Stream ecology of an urbanizing watershed in the New Jersey Pine Barrens

1. Stream ecology of an urbanizing watershed in the New Jersey Pine Barrens W.J. Cromartie*, J. Akers, D. Cummings, J. Cook, J. Leckenbush and G. Millar. Environmental Studies Program, Richard Stockton College, Pomona, NJ, USA

2. ABSTRACT In the NJ Pine Barrens, landuse, water chemistry and aquatic biota are changing as urban development encroaches. The watershed of Babcock Creek, in Atlantic County, presents an opportunity to study four tributaries, each of which has been affected in different ways by changing landuse. Viewed counter-clockwise, from south to north: Adams Branch is highly urbanized, with elevated pH, and the ditched streambed carries a heavy load of sand. Jack Pudding Branch has the most agricultural land and high pH. Its upper section is impounded and ditched as well. Babcock Creek, the central stem, is least disturbed. Much of its watershed is hardwood swamp or Atlantic white cedar forest. Mankiller Branch shows chemical alteration, possibly from highway runoff. There is a good correlation between pH and percent development within 1000 feet of the stream. The macroinvertebrate fauna of woody debris (submerged sticks 3-35 mm in diameter) provides a readily sampled assemblage for biological monitoring in low-gradient, blackwater streams. We collected replicated stick samples at eight sites, both upstream, near disturbed areas, and downstream at confluences, to test whether disturbance effects persisted. We sampled during three seasons over three years, including water chemistry data. We analyzed results using multivariate statistics and GIS. Adams branch is generally the most impoverished; flash flooding and shifting sediments may be responsible. Mankiller Branch had generally low invertebrate numbers. Jack Pudding Branch had low numbers, especially at the upstream site. Our results indicate that the macro-invertebrate assemblage on woody debris responds differently to each of the suspected impacts. These differences were seen both at upstream sites and near the confluences, although the land surrounding the confluences was relatively undisturbed. We therefore suspect that chemical changes, as well as increased sediment and physical alteration are responsible. key words: blackwater, macroinvertebrate, disturbance, biomonitoring

3. Babcock Creek watershed The Great Egg Harbor River Watershed is designated Watershed Management Area #15 by the NJ Department of Environmental Protection. Points shown are AMNET biomonitoring network sampling sites. NEW JERSEY

4. Sample points 2003-05

5. Babcock Creek above Spruce Street – Reference Site This branch shows the richest fauna of the four tributaries to Babcock Creek. The pH and SC are close to typical Pinelands levels or only slightly elevated (Zampella et al. 2001, 2003). Study Areas

7. Adams Branch – Ditched and unstable Adams Branch receives runoff from a regional shopping mall, the Atlantic City Racecourse, and two condominium developments. The stream is ditched almost its entire length and carries a heavy load of sand and urban trash. Trees along the channel are collapsing into the stream. Base flow is extremely low.

8. Figure 1. Hydrograph of Adams Branch, above, showing the flash flooding of this highly urbanized stream, contrasting with a more typical Pine Barrens stream, right, dominated by groundwater flow (Courtesy Dr. Claude M. Epstein).

9. Table 1. Selected landuse characteristics for the Babcock Creek watershed. Derived from NJ Department of Environmental Protection data. Analyzed with Arc GIS8 (ESRI Software)

10. FIELD RESEARCH METHODS Two samples of approximately 1-2 meters total length of woody debris, 5-35 mm diameter (total surface area 0.02-0.15 m2), were collected at each site, washed with a soft scrub brush over an 0.5 mm sieve and examined under a stereo microscope for any remaining invertebrates. Analysis showed that excluding the “handpicked” invertebrates did not materially affect the results. All invertebrates were preserved in 70% ethanol with 5% glycerin. Samples were sorted and invertebrates were identified to order, except Chironomidae, Simulidae and non-insects. Data were analyzed with the program PC-ORD (version 4 for Windows, MjM Software Design). Counts were converted to number per M2 of stick surface and log transformed. Simulids, which occurred in nearly all sites, were excluded from the analysis because their strong seasonality distorted the ordination results. Other infrequent groups were also omitted. Specific conductance (SC, values in microsiemens (mS)) and pH were measured in the field using Thermo-Orion electronic meters .

11. Table 2. Chemical characteristics, % development (in entire watershed) and major invertebrate taxa for sample sites in the Babcock Creek watershed 2003-2005. Samples are listed by total number of Trichoptera, from greatest to least

12. Trichoptera on woody debris: left, Hydropsyche and Chimarra, right, probably Brachycentrus or Micrasema

13. Figure 2. Detrended Correspondence Analysis: biplot of averaged macroinvertebrate data vs. environmental variables (pH, % development in 1000’ buffer and specific conductance). Axis 1 correlates to pH and % development; axis 2 correlates (weakly) to SC. Note that Babcock Creek and Adams Branch form distinct clusters in the DCA ordination space.

14. Figure 3. DCA scores for averaged data vs. PH, % developed within 1000’ and specific conductance (SC). The size of each triangle is proportional to the value for the variable being plotted.

15. Figure 4. DCA for a larger set of unaveraged samples in the entire GEHR watershed, showing the same variables plotted against the first two axes. The pattern seen in the Babcock watershed is evident here, although weaker

16. Figure 5. Biplot of DCA ordination vs. pH, % development in entire watershed and SC of the full dataset of 85 samples from the GEHR watershed. The pattern seen in the averaged results from the Babcock watershed alone is also apparent here. Compare figure 2.

17. Figure 6. Nonmetric Multidimensional Scaling (NMS) ordination of unaveraged Babcock watershed samples, plotted vs. pH to show that similar results are also obtained with this technique.

18. Figure 7. DCA ordination of averaged Babcock watershed samples, plotted vs. abundance of selected macroinvertebrate taxa. Note the similar pattern for Ephemeroptera, Plecoptera and Trichoptera (EPT). Chironomidae are abundant in nearly all samples, including the least disturbed sites, while snails are found only in the most altered streams.

19. Discussion This study reinforces our view that the fauna of woody debris is a good indicator of habitat conditions in low-gradient, blackwater streams in the New Jersey Pine Barrens. Snags and sticks are key habitats and contribute significantly to diversity and productivity in Coastal Plain rivers and streams (Benke et al. 1984, Benke and Jacobi. 1994, Smock et al. 1985, Smock and Roeding 1986). The multivariate community analysis clearly separates the least disturbed sites from those that have been impacted by development. This is an improvement over the 1999-2000 NJDEP AMNET biomonitoring scores (NJDEP 2003), which rated the two sites sampled in the Babcock Creek watershed as moderately impaired, with Babcock Creek rated below Jack Pudding Branch. This seems to have resulted from using a composite scoring system that does not take into account the trophic peculiarities of low-gradient streams, especially the great role played by filter-feeders (see Smock and Roeding 1986, Meyer 1990) . The NJ DEP is currently revising its AMNET assessment protocols for Coastal Plain streams. Almost all Babcock Creek sites are richer in Ephemeroptera, Plecoptera and Trichoptera than the more developed and chemically altered tributaries (Table 2). In general, DCA and NMS axis one corresponds to the pH differences among sites with more or less disturbed land in the watershed. Frequent flash flooding, which washes out much woody debris and scours the rest with sand, as well as chemical alteration, causes the extreme impoverishment of Adams Branch. Mankiller Branch is apparently affected by high specific conductance, possibly from road salt. More samples are needed to confirm this. More sampling is also needed at the confluences of the tributaries with the main stem to understand the recovery of the fauna (for example, at the downstream end of Jack Pudding Branch, Table 2). Although separation of samples into orders and families gives results consistent with observed alterations of the chemistry and hydrology, we still need to determine why the fauna responds to chemical changes as it does. Analyzing which genera are affected may clarify the reasons for the different responses of the macroinvertebrates in each tributary. We plan to collect more samples at all eight sites in late summer or fall 2005, and then to focus on one site per tributary for future monitoring. Babcock Creek at Spruce Street or Holly Street may be the best reference site.

20. Literature Cited Benke, A., Van Arsdall, T., Gillespie, D. and F. Parrish. 1984. Invertebrate productivity in a subtropical blackwater river: the importance of habitat and life history. Ecological Monographs 54: 25-63. Benke, A. and D. Jacobi. 1994. Production dynamics and resource utilization of snag-dwelling mayflies in a blackwater river. Ecology 75: 1219-1232. McCune, B. and M. Mefford. 1999. PC-ORD. Mulitvariate Analysis of Ecological Data, Version 4. MjM Software Design, Glenden Beach OR. 237 pp Meyer, J. 1990. A blackwater perspective on riverine ecosystems. Bioscience 40: 641-651. Meyer, J. 1990. A blackwater perspective on riverine ecosystems. Bioscience 40: 641-651. New Jersey Department of Environmental Protection, Water Monitoring and Standards Water Assessment Team. 2003. Integrated Water Quality Monitoring and Assessment Methods Document. Draft. NJDEP. http://www.state.nj.us/dep/wmm/sgwqt/wat/integratedlist/integratedlist2004.pdf Smock, L. and C. Roeding. 1986. The trophic basis of production...of a southeastern U.S.A. blackwater stream. Holarctic Ecology 9: 165-174. Smock, L. A., E. Gilinsky, and D. L. Stoneburner. 1985. Macroinvertebrate production in a Southeastern United States blackwater stream. Ecology 66:1491–1503. Zampella, Robert A., John F. Bunnell, Kim J. Laidig, and Charles L. Dow. 2001. The Mullica River Basin: A Report To The Pinelands Commission On The Status Of The Landscape And Selected Aquatic And Wetland Resources. NJ Pinelands Commission. New Lisbon NJ. 371 pp. Zampella, Robert A., John F. Bunnell, Kim J. Laidig, and Nicholas Procopio. 2003. The Rancocas Creek Basin: A Report To The Pinelands Commission On The Status Of Selected Aquatic And Wetland Resources. NJ Pinelands Commission. New Lisbon NJ. 130 pp.

21. Acknowledgements It is a pleasure to acknowledge the assistance of many individuals, including Fred Akers, Administrator, Great Egg Harbor Watershed Association; Robert Zampella, John Bunnell, Kim Laidig and Nick Procopio of the NJ Pinelands Commission; Tait Chirenje, Rudi Arndt, Lynn Maun, Tamica Johnson, Bob Fromtling, Jason Gliddon, James Grimes and David Monzo, Division of Natural Sciences and Mathematics The Richard Stockton College of New Jersey. This project received financial support from the NJ Water Resources Research Institute, The Atlantic County Office of Regional Planning and Economic Development, the NJ Department of Environmental Protection Division of Watershed Management and the Richard Stockton College of NJ Research and Professional Development Fund.

22. Further information on the web at: http://www.stockton.edu/~cromartw/GEHR/GEHRhomepage.htm Contact: Jamie Cromartie NAMS, Richard Stockton College, PO Box 195 Pomona NJ 08240 USA <jamie.cromartie@stockton.edu>