitat, and fish community metrics • Assess potential relationship between watershed land use and shallow-water estuarine fish communities*. *Relationship between watershed land use and riparian land use observed for agricultural, forested and developed landscapes

6. Sampling Locations and Watershed Land Use on the Chesapeake Bay • 166,000 km2 watershed • 18,804 km of shoreline • 320 km long • 5.5 to 56 km wide • only 6.5 m average depth • 15 million people live in basin

7. Watershed Selection Selection Criteria • 25 Watersheds selected • Salinity regime = oligo-mesohaline • At least three watersheds in each land use class were sampled • Land use categories 1) forested • 2) agricultural • 3) developed

8. 5 SITES per watershed were sampled… • At each SITE we assessed • Habitat Condition • Shoreline (alteration) • Subtidal (physical structure) • Biotic Communities • Fish • Prey species • Water chemistry/physical

9. Habitat Assessments

10. Fish Community Metrics Fish Community Metrics Reference Species Richness/Diversity Measures Species Richness this paper Proportion of benthic-associated species Deegan et al. 1997 Number of dominant species (90% of total abundance) Deegan et al. 1997 Number of resident species Deegan et al. 1997 Fish Abundance Ln Abundance Deegan et al. 1997 Trophic Composition Trophic Index Jordan and Vaas 2000 Nursery Function Number of estuarine spawning species Deegan et al. 1997 Number of estuarine nursery species Deegan et al. 1997 Eight metrics were assessed for consistency as indicators of aquatic ecosystem health based on fish community structure and function.

11. Statistical Analyses • Assessment of applicability and consistency of metrics • Comparison among Fish Community Index scores, shoreline condition and subtidal habitat measures • Comparison of Fish Community Index with overall watershed land use patterns

12. Fish Community Metrics Assessment • Metrics were combined into an aggregate index by summing standardized individual metric values. • All but one of the examined fish community metrics was positively and highly correlated (r>0.5) with the summed metrics. • Total abundance was excluded from the final fish community index (FCI).

13. All Significant positive relationships

14. Except…

15. which indicated that the use of all the metrics, with the exception of total abundance, is supported for the development of a multi-metric FCI of the nearshore in coastal plain estuarine ecosystems. Additionally, we examined the metrics using PCA…

16. Fish Community Metrics Assessment • Metrics were combined into an aggregate index by summing standardized individual metric values. • All but one of the examined fish community metrics was positively and highly correlated (r>0.5) with the summed metrics. • Total abundance was excluded from the final fish community index (FCI).

17. Do Fish Respond to Variations in Nearshore Condition?

18. p<0.001; all different p=0.003; High vs.Minimal FCI scores were significantly different among all subtidal habitat categories. Higher scores were associated with increasing abundance of subtidal habitat FCI scores were significantly lower at sites with highly altered shorelines versus minimally altered shorelines. Fish Community and Habitat Comparisons

19. Watershed Land Use versus Fish p=0.03 • FCI scores were significantly lower in developed and agricultural watersheds versus forested watersheds.

20. Habitat Comparisons Increased shoreline condition was associated with increased available Subtidal structure (shelter for fish).

21. Developed Highly Altered Minimal Habitat Moderate Habitat Agricultural Moderately Altered Abundant Habitat Forested Unaltered

22. Summary • Seven of eight tested Fish Community Metrics were included in a final index, and may be useful indicators of biotic integrity in shallow water estuarine systems. • Linkages could be discerned between FCI scores and not only local habitat influences, but also on a larger watershed scale.Thus, HABITAT CONDITON shows promise as an indicator of estuarine health. • Linkages existed among habitat at various scales (e.g. Decreases in FCI scores were evident with developed watersheds and shorelines which were subsequently linked with the loss of subtidal habitat structure) • Future management tools?

23. Future Research • Assessment of shoreline • condition impacts on fish communities at multiple spatial scales • Acoustic habitat mapping in the nearshore and comparison of specific habitats with biota • Explore temporal trends in fish communities indices • Examine additional biological communities in association with shoreline condition (e.g. benthic macroinvertebrates). Ongoing continuous shoreline surveys extract information on shoreline condition (land use, structures, bank condition etc.) for comparison with biotic communities GPS Continuous Survey http://ccrm.vims.edu/gis/gisdata.html

24. For instance…a metric measuring benthic community health increased as shoreline and watershed land use exhibited more natural conditions

25. Thanks to: Colleagues at SERC, Penn State, ECU and VIMS; funding source: Environmental Protection Agency, STAR Program