1. Examining the Impacts of Land Use Along the Forge River on Benthic Communities in the Past, Present and Future Voci, Jennifer M; Furman, Bradley T; Peterson, Bradley J School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11790 JVOCI@yahoo.com 1. Abstract Due to past and present residential, commercial and agricultural development, the health of the Forge River on Long Island, NY, has been negatively impacted. High nitrogen inputs have led to harmful algal blooms, resultant hypoxia and the collapse of commercially and recreationally important fisheries in this region. Erosion, organic detritus and historical duck farming has resulted in the accumulation of fine organic mud, inhibiting the establishment of robust benthic communities. This study tests the hypothesis that current sediment type and water quality are not suitable to establish benthic communities like those that previously existed. Biocores throughout the Forge River and its 6 tributaries were collected for benthic/epibenthic invertebrates and sediment grain size distribution. This effort yielded 3,789 individuals from 35 taxa. Interestingly, when examined across all cores, no one species comprised more than 20% of the total capture. Overall, diversity, richness and organismal abundance were all higher within the main axis of the river than in the tributaries. Evidence for elevated organic content in surface sediments was widespread, as Capitellid worms were common throughout the river proper. These anoxia and sulfide tolerant species were the single most recorded taxa suggesting that the substrate is limiting benthic recruitment. 2. Introduction The Forge River, located in the Town of Brookhaven, NY, is a slow moving estuary that empties into Moriches Bay and has a surface watershed of 43.06km 2 from the river and surrounding tributaries 1. In the mid-1900’s, duck farms were present and operable 2. Residential and commercial development and altered land type surrounding the river and its tributaries continues to increase and has impacted the river system through effluent (duck farms), sewage, septic systems 3, lawn fertilization, and altered land surface. These anthropogenic influences have contributed to erosion, nutrient inputs and sediment runoff; and have led to algal blooms, hypoxia, accumulation of organic mud and fish kills 1,2. Due to the poor history of the river, the current condition of the benthos may not be suitable for the survival and/or establishment of robust benthic communities which may be commercially and recreationally important to local economy 3. This report will delve into current sediment characteristics and investigate what organisms are currently residing there and the implications on current and future benthic communities. 4. Methods o Epi/Infaunal community composition conducted using 4 : o 15.24 x 15.24cm Ponar ® grab dredge, 51mm external diameter acrylic core from dredge sample o Combined with rose bengal and 10% buffered formalin o Organisms sorted and identified using compound microscope o Sediment grain size analyses 4 : o Sample combined with 50ml 1% Calgon solution, processed through 500μm sieve using wet-sieve technique o Partitioned into percent composition of Gravel, Sand, Silt and Clay o Samples dried for a minimum of 24hours and weighed o Biocore and grain size correlations: o Correlations between sediment type and organisms o Correlations between organisms o Used Pearson statistical analysis to determine dependence between variables 5. Results 7. References 1- Swanson RL, Gobler C, Brownawell B (2009). Some aspects of the Forge River Ecology, Unpublished report to the Town of Brookhaven, Long Island, NY 2- Swanson RL, Brownawell B, Wilson RE (2009). What history reveals about Forge River pollution, Unpublished report to the Town of Brookhaven, Long Island, NY 3- Cameron Engineering & Associates, CH2M Hill, Town of Brookhaven (2012). Forge River watershed management plan. 4- Peterson BJ. 2013. Finfish and Benthic Invertebrate study. 5- Horng CY, Taghon GL (1999). Effects of contaminated sediments on particle size selections by the polychaete Capitella sp. I. Journal of Experimental Marine Biology and Ecology. 242(1999): 41-57. 3. Questions o What is the abundance and diversity of benthic infauna in the Forge River Estuary? o Does sediment size/composition play a role in benthic community abundance and diversity? o Are there any noticeable gradients within the river or between tributaries and the river 6. Discussion/Conclusion The most recorded taxa throughout the river and its tributaries was that of the Capitellid worm. An anoxia and sulfide tolerant species 4 that is usually found in organic mud 5. These worms are often used as biological indicators 5 and can be present in highly contaminated sediment. They have been shown to selectively choose smaller grain size 5, but showed no correlation between sediment size in this study. There was a negative correlation between both Exogone and %clay, and between Lysianassidae and %clay. The average number of individuals of both Exogone and Lysianassidae decreased as the %clay increased, also representing a north-south gradient among the river. Results display a distinct correlation between the main axis of the river and clay. %Clay increased as the river segment went north-south. %Sand decreased north-south, but then increased sharply at the mouth of the river. %Silt displayed the opposite effect. No correlation between organisms. Future studies may benefit from examining metal composition or other possible contaminants in surficial sediments as well as benthic flora composition. It may also be important to note that the river was dredged pre-Hurricane Sandy, 2012, for the purpose of buffering the shoreline. That may have provided another opportunity to study the resultant ecosystem after a dredging event. Figure 3: Percent grain size of each sampling location. Figure 7: Image of an Exogone worm. 8. Acknowledgements I would like to thank Peter Miller for his help on sediment grain size analyses, and Rebecca Kulp for all of her effort in providing tools and equipment. I would also like to thank Dr. Peterson for giving me the opportunity to work in his lab as well as Brad Furman and Dr. Carroll for their advice and support on this project. Figure 5: Image of a Lysianassidae amphipod. Figure 1: Setup of the wet-sieve technique for grain size analyses.Figure 2: Pipetting procedure Figure 4: Percent grain size by river segment from upper to mouth. Figure 6: Mean number of Lysianassidae decreases as %clay increases. Figure 8: Mean number of Exogone decreases as %clay increases.