Polychlorinated chemical residues in fish from major watersheds near the Great Lakes, 1979

Over 50 non-PCB polyhalogenated organic chemicals have been identified by GC/MS in fish from the Great Lakes and other major watersheds near the Great Lakes. p,p′-DDE, hexachlorobenzene, and components of tech-chlordane were the most frequently found chemicals. Also described are advances in sample preparation methodology which allow the identification of many frequently occuring unusual chemicals. Several chemicals not previously reported in environmental samples are identified.     

Heredity and risk of disease

Mathematical modeling of competing risks often uses a single risk function for all individuals within a population. In this paper we use several specific examples to argue that such representations remain approximations until account is taken of the existence of genetic variability within and between populations, and the impact of this upon liability to disease. The extent of human genetic variability is also indicated.     

Exposure to the sobriety "Checkpoint Strikeforce" campaign in Maryland: impact on driver perceptions of vulnerability and behavior

OBJECTIVES: To compare drivers who were: (1) exposed to Maryland's sobriety "Checkpoint Strikeforce" campaign; (2) not exposed but were aware of it; and (3) neither exposed nor aware of it. This six-month campaign involved periodic road-side sobriety checkpoints, in which police attempted to detect and arrest drunk drivers and a series of radio Public Service Announcements (PSAs) that promoted public awareness. METHODS: A statewide sample of 1725 drivers were interviewed by telephone to determine their exposure to and awareness of this campaign, as well as their beliefs and behaviors concerning drunk driving and seat belt usage. RESULTS: Relatively few people (9.6%) were exposed in any way to the campaign; however almost 30% were aware of it. Significant increases in perceived vulnerability to arrest for drinking and driving were found among those who were exposed. There were no differences in reported drinking and driving, but seat belt usage in the last 30 days was higher among those who were exposed. There were no differences among those people who had been directly exposed to the campaign (i.e., personally gone through a sobriety checkpoint) and those who were indirectly exposed (i.e., knew a family member or someone else who went through a checkpoint). CONCLUSIONS: Exposure to a sobriety checkpoint was associated with increased perceptions of drink-driving risk (i.e., likelihood of getting caught by the police), which was not dependent upon having personally experienced it. Awareness without exposure appears to be insufficient to change perceived risk. The need to increase the reach and frequency of the sobriety "Checkpoint Strikeforce" campaign is indicated.     

Photodegradation of haloacetic acids in water

The global distribution and high stability of some haloacetic acids (HAAs) has prompted concern that they will tend to accumulate in surface waters and pose threats to humans and the ecosystem. It is important to study the degradation pathways of HAAs in aqueous systems to understand their ecotoxicological effects. Previous studies involving thermal degradation reactions show relatively long lifetimes for HAAs in the natural environment. Photolysis and photocatalytic dissociation are potentially efficient routes for the degradation of HAAs such as trichloroacetic acid to hydrochloric acid, carbon dioxide and chloroform, although such processes are poorly understood in surface waters. In our present study, we have used light to degrade the HAAs in the presence of titanium dioxide suspensions. All chloro and bromo HAAs degrade in photocatalysis experiments and the rate of degradation is directly proportional to the number of halogen atoms in the acid molecule. The half-lives of the HAAs from the photodegradation at 15 degrees C in the presence of suspended titanium dioxide photocatalyst are 8, 14, 83 days for the tri-, di- and mono-bromoacetic acids. Tri-, di- and mono-chloroacectic acids have half-lives of 6, 10 and 42 days respectively. The mixed bromochloro and chlorodifluoroacetic acids degrade with half-lives of 18 and 42 days respectively. Our results therefore suggest that the photocatalytic process can provide an additional degradation pathway for the HAAs in natural waters.     

Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.     

Bioavailable phosphorus in runoff from alfalfa, smooth bromegrass, and alfalfa-smooth bromegrass

Runoff from sloping landscapes cropped with established alfalfa (Medicago sativa L.) may contain bioavailable P (BAP) which accelerates eutrophication of surface water bodies. Such BAP exists as either dissolved reactive P (DRP) or bioavailable reactive particulate P (BPP). We hypothesized that before and after harvest, sod-forming smooth bromegrass (Bromus inermis Leyss.) or alfalfa-smooth bromegrass mixtures would have less BAP, DRP, and BPP runoff losses than taprooted alfalfa. Swards established in 1992 near Lancaster, WI were subjected to a 72 mm simulated rainfall applied for 1 h in 1993 and 1994 to forage regrowth at 4 and 6 wk after first harvest and immediately (0 wk) after second harvest. Hourly BAP losses for all sward types were 82% less when 1.5 Mg ha(-1) of forage dry matter was present. High DRP losses (>0.050 kg ha(-1)) were associated with high DRP concentrations (>7.1 micromol L(-1)) and high surface soil P concentrations (>59 mg kg(-1)) resulting from broadcast maintenance P fertilizer. High BPP losses (>0.035 kg ha(-1)) were associated with high runoff volumes (>24 mm) and sediment concentrations (>2 g L(-1)). Summed over all 6 rainfall simulations, total BAP loss was only 0.07 kg ha(-1) at the 6 wk stage of regrowth compared with 0.35 at 4 wk, and 0.41 at 0 wk. Moreover, there was no significant difference between sward types for DRP concentration, DRP loss, or BAP loss. We conclude that avoiding excessive defoliation was more effective at reducing BAP losses than specific forage species selection.     

Interactions between morphological and physiological plasticity optimize energy acquisition in corals

Morphological plasticity in response to environmental heterogeneity may be performance enhancing or may simply result from an intrinsic instability in morphology during development. Although patterns of morphological change are well documented for numerous taxa, it is often unclear whether this plasticity enhances the performance of organisms in the habitat to which they have acclimatized. Reef-building corals are an ideal model system in which to investigate this question. We here develop a three-dimensional geometric model and present a comprehensive photosynthesis data set with experimentally calibrated photosynthesis models that predicts energy acquisition by foliose corals as a function of colony shape. This allows us to assess the extent to which changes in colony morphology along an environmental gradient track the predicted optimal colony morphologies. Our results provide strong evidence that phenotypic plasticity in foliose corals optimizes photosynthetic energy acquisition and is not simply a mechanism to increase light capture. We show that the optimal morphology is constrained at the boundaries of the environmental gradient, with non-optimal morphologies in these habitats having greatly reduced energy acquisition. However, at the center of the environmental gradient, flexibility in photophysiology allows energy acquisition to be very similar for multiple morphologies. Our results highlight the importance of phenotypic plasticity at multiple scales. Variation in overall morphology is important at niche boundaries at which conditions are consistently more stressful, whereas physiological flexibility is important in intermediate and less predictable habitats in which a rapid and reversible response to environmental fluctuations is required.     

Variation in colony geometry modulates internal light levels in branching corals, <Emphasis Type="Italic">Acropora humilis</Emphasis> and <Emphasis Type="Italic">Stylophora pistillata</Emphasis>

Colonial photosynthetic marine organisms often exhibit morphological phenotypic plasticity. Where such plasticity leads to an improved balance between rates of photosynthesis and maintenance costs, it is likely to have adaptive significance. To explore whether such phenotypic plasticity leads to more favourable within-colony irradiance for reef-building branching corals, this relationship was investigated for two coral species Acropora humilis and Stylophora pistillata, along a depth gradient representing light habitats ranging from 500 to 25 μmol photons m⁻² s⁻¹, during 2006 at Heron Island, Great Barrier Reef (23.44°S, 151.91°E). In the present study changes in flow-modulated mass transfer co-varied with light as a function of depth. In low-light (deep) habitats, branch spacing (colony openness) in A. humilis and S. pistillata was 40–50% greater than for conspecifics in high-light environments. Also, branches of A. humilis in deep water were 40–60% shorter than in shallow water. Phenotypic changes in these two variables lead to steeper within-colony light attenuation resulting in 38% higher mean internal irradiance (at the tissue surface) in deep colonies compared to shallow colonies. The pattern of branch spacing was similar for S. pistillata, but this species displayed an alternate strategy with respect to branch length: shade adapted deep and cave colonies developed longer and thinner branches, allowing access to higher mass transfer and irradiance. Corals in cave habitats allowed 20% more irradiance compared to colonies found in the deep, and had a 47% greater proportion of irradiance compared to colonies in the shallow high-light environment. Such phenotypic regulation of internal light levels on branch surfaces partly explains the broad light niches of many branching coral species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.