Ecosystem condition assessments were conducted for 12 mangrove sites in the northern Gulf of Mexico. Nine sites were selected randomly; three were selected a priori based on best professional judgment to represent a poor, intermediate and good environmental condition. During single visits a visual assessment generated numerical scores for each site relative to the reference condition range. Relationships were examined among variables to evaluate relevance of visual observations and empirical data of environmental condition. Sites in poorest visual condition possessed low concentrations of soil contaminants as hydrological attributes that restricted contaminant inflow lowered visual scores. Bacterial abundance related to the greatest number of variables, and was the only indicator that correlated with the visually derived score (0.60, p < 0.05). Soil enzymatic activity ratios within classes provided estimates of microbial nutrient status. Low peptidases/phosphatase and glycosidases/phosphatase ratios supported the conclusion reached from the molar ratios of nutrients, that mangrove soils were phosphorous limited. A positive correlation (0.71, p < 0.05) observed between C:N ratios in leaf tissue and soil from all mangrove sites indicated that relative molar ratios of major nutrients in leaf tissue were reflective of limitations in the soil. Principal components analysis guided a reduction in variables retained for analysis, and provided an ordination of the sites which grouped into three clusters and two outliers. Grouping was primarily influenced by soil C:N. In future studies measuring major nutrients in soil, C:N:P, could possibly function as a single, cost effective indicator to validate rapid visual condition assessments of mangroves.

A 6-year survey (1993-1998) is summarized for fish collected from chemically contaminated, urbanized bayous in northwest Florida. Fifty-two monthly collections (January November) using trawls and seines occurred at 22 sites located in three adjacent bayous associated with the Pensacola Bay Estuary. Hurricanes Erin (Category 2) and Opal (Category 3) made landfall near the study area, and a state-wide entanglement net ban was initiated during the survey period. Approximately 585,000 fish were collected, which represented 80 species and 66 genera. The assemblages were dominated by estuarine-dependent and resident species similar to those commonly found in several nearby estuaries. Of these, Leiostomus xanthurus, Brevoortia patronus, Anchoa mitchilli, Lagodon rhomboides, and Menidia peninsulae composed 95% or more of the total catch. The total number of species for each collection ranged from 8 to 23, total abundances varied from 140 to 14,315 individuals, and Shannon diversity index values (H') were between 0.02 and 0.97. Mean species numbers and diversity index values were more consistent monthly than fish total abundance, which was influenced by seasonal occurrences of estuarine-dependent species. Hurricane effects were specific to the hurricane, structural parameter, species, and bayou. The posthurricane reductions in salinity (17% to 69%) and the few changes in fish abundance were usually temporary and within monthly and interannual variability. The resiliency of the fish assemblages to natural and anthropogenic stresses represents a survival advantage and readiness for future climatic change.

Water quality was assessed following Hurricane Katrina in the affected waters of Alabama, Mississippi, and Louisiana. Post-landfall water quality was compared to pre-hurricane conditions using indicators assessed by EPA’s National Coastal Assessment program and additional indicators of contaminants in water and pathogens. Water quality data collected after Hurricane Katrina suggest that the coastal waters affected by the storm exhibited higher salinity and concentrations of chlorophyll a , dissolved inorganic phosphorus, and total suspended solids following the storm compared to the previous 5-year averages. Higher bottom dissolved oxygen concentrations and light attenuation were also observed. Contaminant concentrations measured in the water column were very low or undetectable, as were the presence of pathogens. Overall water quality did not significantly differ from water quality assessed in the five years preceding the storm. Statistical analyses indicate that use of a probabilistic survey design is appropriate for making pre-storm and post storm comparisons for water quality condition on an areal basis.

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor–response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds. Nine classes of estuaries were identified by applying cluster analysis to a database for 138 U.S. estuarine drainage areas. The database included physical measures of estuarine areas, depth and volume, as well as hydrologic parameters (i.e., tide height, tidal prism volume, freshwater inflow rates, salinity, and temperature). The ability of an estuary to dilute or flush pollutants can be estimated using physical and hydrologic properties such as volume, bathymetry, freshwater inflow and tidal exchange rates which influence residence time and affect pollutant loading rates. Thus, physical and hydrologic characteristics can be used to estimate the susceptibility of estuaries to pollutant effects. This classification of estuaries can be used by natural resource managers to describe and inventory coastal systems, understand stressor impacts, predict which systems are most sensitive to stressors, and manage and protect coastal resources.

Contaminant concentrations were determined for media associated with 13 Florida seagrass beds. Concentrations of 10 trace metals were more commonly detected in surface water, sediment and two seagrass species than PAHs, pesticides and PCBs. Concentrations of copper and arsenic in surface water exceeded Florida aquatic life criteria more frequently than other trace elements. Total organic carbon, mercury, chromium, zinc, total chlordane, total PAHs, total PCBs, DDD and DDE were significantly greater in seagrass-rooted sediments than adjacent non-vegetated sediments. Total DDT, DDD, DDE, total chlordane, arsenic, copper and nickel exceeded proposed sediment quality guidelines at six of 13 grass beds. Pesticides, PAHs, and PCBs were below detection in seagrass tissues. Mercury, cadmium, nickel, lead and silver were detected in 50% or more of the tissues for Thalassia testudinum (turtle grass) and Halodule wrightii (shoal grass). Spatial, interspecific and tissue differences were usually an order of magnitude or less.

Fish were collected by otter trawl at 367 sites from 119 coastal water bodies in the northern Gulf of Mexico, ranging from north-central Florida to the Rio Grande, Texas, during the summer months of 1992-1994. The fish were identified and enumerated, and tissue contaminants (in fillets), and external abnormalities (body, buccal, branchial, and ocular) were determined. Results were compared for sites east and weft of the Mississippi River, within the Mississippi River, seven estuarine categories, and over 3 years. Approximately 31,000 individual fish were captured, representing 100 genera and 141 species. Thirteen species comprised 91 % of the total abundance; abundances of 128 species were 1% or less. Pinfish Lagodon rhomboides, Atlantic croaker Micropogonias undulatus, Gulf menhaden Brevoortia patronus, and bay anchovy Anchoa mitchilli were the more dominant species. Fourteen species were collected from at least 10% of the sites; 85 species were captured at no more than 1% of the sites. Atlantic croakers and hardhead catfish Ariopsis felis were collected more frequently (>50% of sites). Indices of community structure from the full data set ranged as follows: 2.8 for the Shannon-Wiener index, 0.90 for Simpson's index, and 0.56 for Pielou's evenness index. Chemical contaminants (predominantly total mercury and polychlorinated biphenyls [PCBs]) exceeded federal risk-based consumption guidelines in 2.7% of fillets from four species. External abnormalities occurred on 17 species and approximately 1% of the total number of fish examined. Community structural properties varied temporally across years and spatially over estuarine categories and between areas east and west of the Mississippi River. Four distinct assemblages were identified by cluster analysis of species abundance. Cluster membership was associated with salinity, depth, dissolved oxygen, water clarity, and geographic area.

The genotoxic potential of sediment pore water collected from coastal areas in the Gulf of Mexico has not been reported frequently in the literature. This report summarizes a study of the microbial mutagenicity of 31 pore water samples obtained from sediment affected by non-point source runoff and compares the results with those for more traditional chemical and biological indicators of sediment quality. Genotoxicity was determined pre- and post-enzyme activation using a proprietary short-term microbial assay for pore water centrifuged from sediment collected adjacent to a Florida coastal golf complex and from an urbanized bayou-estuary. Sediment and the associated pore water also were analyzed for acute toxicity to Hyallela azteca, Palaemonetes pugio, or Americamysis bahia and for benthic macroinvertebrate diversity (sediment only). Genotoxicity (direct and enzyme-activated) was detected in 4 of 17 (golf complex) and in 10 of 14 (urbanized bayou) pore water samples. The lowest toxic pore water concentrations were between 1.8% and 44.4% (direct) and between 2.6% and 25% (enzyme-activated). The results of the genotoxic assay paralleled those based on exceedance of proposed sediment quality guidelines, pore water acute toxicity and Shannon-Wiener diversity index values for 81%, 58%, and 65% of the comparisons, respectively. (c) 2006 Wiley Periodicals, Inc.

Baseline information on the chemical and biological quality of sediments is provided for six coastal locations in the northern Gulf of Mexico, which were considered possible candidates for regional reference areas. Chemical quality, toxicity and benthic community composition were determined for sediments collected three times from each of 12 sites during an approximate one-year period. Potential contaminants in the usually sand-dominated sediments exceeded individual threshold effects level guidelines proposed for Florida coastal areas in approximately 31% of the samples collected from 8 of 12 sites. No probable effects level guidelines were exceeded. Acute toxicity occurred in 16% or less of the sediment samples and no significant chronic toxicity was observed to the infaunal amphipod, Leptocheirus plumulosus. Approximately, 11% and 17% of the sediments were classified as poor or marginal, based on low benthic taxa abundance and diversity index values, respectively. Sediment quality at many sites was less degraded than that for nearby coastal areas receiving point and non-point source contaminants, which suggests their suitability to serve as reference sediments although further confirmation is recommended. In a broader context, the results of this survey reflect the complexity infield verification of reference conditions for near-coastal sediments. This is attributable largely to the natural variability in their physical, biological, and chemical characteristics and to the lack of biocriteria for benthic macro and meiofauna.

A shading experiment was conducted over a growing season to measure the effects of light reduction on Vallisneria americana in Perdido Bay on the Florida–Alabama border and to determine the response of heterotrophic bacteria in the rhizosphere. Plants subjected to 92% light reduction showed the most pronounced effects in chlorophyll a concentration, above- and below-ground biomass, and leaf dimensions. These results further suggested that the V. americana life cycle, as exhibited in temperate waters, was impaired. Heterotrophic bacteria were enumerated and identified (i) from the roots and sediments of fully illuminated plants and from unvegetated sediments at three intervals and (ii) from the roots of plants that have been subjected to 92% light reduction for 3 months. Up to two orders of magnitude greater numbers of bacteria were enumerated from root samples than sediment samples on a dry weight basis. Bacteria enumerated from the roots of plants subjected to light reduction (1.3±1.1×108 CFU g−1) were significantly higher than numbers of bacteria enumerated from the roots of fully illuminated plants (4.8±1.8×107 g−1 in the summer) or sediment samples (1.4±0.03×106 g−1). This suggests the roots of seagrasses stressed by light reduction provided more nutrients for bacterial growth. Higher percentages of Gram-negative bacteria were isolated from roots (up to 85% in the fall) than sediments (0–15%). Examination of isolates for traits characteristic of rhizosphere bacteria (siderophore production, formation of the phytohormone indole-3-acetic acid, and antifungal activity) did not show a clear distinction between root-associated and sediment isolates. Taxonomic identifications of root-associated bacteria based on MIDI analysis of fatty acid methyl esters were consistent with bacteria known to be associated with other plants or found at oxic–anoxic interfaces. In addition, the bacterial identifications showed most species were associated with only roots or only sediments. These results support studies suggesting seagrass rhizospheres harbor distinct bacterial communities.

Renewed interest in the use of Metarhizium anisopliae and its toxins for insect control prompted the following safety assessment. A neutral extract (methylene chloride, pH 7.2), derived from M. anisopliae cultures, was evaluated for toxicity and mutagenicity using aquatic animal bioassays and the Ames test. The average LC50 of the neutral extract obtained in static, acute 96-h tests conducted with ≤24-h-old Mysidopsis bahia was 2.41 mg L−1. By partially purifying destruxins from the neutral extract, it was shown that destruxins alone were not responsible for the observed toxicity in mysids. The neutral extract was fetotoxic to developing grass shrimp, Palaemonetes pugio, and frog, Xenopus laevis, embryos; the LC50 values were 52 and 32 mg L−1, respectively. Eye spot abnormalities were observed in shrimp and frog embryos exposed to the neutral extract. In extract-exposed frog embryos, moderate to severe cranial, facial, and gut malformations were also observed. The neutral extract was toxic to juvenile mosquito fish, Gambusia affinis, at an LC50 value of 141 mg L−1. Adult female G. affinis surviving a 24-h exposure to 200 μg ml−1 of the neutral extract produced healthy broods. After 3 months, no mortalities or adverse effects were observed in adult G. affinis fed a diet partially composed of a freeze-dried M. anisopliae culture. The neutral extract did not show mutagenicity in the Ames test using strains TA98 and TA100 with and without metabolic activation by rat liver S9. Significant (p  ≤ 0.05) mortalities were obtained when embryos of grass shrimp and inland silverside fish, Menidia beryllina, were exposed to the same lot of M. anisopliae conidiospores. Exposure of frog embryos to M. anisopliae conidiospores did not cause significant (p > 0.05) mortalities or malformations.