Benthic sampling program in Biscayne Bay, 1981-1982

The Biscayne Bay Benthic Sampling Program was divided into two phases. In Phase I, sixty sampling stations were established in Biscayne Bay (including Dumfoundling Bay and Card Sound) representing diverse habitats. The stations were visited in the wet season (late fall of 1981) and in the dry season (midwinter of 1982). At each station certain abiotic conditions were measured or estimated. These included depth, sources of freshwater inflow and pollution, bottom characteristics, current direction and speed, surface and bottom temperature, salinity and dissolved oxygen, and water clarity was estimated with a secchi disk. Seagrass blades and macroalgae were counted in a 0.1-m2 grid placed so as to best represent the bottom community within a 50-foot radius. Underwater 35-mm photographs were made of the bottom using flash apparatus. Benthic samples were collected using a petite Ponar dredge. These samples were washed through a 5-mm mesh screen, fixed in formalin in the field, and later sorted and identified by experts to a pre-agreed taxonomic level. During the wet season sampling period, a nonquantitative one-meter wide trawl was made of the epibenthic community. These samples were also washed, fixed, sorted and identified. During the dry season sampling period, sediment cores were collected at each station not located on bare rock. These cores were analyzed for sediment size and organic composition by personnel of the University of Miami. Data resulting from the sampling were entered into a computer. These data were subjected to cluster analyses, Shannon-Weaver diversity analysis, multiple regression analysis of variance and covariance, and factor analysis. In Phase II of the program, fifteen stations were selected from among the sixty of Phase I. These stations were sampled quarterly. At each quarter, five Petite Ponar dredge samples were collected from each station. As in Phase I, observations and measurements, including seagrass blade counts, were made at each station. In Phase II, polychaete specimens collected were given to a separate contractor for analysis to the species level. These analyses included mean, standard deviation, coefficient of dispersion, percent of total, and numeric rank for each organism in each station as well as number of species, Shannon-Weaver taxa diversity, and dominance (the compliment of Simpson's Index) for each station. Multiple regression analysis of variance and covariance, and factor analysis were applied to the data to determine effect of abiotic factors measured at each station. (PDF contains 96 pages)

Magnitude and extent of chemical contamination and toxicity in sediments of Biscayne Bay and vicinity

The toxicity of sediments in Biscayne Bay and many adjoining tributaries was determined as part of a bioeffects assessments program managed by NOAA’s National Status and Trends Program. The objectives of the survey were to determine: (1) the incidence and degree of toxicity of sediments throughout the study area; (2) the spatial patterns (or gradients) in chemical contamination and toxicity, if any, throughout the study area; (3) the spatial extent of chemical contamination and toxicity; and (4) the statistical relationships between measures of toxicity and concentrations of chemicals in the sediments. The survey was designed to characterize sediment quality throughout the greater Biscayne Bay area. Surficial sediment samples were collected during 1995 and 1996 from 226 randomly-chosen locations throughout nine major regions. Laboratory toxicity tests were performed as indicators of potential ecotoxicological effects in sediments. A battery of tests was performed to generate information from different phases (components) of the sediments. Tests were selected to represent a range in toxicological endpoints from acute to chronic sublethal responses. Toxicological tests were conducted to measure: reduced survival of adult amphipods exposed to solid-phase sediments; impaired fertilization success and abnormal morphological development in gametes and embryos, respectively, of sea urchins exposed to pore waters; reduced metabolic activity of a marine bioluminescent bacteria exposed to organic solvent extracts; induction of a cytochrome P-450 reporter gene system in exposures to solvent extracts; and reduced reproductive success in marine copepods exposed to solid-phase sediments. Contamination and toxicity were most severe in several peripheral canals and tributaries, including the lower Miami River, adjoining the main axis of the bay. In the open basins of the bay, chemical concentrations and toxicity generally were higher in areas north of the Rickenbacker Causeway than south of it. Sediments from the main basins of the bay generally were less toxic than those from the adjoining tributaries and canals. The different toxicity tests, however, indicated differences in severity, incidence, spatial patterns, and spatial extent in toxicity. The most sensitive test among those performed on all samples, a bioassay of normal morphological development of sea urchin embryos, indicated toxicity was pervasive throughout the entire study area. The least sensitive test, an acute bioassay performed with a benthic amphipod, indicated toxicity was restricted to a very small percentage of the area. Both the degree and spatial extent of chemical contamination and toxicity in this study area were similar to or less severe than those observed in many other areas in the U.S. The spatial extent of toxicity in all four tests performed throughout the bay were comparable to the “national averages” calculated by NOAA from previous surveys conducted in a similar manner. Several trace metals occurred in concentrations in excess of those expected in reference sediments. Mixtures of substances, including pesticides, petroleum constituents, trace metals, and ammonia, were associated statistically with the measures of toxicity. Substances most elevated in concentration relative to numerical guidelines and associated with toxicity included polychlorinated biphenyls, DDT pesticides, polynuclear aromatic hydrocarbons, hexachloro cyclohexanes, lead, and mercury. These (and other) substances occurred in concentrations greater than effects-based guidelines in the samples that were most toxic in one or more of the tests. (PDF contains 180 pages)

Recreational Fisheries in Biscayne National Park, Florida, 1976–19

Recreational creel survey data from 28,923 intercepts collected from Biscayne National Park, Florida and surrounding waters were analyzed for January 1976 through July 1991, prior to disruptions caused by Hurricane Andrew in 1992. A total of 261,268 fish and shellfish representing 170 species or higher taxa were recorded. The average trip landed 9.03 fish and/or shellfish. Mean annual landings per angler were 4.77 fish/angler/trip (from 3.8 in 1991 to 5.83 in 1981) and dropped significantly for each of the 2 years following Florida's adoption of mutiple new minimum size limits in 1985 and 1990. The relative contribution to total numerical landings by recreational party type were: skilled anglers (34.0%), food (19.8%), family (14.5%), novice (11.5%), spearfishing (10.3%), lobstering (9.6%), and other (0.3%). FIve species or higher taxa accounted for more than 50% of total landings by number: white grunt, Haemulon plumieri, 15.8%; spiny lobster, Panulirus argus, (10.6%; gray snapper, Lutjanus griseus, 10.6%; unidentified grunts, Haemulon spp., 7.3%; and dolphin, Coryphaena hippurus, 6.6%. An average of 4.39 fish or shellfish were reported released per trip. Five taxa accounted for 67% of all releases. Lobster divers reported the highest average release rate (5.73 per trip) and spearfishing the lowest (0.70 per trip). The ratio of releases to landings was 0.49:1 for all taxa, but ranged from 0.03:1 for dolphin to 1.19:1 for unidentified grunts. Spearfishing accounted for 12.0% of the total fishing trips sampled but only 10.3% of the total number organisms landed and 7.6% of all organisms caught. Hogfish, Lachnolaimus maximus, accounted for 49% if total spearfishing landings (13,286 of 27,015) and 84.3% of total 15,762 hogfish landed.

Biscayne Bay commercial pink shrimp, Farfantepenaeus duorarum, fisheries, 1986-2005

The Biscayne Bay bait (1986–2005) and food (1989–2005) fisheries for pink shrimp were examined using dealer-reported individual vessel-trip landings data, separated by waterbody code to represent only catches from Biscayne Bay. Annual landings varied little during the 1980’s and early 1990’s, and landings of the bait shrimp fishery exceeded those of the food shrimp fishery. The number of trips and landings in both fisheries increased from the late 1990’s through 2002 and food shrimp landings exceeded landings of bait shrimp; landings in both fisheries decreased sharply in 2003. Landings in both fisheries increased in 2004 and 2005, but the increase in food shrimp landings was stronger. Annual catch per trip was much lower in the bait fishery than the food fishery. Each fishery exploited shrimp of a different size. The bait fishery targeted shrimp less than 19 mm carapace length (CL), whereas the food fishery caught shrimp greater than 19 mm CL. We compared monthly bait shrimp catch per unit of effort (CPUE) from the fishery to an estimate of shrimp density from a fishery-independent sampling effort over a 3-yr period and found a strong statistical relationship with the density estimate lagged by 3 mo. The relationship supported the use of bait shrimp fishery CPUE as an index of abundance in upcoming assessments of the effect of a massive water-management-based ecosystem restoration project on pink shrimp in Biscayne Bay. Project implementation will affect freshwater inflows to the bay and salinity patterns. An abundance index with a lengthy pre-implementation history that can be carried into the operational phase of the restoration project will be invaluable in assessing project effects and protecting an important fishery resource of Biscayne Bay. The bait shrimp fishery can provide a continuing index of shrimp abundance from late 1986 forward.

Human use pharmaceuticals in the estuarine environment: a survey of the Chesapeake Bay, Biscayne Bay, and Gulf of the Farallones

The assessment of emerging risks in the aquatic environment is a major concern and focus of environmental science (Daughton and Ternes, 1999). One significant class of chemicals that has received relatively little attention until recently are the human use pharmaceuticals. In 2004, an estimated 2.6 billion prescriptions were written for the top 300 pharmaceuticals in the U.S. (RxList, 2005). Mellon et al. (2001) estimated that 1.4 million kg of antimicrobials are used in human medicine every year. The use of pharmaceuticals is also estimated to be on par with agrochemicals (Daughton and Ternes, 1999). Unlike agrochemicals (e.g., pesticides) which tend to be delivered to the environment in seasonal pulses, pharmaceuticals are continuously released through the use/excretion and disposal of these chemicals, which may produce the same exposure potential as truly persistent pollutants. Human use pharmaceuticals can enter the aquatic environment through a number of pathways, although the main one is thought to be via ingestion and subsequent excretion by humans (Thomas and Hilton, 2004). Unused pharmaceuticals are typically flushed down the drain or wind up in landfills (Jones et al. 2001).

1983 Biscayne Bay hydrocarbon study: final report

A two year, comprehensive, quantitative investigation was conducted to analyze and identify the spatial distribution of petrogenic and biogenic hydrocarbons in sediments, surface waters, fish and shellfish of Biscayne Bay, Florida. The goal for the first year of the project was to establish baseline information to support oil spill impact assessment and clean-up. One hundred fifty-five sediment and eleven biota samples were collected. The areas sampled included the Miami River, Intracoastal Waterway, tidal flats, access canals and environmentally sensitive shorelines. The second year of the study centered on areas exhibiting petroleum contamination. These areas included the Miami River, Little River, Goulds Canal, Black Creek and Military Canal. Surface and subsurface sediment, biota and surface water were collected. Sample collection, analyses, and data handling for the two year project were conducted so that all information was court-competent and scientifically accurate. Chain of custody was maintained for all samples. Total hydrocarbon content of surface sediments ranged from below detection limits to a high of 2663.44 pg/g. Several sample stations contained petroleum contamination. The majority of biota samples exhibited hydrocarbon concentrations and characteristics that indicated little, if any, petroleum contamination. Surface water samples ranged from 0.78 to 64.47 μg/L and several samples contained petroleum hydrocarbons. Our results indicate several areas of petroleum contamination. These areas are characterized by industrial complexes, port facilities, marinas, major boating routes and many of the major tributaries emptying into Biscayne Bay.

Fisheries assessment of Biscayne Bay 1983

Creel and trawl surveys of Biscayne Bay were carried out in 1982-1983 to assess commercial fish and macro-invertebrate habitats and fisheries. Dredged and/or barren bottom was dramatically less productive than seagrass, algae or hard bottom areas. Low fish abundance and diversity in north Biscayne Bay appeared to be correlated with high turbidity and low seagrass abundance. Substantive increases in fish and crustacean productivity in north Biscayne Bay will occur only if seagrass communities can be re-established. Deeper dredged areas in North Bay will not likely become recolonized with seagrass even if turbidity levels are reduced. Hard bottom areas in South Bay are associated with high diversity of fish fauna and serve as nursery areas for several highly desirable species (e.g. hogfish, yellowtail snapper, lane snapper). The area between Julia Tuttle and 79th Street Causeways, which had very dense seagrass abundance, was the richest area on either North or South Biscayne Bay for juvenile fish and shrimp. This basin can serve as a model for the potential of the remainder of North Bay.

Denitrification and inference of nitrogen sources in the karstic Floridan Aquifer

Aquifer denitrification is among the most poorly constrained fluxes in global and regional nitrogen budgets. The few direct measurements of denitrification in groundwaters provide limited information about its spatial and temporal variability, particularly at the scale of whole aquifers. Uncertainty in estimates of denitrification may also lead to underestimates of its effect on isotopic signatures of inorganic N, and thereby confound the inference of N source from these data. In this study, our objectives are to quantify the magnitude and variability of denitrification in the Upper Floridan Aquifer (UFA) and evaluate its effect on N isotopic signatures at the regional scale. Using dual noble gas tracers (Ne, Ar) to generate physical predictions of N2 gas concentrations for 112 observations from 61 UFA springs, we show that excess (i.e. denitrification-derived) N2 is highly variable in space and inversely correlated with dissolved oxygen (O2). Negative relationships between O2 and δ15N NO3 across a larger dataset of 113 springs, well-constrained isotopic fractionation coefficients, and strong 15N:18O covariation further support inferences of denitrification in this uniquely organic-matter-poor system. Despite relatively low average rates, denitrification accounted for 32 % of estimated aquifer N inputs across all sampled UFA springs. Back-calculations of source δ15N NO3 based on denitrification progression suggest that isotopically-enriched nitrate (NO3-) in many springs of the UFA reflects groundwater denitrification rather than urban- or animal-derived inputs. © Author(s) 2012.

Water quality impacts and palaeohydrogeology in the East Yorkshire Chalk Aquifer, UK

A large hydrochemical data-set for the East Yorkshire Chalk has been assessed. Controls on the distribution of water qualities within this aquifer reflect: water-rock interactions (affecting especially the carbonate system and associated geochemistry); effects of land-use change (especially where the aquifer is unconfined); saline intrusion and aquifer refreshening (including ion exchange effects); and aquifer overexploitation (in the semi-confined and confined zones of the aquifer). Both Sr and I prove useful indicators of groundwater ages, with I/Cl ratios characterising two sources of saline waters. The hydrochemical evidence clearly reveals the importance of both recent management decisions and palaeohydrogeology in determining the evolution and distribution of groundwater salinity within the artesian and confined zones of the aquifer. Waters currently encountered in the aquifer are identified as complex (and potentially dynamic) mixtures between modern recharge waters, modern seawater, and old seawaters which entered the aquifer many millennia ago.