Delta-15 Nitrogen from All Shores of Maui and Benthic, Algae, and Urchin Data from Kahekili, West Maui, 2007-2009 (NODC Accession 0068665)

METHODOLOGY: Island-wide Coastal Surveys In the summer of 2007, an island-wide survey of intertidal algal delta-15 nitrogen (N) values from all accessible coastlines on Maui was conducted to locate areas and potentially identify sources of anthropogenic N enrichment. Surveys initially conducted every 1.5 km in populated areas and every 8 km in unpopulated areas. Where possible, three sites 0.3 km apart were sampled in triplicate per genera and two to three genera were collected when possible. The following macroalgae were collected: Acanthophora spicifera, Ahnfeltiopsis concinna, Asteronema breviarticulatum, Cladophora sericea, H.Musciformis, and U.fasciata. Using this approach, a total of 116 sites and 516 samples were collected around Maui.Fine-scale Mapping SurveysThis survey aimed to identify the presence of sewage N along the coastline in areas with elevated delta-15 N values and high recreational use. All sampling occurred in the intertidal zone. Sites extended along about 1.2 km of coastline centered on the highest delta-15 N values. Naturally occurring, attached samples of U.fasciata were collected for delta-15 N analysis(in triplicate per site for some sites), from sites approximately 100 m apart for the first five sites in the north, then every 50 m for the remainder of the sites to the south of Kihei. Mapping the Lahaina Effluent Plume with Deployed AlgaeTo determine the extent to which the effluent plume from the LahainaWastewater Reclamation Facilities (WWRF) stretched across the adjacent coralreef, an approach similar to Costanzo et al. (2001) was used, though,in this case, samples of U.faciata were deployed (n=96 per deployment)0.5 m from the benthos. In January 2009, 32 semi-permanent were installed spanning the entire coral reef adjacent to sites 16-27. To address the presence of effluent on the reef we installed six transects (T1-T6) each with four sites (A-D) at the following depths (m) 1.5 (A),2 (B), 3 (C) and 6 (D). An additional eight sites (S1-S8) were installed in the shallow zone containing warmer-than-ambient-freshwater seeps(at 1.5 m depth). Samples of U.fasciata were first acclimated to low nutrient seawater for seven days to deplete internal N stores by housing individual samples in 1.0 L beakers with aeration lines in water baths to prevent the seawater from heating and the seawater was changed every two days. Acclimated samples were then housed in 10 x 10 cm cages enclosed in plastic mesh and attached to float lines hovering approximately 0.5 mfrom the benthos. T3B was located directly over a warm freshwater seep and an additional seep site (NS) was added in May to the north of T2B. Algal Sample Preparation Samples were prepared in triplicate per collection site (per genus for the coastline survey) for tissue delta-15 N analysis. For deployed samples, field and acclimated samples were prepared in triplicate to obtain the initial and acclimated delta-15 N values. Samples were rinsed in deionized water, dried at 60 deg C to a constant weight, ground with mortar and pestle into powder and sent for mass spectrometer analysis to the Biogeochemical Stable Isotope Laboratory, University of Hawaii atManoa, for tissue delta-15 N determinations. A small portion of the samples from the fine-scale mapping survey were sent to the USGS Reston Stable Isotope Laboratory, Reston, Virginia. Samples were weighed then analyzed with a Carlo Erba NC2500 Elemental Analyzer, Finnigan MAT ConFloll, and Finnigan MAT DeltaS. Water Chemistr yA seep sampling device was created to obtain 100% seep water and was sent for nutrient water chemistry and delta-15 N analyses. Another seep sampler was created that allows air to be released from the top of a large (250 ml) cylinder as water flows through an attached funnel that placed over the seep. This allows the water derived only from the seep to fill the cylinder instead of the more general fresh water displacement method which has high potential of sample contamination for obvious reasons. INSTRUMENT TYPES: seep samplers mass spectrometer Carlo Erba NC2500 Elemental Analyzer Finnigan MAT ConFlollFinnigan MAT Deltas REFERENCES: Costanzo, S.D., ODonohue, M.J., Dennison, W.C., Loneragan, N.R., Thomas, M., 2001. A new approach for detecting and mapping sewage impacts. Marine Pollution Bulletin, 42, 149-156. Dailer, Meghan L. and Robin S. Knox, Jennifer E. Smith, Michael Napier, Celia M. Smith, 2010. Using delta-15 Nitrogen values in algal tissue to map locations and potential sources of anthropogenic nutrient inputs on the island of Maui, Hawaii, USA. Marine Pollution Bulletin, 60, 655-671.