Effects of several metals on spore,biomass, and geosmin production byStreptomyces tendae andPenicillium expansum

Cultures ofStreptomyces tendae andPenicillium expansum grown on Actinomyces and Czapek's media, respectively, were exposed to 5 mg L^–1 of manganese, magnesium, iron, cobalt, nickel, copper and zinc, supplied as sulfate salts. Only copper markedly increased geosmin (1, 10-dimethyl-9-decalol), biomass, and spore production. inductively coupled plasma-atomic emission spectrometric analysis ofS. tendae andP. expansum cells did not indicate an accumulation of copper. Both 1 and 5 mg L^–1 copper, as copper sulfate, increased total geosmin production in cultures ofS. tendae on several media, but decreased production on others, suggesting that substrate composition affects responses to copper.     

Influence of environmental factors on the growth in culture of a New Zealand strain of the fast-spreading algaHydrodictyon reticulatum (water-net)

Hydrodictyon reticulatum (L.) Lagerh. is a recent addition to the New Zealand flora and is expanding its distribution rapidly. Proliferations of the alga now constitute an economic nuisance in waters which have not previously suffered filamentous algal blooms. To better understand the current and likely future spread of the alga and to identify possible management options the alga's growth requirements have been investigated. A strain isolated from New Zealand tolerated temperatures between 5 and 40 °C and salinities from 0 to 5. Optimal growth was at 25 °C, 150 mol photon m^–2s^–1 and in freshwater. Nett photosynthesis was saturated at photon flux densities of 100 and 160 mol m^–2s^–1 at 12 and 20 °C, respectively. Growth rate was linearly related to internal N concentration and hyperbolically to internal P concentration. Minimum cellular nutrient contents, by weight, were 1% N and 0.2% P. Growth was saturated at contents of 5% N and 0.5% P under the conditions of culture (20 °C, 150 mol photon m^–2s^–1). The alga maintained optimal cellular N content at low ambient nitrate concentrations (100 mg m^–3) half optimum content at 18 mg m^–3. Affinity for filtrable reactive phosphorus was not unusually high compared to other filamentous algae. We suggest that this alga is occupying a niche in New Zealand which has been precluded from other filamentous nuisance algae by low N concentration and N:P ratio. The significance of these findings in setting environmental targets for management of this nuisance alga is discussed.Author for correspondence     

Biofiltering efficiency in removal of dissolved nutrients by three species of estuarine macroalgae cultivated with sea bass (Dicentrarchus labrax) waste waters 2. Ammonium

Three estuarine macroalgae (Ulva rotundata,Enteromorpha intestinalis, Gracilariagracilis) of economic potential were cultivated in the laboratory toassess their biofiltering capacities for ammonium in waste effluents from a seabass (Dicentrarchus labrax) cultivation tank. The studywasdeveloped to investigate the functioning of N nutrition of the three species.Atlow water flow (< 2 volumes d^–1) the three species strippedefficiently the ammonium dissolved in the waste water from the fish tank, withaminimum biofiltering efficiency estimate of 61% in unstarved cultures ofG. gracilis at a water flow of 2 volumesd^–1. Maximum velocity for ammonium uptake (89.0 molNH₄ ⁺ g^–1 dry wth^–1) was found in U. rotundata,whereas G. gracilis showed the highest affinity for thisnutrient. The net ammonium uptake rate was significantly affected by the waterflow, being greatest at the highest flow assayed (2 volumesd^–1). Variations of tissue N and C:N ratios during aflow-through experiment suggested that N was not limiting macroalgal growth.However, when ammonium was supplied at a flow rate of 0.5 volumesd^–1, specially in a three-stage design, the marked reductionintissue N and the biomass C:N:P ratios suggested a more general nutrientdeficiency. A significant correlation was found between growth rates and the Nbiomass gained in the cultures. The three-stage design under low water flow(0.5volumes d^–1) showed that the highest ammonium uptake rates (upto 80.9 mol NH₄ ⁺ g^–1 dry wtd^–1 in U. rotundata) were found inthe first stage, with decreasing rates in the following ones. As a result, lowincrements or even losses of total N biomass in these stages were found,suggesting that ammonium was excreted from the algae. We conclude that thesespecies present a potential ability to biofilter the ammonium dissolved inwastewater from a D. labrax cultivation tank, suggesting thatscaling up the biofiltration designs, future practises using these macroalgaemay be implemented in the local fish farms, resulting in both environmental andeconomical advantages.     

Neomysis integer in a shallow hypertrophic brackish lake: distribution and predation by three-spined stickleback (Gasterosteus aculeatus)

The mysid shrimp Neomysis integer is a common invertebrate predator in brackish waters of Western Europe and is thought to play a central role in the food web owing to its predation on zooplankton. Neomysis distribution and abundance were investigated for 3 years in brackish, shallow and hypertrophic Lake Ferring (surface area: 3.2 km², mean depth: 1.4 m, salinity: 3–6, total P: 0.29–0.78 mg P l^-1, Secchi depth: 0.14–0.22 m). Mean summer abundance of Neomysis varied from 53 to 882 ind. m^-2. Neomysis density within the lake was relatively uniform and not related to sediment type, but increased with increasing depth. The high abundance of Neomysis is considered to reflect a fish stock almost completely dominated by small-sized fish species (mainly three-spined stickleback, Gasterosteus aculeatus). Three-spined stickleback density was high and catch per unit effort ranged between 30 and 80 per gill net. Stomach analyses showed that the sticklebacks preyed on Neomysis, but preferred specimens smaller than 3–4 mm, and only occasionally consumed those larger than 5–7 mm. In summer, between 33 and 67% of the Neomysis ingested by sticklebacks were smaller than 3 mm, while in the lake as a whole, only 5–14% were smaller than 3 mm. The periods when Neomysis is vulnerable to stickleback predation are restricted to a few weeks in late May and late July, when the new generations emerge. Sticklebacks therefore have a limited capacity for controlling large Neomysis, including gravid females.     

Effects of environmental parameters on net photosynthesis of a free-living brown seaweed,Cystoseira barbata formarepens: determination of optimal photosynthetic culture conditions

The net photosynthesis of the Mediterranean brown seaweedCystoseira barbata f.repens is measured according to irradiance, temperature and salinity. There is not only, a good utilization of low light intensities (light-shade adaptation), but also a specific ability to use a broad range of irradiance, which corresponds in the photosynthesis-irradiance curves to a high initial slope and an extended light saturation level from 300 to 1500 mol photon m^–2 s^–1; only very high irradiances induce photoinhibition. Maximum net photosynthesis occurred at temperatures ranging from 20 °C to 30 °C. The alga tolerates not only a low level of salinity, but also a slight increase in salinity; however, at more than 47.5 g 1^–1 NaCl, oxygen exchange is significantly reduced.Light, temperature and salinity requirements are discussed, taking into account ecological considerations. Yields and quality of alginic acid are presented according to the irradiance and yearly evolutionin situ in order to aid future cultivation of this species.     

Cultivation and carrageenan yield and quality ofKappaphycus alvarezii in the waters of Vietnam

The carrageenan-producing red algaKappaphycus alvarezii (Doty) Doty was brought to Vietnam from Japan in 1993. Branch fragments of this species were cultivated in a pond, lagoon, inlet and offshore in Vietnam for the first time. The best daily growth rate (DGR) of plants grown in the lagoon area attained 9–11 % day^–1 in May to June (cold season). The water temperature and salinity in this area ranged from 27.2–32.4 °C and 31.4–33.7 °C, respectively. DGR of plants grown in the inlet ranged from 7 to 9% day^–1 in June. Grazing by fish has been observed to occur in this area. The DGR of plants grown in the pond ranged from 5–6% in January–July, but decreased to less than 4% day^–1 in August (hot season). K. alvarezii in Vietnam showed a carrageenan yield of 18.8–24.6% and gel strength of 1566–1712 g cm^–2. These values are similar ones obtained fromK. alvarezii cultivated in the Philippines and Indonesia.     

Biofiltering efficiency in removal of dissolved nutrients by three species of estuarine macroalgae cultivated with sea bass (Dicentrarchus labrax) waste waters 1. Phosphate

The potential of three estuarine macroalgae (Ulvarotundata, Enteromorpa intestinalis andGracilaria gracilis) as biofilters for phosphate ineffluents of a sea bass (Dicentrarchus labrax) cultivationtank was studied. These seaweeds thrive in Cádiz Bay and were alsoselected because of their economic potential, so that environmental andeconomicadvantages may be achieved by future integrated aquaculture practices in thelocal fish farms. The study was designed to investigate the functioning of Pnutrition of the selected species. Maximum velocity of phosphate uptake (2.86mol PO₄ g^–1 dry wth^–1) was found in U. rotundata.This species also showed the highest affinity for this nutrient. At low flowrates (< 2 volumes d^–1), the three species efficientlyfiltered the phosphate dissolved in the waste water, with a minimum efficiencyof 60.7% in U. rotundata. Net phosphate uptake rate wassignificantly affected by the water flow, being greatest at the highest rateassayed (2 volumes d^–1). The marked decrease in tissue P shownby the three species during a flow-through experiment suggested that growth wasP limited. However, due to the increase in biomass, total P biomass increasedinthe cultures. A significant correlation was found between growth rates and thenet P biomass gained in the cultures. A three-stage design under low water flow(0.5 volumes d^–1) showed that the highest growth rates (up to0.14 d^–1) and integrated phosphate uptake rates(up to 5.8 mol PO₄ ^3– g^–1dry wt d^–1) were found in E.intestinalis in the first stage, with decreasing rates in thefollowing ones. As a result, phosphate become limiting and low increments oreven losses of total P biomass in these stages were found suggesting thatphosphate was excreted from the algae. The results show the potential abilityofthe three species to reduce substantially, at low water flow, the phosphateconcentration in waste waters from a D. labrax cultivationtank, and thus the quality of effluents from intensive aquaculture practices.     

Zooplankton distribution in four ponds of different salinity: a seasonal study in the solar salterns of Sfax (Tunisia)

The seasonal distribution of metazooplankton and large-sized ciliates was studied in four ponds of different salinity in the solar salterns of Sfax (Tunisia). Total zooplankton abundance varied from 1 × 10³ to 4.7 × 10⁶ ind m^–3. Salinity had a negative effect on the abundance of copepods and rotifers which were absent in the pond with the highest salt concentration (180) in which the number of taxa was low and Artemia or the ciliate Fabrea largely dominated the zooplankton community. Temperature and the presence of Dunaliella salina as prey appeared as key factors in controlling the abundance of Artemia, while organic detritus appeared as important in the diet of Fabrea. Change in zooplankton species composition along the hypersaline gradient (40–90) was primarily related to salinity. However, our data suggest the importance of both the abundance and composition of food in the spatial and temporal variations of some zooplankton species.     

Bottom-up controls on a mixed-species HAB assemblage: A comparison of sympatric Chattonella subsalsa and Heterosigma akashiwo (Raphidophyceae) isolates from the Delaware Inland Bays, USA

Recent novel mixed blooms of several species of toxic raphidophytes have caused fish kills and raised health concerns in the highly eutrophic Inland Bays of Delaware, USA. The factors that control their growth and dominance are not clear, including how these multi-species HAB events can persist without competitive exclusion occurring. We compared and contrasted the relative environmental niches of sympatric Chattonella subsalsa and Heterosigma akashiwo isolates from the bays using classic Monod-type experiments. C. subsalsa grew over a temperature range from 10 to 30 °C and a salinity range of 5–30 psu, with optimal growth occurring from 20 to 30 °C and 15 to 25 psu. H. akashiwo had similar upper temperature and salinity tolerances but also lower limits, with growth occurring from 4 to 30 °C and 5 to 30 psu and optimal growth between 16 and 30 °C and 10 and 30 psu. These culture results were confirmed by field observations of bloom occurrences in the Inland Bays. Maximum nutrient-saturated growth rates (μ_max) for C. subsalsa were 0.6 d⁻¹ and half-saturation concentrations for growth (K_s) were 9 μM for nitrate, 1.5 μM for ammonium, and 0.8 μM for phosphate. μ_max of H. akashiwo (0.7 d⁻¹) was slightly higher than C. subsalsa, but K_s values were nearly an order of magnitude lower at 0.3 μM for nitrate, 0.3 μM for ammonium, and 0.2 μM for phosphate. H. akashiwo is able to grow on urea but C. subsalsa cannot, while both can use glutamic acid. Cell yield experiments at environmentally relevant levels suggested an apparent preference by C. subsalsa for ammonium as a nitrogen source, while H. akashiwo produced more biomass on nitrate. Light intensity affected both species similarly, with the same growth responses for each over a range from 100 to 600 μmol photons m⁻² s⁻¹. Factors not examined here may allow C. subsalsa to persist during multi-species blooms in the bays, despite being competitively inferior to H. akashiwo under most conditions of nutrient availability, temperature, and salinity.     

Light acclimation and photoinhibition in threeSpirulina platensis (cyanobacteria) isolates

Three isolates ofSpirulina platensis (Norst) Geitler marked BP, P4P and Z19/2 were compared with respect to their response and acclimation capability to high photon flux densities (HPFD). Cultures exposed to HPFD (1500–3500 mol photon m^–2 s^–1) exhibited a marked decrease in light-dependent O₂ evolution rate. P4P was more sensitive to HPFD than the two other isolates. All three isolates recovered from photoinhibition when placed under low PFD. The BP isolate was able to recover also in the dark but to a lower extent and at a lower rate, while no recovery was observed in the other two isolates under dark conditions. No recovery was observed when protein synthesis was inhibited using chloramphenicol. Cultures grown at 200 mol photon m^–2 s^–1 differed from cultures grown at 120 mol photon m 2 s-1 by their lower maximal photosynthetic rate (P _max ) and higher light saturation (I _k ) value, while being more resistant to HPFD stress. The ability ofSpirulina isolates to acclimate and withstand HPFD may provide useful information for the selection of strains useful for outdoor mass cultivation.Author for correspondence     

New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales,Rhodophyta)

A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30–40% d^–1, which are reached in salinities between 5 and 40, and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l^–1 and for herbicides between 0.002 and 0.02 mg l^–l. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results.In conclusion, this is a simple, sensitive and reproducible test method for assessing the toxicity of substances, wastewaters and anti-fouling paints in brackish and marine environments.     

Indirect photometric ion chromatographic analysis of anions in Haematococcus pluvialis culture media

An indirect photometric ion chromatographic method for the simultaneous determination of chloride, nitrate and sulfate ions was developed and applied to the determination of anions, mainly nitrate, in the alga Haematococcus pluvialis culture media. Using phthalic acid/sodium tetraborate aqueous solution as the mobile phase, anions can be detected indirectly by a UV detector. The calibration curves for these anions gave good linearity from 1 to 1000 g ml^–1.     

Remarkable Salinity Tolerance of Seven Species of Naked Amoebae (gymnamoebae)

The salinity tolerance of naked amoebae collected from sites ranging from ca. 0‰ to 160‰ were compared in laboratory experiments. Amoebae were collected from hypersaline ponds around the perimeter of the Salton Sea, California, where salinities averaged 160‰, and directly from the shoreline waters of the Sea where salinities were generally between 44 and 48‰. Naked amoebae were also collected from the intertidal zone of a Florida beach, a habitat subject (on occasion) to salinity fluctuations within the range 6–85‰. From these combined sites, 6 clones of amoebae were isolated for salinity tolerance experiments (2 marine beach isolates, 2 Salton Sea isolates, and 2 hypersaline pond isolates). A seventh clone, Acanthamoeba polyphaga, a common freshwater/soil amoeba, was obtained from a Culture Collection. Laboratory experiments compared the effects of gradually changing culture salinity versus no salinity acclimatization. Growth rate and culture yield were used as indices of effect. Generally, amoebae were tolerant over a wide range of salinity conditions (in terms of growth and yield) and were not markedly influenced by pre-conditioning to salinity changes throughout the experiments. Overall, the freshwater amoeba Acanthamoeba grew between 0 and 12‰, the marine clones grew in the range of 2–120‰, and the Salton Sea clones reproduced between 0 and 138 ‰. The hypersaline clones were the most resilient and grew between 0 and 270‰ salt. The survival and activity of large populations of naked amoebae in sites subject to salinity fluctuations suggest that they should be considered in future studies to better understand their, as yet, undefined ecological role.     

A bloom of Dunaliella parva in the Dead Sea in 1992: biological and biogeochemical aspects

A bloom of the unicellular green alga Dunaliella parva (up to 15 000 cells m1^–1) developed in the upper 5 m of the water column of the Dead Sea in May-June 1992. This was the first mass development of Dunaliella observed in the lake since 1980, when another bloom was reported (up to 8800 cells m1^–1). For a bloom of Dunaliella to develop in the Dead Sea, two conditions must be fulfilled: the salinity of the upper water layers must become sufficiently low as a result of dilution with rain floods, and phosphate must be available. During the period 1983–1991 the lake was holomictic, hardly any dilution with rainwater occurred, and no Dunaliella cells were observed. Heavy rain floods in the winter of 1991–1992 caused a new stratification, in which the upper 5 m of the water column became diluted to about 70% of their former salinity. Measurements of the isotopic composition of inorganic carbon in the upper water layer during the bloom (¹³C = 5.1) indicate a strong fractionation when compared with the estimated –3.4 prior to the bloom. The particulate organic carbon formed was highly enriched in light carbon isotopes ( ¹³ C = – 13.5). The algal bloom rapidly declined during the months June–July, probably as a result of the formation of resting stages, which sank to the bloom. A smaller secondary bloom (up to 1850 cells m1–1) developed between 6 and 10 m depth at the end of the summer. Salinity values at this deep chlorophyll maximum were much beyond those conductive for the growth of Dunaliella, and the factors responsible for the development of this bloom are still unclear.     

Feeding by ciliates on two harmful algal bloom species, Prymnesium parvum and Prorocentrum minimum

We have focused on ciliates as potential grazers on toxic phytoplankton because they are major herbivores in aquatic food webs. Ciliates may exert top down control on toxic phytoplankton blooms, potentially suppressing or shortening the duration of harmful algal blooms (HABs). We measured the growth rates of several ciliate species on uni-algal and mixed diets of both HAB and non-HAB algae. The tintinnids Favella ehrenbergii, Eutintinnus pectinis and Metacylis angulata and the non-loricate ciliates Strombidinopsis sp. and Strombidium conicum were isolated from Long Island Sound (LIS), and fed HAB species including the prymnesiophyte Prymnesium parvum (strain 97-20-01) and the dinoflagellate Prorocentrum minimum (strains Exuv and JA 98-01). Ciliates were fed algal prey from cultures at various growth phases and at varying concentrations. We observed no harmful effects of P. minimum (Exuv) on any of the ciliates. However in a comparison of strains, P. minimum (Exuv) supported high growth rates, whereas P. minimum (JA 98-01) supported only nominal growth. P. parvum was acutely toxic to ciliates at high concentrations (2×10⁴–3×10⁴ cells ml⁻¹). At low concentrations (5×10³–1×10⁴ cells ml⁻¹), or in culture filtrate, ciliates survived for at least several hours. In mixed diet experiments, as long as a non-toxic alga was available, ciliates survived and at times grew well at concentrations of P. parvum (5×10²–3×10⁴ cells ml⁻¹) that would otherwise have killed them. The present study suggests that prior to the onset of toxicity and bloom formation ciliates may exert grazing pressure on these HAB species, potentially contributing to the suppression or decline of P. minimum and P. parvum blooms.     

Intra-isolate Heterogeneity and Reproducibility of PCR-based Genotyping of Cryptosporidium parvum Using the β-tubulin Gene

Cryptosporidium parvum is a common contaminant in surface waters and presents significant problems for the water industry, public health and agriculture. Consequently, ascertaining the contaminating source of waterborne oocysts is of paramount importance. Based on currently available information, isolates of C. parvum can be differentiated into at least two genotypes using polymorphic genetic markers: genotype 1, to date isolated almost exclusively from humans, and genotype 2 isolates from humans and many other animals. Differentiation into these two genotypes has been based on either restriction fragment length polymorphisms or sequencing of PCR amplified gene fragments. The objective of this study was to evaluate the reproducibility of genotyping methods using a single isolate of C. parvum. A 620 bp fragment of the C. parvum -tubulin gene, generated by PCR from multiple aliquots of a single preparation of oocysts of the Iowa isolate, was sequenced. Significant sequence heterogeneity was detected within this single isolate; there was more sequence variation between clones originating from the Iowa isolate (up to 0.9 %) than between individual clones originating from different isolates of C. parvum. Over 6 % of the -tubulin gene sequence positions (38 out of 620 bp) were variable when comparing multiple clones from the one isolate. The results indicated that while the various procedures used for genotyping isolates may introduce some sequence errors, the Iowa isolate used for this investigation appeared to be composed of multiple sub-genotypes. While none of the sequence variations resulted in clones of the Iowa isolate (genotype 2) being mis-identified as genotype 1, the results have important implications if minor sequence variations are to be used for subtyping isolates and drawing conclusions regarding the origin of, or relationships between, C. parvum oocysts in water and the community.     

Life cycle and production of Hydrobia acuta Drap. (Gastropoda: Prosobranchia) in a hypersaline coastal lagoon

The life cycle and annual production of Hydrobia acuta was studied in a hypersaline lagoon (s = 39 in summer), forming a part of solar salt works. Quantitative random samples were taken at regular intervals over a period of 15 months using a corer, and snails collected were counted and measured. Weight and biomass was calculated from a length-weight relationship and from measurements of ash content. H. acuta was a strictly annual species in the study lagoon. Recruitment takes place over a brief period in May and June, after which the breeding population dies. Growth of the new generation was slow during summer, probably due to the unfavourably high salinity. A period of rapid growth took place in autumn coinciding with a drop in salinity caused by rainfall. In winter Hydrobia hibernated by burrowing deeply into the sediment. Growth recommenced in spring when the lagoon was reflooded, but by this time the number of survivors was low.The maximum density of snails was 6 000 m^–2 and maximum biomass 500 mg organic dry wt · m^–2. Annual cohort production was estimated as 786 mg organic dry wt · m^–2 · a^–1. These figures are low compared to other studies on hydrobiid snails, and for production in inland waters, but the value for annual P/B = 4.5 is typical for a univoltine species. The relevance of the results to foraging by wading birds (the main consumers), is discussed.     

Growth inhibition by high light intensities in algae from lakes undergoing acidification

Blooms ofChrysochromulina breviturrita Nich. (Prymnesiophyceae) have been found to be restricted to lakes above pH 5.5 even though the alga is able to tolerate pH 4.0 in laboratory culture. A possible explanation is the increased transparency in acidifying lakes and a sensitivity ofC. breviturrita to high light intensities. A comparison was made withMougeotia sp., a filamentous green alga which co-occurs in moderately acidic lakes and has a similar pH tolerance range. This alga forms dense, floating mats or amorphous clouds in the upper littoral zone, where it would be exposed to full sunlight irradiances. In cultures ofC. breviturrita, prolonged exposures to 1600 μE · m⁻² · s⁻¹ (I₀′) resulted in reductions in cell yield which were dependent age at the onset of exposure to high light intensity. Only cultures exposed to high light intensities during late stationary phase were able to recover to control levels and no recovery occurred if these cultures were nitrogen deficient.Mougeotia was more tolerant of both high light intensity and nitrogen limitation during the recovery period. The inability ofC. breviturrita to recover from the effects of high light intensity during nitrogen deprivation may be particularly important in small, stratified lakes which are undergoing acidification. The slow rate of vertical circulation, and increasing transparency, would prolong exposure of the alga to the high irradiance levels of nutrient-deficient epilimnetic waters. This suggests that the geographic distribution ofC. breviturrita may be explained in part by the increasing light intensities in lakes undergoing acidification.     

The impact of red mud on growth of wetland vegetation and substrate fertility

Greenhouse experiments were conducted to evaluate the impact of red mud, the residue of the Bayer process for extracting alumina from bauxite, on wetland to investigate whether red mud can be used for wetland restoration. Two wetland species,Spartina alterniflora Loisel. andSagittaria lancifolia L., were used to test their response to the following substrate treatments: 100% marsh sediment, 100% red mud, a mixture of 50% marsh sediment and 50% red mud, a mixture of 50% red mud and 50% compost, and neutralized red mud. Each substrate treatment received two fertilization levels, fertilized (N–P–K) and unfertilized. Red mud could support the growth of the salt marsh species,Spartina alterniflora, but not the fresh marsh species.Sagittaria lancifolia. The high Na content and salinity of red mud, even when mixed with marsh sediment or compost, appeared to be the primary cause for the high mortality ofSagittaria in these substrates. Fertilization did not reduce the stress response ofSagittaria to red mud, but significantly increased the growth ofSpartina. Red mud is low in available N and P and required fertilizer or organic matter (e.g., compost) addition to increase fertility. In experiments with both fresh and salt marsh sediments, the concentrations of soluble heavy metals, with the exception of Mn, were not significantly greater for red mud than for marsh sediment. Thus, the release of heavy metals from red mud over the short-term may not pose an environmental concern. However, the mobilization of heavy metals over the long-term and the influence of plants in accumulating metals requires further investigation.     

Arsenic concentrations in water and fish from Chautauqua Lake,New York

Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l^–1, = 49.0 ag l^–1. Well water samples generally contained less than 10 g l^–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l^–1) and many samples exceeded the maximum permissible limit (50 g l^–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g^–1 ), X = 0.7 g g^–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g^–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers.