Reproductive ecology of <Emphasis Type="Italic">Fungiacyathus marenzelleri</Emphasis> from 4100 m depth in the northeast Pacific Ocean

Fungiacyathus marenzelleri (Vaughan, 1906) is a deep-water solitary coral, cosmopolitan in distribution that is found at depths of 300–6,328 m. This study examined gametogenesis, inter-annual variability and reproductive periodicity of F. marenzelleri collected from Station M (34°50′N, 123°00′W) in the northeast Pacific at a depth of 4,100 m. Samples were collected (May, June, October 1996; August 1998; February, June 2001; and June 2002) and histologically processed with spermatogenic stage, oocyte size and fecundity measured. Four stages of spermatogenesis were identified and all males contained multiple stages of sperm development in each seasonal sample. Three stages of oocyte development were identified; previtellogenic (<28–150 μm), vitellogenic (150–300 μm) and late vitellogenic (300–400 μm). Comparison of mean oocyte diameters among sampling dates showed there were no inter-annual variations or seasonal differences. Overall, fecundity was 1,290 (±407) oocytes polyp⁻¹, and with no significant differences between sample months. Fecundity was not polyp-size dependent. This study shows a similar quasi-continuous mode of reproduction to this species examined from the Northeast Atlantic Ocean, but the fecundity is reduced by 50%. The reproductive output may fluctuate in relation to the input of organic material at this site, as shown by non-significant trends in the oocyte size-frequency and fecundity data. A quasi-continuous output of gametes would promote successful fertilisation and wide dispersal of the lecithotrophic larvae.     

Using multi-objective classification to model communities of soil microarthropods

In agricultural soil, a suite of anthropogenic events shape the ecosystem processes and populations. However, the impact from anthropogenic sources on the soil environment is almost exclusively assessed for chemicals, although other factors like crop and tillage practices have an important impact as well. Thus, the farming system as a whole should be evaluated and ranked according to its environmental benefits and impacts. Our starting point is a data set describing agricultural events and soil biological parameters. Using machine learning methods for inducing regression and model trees, we produce empirical models able to predict the soil quality from agricultural measures in terms of quantities describing the soil microarthropod community. We are also interested in discovering additional higher level knowledge. In particular, we have identified the most important factors influencing the population densities of springtails and mites and their biodiversity. We also identify to which agricultural actions different microarthropods react distinctly. To obtain this higher level knowledge, we employ multi-objective regression trees.     

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.     

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.     

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.