Variation in secondary metabolite and aragonite concentrations in the tropical green seaweed Neomeris annulata: effects on herbivory by fishes

The tropical alga Neomeris annulata (Dickie) (Dasycladaceae: Chlorophyta) produces brominated sesquiterpenes and deposits aragonite throughout the thallus. This study, conducted throughout 1990–1991, showed that the fleshy, apical portions of the thalli (tips) were high in secondary metabolite concentrations (1.5%, mean combined secondary metabolites based on dry mass) and relatively low in calcium carbonate (aragonite form) (65.2% ash). The basal portions were lower in combined secondary metabolites (0.2% dry mass), and higher in aragonite (90.0% ash). The crude organic extract of the alga deterred fish feeding in the field at concentrations of 5, 10 and 15% dry mass, but not at a lower concentration of 1.5%. Natural concentrations of crude organic extract ranged from 1.5 to 15.3% in whole individuals and averaged 5.1% based on dry mass. Two brominated sesquiterpenes were isolated as major metabolites from the crude extract, but only one deterred feeding at natural concentrations. Ash concentrations in N. annulata were 60% dry mass in both the tips and bases. Aragonite strongly deterred feeding at concentrations of 65 and 90% dry mass. When a naturally occurring combination of organic extract and aragonite in the tips (10% crude extract and 65% aragonite) was compared with that of the bases (0.8% crude extract and 90% aragonite), no significant difference in grazing was observed. Combinations of secondary metabolites and aragonite were also tested against one or the other single defense. The combination of defenses proved a more effective deterrent than either secondary metabolites or aragonite alone.     

Secondary metabolites of the cyanobacterium Microcoleus lyngbyaceus and the sea hare Stylocheilus longicauda: palatability and toxicity

The cyanobacterium Microcoleus lyngbyaceus (Kütz.) Crouan (Lyngbya majuscula Gomont) produces a variety of nitrogen-containing secondary metabolites. M. lyngbyaceus is eaten by the specialist sea hare Stylocheilus longicauda, which sequesters secondary metabolites from its diet and transforms some sequestered metabolites into related compounds. We examined the palatability and toxicity of the metabolites malyngamide A, malyngamide B, and a mixture of majusculamides A and B (from M. lyngbyaceus), and malyngamide B acetate (from S. longicauda, derived from malyngamide B), in order to explore a series of hypotheses about why M. lyngbyaceus produces secondary metabolites and why S. longicauda sequesters and transforms them. All three M. lyngbyaceus metabolites significantly reduced feeding by omnivorous pufferfish (Canthigaster solandri) and crabs (Leptodius spp.). Direct comparisons indicated that neither malyngamide A nor the majusculamide mixture differed significantly in palatability from malyngamide B. The S. longicauda metabolite malyngamide B acetate did not significantly deter feeding by either consumer. Direct comparisons indicated that pufferfish found malyngamide B acetate more palatable than malyngamide B, and that crabs showed a non-significant trend in this direction. Palatability of the metabolites did not correlate with toxicity. Although no significant differences were observed among the M. lyngbyaceus metabolites in their palatability, two toxicity assays consistently ranked malyngamide A more toxic than malyngamide B, which was more toxic than the majusculamide mixture. The majusculamide mixture did not significantly differ in toxicity from malyngamide B acetate, even though the two differed strongly in palatability.     

137Cs determination and mutagenicity tests in wild Mus musculus domesticus before and after the Chernobyl accident

Wild rodents were collected alive in a suburban area to the north of Rome before, during, 6 months and 1 year after the Chernobyl accident. Radionuclide determinations to assess their content of (137)Cs and mutagenicity tests (bone-marrow micronucleus test and sperm abnormalities assay) were performed on the captured animals. The results obtained for the species Mus musculus domesticus (which was the rodent captured in highest numbers), compared with the results obtained before the fallout, showed an increase of both micronucleated polychromatic erythrocytes (MPCEs/1000 PCEs) and (137)Cs content during and after the fallout.     

Natural pollution caused by the extremely acidic crater lake Kawah Ijen, East Java, Indonesia

Background. Aims and Scope Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH 〈 0.3. It is the source of the extremely acid and metal-polluted river Banyupahit (45 km). The lake has a significant impact on the river ecosystem as well as on a densely populated area downstream, where agricultural fields are irrigated with water with a pH between 2.5 and 3.5. The chemistry of the river water seemed to have changed over the past decade and the negative effect in the irrigation area increased. A multidisciplinary approach was used to investigate the altered situation and to get insight in the water chemistry and the hydrological processes influencing these alterations. Moreover, a first investigation of the effects of the low pH on ecosystem health and human health was performed. Methods Water samples were taken at different sites along the river and in the irrigation area. Sampling for macroinvertebrates was performed at the same sites. Samples of soil and crop were taken in the irrigation area. All samples were analysed for metals (using ICP-AES) and other elements, and concentrations were compared to local and international standards. Results and Discussion The river carries a very high load of SO4, NH4, PO4, Cl, F, Fe, Cu, Pb, Zn, Al and other potentially toxic elements. Precipitation and discharge data over the period of 1980 – 2000 clearly show that the precipitation on the Ijen plateau influences water chemistry of the downstream river. Metal concentrations in the river water exceed the concentrations mentioned in Indonesian and international quality guidelines, even in the downstream river and the irrigation area. Some metal concentrations are extremely high, especially iron (up to 1600 mg/l) and aluminium (up to 3000 mg/l). The food-webs in the acidic parts of the river are highly underdeveloped. No invertebrates were present in the extremely acid water and, at pH 2.3, only chironomids were found. This also holds true for the river water with pH 3.3 in the downstream area. Agricultural soils in the irrigation area have a pH of 3.9 compared to a pH of 7.0 for soils irrigated with neutral water. Decreased yields of cultivated crops are probably caused by the use of Al containing acid irrigation water. Increased levels of metals (especially Cd, Co, Ni and Mn) are found in different foodstuffs, but still remain within acceptable ranges. Considering local residents” diets, Cd levels may lead to an increased risk for the human health. Fluoride exposure is of highest concern, with levels in drinking water exceeding guideline values and a lot of local residents suffering from dental fluorosis. Conclusions, Recommendations and Outlook In short, our data indicate that the Ijen crater lake presents a serious threat to the environment as well as human health and agricultural production.     

Determination of fluoroquinolone antibiotics in wastewater effluents by liquid chromatography-mass spectrometry and fluorescence detection

The occurrence of quinolone antibiotics (QAs) was investigated in wastewater effluents and surface river/lake waters in the US and Canada by using solid-phase extraction with mixed phase cation exchange disk cartridge and liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography fluorescence detection (LC-FLD). Ofloxacin (OFL) was detected in secondary and final effluents of a wastewater treatment plant (WWTP) in East Lansing, Michigan, at concentrations of 204 and 100 ng/l, respectively. The mass flow calculation, estimated by multiplying the OFL concentration in the final effluent by the average influent volume of the WWTP, showed that the discharge of OFL to the river was 4.8 g/day. The OFL concentrations in wastewater effluents measured in this study are comparable to or less than those observed in several European countries. QAs were not detected in river and lake waters analyzed in this study, which may due to dilution effects and to the higher detection limits, relative to those reported previously. OFL concentrations were approximately 1-2 orders of magnitude lower than the EC50 concentrations for environmental bacterium. However, greater concentrations of other QAs in sewage sludge from WWTPs may result in cumulative effects. Considering that the sewage sludge is applied to the land as fertilizers, soil-dwelling organisms could experience greater exposures to such antibiotics. Monitoring studies of QAs in sewage from WWTPs and in sediment/soil near aquaculture facilities and livestock farms will be necessary for the evaluation of the environmental distribution and risk of these compounds.     

Estimation of the contribution of a municipal waste incinerator to the overall emission and human intake of PCBs in Wilrijk, Flanders

The contribution of the emission of PCBs by a municipal waste incinerator in Wilrijk, a relatively industrialized district in the largest city of Flanders, to the total emission to air and to the total human intake was estimated. Therefore it was compared to the emission of PCBs by evaporation from PCB containing applications (transformers, capacitors, paint, ink, etc.) and to the intake of PCBs with food. As there was a lack of PCB data from the incinerator, the PCB emission concentration was estimated using three different approaches. A PCB measurement of the incinerator emission, performed later on, fell within the predicted range of 0.0004-0.005 ng TEQ/Nm3. Emission of PCBs from PCB containing applications and intake from food were deduced from information available on Flemish and European level. The results indicate a PCB contribution from the incinerator to local emissions between 0.3% and 3% of the emission from PCB containing applications and a contribution to human intake less than 6 x 10(-4)% of the intake from food.     

A comparison of polycyclic aromatic hydrocarbon and petroleum hydrocarbon uptake by mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) in Hong Kong coastal waters

The ability of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) to accumulate polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons (PHCs) from five sites in Hong Kong's coastal waters was compared. Mussels consistently had higher levels of contaminants, but their utility was limited at one highly polluted site due to mortality. Mussels and SPMDs ranked sites differently in terms of individual contaminant levels. Although SPMDs overcome many of the disadvantages of using living organisms to measure contaminants in marine waters, they cannot be used as "mimics" due to different PAH and PHC accumulation patterns.     

Risk to breeding success of waterbirds by contaminants in Hong Kong: evidence from trace elements in eggs

Concentrations of 17 trace elements (As, Se, Rb, Sr, Ag, Sb, Cs, Tl, Pb, V, Cr, Mn, Co, Cu, Zn, Cd, and Hg) were determined in eggs of little egrets (Egretta garzetta), black-crowned night herons (Nycticorax nycticorax) and bridled terns (Sterna anaethetus) from northwestern and northeastern coastal areas of Hong Kong. Results indicated significant differences among the three species. Eggs of little egrets and black-crowned night herons appeared to be good bioindicators for monitoring selected elements (As, Pb, Zn Cr, Cu, and V) due to consistent correlations between metal concentrations in eggs and those in coastal marine sediments. Based on limited toxicological information, the predicted no effect concentrations (PNECs) of Hg and Se in the bird eggs were estimated as 0.5 to 1.8 and 0.90 to 1.45 mug g(-1), dry wt., respectively. Hazard quotients (HQs) indicated that Hg and Se might pose some risk to certain waterbirds in Hong Kong.     

Fate of disinfection by-products in groundwater during aquifer storage and recovery with reclaimed water

Knowledge on the behaviour of disinfection by-products (DBPs) during aquifer storage and recovery (ASR) is limited even though this can be an important consideration where recovered waters are used for potable purposes. A reclaimed water ASR trial in an anoxic aquifer in South Australia has provided some of the first quantitative information at field-scale on the fate and transport of trihalomethanes (THMs) and haloacetic acids (HAAs). The results revealed that THM half-lives varied from <1 to 65 days, with persistence of chloroform being highest and bromoform lowest. HAA attenuation was rapid (<1 day). Rates of THM attenuation were shown to be highly dependent on the geochemical environment as evidenced by the 2-5 fold reduction in half-lives at the ASR well which became methanogenic during the storage phase of the trial, as compared to an observation well situated 4 m away, which remained nitrate-reducing. These findings agree with previous laboratory-based studies which also show persistence declining with increased bromination of THMs and reducing redox conditions. Modelling suggests that the chlorinated injectant has sufficient residual chlorine and natural organic matter for substantial increases in THMs to occur within the aquifer, however this is masked in some of the field observations due to concurrent attenuation, particularly for the more rapidly attenuated brominated compounds. The model is based on data taken from water distribution systems and may not be representative for ASR since bromide and ammonia concentrations in the injected water and the possible role of organic carbon in the aquifer were not taken into consideration. During the storage phase DBP formation potentials were reduced as a result of the removal of precursor material despite an increase in the THM formation potential per unit weight of total organic carbon. This suggests that water quality improvements with respect to THMs and HAAs can be achieved through ASR in anoxic aquifers.     

Polychlorinated biphenyls in Narragansett Bay surface sediments

Polychlorinated biphenyls (PCBs) were evaluated in 41 surface sediments collected from Narragansett Bay, RI in 1997-1998. Highest concentrations of total PCBs (1760 ng/g) were in rivers at the head of the bay and the values decreased southward toward the mouth of the bay, with elevated concentrations in some of the coves. The PCB levels in approximately 43% of the samples exceeded the effects range median (ERM) guideline [Environ. Manage. 19 (1995) 81] indicating possible adverse biological effects at these stations. Principal component analysis (PCA) of the surface sediment PCBs separated the Taunton River samples from the rest of the samples. This result suggests that this river has a different PCB composition and sources than the other areas investigated. It also showed that this river has a limited influence on other bay stations as the adjacent samples downstream did not have the same chemical signature. Congener ratios derived from the PCA were useful in distinguishing stations that had different sources of PCBs than the bulk of the bay sediments. Although Aroclor 1268 and 1270 accounted for <1% of all PCB production, their major components, CB206 and CB209, account for 3-6% of the CBs in most bay samples. This may reflect more local use of these Aroclor mixtures and/or be indicative of their relative stability, compared to less chlorinated mixtures. Using linear alkyl benzenes (LABs) as a marker for sewage derived PCBs suggested that up to 95% of the PCBs at the most contaminated sites in the Seekonk, Providence, and Taunton Rivers were sewage derived. This analysis also showed that there is a high background level (167 ng/g) of PCBs in the Seekonk and Providence River, while the Taunton River had a relatively low background level (23.7 ng/g). At the furthest stations south in the Providence River, the sewage derived PCBs only accounted for 23% of the total which suggests that PCB associated with sewage particles are rapidly deposited and are therefore not the most significant source of these compounds to the lower reaches of Narragansett Bay.