Changes in nucleic acids over the molt cycle in relation to food availability and temperature in Homarus americanus postlarvae

Postlarval lobsters Homarus americanus Milne Edwards hatched from three females collected in 1989 from Block Island Sound, Rhode Island were reared individually in the laboratory under nine treatment combinations of temperature (15, 18 and 21°C) and feeding (starved, low ration and full ration). Total RNA, DNA (mgind.^-1), RNA:DNA ratios and molt stage were determined for individuals sampled at daily intervals. Postlarval lobsters had high resistance to starvation. A majority of the lobsters survive 12 d of food deprivation, with some surviving up to 24–29 d. During starvation, cell biomass (estimated from protein:DNA) decreased to a minumum size, whereas cell number (based on total DNA) was generally conserved. The molt cycle was arrested at molt stage C in the starved postalrvae. Instar duration was inversely related to temperature. However, the duration of the postlarval instar did not differ between the low and full ration treatments. Uncoupling of cell growth and the molt cycle was evident in the full and low ration treatments. In the full ration treatments, the postmolt through early premolt was characterized by a rapid increase in total RNA and DNA. Maximum cell biomass was attained by molt stage C or D₀. In the low ration treatments, total RNA and DNA were less than those in the full ration treatments and the maximum cell biomass was attained only at molt stage D_2-3. Notably, different feeding regimes resulted in different patterns in RNA:DNA ratios over the molt cycle during the postlarval instar. RNA:DNA ratio was a sensitive indicator of recent (2 to 3 d) food deprivation. However, this ratio was positively related to the level of feeding only at molt stages C to D₁ and was inversely related to temperature regime. These results indicate that the use of RNA:DNA ratios to estimate the relative nutritional state of postlarval tobsters must be qualified with respect to the period of the molt cycle and the temperature regime.     

CALCIUM CARBONATE PRECIPITATION AND TURBIDITY MEASUREMENTS IN OTISCO LAKE,NEW YORK1

ABSTRACT: Calcium carbonate precipitate, known as “whiting,” forms in a large number of hard water lakes and reservoirs, and thus contributes to turbidity measurements in these systems. Here we document the occurrence of “whitings,” and the associated impact on turbidity, in Otisco Lake, New York. A simple, potentially broadly applicable, technique, measurement of turbidity before and after acidification, successfully quantified this component of turbidity in the lake. Calcium carbonate represented 32 percent of the turbidity in the upper waters of Otisco Lake for a three-month period, and at times was as much as 70 percent. Routine monitoring of this component of turbidity in raw water sources, where it is significant, should provide insight into water quality management and treatment plant operations.     

DETERMINATION OF CROP PRODUCTION LOSS DUE TO INADEQUATE DRAINAGE IN A LARGE WATERSHED1

ABSTRACT Results of a field survey designed to assess the extent of crop production losses due to inadequate drainage in a large watershed of Iowa is presented. Information on the current status of drainage of the watershed, located in the Des Moines River basin, was collected through personal interviews with 256 farmers from 60 legal drainage districts. The results of the survey indicate that 95 percent of the area in upper Des Moines River basin has inadequate district mains or main outlet drains currently having a design capacity of ≤ 0.64 cm/day drainage coefficient. Outlet capacity of 1.27 cm/day d.c. would be required for full production. Inadequate drainage in the watershed is currently responsible for crop yield reduction equal to about one-third of the maximum yield potential for average weather conditions.     

Adaptive sampling and analysis programs for contaminated soils

Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application.     

Application of SMR to Modeling Watersheds in the Catskill Mountains

Very few hydrological models commonly used in watershed management are appropriate for simulating the saturation excess runoff. The Soil Moisture Routing model (SMR) was developed specifically to predict saturation excess runoff from variable source areas, especially for areas where shallow interflow controls saturation. A recent version of SMR was applied to two rural catchments in the Catskill Mountains to evaluate its ability to simulate the hydrology of these systems. Only readily available meteorological, topographical, and landuse information from published literature and governmental agencies was used. Measured and predicted streamflows showed relatively good agreement; the average Nash–Sutcliffe efficiency for the two watersheds were R ²=72% and R ²=63%. Distributed soil moisture contents and the locations of hydrologically sensitive areas were also predicted well.     

Organochlorine contamination in shorebirds from Washington state and the significance for their falcon predators

Arctic-breeding shorebirds collected in western Washington state during winter and spring, and a comparative sample collected in coastal California during the winter were analyzed for organochlorine contaminants to determine the potential impact of these residues on populations of peregrine falcons (Falco peregrinus) and merlins (F. columbarius) which prey upon shorebirds in western Washington. Dunlins (Calidris alpina), an important winter prey for falcons in western Washington, were collected between 1975 and 1981. During winter 1980–81, dunlins carried low organochlorine residues; DDE levels ranged from 0.01 to 1.2 ppm, and PCB levels ranged from 0.02 to 0.82 ppm (wet weight). Levels of other organochlorine contaminants (HCB, Chlordane compounds, Dieldrin, and Heptachlor Epoxide), analyzed in a subsample of dunlins, were consistently lower than DDE and PCB levels, and ranged from 0.001 to 0.22 ppm (wet weight). Dunlins in western Washington did not significantly increase their DDE or PCB burdens over the 1980–81 winter. A decline in DDE residues between 1978 and 1981 was noted, and declines in PCB residues from both 1975 and 1978 to 1980–81 were noted. Residues in other wintering shorebirds from western Washington were similar. Wintering sanderlings (Calidris alba) from California, revealed much higher DDE contamination than in Washington (up to 32 ppm, wet weight). Spring migrant shorebirds in western Washington contained both low and very high DDE residues (up to 417 ppm, wet weight). There is evidence suggesting these high DDE concentrations are accumulated along the Pacific coast of North America.     

Monitoring dissolved organic carbon in surface and drinking waters

The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.     

Effective monitoring of pollution by toxic trace elements in waters,sediment and biota of the Derwent River Estuary,Tasmania, through long-term retention of analytical facilities

This study considers the effectiveness of the monitoring of toxic trace elements in various media from a polluted river estuary over a period of 15 years, using the same analytical techniques, facilities and, in some cases, the same operators. It shows that reliable comparisons can be made for monitoring waters, sediment and biota from the Derwent River Estuary between 1975 data and that from 1990. Rigorous studies were undertaken before and during 1975 to ensure that reliable data was achieved at that time. Such studies are reviewed and included the evaluation of digestion techniques for a range of heavy metals, specific attention to the reliability of mercury determination in sediments between laboratories, a comparison of direct calibration and standard addition techniques for metals in seawater, recoveries of an organomercury compound from fish, and sources of error arising from sample preparation of biota for subsequent metal analysis. Comparative results for standard reference materials in both 1975 and 1990 show good agreement and are considered reliable except for lead at low concentrations. The long-term retention of the analytical facilities permits a direct comparison of data from 2 monitoring programmes over the space of 15 years.