Maryland Biological Stream Survey’S Sentinel Site Network: a Multi-Purpose Monitoring Program
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Maryland Biological Stream Survey’s Sentinel Site Network: A Multi-purpose Monitoring Program Prepared by Andrew J. Becker Scott A. Stranko Ronald J. Klauda Anthony P. Prochaska John D. Schuster Michael T. Kashiwagi Patrick H. Graves Maryland Department of Natural Resources Resource Assessment Service Monitoring and Non-tidal Assessment Division 580 Taylor Avenue C-2 Annapolis MD 21401 Prepared for Maryland Department of Natural Resources Wildlife and Heritage Service Natural Heritage Program 580 Taylor Avenue E-1 Annapolis MD 21401 April, 2010 This study was funded in part by State Wildlife Grant funds provided to State wildlife agencies by the U.S. Congress, and administered through the Maryland Department of Natural Resources’ Natural Heritage Program - - 1 ABSTRACT Each year since 2000, the Maryland Biological Stream Survey, led by the Maryland Department of Natural Resources (MDDNR), Monitoring and Non-tidal Assessment Division, monitors several high quality reference streams in the Sentinel Site Network (SSN) to assess annual variability in stream conditions associated with natural factors. Data are collected on the biology, chemistry, physical habitat, water and air temperature, and land cover/use at each Sentinel Site. The major goal of this report is to describe the temporal variability in conditions at 27 SSN streams based on 10 years of annual sampling, 2000 through 2009. The secondary goal of this report is to present biological indicators as parts in a tool box of assessment parameters that could be used to track climate change effects on Maryland’s non-tidal streams, and to conduct exploratory analyses of SSN data from the 10-year baseline of stream conditions against which future climate influences can be assessed. Between 2000 and 2009, drought conditions occurred in Maryland during 2001, 2002, and 2007. Conversely, the year 2003 was wetter than normal. Precipitation amounts and stream flows were near normal in the other six years. Biological indicator scores for benthic macroinvertebrates and fish responded to the 2001 and 2001 drought conditions at Sentinel Sites in only one of the four geographic regions: The Coastal Plain – western shore. Macroinvertebrate Index of Biotic Integrity (IBI) scores, fish IBI scores, and total numbers of individual fish collected decreased at Sentinel Sites in this region during 2003, following two years of drought, but returned to normal numbers in 2004. The aquatic biota at Sentinel Sites in this region also decreased slightly in 2008, a year after the 2007 drought. Stream biota did not appear to respond negatively to the relatively wet year, 2003, in any region, based on the parameters measured by the SSN. Neither the macroinvertebrate nor fish IBI scores varied significantly across years at Sentinel Sites in the Coastal Plain – eastern shore, Piedmont, or Highlands regions. The percentages of coldwater-preference benthic macroinvertebrate taxa richness and percent brook trout (a coldwater-obligate) abundances were negatively associated with year, apparent decreases that were not statistically significant, at the 27 Sentinel Sites. We now have a list of coldwater taxa and a 10-year baseline of species composition data against which results of future Sentinel Site sampling can be compared. If coldwater taxa richness or abundance decreases significantly over time and water temperatures increase, these findings could indicate climate change impacts on Maryland streams. Water temperatures collected by in-situ data loggers at all Sentinel Sites did not vary significantly between 2000 and 2009, at any spatial scale (site, region, or statewide). Land cover/use (i.e., forest loss or urban increase) changed between 2002 and 2008 in the catchments of seven of the 27 Sentinel Sites. The site in the Mattawoman Creek watershed had the largest loss of forest cover (932 acres). The Sentinel Site in the Timber Run watershed experienced the largest increase in land cover/use (10 acres of urban land). Biological indicator scores were not significantly affected by the land cover/use changes at - - 2 these two Sentinel Sites, nor at the other five sites where smaller land cover/use changes occurred between 2002 and 2008. None of the 27 Sentinel Sites drain catchments that are located entirely on protected lands. Therefore, several sites are vulnerable to urban/suburban development and other anthropogenic impacts in the future. It is critically important that the current 27 Sentinel Sites and their catchments are protected. It is also desirable that the SSN be expanded, that the SSN data be used by a diverse array of interested parties, and that we find ways to extend the current 10-year baseline period of record and continue the SSN for many decades. Implementation of recommendations that emerged from a workshop sponsored by the Maryland Water Monitoring Council in November 2009 (www.marylandwatermonitoring.org) could help achieve the goal of SSN expansion and persistence over the long run. In the coming months, MDDNR will seek funding and partners who can contribute resources and/or monitoring sites to an expanded SSN that could provide the framework for a long-term network, implemented statewide, to track climate change effects on Maryland’s non-tidal waters. - - 3 INTRODUCTION The Maryland Biological Stream Survey (MBSS), started in 1995 by the Maryland Department of Natural Resources (MD DNR), assesses the ecological condition of 1st through 4th order, non-tidal streams at statewide, basin, and watershed scales, by measuring key chemical, physical, and biological parameters. Spanning 15 years, the MBSS also provides an opportunity to document changes in stream condition over time and elucidate discernable trends. Each year since 2000, the MBSS has monitored several high quality, reference streams in the Sentinel Site Network (SSN), to assess natural annual variability in stream conditions (Prochaska 2005, Becker et al. 2007, Becker et al. 2008). In streams relatively uninfluenced by anthropogenic disturbance, temporal trends in ecological condition should be attributable primarily to seasonal and annual variations in precipitation (and resultant droughts or floods) and temperature/dissolved oxygen regimes, as well as biotic interactions. Stress caused by these natural changes can have drastic effects on stream biota (e.g., benthic macroinvertebrates and fish), effects that should be detected by the biological indicators and ancillary chemical/physical measurements taken by the SSN. Therefore, monitoring a set of minimally-disturbed (more ideally, pristine) streams in places not likely to experience anthropogenic impacts (i.e., the SSN) offers the best means of discerning changes in biological indicator scores across years at stream sites sampled along the entire gradient of disturbance that are also being influenced by natural variability. Although pristine streams no longer exist in Maryland, monitoring several of the best remaining streams, or those perhaps “mostly recovered” from past degradation (personal communication with R.P. Morgan II), is a useful approach for evaluating variability in stream conditions associated with natural influences. The SSN includes some of the best remaining non-tidal streams in Maryland, based on chemical, physical, and biological parameters measured by the MBSS. SSN sites represent all regions, 1st through 3rd orders, and are located in catchments that, hopefully, will not experience major anthropogenic disturbances in the foreseeable future. The major goal of this report is to describe the temporal variability in conditions at 27 SSN streams based on ten years of annual sampling from 2000 through 2009. The abundance and species composition of stream fish and invertebrate communities respond to seasonal and annual changes in biotic and abiotic conditions (McElravy et al. 1989, Grossman et al. 1990, Boulton et al. 1992, Poff and Allan 1995). Understanding natural variability is critical to the interpretation and application of stream assessments, including the designation of impaired waters and also documenting then adjusting stream assessment results to account for natural variability influences on stream condition, particularly the biota. Natural variability in lotic environments can be manifested in floods and droughts that, in turn, influence water quality and quantity, channel morphology, substrate composition, and habitat availability. - - 4 In addition to documenting changes in precipitation, temperature, and other factors at seasonal and annual scales, and then assessing the effects of this relatively short-term natural variability on stream biota, the SSN should also be useful for tracking long-term (i.e., multi-decadal) changes associated with climate change. Discriminating the effects of climate change on stream conditions from shorter-term variability in weather and anthropogenic influences, such as urbanization, will be difficult but essential for planning adaptation responses to climate change. Global climate change has the potential to significantly impacts Maryland’s aquatic ecosystems ( MCCC 2008a, b; Pyke et al. 2008; Hayhoe et al. 2008; Najjar et al. 2009). Global mean surface air temperatures increased 0.74 C +/- 0.18 C over the last century (1906-2005). Based on climate change modeling, air temperatures are projected to continue increasing through the 21st century . Global mean surface temperature increases are related to greenhouse gas emissions, with low rates yielding a likely increase from 1.1 C to 2.9 C by 2100, while high