The effects of ammonium and phosphate enrichments on clorophyll a,pigment ratio and species composition of phytoplankton of Vineyard Sound

Seawater containing natural phytoplankton populations from Vineyard Sound, USA was enriched in the laboratory with three levels each of ammonium and phosphate and with a combination of ammonium and phosphate which provided three different N:P ratios. The addition of ammonium produced more cells and chlorophyll a than the control or the phosphate enrichments. However, enrichment with ammonium and phosphate, regardless of the N:P ratio, yielded the most cells and chlorophyll a. Thus, nitrogen seems to be the primary limiting nutrient, with phosphate showing secondary limiting effects. The ratios of photosynthetic pigments decreased with the increased chlorophyll a production in the enriched cultures. There were no significant changes in the species composition within the cultures, so that the observed changes in pigment ratio and chlorophyll a content were due to physiological responses.     

The trophic role of glycolic acid in coastal seawater. II. Seasonal changes in concentration and heterotrophic use in Ipswich Bay,Massachusetts, USA

Glycolic acid is a known algal excretory product which is found in marine waters and is readily metabolized by marine bacteria. The following parameters were measured over the course of a year in Ipswich Bay: chlorophyll a, temperature, viable bacteria, heterotrophic uptake of glycolate, and glycolate concentrations. The latter two were combined to give estimates of the flux of glycolate for a station 3 km out in the bay and for an inshore station. Pronounced seasonal changes were found for all parameters. Statistically significant correlations between heterotrophic V _max and glycolic acid concentrations and temperature were found, but not between planktonic chlorophyll a and any of the other parameters. Measurements of glycolic acid flux yielded an annual flux of 2.84 g m^-2 for the bay station, which is about 0.5% of the bay phytoplankton production. Glycolic acid turns over roughly 12 times per year in the bay. It contributes perhaps as much to bacterial metabolism as any other single substrate, but is apparently not of dominating importance.     

Regulation of nitrate and ammonium uptake in the Greenland Sea

The uptake of nitrate and ammonium was investigated experimentally during early spring 1989 in the Greenland Sea, with particular attention placed on the roles of irradiance, nitrogen concentrations and nitrateammonium interactions. The phytoplankton assemblage was dominated by the colonial prymnesiophyte Phaeocystis pouchetii. Nitrate concentrations ranged from undetectable at the end of the cruise to greater than 10 M, and ammonium levels ranged from less than 0.1 to 1.9M. The uptake of both nitrate and ammonium as a function of irradiance was found to be a saturation response. Photoinhibition occurred and was found to be greater for ammonium uptake. Ammonium uptake also saturated at irradiance levels five times lower than those needed to saturate nitrate uptake. Nitrate and ammonium uptake as a function of nitrogen concentration also was characterized by a saturation response, with the estimated half-saturation constant (K _s) value for nitrate uptake being 0.29 M. Elevated ammonium concentrations inhibited nitrate uptake, and the response appeared to be one of exponential decrease with increasing concentrations of ammonium. The most important factor in the Greenland Sea influencing ammonium uptake during the spring was irradiace, while both irradiance and ammonium concentrations played major roles in regulating nitrate uptake and new production.     

Occurrence and rhythmic behaviour of Tropidoneis lepidoptera in the epipelon of Barnstable Harbor,Massachusetts, USA

The identity of a Tropidoneis sp. previously reported from the intertidal sand flats at Barnstable Harbor, Massachusetts (USA) has been resolved as T. lepidoptera (Greg.) Cl., and its vertical migratory behaviour compared with that of the more common Hantzschia virgata var. intermedia (Grun.) Round.     

Seasonal variations in compostability and production of vermiprotein by Eisenia fetida

The potential of E. fetida to degrade wastes into vermicompost and to produce vermiprotein in the form of worm-biomass during different seasons was evaluated. Results revealed that the environmental factors prevailing during different seasons did influence directly the life activities of the worm and indirectly the compostability of the wastes. Feeding activities of E. fetida reduced the time of production of an efficient organic pool with energy reserves as vermicompost. Further, the amount of vermicompost produced by the worm activity depended primarily on the environmental factors and secondarily on the nature of organic wastes.     

Distribution and structure of benthic assemblages in Puget Sound,Washington, USA

Benthic infauna was collected with a 0.2 m² van Veen grab at 48 stations in Puget Sound, Washington, USA during February–March 1969. All the crustaceans, lamellibranchs, and echinoderms were identified and counted. Particle size distributions and nitrogen contents of the sediments, depths, and temperature and salinity of the bottom water were determined at all stations. The first three factors of a factor analysis applied to between-stations measures of affinity, explained 41.26% of the total variance. The first factor had representative stations on shallow-water mud bottoms, the second factor on bottoms dominated by coarse sediments, and the third factor had representative stations on deep-water mud bottoms. The multiple correlation coefficients for each of the three factors with depth and mean particle size of the sediments were 0.752, 0.897, and 0.706, respectively. The factor analysis did not result in clusters of stations that could be interpreted as discrete benthic communities. The number of species per 0.6 m² ranged from 8 to 55 species, with a mean of 26.4 species. The frequency distribution of specimens among the species was in good agreement with a log-normal distribution. The number of specimens per 0.6 m² ranged from 57 to 1733 specimens, with a mean of 584.0 specimens. The species diversity ranged from 0.34 bits/individual to 4.35 bits/individual, and there was a weak trend of increasing diversity towards coarser sediments. The first three factors applied to the matrix of between-species correlation coefficients explained 43.72% of the total variance. With each factor there was one group of species with high positive loadings and one group with high negative loadings. Each group of species could be identified with particular environments. The standing crop, measured as ash-free dry weight, ranged from 0.490 to 54.093 g/m², with a mean of 13.752 g/m². Only about 24% of the variability in standing crop could be attributed to variability in sediment types, nitrogen content in the sediments, salinity of the bottom water, and depth.     

Sources and concentrations of vascular plant material in sediments of Buzzards Bay,Massachusetts, USA

Samples of surface sediment from Buzzards Bay and creek sediment from Great Sippewissett Marsh were analyzed for lignin and stable carbon isotope composition in 1984. The lack of change in composition of lignins in detritus of Spartina alterniflora over two years of decomposition and similar aldehyde/acid ratios of lignin oxidation products of plant and sediment samples indicated minimal diagenesis of lignins in sediments. Remains of non-woody angiosperm tissues made up the bulk of the vascular plant debris in Great Sippewissett Marsh and Buzzards Bay sediments. These plant remains were evenly distributed over the sampling area in Buzzards Bay. Based on model calculations, salt marshes potentially contributed a significant fraction of the total amount of vascular plant debris in coastal marine sediments. The bulk of the organic matter in Buzzards Bay sediments, however, was derived from phytoplankton; vascular plant remains made up only 5 to 7% of the total amount of organic carbon in these sediments.     

Long-term variability in the structure of subtidal benthic communities in Puget Sound,Washington, USA

Data on benthic infauna from 4 permanent stations in Puget Sound off Seattle, USA, collected during 1963–1964, 1967, and 1969, revealed considerable stability in numbers of species and specimens and in diversity within stations among sampling dates. The species composition of the faunal assemblages also remained rather constant during the period of investigation, but the relative dominance among the numerically important species varied somewhat. Biomass data did not differ significantly in 1964 and 1969, but the 1967 data were considerably lower at all stations.     

Seasonal variation in paediatric blood lead levels in Syracuse,NY, USA

Venous blood lead values for 2,633 children aged 0–4 years in Syracuse, New York, collected between 1 April 1992 and 31 March 1993 were summarised by census tract for study of geographic variability. A demographic exposure model is presented showing housing stock and SES (socioeconomic status) parameters as the most significant predictor variables. A seasonal trend in blood lead levels was observed with late summer values about 40% higher than late winter values for census tracts with the highest geometric mean PbB levels. Seasonal variation is compared with a biokinetic uptake model to examine hypotheses about temporal variations in soil and dust lead exposure patterns.     

The influence of land use and climate change on forest biomass and composition in Massachusetts, USA

Land use and climate change have complex and interacting effects on naturally dynamic forest landscapes. To anticipate and adapt to these changes, it is necessary to understand their individual and aggregate impacts on forest growth and composition. We conducted a simulation experiment to evaluate regional forest change in Massachusetts, USA over the next 50 years (2010-2060). Our objective was to estimate, assuming a linear continuation of recent trends, the relative and interactive influence of continued growth and succession, climate change, forest conversion to developed uses, and timber harvest on live aboveground biomass (AGB) and tree species composition. We examined 20 years of land use records in relation to social and biophysical explanatory variables and used regression trees to create "probability-of-conversion" and "probability-of-harvest" zones. We incorporated this information into a spatially interactive forest landscape simulator to examine forest dynamics as they were affected by land use and climate change. We conducted simulations in a full-factorial design and found that continued forest growth and succession had the largest effect on AGB, increasing stores from 181.83 Tg to 309.56 Tg over 50 years. The increase varied from 49% to 112% depending on the ecoregion within the state. Compared to simulations with no climate or land use, forest conversion reduced gains in AGB by 23.18 Tg (or 18%) over 50 years. Timber harvests reduced gains in AGB by 5.23 Tg (4%). Climate change (temperature and precipitation) increased gains in AGB by 17.3 Tg (13.5%). Pinus strobus and Acer rubrum were ranked first and second, respectively, in terms of total AGB throughout all simulations. Climate change reinforced the dominance of those two species. Timber harvest reduced Quercus rubra from 10.8% to 9.4% of total AGB, but otherwise had little effect on composition. Forest conversion was generally indiscriminate in terms of species removal. Under the naive assumption that future land use patterns will resemble the recent past, we conclude that continued forest growth and recovery will be the dominant mechanism driving forest dynamics over the next 50 years, and that while climate change may enhance growth rates, this will be more than offset by land use, primarily forest conversion to developed uses.     

Seasonal variations in microzooplankton grazing in the region of the Subtropical Convergence

Microzooplankton grazing and community structure were investigated in the region of the Subtropical Convergence (STC) during three cruises of the South African Antarctic Marine Ecosystem Study (SAAMES) in austral summer (January/February 1993; December 1994/January 1995) and winter (June/July 1993). Chlorophyll a concentrations were consistently dominated by the <20 m size fraction during all three cruises, while the contribution of the microphytoplankton (>20 m) to total chlorophyll a concentrations varied considerably between cruises. Microzooplankton communities were numerically dominated by protozoans comprising ciliates (aloricates and tintinnids) and dinoflagellates. Instantaneous growth coefficients of phytoplankton in the vicinity of the STC showed no seasonal trends. However, marked seasonal differences were observed in the size structure of the phytoplankton. The grazing impact of microzooplankton was highest when the <20 m chlorophyll fraction contributed >95% of the total. Under these conditions, the instantaneous grazing rates ranged between 0.15 and 0.66 d^-1. These correspond to daily losses of 14 to 48% of the inntial standing stock and between 45 and 81% of the potential primary production. At stations where microphytoplankton contributed significantly (-20%) to total chlorophyll concentrations, the grazing coefficients were lower, ranging between 0 and 0.53 d^-1. This corresponds to a loss of <41% of the initial standing stock, or between 0 and 56% of the potential production. Our data suggest that microzooplankton represent the main grazing sink for production when the <20 m chlorophyll size-class dominates total chlorophyll. These facts suggest that the efficiency of the biological pump may vary over time.     

Removal of ammonium and nitrate through Anammox and FeS-driven autotrophic denitrification

● Simultaneous NH₄⁺/NO₃^– removal was achieved in the FeS denitrification system ● Anammox coupled FeS denitrification was responsible for NH₄⁺/NO₃^– removal ● Sulfammox, Feammox and Anammox occurred for NH₄⁺ removal ● Thiobacillus, Nitrospira , and Ca. Kuenenia were key functional microorganisms An autotrophic denitrifying bioreactor with iron sulfide (FeS) as the electron donor was operated to remove ammonium (NH₄⁺) and nitrate (NO₃⁻) synergistically from wastewater for more than 298 d. The concentration of FeS greatly affected the removal of NH₄⁺/NO₃⁻. Additionally, a low hydraulic retention time worsened the removal efficiency of NH₄⁺/NO₃⁻. When the hydraulic retention time was 12 h, the optimal removal was achieved with NH₄⁺ and NO₃⁻ removal percentages both above 88%, and the corresponding nitrogen removal loading rates of NH₄⁺ and NO₃⁻ were 49.1 and 44.0 mg/(L·d), respectively. The removal of NH₄⁺ mainly occurred in the bottom section of the bioreactor through sulfate/ferric reducing anaerobic ammonium oxidation (Sulfammox/Feammox), nitrification, and anaerobic ammonium oxidation (Anammox) by functional microbes such as Nitrospira, Nitrosomonas, and Candidatus Kuenenia. Meanwhile, NO₃⁻ was mainly removed in the middle and upper sections of the bioreactor through autotrophic denitrification by Ferritrophicum, Thiobacillus, Rhodanobacter, and Pseudomonas, which possessed complete denitrification-related genes with high relative abundances.     

Partitioning of nitrogen and carbon in cultures of the marine diatom Thalassiosira fluviatilis supplied with nitrate,ammonium, or urea

Small or negligible differences in growth rates, average cell size, yields in cell numbers and total cell volumes were found in cultures of Thalassiosira fluviatilis inriched with nitrate, ammonium, or urea. Intracellular pools of unassimilated nitrate, nitrate, and ammonium were found in nutrient-rich conditions, but urea was not accumlated internally. Nitrogen assimilation into organic combination rather than nitrogen nutrient uptake was a critical rate-limiting step in nitrogen utilization. The free amino acid pool, protein, lipid-associated nitrogen, pigments, and total cell nitrogen were all highest in young or mature phase cells and decreased with age in senescent cells, whereas chitan, lipid, carbohydrate, and total cellular carbon all continued to increase during senescence. Dissolved organic nitrogen compounds accumulated in the medium only during senescence. C:N and lipid:protein were sensitive indicators of nitrogen depletion and age in T. fluviatilis.     

Seasonal fluctuations of benthic macrofauna in the apalachicola estuary,Florida, USA: The role of predation

Long-term monitoring studies revealed a negative correlation between the abundance of bottom-feeding fishes (Leiostomus xanthurus and Micropogonias undulatus) and benthic macrofaunal density, suggesting a causal relationship. To test this hypothesis, large (3x3 m) topless predator-exclusion cages (mesh opening=6 mm) of a design that produced minimal physical artifacts were constructed at two shallow mud-bottom oligohaline stations. Two-sided control cages and uncaged control areas were also sampled Experiments coincided with maximum abundances of bottom-feeding fishes in the spring and motile macroinvertebrates (penaeid shrimp) in the fall. During short-term (two-month) exclusion experiments in the spring and fall of 1980, large predators (those excluded by 6-mm mesh) were not a major factor in regulating the densities of most macrofaunal species. Predation may be important during other seasons, although this possibility was not tested. Densities of Leiostomus xanthurus and Penaeus setiferus during 1980 were lower than in previous years. Despite the reduced abundance of bottom-feeding fishes, macrofaunal densities still declined during late winter/early spring. It is postulated that increased river flow and lowered salinities during the late winter/early spring may contribute to the decline of macrofaunal densities by reducing larval recruitment.     

Seasonal variations in different physico-chemical parameters of the effluents of Century Pulp and Paper Mill, Lal Kuan, Uttarakhand

The present study was undertaken with the objective to study the characteristics of the effluent of Century Pulp and Paper Mill, Lalkuan (Uttarakhand) in different seasons. The variations in the physicochemical characteristics were observed and monitored up to 12 months at three different sites. Mean values of temperature, pH, chlorides and total phenols of the effluent were found below, whereas colour, BOD5, COD and lignin concentrations were above the minimum national standards (MINAS).     

Seasonal and treatment-process variations in invertebrates in drinking water treatment plants

• Seasonal and treatment-process variations in invertebrates in a DWTP were analyzed. • The propagation and leakage of invertebrates in BAC filter were the most serious. • Invertebrates can survive and reproduce in chlorine disinfected clear water tanks. • Proportions of endogenous invertebrates increased along the treatment process. Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years. We performed a monthly survey of invertebrate abundance and taxa in the effluent of each treatment stage in a drinking water treatment plant between May 2015 and April 2016 and analyzed seasonal and treatment-process variations in invertebrates. The results showed that invertebrate abundances in raw water, effluent of the biological activated carbon (BAC) filter, and finished water significantly correlated with water temperature, whereas no correlation was observed between water temperature and invertebrate abundance in the effluents of the sedimentation tank and sand filter. The dominant taxa in the effluent of each treatment stage were rotifers, nematodes, and crustaceans. The sedimentation tank could efficiently remove invertebrates with an annual average removal rate of 92%. The propagation and leakage of invertebrates occurred in the sand and BAC filters but more seriously in the latter. The average reproduction rate in the BAC filter was 268.8% with rotifers as the taxon that leaked the most. Invertebrate survival and reproduction were also observed in the chlorine-disinfected clean water reservoir with an average reproduction rate of 41.9%. Owing to differences in chlorine resistance, the reproduction ability of the dominant taxa was in the order nematodes>crustaceans>rotifers. The proportion of endogenous invertebrates gradually increased along the treatment process. The average proportion of endogenous invertebrates in the finished water was higher than 79.0%. Our findings suggested that waterworks should pay more attention to endogenous invertebrate growth.     

Seasonal variations in physico-chemical parameters and heavy metals in water and sediments of Uppanar estuary, Nagapattinam, India

The present study was carried out to determine the physico-chemical characteristics and heavy metals in water and sediments in Uppanar Estuary, Nagapattinam, Southeast coast of India during January to December 2007. The minimum and maximum values of atmospheric and surface water temperatures (degrees C), salinity (per thousand), pH and dissolved oxygen (ml l(-1)) were: 26.0-35.0; 25.0-33.5; 8.0-35.0; 7.2-8.2 and 2.8-5.5 respectively. The ranges of nitrate, nitrite, phosphate and silicate were: 7.05-24.23; 0.82-3.15; 0.31-2.18 and 40.0-198.0 (microM) respectively. The ranges of heavy metals in water (microg 1(-1)) and sediment (microg g(-1)) copper zinc, cadmium and mercury were: 2.45-18.25; 26.43-101.24; 1.23-24.35 and 0.01-0.22 and 5.02-81.27; 22.47-75.42; 2.25-10.06 and 0.01-0.16 respectively.     

Seasonal variation in utilization of biogenic microhabitats by littorinid snails on tropical rocky shores

Mobile species may actively seek refuge from stressful conditions in biogenic habitats on rocky shores. In Hong Kong, the upper intertidal zone is extremely stressful, especially in summer when organisms are emersed for long periods in hot desiccating conditions. As a result, many species migrate downshore between winter and summer to reduce these stressful conditions. The littorinids Echinolittorina malaccana and E. vidua, for example, are found on open rock surfaces high on the shore in winter but the majority migrate downshore in summer to the same tidal height as a common barnacle, Tetraclita japonica. In the laboratory, where environmental conditions could be controlled to approximate those occurring on the shore, we tested whether the downshore migration allowed littorinids to select barnacles as biogenic habitats to reduce stress and if this behaviour varied between seasons. In summer, littorinids demonstrated a strong active preference for the barnacles, which was not observed in the cool winter conditions, when animals were found on open rock surfaces even when barnacles were present. Littorinids, therefore, only actively select biogenic habitats during the summer in Hong Kong when they migrate downshore, suggesting that such habitats may play an important, temporal, role in mitigating environmental stress on tropical shores.