David M. Nelson (presenter), and Mark E. Monaco

NOAA/NOS Biogeography Program

1305 East-West Hwy., 9th Floor

Silver Spring, Maryland 20910

A Habitat Affinity Index (HAI) was developed for fish and invertebrate species in estuarine waters of the Mid-Atlantic and Southeast regions. HAI defines habitat affinity based on the relative concentration of a species in a particular habitat, compared with the availability of that habitat in the study area. In the Mid-Atlantic region, EPA's EMAP program provided trawl survey data for 120 sites, 482 samples, July through September, for four consecutive years (1990-1993). In the Southeast region, EPA/EMAP trawl survey data were for 153 stations, July through September, for two years (1994-1995). Dissolved oxygen, temperature, salinity, depth, substrate type, sediment contaminants and toxicity were measured at each site along with trawl catch by species and size. Although most estuarine species occur across a range of environmental gradients, many had discernible habitat affinities. In the Mid-Atlantic region, three-fourths of sciaenids had affinity for a particular salinity zone, whereas three-fourths of flatfish had affinity for a particular substrate type. In the Southeast region, the maximum catch of any given species was consistently greater at the non-polluted sites, although overall catch was not significantly greater at non-polluted sites. These analyses feature consistent sampling methods applied across an entire biogeographic province. In addition, a variance estimator allows statistical tests and comparisons among estuarine systems. A similar analysis is planned for Gulf of Mexico data.

I. Brief overview of NOS Biogeography Program.

II. Fish Habitat Affinity Index (HAI) in Mid-Atlantic region.

III. Habitat Affinity Index (HAI) in Southeast region.

IV. Relevance to Conservation Biology and GAP.

The Biogeography Program of NOAA's National Ocean Service (NOS) was formerly within the Strategic Environmental Assessments (SEA) Division. It is now part of Center for Coastal Monitoring and Assessment (CCMA) within NOS National Centers for Coastal Ocean Science (NCCOS). The NOS re-organization became effective in 1999.

The overall mission of NOS' Biogeography Program can be summarized with three questions:

1. What and where are the species?

2. What and where are the habitats?

3. What is the association between species and their habitats?

NOAA's Estuarine Living Marine Resources (ELMR) project was initiated in the 1980's, with these accomplishments to date:

• A database on distribution and relative abundance of 153 species in 122 estuaries nationwide was completed in 1994.

• Estuarine salinity zones (Seawater, Mixing, Tidal Fresh) provide the spatial framework (NOAA 1985).

• Data summary reports have been published for the West Coast, Gulf of Mexico, Southeast, Mid-Atlantic and North Atlantic regions (Monaco et al. 1990, Nelson et al. 1991, Nelson et al. 1992, Stone et al. 1994, Jury et al. 1994).

• Life history summary reports have been published for the West Coast and Gulf of Mexico (Emmett et al. 1991, Pattillo et al. 1997).

• A national report summarizing the evolution and accomplishments to date will be published in late 1999 (Nelson and Monaco in prep.)

• ELMR data are being revised on a regional basis, using refined seasonal salinity zones (Orlando et al. 1993, 1994) as a spatial framework within GIS, and incorporating recent fishery-independent monitoring data sets.

• ELMR data have been used for developing estuarine Essential Fish Habitat (EFH) maps in Gulf of Mexico, Southeast, Mid-Atlantic, and New England regions (NOAA 1997, NOAA 1998, NOAA/GMFMC 1998)

• Other applications include Environmental Sensitivity Index (ESI) mapping (RPI 1997, RPI 1998).

Related projects within the Biogeography Program include:

• Habitat Suitability Modeling (Brown et al. 1997, Rubec et al. 1999).

• Analytical studies using ELMR and other specialized data sets (Monaco et al. 1992, Bulger et al. 1993, Bulger et al. 1995, Christensen et al. 1997, Monaco and Ulanowicz 1997).

• Incorporating ELMR and other data sets into NOAA's Coastal Assessment and Data Synthesis system (Orlando 1999).

II. Summer habitat affinities of estuarine fish in Mid-Atlantic region.

This study was published in 1998 in Fisheries Management and Ecology (Monaco et al. 1998), and reprints are available from the authors.

This study uses four years (1990-1993) of trawl survey data from estuarine waters of the Mid-Atlantic region, Massachusetts to Virginia. Data are from the U.S. EPA's EMAP Program (Environmental Monitoring and Assessment Program). Sampling occurred at 120 sites, July through September only, for a total of 482 samples. Dissolved oxygen (DO), temperature, salinity, depth, substrate type, sediment contaminants and toxicity were measured at each site along with trawl catch by species and size. Pollution stressed sites were excluded from this analysis, based on low DO and sediment toxicity.

A "Habitat Affinity Index" (HAI) is based on the "electivity index" for selection of prey, used by Ivlev (1961) and Strauss (1979). It defines habitat affinity based on the relative concentration of a species in a particular habitat, compared with the availability of that habitat in the study area. HAI varies from -1 to +1 for a given species within a given habitat, where -1 = complete absence from habitat, 0 = neutral with respect to habitat, +1 = exclusive presence in habitat. A variance estimator for HAI allows development of confidence intervals and statistical tests.

Results of the study can be summarized as:

• Spot and white perch represented the highest proportion of the catch, but hogchoker was the most ubiquitous species.

• Although most estuarine species occur across a range of environmental gradients, many had discernible habitat affinities.

• Salinity was the dominant factor affecting species distribution among estuarine habitats.

• Three-fourths of sciaenids had affinity for a particular salinity zone.

• Three-fourths of flatfish had affinity for a particular substrate type.

Strengths of the analysis can be summarized as:

• Consistent sampling methods across an entire biogeographic province.

• Enables comparisons among estuarine systems.

• Variance estimator allows statistical testing.

Weaknesses of the analysis can be summarized as:

• Sampling is in summer only, so seasonal migrations are not accounted for.

• Shallow, vegetated estuarine habitats not sampled by trawl survey.

• Larval and early juvenile life stages not captured by trawl gear.

III. Summer habitat affinities of South Atlantic estuarine species.

This study has been submitted to Estuaries (Monaco et al. in press), but not yet published as of September 1999. A similar study using EPA/EMAP data from Gulf of Mexico estuaries is in progress.

This study uses two years (1994-1995) of EPA/EMAP trawl survey data from estuarine waters of the South Atlantic region, from North Carolina to Florida, 153 stations, July through September only. Dissolved oxygen (DO), temperature, salinity, depth, substrate type, sediment contaminants and toxicity were measured at each site along with trawl catch by species and size. A "Habitat Affinity Index" (HAI) is derived similar to the Mid-Atlantic analysis.

The primary objective is to define HAI's at undegraded sites, to represent the "natural" habitat affinities of species without the confounding effects of pollution.

a secondary objective is to compare species catch and HAI values at undegraded vs. degraded sites. To meet these objectives, pollution-stressed (degraded) sites (based on low DO and sediment toxicity) were partitioned for analysis, and compared with undegraded sites.

Why use HAI, rather than a multivariate regression approach for environmental parameters?

• Data sets are not normally distributed, and not robust enough to apply standard parametric statistics.

• HAI has a variance estimator which allows statistical testing.

Results can be summarized as:

• Atlantic croaker, white shrimp, and spot represented the highest proportion of the catch, but blue crab was the most ubiquitous species.

• Although most estuarine species occur across a range of environmental gradients, many had discernible habitat affinities.

• As in the Mid-Atlantic analysis, salinity was the dominant factor affecting species distribution among estuarine habitats.

• All sciaenids had affinity for a particular salinity zone.

• All invertebrates had affinity for a particular substrate type.

• Although overall catch was not significantly greater at undegraded sites, the maximum catch of any given species was consistently greater at the undegraded sites.

• The habitat affinities demonstrated at undegraded sites are less discernible at the degraded sites. For example, the salinity zone affinity of Atlantic croaker and substrate affinity of hogchoker are evident at undegraded sites, but less so at degraded sites.

IV. Relevance to Conservation Biology and Gap Analysis Program.

• These habitat affinity studies help to describe particular habitat parameters which are essential for given species. This may be useful in which estuarine waters to designate for special management or protection.

• The Habitat Affinity Index (HAI) and Habitat Suitability Modeling (HSM) studies represent tools which may be useful in refining our knowledge of the association between species and their habitats.

• The ELMR database provides a baseline of information on estuarine species and habitats on a regional and national basis.

• Applications of the ELMR data base are demonstrated in recent Essential Fish Habitat (EFH) amendments to Fishery Management Plans (FMP's) in the Gulf of Mexico, South Atlantic, Mid-Atlantic, and New England regions

Brown, S.K., K.R. Buja, S.H. Jury, M.E. Monaco, and A. Banner. 1997. Habitat Suitability Index Models for Casco and Sheepscot Bays, Maine. NOAA/NOS SEA Division, Silver Spring, MD. 86 p.

Bulger, A.J., B.P. Hayden, M.E. Monaco, D.M. Nelson, and M.G. McCormick-Ray. 1993. Biologically-based estuarine salinity zones derived from a multivariate analysis. Estuaries 16(2):311-322.

Bulger, A.J., T.A. Lowery, and M.E. Monaco. 1995. Estuarine-catadromy: A life history strategy coupling marine and estuarine environments via coastal inlets. NOAA/NOS SEA Division, Silver Spring, MD. 110 p.

Christensen, J.D., M.E. Monaco, and T.A. Lowery. 1997. An index to assess the sensitivity of Gulf of Mexico species to changes in estuarine salinity regimes. Gulf Res. Rep. 9(4):219-229.

Emmett, R.L., S.L. Stone, S.A. Hinton, and M.E. Monaco. 1991. Distribution and abundance of fishes and invertebrates in West Coast estuaries, Volume II: Species life history summaries. ELMR Rep. No. 8. NOAA/NOS SEA Division, Rockville, MD. 329 p.

Ivlev, V.S. 1961. Experimental ecology of the feeding of fishes. Yale Univ. Press, New Haven, CT.

Jury, S.H., J.D. Field, S.L. Stone, D.M. Nelson, and M.E. Monaco. 1994. Distribution and abundance of fishes and invertebrates in North Atlantic estuaries. ELMR Rep. No. 13. NOAA/NOS SEA Division, Silver Spring, MD. 221 p.

Monaco, M.E., and R.E. Ulanowicz. 1997. Comparative ecosystem trophic structure of three U.S. mid-Atlantic estuaries. Mar. Ecol. Prog. Ser. 161:239-254.

Monaco, M.E., D.M. Nelson, R.L. Emmett, and S.A. Hinton. 1990. Distribution and abundance of fishes and invertebrates in West Coast estuaries, Volume I: Data summaries. ELMR Rep. No. 4. NOAA/NOS SEA Division, Silver Spring, MD. 232 p.

Monaco, M.E., R.S. Easton, and J.L. Hyland. In press. Summer habitat affinities of U.S. South Atlantic estuarine species via an index approach. Estuaries 00:000-000.

Monaco, M.E., S.B. Weisberg, and T.A. Lowery. 1998. Summer habitat affinities of estuarine fish in U.S. Mid-Atlantic coastal systems. Fish. Manag. Ecol. 5:161-171.

Monaco, M.E., T.A. Lowery, and R.L. Emmett. 1992. Assemblages of U.S. west coast estuaries based on the distribution of fishes. J. Biogeography 19:251-267.

Nelson, D.M. (ed.), M.E. Monaco, C.D. Williams, T.E. Czapla, M.E. Pattillo, L.C. Clements, L.R. Settle, and E.A. Irlandi. 1992. Distribution and abundance of fishes and invertebrates in Gulf of Mexico estuaries, Volume I: Data summaries. ELMR Rep. No. 10. NOAA/NOS SEA Division, Rockville, MD. 273 p.

Nelson, D.M., and M.E. Monaco. In prep. National Overview and Evolution of NOAA's Estuarine Living Marine Resources (ELMR) Program. NOAA/NOS Biogeography Program, Silver Spring, MD.

Nelson, D.M., M.E. Monaco, C.D. Williams, T.E. Czapla, M.E. Pattillo, L. Coston-Clements, L.R. Settle, and E.A. Irlandi. 1991. Distribution and abundance of fishes and invertebrates in southeast estuaries. ELMR Rep. No. 9. NOAA/NOS SEA Division, Rockville, MD. 177 p.

NOAA. 1985. National Estuarine Inventory: Data atlas. Volume 1. Physical and Hydrologic Characteristics. NOAA/NOS Strategic Assessment Branch, Rockville, MD, 103 p.

NOAA. 1997. Work plan: Products and Services for the identification of Essential Fish Habitat in the South Atlantic region. NOAA/NOS SEA Division, and South Atlantic Fishery Management Council, 13 p.

NOAA. 1998. Work plan: Products and Services for the identification of Essential Fish Habitat in the Mid-Atlantic and New England regions. NOAA/NOS SEA Division, and NOAA/NMFS Howard Lab., 8 p.

NOAA/GMFMC. 1998. Product overview: Products and services for the identification of essential fish habitat in the Gulf of Mexico. NOAA/NOS SEA Division, NOAA/NMFS Galveston Lab, and Gulf of Mexico Fishery Management Council. 11 p.

Orlando, S.P. 1999. NOAA’s National Coastal Assessment and Data Synthesis Framework. NOAA/NOS Special Projects Office, Silver Spring, MD. 4 p.

Orlando, S.P., Jr., L.P. Rozas, G.H. Ward, and C.J. Klein. 1993. Salinity Characteristics of Gulf of Mexico Estuaries. NOAA/NOS SEA Division, Silver Spring, MD. 209 p.

Orlando, S.P., Jr., P.H. Wendt, C.J. Klein, M.E. Pattillo, K.C. Dennis, and G.H. Ward. 1994. Salinity Characteristics of South Atlantic Estuaries. NOAA/NOS SEA Division, Silver Spring, MD. 117 p.

Pattillo, M.E., T.E. Czapla, D.M. Nelson, and M.E. Monaco. 1997. Distribution and abundance of fishes and invertebrates in Gulf of Mexico estuaries, Volume II: Species life history summaries. ELMR Rep. No. 11. NOAA/NOS SEA Division, Silver Spring, MD. 377 p.

RPI. 1996. Sensitivity of Coastal Environments and Wildlife to Spilled Oil, North Carolina, A Coastal Atlas. Three volumes. Prepared by Research Planning, Inc. for NOAA. Volume 1, 14 text pages, 35 maps; Volume 2, 16 text pages, 50 maps; Volume 3, 16 text pages, 49 maps.

RPI. 1997. Sensitivity of Coastal Environments and Wildlife to Spilled Oil, Georgia, A Coastal Atlas. Prepared by Research Planning, Inc., for NOAA. 16 text pages, 38 maps.

Rubec, P.J., J.C.W. Bexley, H. Norris, M.S. Coyne, M.E. Monaco, S.G. Smith, and J.S. Ault. 1999. Suitability modeling to delineate habitat essential to sustainable fisheries. American Fisheries Society Symposium 22:108-133.

Stone, S.L., T.A. Lowery, J.D. Field, S.H. Jury, D.M. Nelson, M.E. Monaco, C.D. Williams, and L.A. Andreasen. 1994. Distribution and abundance of fishes and invertebrates in Mid-Atlantic estuaries. ELMR Rep. No. 12. NOAA/NOS SEA Division, Silver Spring, MD. 280 p.

Strauss, R.E. 1979. Reliability estimates for Ivlev's electivity index, the forage ratio, and proposed linear index of food selection. Trans. Am. Fish. Soc. 108:344-352.