Effects of ultraviolet-B enhancement on marine trophic levels in a stratified coastal system

We examined the effects of enhanced UV-B radiation (relative to ambient) on marine trophic levels inhabiting a stratified coastal ecosystem, using living models (13 000 liter marine enclosures) of a temperate estuarine water column. The experiment was carried out in June and July 1994 on a plankton community drawn from lower Narragansett Bay, Rhode Island, USA. The effects of altered UV-B radiation (elevated 50% over ambient, tenfold DNA-weighted) on three trophic strata: the primary producers (photosynthetic algae), primary herbivores (copepods), and fish eggs and larvae (Anchoa mitchilli Cuvier and Valenciennes) were examined. The goal was to determine if UV-B–induced alterations at the base of the food chain had impacts on other elements of the trophic web. Phytoplankton abundance (P=0.02) and biomass (P=0.007) were significantly reduced in UV-B–enhanced treatments, above but not below the thermocline (2.25 m), during the second week of the study. Copepod nauplii were significantly less abundant in UV-B–enhanced mesocosms than in control treatments during the third and fourth weeks of the study (P=0.01). A portion of the impact on nauplii may be a result of alterations at the base of the food web. The greater mortality of nauplii in UV-B–enhanced systems did not translate to reduced abundance of copepodite (P=0.83) or adult (P=0.29) copepods. No significant effects were observed for microzooplankton (P=0.15). Neither the mortality rates nor the growth rates of larval anchovy were significantly affected by the experimental increase in UV-B (P>0.05). Despite the tenfold increase in biologically damaging UV-B, effects were not seen at higher trophic levels, most likely because of the rapid extinction of UV-B in the highly colored coastal water. Received: 13 November 1996 / Accepted: 18 July 1997     

Natural organic matter controls metal speciation and toxicity for marine organisms: a review

Environmental Chemistry Letters - Heavy metals are occurring in the aquatic environment as the result of natural or anthropogenic inputs, and depending on concentration, availability and resilience...     

Availability of arsenic to estuarine and marine organisms: A field and laboratory evaluation

The high concentrations of arsenic entering Restronguet Creek, Cornwall (England), make this an ideal area for speciation and availability studies. This paper reports the results of a number of surveys and experiments carried out between January 1978 and June 1981, designed to investigate As availability in selected estuarine and marine organisms. Seasonal variations in dissolved As inputs are reflected in the As content of the seaweedFucus vesiculosus and also in two gastropod species,Littorina littorea andL. littoralis, which derive significant amounts of As by grazing onF. vesiculosus. In contrast, no seasonal variation in As concentration was observed in tissues of the bivalveScrobicularia plana. Transplant experiments and radiotracer studies confirm that sediments are the major source of As to this deposit-feeder. The mantle margin ofs. plana has a significant, but as yet unknown, role in As accumulation. Transplant experiments with these and other estuarine and marine organisms have revealed differences in the relative availability of dissolved and particulate As. Notably, As accumulation inMytilus edulis was negligible compared with other molluscs. The results are discussed in terms of the selection of suitable indicators of various forms of As contamination.     

Explaining long-distance dispersal: effects of dispersal distance on survival and growth in a stream salamander

Long-distance dispersal (LDD) may contribute disproportionately to range expansions, the creation of new evolutionary lineages, and species persistence in human-dominated landscapes. However, because data on the individual consequences of dispersal distance are extremely limited, we have little insight on how LDD is maintained in natural populations. I used six years of spatially explicit capture-mark-recapture (CMR) data to test the prediction that individual performance increases with dispersal distance in the stream salamander Gyrinophilus porphyriticus. Dispersal distance was total distance moved along the 1-km study stream, ranging from 0 to 565 m. To quantify individual performance, I used CMR estimates of survival and individual growth rates based on change in body length. Survival and growth rates increased significantly with dispersal distance. These relationships were not confounded by pre-dispersal body condition or by ecological gradients along the stream. Individual benefits of LDD were likely caused by an increase in the upper limit of settlement site quality with dispersal distance. My results do not support the view that the fitness consequences of LDD are unpredictable and instead suggest that consistent evolutionary mechanisms may explain the prevalence of LDD in nature. They also highlight the value of direct CMR data for understanding the individual consequences of variation in dispersal distance and how that variation is maintained in natural populations.     

Experimental studies on the effects of copper on a marine food chain

Effects of copper sulphate on a marine food chain were investigated in large tanks at Loch Ewe on the west coast of Scotland. The food chain consisted of phytoplankton, the bivalve Tellina tenuis da Costa, and O-group plaice (Pleuronectes platessa L). During initial months after settlement, T. tenuis siphons are an important food for juvenile plaice, which feed by grazing the siphon tips; these subsequently regenerate. Copper dose rates of 10, 30 and 100 μg Cu/1 were investigated; the distribution of added copper was monitored and its metabolic effects were determined. Copper levels in water, sand, in algae on tank walls, in T. tenuis shell and flesh, and in plaice muscle and viscera were measured by atomic absorption spectrophotometry. Copper accumulated in sand, T. tenuis flesh and shell, and plaice viscera. Accumulations were dose-dependent and in no case was a plateau concentration reached. Most of the added dose was taken up by the sand; accumulations in T. tenuis shell were small — less than twice background in all cases. High levels were found in T. tenuis flesh, where concentrations after 100 days were 270, 470 and 1100 μg Cu/g dry flesh for dose concentrations of 10, 30 and 100 μg Cu/1, respectively. The mean control concentration was less than 50 μg Cu/g dry flesh. There was no accumulation of copper in plaice muscle. Visceral accumulations after 100 days were 71, 147 and 567 μg Cu/g dry flesh for dose concentrations of 10, 30 and 100 μg Cu/1, respectively. The mean control level was 30 μg Cu/g dry flesh. The effect of copper on phytoplankton metabolism was investigated by measuring plant pigment levels and rates of primary photosynthetic fixation of C¹⁴-labelled bicarbonate. All dose concentrations reduced both the standing crop and the rate of photosynthesis per unit of chlorophyll a. The effects of copper on growth and condition of T. tenuis and P. platessa were investigated. All dose concentrations adversely affected T. tenuis condition (dry flesh weight for standard individual). The effect was most marked during deposition of winter reserves. In the absence of plaice predation, there was a decrease in the mean siphon weight for T. tenuis exposed to 30 and 100 μg Cu/1. For plaice, all dose concentrations of copper resulted in reduced growth, but there was no significant change in condition or biochemical composition. The ash weight of fish exposed to copper was significantly higher than for controls.     

A new photodegradable molecule as a low impact ballast water biocide: efficacy screening on marine organisms from different trophic levels

Marine species carried by the ships’ ballast waters are a potentially serious environmental problem. Many strategies are being adopted to minimize the transfer of invasive or pathogenic marine species between different aquatic ecosystems. This problem is often addressed by using biocides for ballast water treatment; however, the biocide could be dangerous to native organisms once the ballast water is discharged. Chemical treatments such as chlorination and addition of glutaraldehyde could cause problems related to toxicity and application costs. The search for new effective molecules with a low environmental impact is pressing. This paper presents data from a preliminary efficacy screening of a promising molecule derived from alkylated naphtoquinones on a battery of ballast water model organisms. Results show that this new molecule is very effective in the absence of light and is extremely photodegradable (half-life <6 h). It can thus be easily degraded when released in the environment. Physical and Chemical Impacts on Marine Organisms, a Bilateral Seminar Italy-Japan held in November 2004.     

Effects of copper on the faunas of marine soft-sediments: An experimental field study

Although laboratory experimental studies have shown that copper is toxic to marine organisms at concentrations found in contaminated sediments, there is little unequivocal evidence of undesirable ecological effects in the field, other than at extreme concentrations. We describe a study in Botany Bay, New South Wales, Australia, in which the concentrations of copper in marine sediments were experimentally enhanced. Changes in the abundance and taxonomic composition of the fauna of copper-treated sediments relative to those of two control treatments were monitored over a period of six months. Univariate (ANOVA) and multivariate (non-metric multidimensional scaling, MDS) analyses of the changes in the fauna showed that increased concentrations of copper (140 to 1200 g g^-1 compared with background concentrations of 29 to 40 g g^-1) had an impact on the fauna. The nature of the response varied among taxa. For example, in some taxa, numbers of individuals decreased through time relative to controls, whereas the abundance of another taxon remained fairly constant through time in the copper treatment while numbers of control individuals increased. Differences in the changes of the faunas through time among the control and copper treatments were not always consistent among replicate experimental units 5 m apart, nor were they consistent between replicate experimental sites 100 m apart. The magnitudes of the changes in the faunas caused by the copper treatment are considered in the context of the magnitude of previously measured natural temporal variation.     

Daphne: a new multimetric benthic index for the quality assessment of marine coastal environment in the Northern Adriatic Sea

A new benthic index, named Daphne, is proposed for the Northern Adriatic coastal area, near the Po river delta. It is based on six characteristics of the community that do not require in-depth taxonomic expertise: number of mollusc species, % of bivalves, % of polychaetes, abundance of the opportunistic species Corbula gibba, % of amphipods and number of 'typical mollusc species' that are individuated by multivariate analysis. The application of the index in selected stations along a gradient of decreasing disturbance shows that it is simple to use in regular monitoring campaigns and that the results are consistent with environmental quality data in the special conditions of this area subjected to considerable river runoff. The index can be used in addition and as a complement to more widespread indices (such as M-AMBI); a comparison of the two indices performance is discussed.     

Influence of the mineralogical composition on microbial activities in marine sediments: an experimental approach

We investigated the influence of the mineralogical composition of marine sediments on bacterial activity in experimental microcosms. Calcite and quartz were added to natural marine sediments and microbial response in terms of total bacterial abundance and biomass, β-D-glucosidase exo-enzymatic activity and bacterial incorporation of a radio-labelled (³H-leucine) substrate were investigated for a period of one month. We report here that after 15 days the mineralogical composition of the sediment (calcite vs. quartz) had an impact on bacterial abundance and activity (reduced for ca 15% and 56%, respectively). However, such impact was mitigated or even disappeared in high organic nutrient conditions.     

Countryside Biogeography of Moths in a Fragmented Landscape: Biodiversity in Native and Agricultural Habitats

Abstract: Studies of fragmented landscapes, especially in the tropics, have traditionally focused on the native fragments themselves, ignoring species distributions in surrounding agricultural or other human-dominated areas. We sampled moth species richness within a 227-ha forest fragment and in four surrounding agricultural habitats (coffee, shade coffee, pasture, and mixed farms) in southern Costa Rica. We found no significant difference in moth species richness or abundance among agricultural habitats, but agricultural sites within 1 km of the forest fragment had significantly higher richness and abundance than sites farther than 3.5 km from the fragment. In addition, species composition differed significantly between distance classes ( but not among agricultural habitats), with near sites more similar to forest than far sites. These results suggest that (1) different agricultural production regimes in this region may offer similar habitat elements and thus may not differ substantially in their capacities to support native moth populations and (2) that the majority of moths may utilize both native and agricultural habitats and move frequently between them, forming "halos" of relatively high species richness and abundance around forest fragments. Correlations between species richness and the amount of nearby forest cover, measured over circles of various radii around the sites, suggest that halos extend approximately 1.0–1.4 km from the forest edge. The extent of these halos likely differs among taxa and may influence their ability to survive in fragmented landscapes.     

An experimental study on recolonization and succession of marine macrobenthos in defaunated sediment

Hypoxia/anoxia in coastal waters is a world wide problem which often results in mass mortality and defaunation of benthos. In this study, field experiments were carried out to examine recolonization and succession of macrobenthic infauna in defaunated sediments, and the time required for recovery from complete defaunation to a stable community. Trays (33 cm length × 25.5 cm width × 11 cm depth) of defaunated sediment were exposed at the subtidal of a pristine site in subtropical Hong Kong. Temporal changes of macrobenthic communities in defaunated sediment were analyzed by univariate and multivariate statistics, and compared with those in undisturbed natural sediment at the same site. Initial colonization of macrobenthos occurred rapidly. A total of 42 species was found, with an average of 258 animals per tray and 24 species per tray recorded in the first month. Abundance showed a small peak (496 animals per tray) after 3 months, reached a sharp peak (1154 animals per tray) after 6 months, and declined thereafter. Species number increased gradually, reached a maximum (68 species per tray) after 9 months, and then decreased. Recolonization was predominantly contributed by larval settlement rather than adult migration. Temporal changes in abundance, species number and diversity of the macrobenthic community in defaunated sediment resemble the spatial changes along a decreasing pollution gradient previously defined by other authors. Results of this experiment suggest that newly available sediment may allow more species to colonize (or coexist) than sediment pre-occupied by an established community. This is probably due to less interspecific competition in the former habitat. No significant difference in abundance or species richness was observed between defaunated and natural sediments after 15 months, suggesting that a stable community had been achieved, although minor variations in species composition were still discernible between defaunated and natural sediments. Received: 24 May 1999 / Accepted: 20 October 1999     

Light absorption by a marine diatom: experimental observations and theoretical calculations of the package effect in a small Thalassiosira species

The relationship between in vivo light absorption efficiency of whole cells and in vitro absorption efficiency of algal pigments has been examined experimentally in the marine diatom Thalassiosira sp. In vitro absorption spectra were obtained for cells disrupted by either ultrasonic treatment or high-pressure shearing stress in a low-temperature (-40°C) pressure cell. A dimensionless measure of the magnitude of the package effect (Q _a ^*), calculated from the ratio of whole-cell to disrupted-cell absorption, ranged from about 0.5 at the blue absorption peak of chlorophyll a (λ=435 nm) to 0.7 at the red chlorophyll a peak (λ=670 nm) to 1.0 at the absorption minimum (λ=600 nm). Cell diameter was found to be an inappropriate measure of size for assessing the magnitude of the package effect. Instead, the effective optical diameter for calculation of intracellular self-shading was found to be less than the cell diameter. This observation is consistent with the fact that most algal pigments are contained within chloroplasts, and that chloroplast volume is necessarily smaller than cell volume.     

Fertilization in a suite of coastal marine invertebrates from SE Australia is robust to near-future ocean warming and acidification

Climate change driven ocean acidification and hypercapnia may have a negative impact on fertilization in marine organisms because of the narcotic effect these stressors exert on sperm. In contrast, warmer, less viscous water may have a positive influence on sperm swimming speed and so ocean warming may enhance fertilization. To address questions on future vulnerabilities we examined the interactive effects of near-future ocean warming and ocean acidification/hypercapnia on fertilization in intertidal and shallow subtidal echinoids (Heliocidaris erythrogramma, H. tuberculata, Tripneustes gratilla, Centrostephanus rodgersii), an asteroid (Patiriella regularis) and an abalone (Haliotis coccoradiata). Batches of eggs from multiple females were fertilized by sperm from multiple males in all combinations of three temperature and three \textpH/P_\textCO2 {\text{pH}}/P_{{{\text{CO}}_{2} }} treatments. Experiments were placed in the setting of projected near-future conditions for southeast Australia, an ocean change hot spot. There was no significant effect of warming and acidification on the percentage of fertilization. These results indicate that fertilization in these species is robust to temperature and \textpH/P_\textCO2 {\text{pH}}/P_{{{\text{CO}}_{2} }} fluctuation. This may reflect adaptation to the marked fluctuation in temperature and pH that characterises their shallow water coastal habitats. Efforts to identify potential impacts of ocean change to the life histories of coastal marine invertebrates are best to focus on more vulnerable embryonic and larval stages because of their long time in the water column where seawater chemistry and temperature have a major impact on development.     

Laboratory studies of the marine copepod Centropages typicus: egg production and development rates

Egg production and development rates of Centropages typicus (Krøyer) were studied in the laboratory under carying food and temperature conditions. Egg production rates in the laboratory ranged from 0 to 124 eggs female^-1 d^-1 and increased with food concentration up to a critical food concentration (P_c) above which egg production was constant. Egg production rates were influenced by temperature, with more eggs being produced at 15°C than at 10°C. Thalassiosira weisflogii and Prorocentrum micans were determined to be equally capable of supporting egg production at concentrations above P_c at 15°C. Rate of egg production was independent of adult female size when food and temperature were constant. Egg production rates of freshly captured females ranged from 0 to 188 eggs female^-1 d^-1 and were higher in April and May than in June or July. Hatching rates of eggs increased with increased temperature; 95% of the eggs at 15°C hatched within 48 h, while only 8% of the eggs at 10°C hatched within 48 h. Development rates, determined at 10°C in excess concentrations of T. weisflogii, were 23.0 d from egg release to copepodid state I, 27.0 d to stage II, 29.5 d to stage III, 32.2 d to stage IV, 38.5 d to stage V and 49 d to adulthood based on the average time required for 50% of the organisms in an experiment to attain a given stage. Adult males were usually observed 2 to 4 d before adult females, and therefore have a slightly faster rate of development. The effects of temperature, food type and food concentration on egg production and the seasonal appearances of diatoms in the New York Bight may account for the observed seasonal cycles in abundance of C. typicus in these coastal waters.     

Linking direct and indirect data on dispersal: isolation by slope in a headwater stream salamander

There is growing recognition of the need to incorporate information on movement behavior in landscape-scale studies of dispersal. One way to do this is by using indirect indices of dispersal (e.g., genetic differentiation) to test predictions derived from direct data on movement behavior. Mark-recapture studies documented upstream-biased movement in the salamander Gyrinophilus porphyriticus (Plethodontidae). Based on this information, we hypothesized that gene flow in G. porphyriticus is affected by the slope of the stream. Specifically, because the energy required for upstream dispersal is positively related to slope, we predicted gene flow to be negatively related to change in elevation between sampling sites. Using amplified DNA fragment length polymorphisms among tissue samples from paired sites in nine streams in the Hubbard Brook Watershed, New Hampshire, USA, we found that genetic distances between downstream and upstream sites were positively related to change in elevation over standardized 1-km distances. This pattern of isolation by slope elucidates controls on population connectivity in stream networks and underscores the potential for specific behaviors to affect the genetic structure of species at the landscape scale. More broadly, our results show the value of combining direct data on movement behavior and indirect indices to assess patterns and consequences of dispersal in spatially complex ecosystems.     

An application of GIS and coastal geomorphology for large scale assessment of coastal erosion and management: a case study of Ghana

Coastal erosion poses serious threat to life and properties along Ghana??s coast. This is because major industries, urban settlements, recreational facilities, heritage and conservation sites are located few metres from the coast. In spite of this threat, management strategies, both past and present, remain an ??ad hoc?? and site specific. Limited attention has been given to large scale assessment and investigation to detect the rate of coastal recession and the size of land lost to the sea to inform integrated management plan and to formulate sustainable management strategies to deal with the problem. This paper provides large scale assessment of coastal recession in Ghana through field investigation, applied coastal geomorphology and GIS techniques to selected case study areas. The assessment covered 203?km out of the 540?km coastline of Ghana. Results of the assessment indicate that coastal erosion is very substantial and wide spread along the coast, but the rate of recession varies across the entire coastline. Significant amounts of losses of settlements have been experienced in some localities in the eastern coast (Keta and Ada) and the central coast (Accra, Shama and Sekondi-Takoradi). In some areas, coastal defences have been built to reduce the impacts, yet many areas are still very vulnerable. Interestingly, the paper identified that the high rates of retreat recorded in many areas have yet to cause major risks in some local communities because of the presence of a buffer of largely undeveloped land that has existed historically between the shoreline and the developments. However, recent increase in coastal tourism in Ghana has led to ??scramble?? for purchase of these buffer lands for development, which increase the risk. Ghana has the opportunity to use education and land use planning to keep the coastline clear of major developments and avoid the temptation of engaging in costly cycle of development-risk-defence experienced in many countries including the UK and the Netherlands. The paper recommends that Ghana should adopt the UK SMP, which has progressively moved away from the traditional re-active and parochial approaches of providing localised hard-engineered coastal defence work to solve what was perceived to be a local problem, to a more pro-active and holistic approach that take full account of coastal dynamics, interrelationships of coastal systems, knock-on effects, environment concerns and developments at the backshore.     

Effect of natural and synthetic organic-Fe(III) complexes in an estuarine mixing model on iron uptake and growth of a coastal marine diatom, Chaetoceros sociale

Cell growth of a coastal marine diatom, Chaetoceros sociale, in the presence of different premixed organic-Fe(III) complexes [EDTA-Fe(III) (100:1 and 2:1), citric-Fe(III) (100:1) and fulvic-Fe(III) (0.1, 0.2 and 1 ppm C)] and solid amorphous hydrous ferric oxide [am-Fe(III) or Fe(III) hydroxide] were experimentally measured in culture experiments at 10 °C under 3000 lux fluorescent light. Fulvic-Fe(III) (0.1 and 0.2 ppm C) and citric-Fe(III) (100:1) induced maximal cell yields of C. sociale. The order of cell yields was: fulvic-Fe(III) (0.1 and 0.2 ppm C) ≥ citric-Fe(III) (100:1) > EDTA-Fe(III) (2:1) ≫ solid am-Fe(III) > EDTA-Fe(III) (100:1) ≫ fulvic-Fe(III) (1 ppm C). The short-term iron uptake rates by C. sociale in fulvic-Fe(III) (0.1 and 0.2 ppm C) and citric-Fe(III) (100:1) media were about five to six times faster than those in EDTA-Fe(III) (100:1) and solid am-Fe(III) media. The dissociative precipitation rates of premixed organic-Fe(III) complexes in seawater at 10 °C were determined by simple filtration (0.025 μm) involving γ-activity measurements of ⁵⁹Fe. The order of estimated initial Fe(III) dissociative precipitation rates of these organic-Fe(III) complexes in seawater were nearly consistent with those of cell yields in the culture experiments and short-term iron uptake rates by C. sociale [except for fulvic-Fe(III) (1 ppm C) medium]. In fulvic-Fe(III) (0.1 and 0.2 ppm C), citric-Fe(III) (100:1) and EDTA-Fe(III) (2:1) media, the concentrations of dissolved organic-Fe(III) complexes in initial culture experiments are prone to supersaturate under the culture conditions. The supersaturated dissolved organic-Fe(III) complex in seawater supplies biologically available inorganic Fe(III) species in culture media through its dissociation at high pH and high levels of seawater cations. Therefore, the natural dissolved organic-Fe(III) complexes supplied by riverine input may play an important role in supplying bioavailable iron in estuarine mixing system and coastal waters. Received: 6 September 1998 / Accepted: 8 April 1999     

Seasonal variations of polycyclic aromatic hydrocarbons in coastal sediments of a marine resource hot spot: the case of pars special economic energy zone,Iran

Environmental Geochemistry and Health - Polycyclic aromatic hydrocarbons (PAHs) are an important group of compounds of major environmental concern, which are in the class of persistent organic...     

Nutritional geometry and macronutrient variation in the diets of gannets: the challenges in marine field studies

Foraging theory proposes that the nutritional driver of food choice and foraging in carnivores is energy gain. In contrast, recent laboratory experiments have shown that several species of carnivore select prey that provides a diet with a specific balance of macronutrients, rather than the highest energy content. It remains, however, to be determined how nutritionally variable the foods of predators in the wild are, and whether they feed selectively from available prey to balance their diet. Here, we used a geometric method named the right-angled mixture triangle (RMT) for examining nutritional variability in the prey and selected diets of a group of wild carnivores and marine top predators, the gannets (Morus spp.). A prey-level diet analysis was performed on Australasian gannets (M. serrator) from two New Zealand locations, and the macronutrient composition of their chosen prey species was measured. We use RMT to extend the comparison in the compositions of foods and diets from Australasian gannets from Australia as well as Northern gannets (M. bassanus) and Cape gannets (M. capensis). We found nutritional variability at multiple scales: intra- and interspecific variability in the pelagic fish and squid prey themselves; and intra- and interspecific variability in the diets consumed by geographically disparate populations of gannets. This nutritional variability potentially presents these predatory seabirds with both opportunity to select an optimal diet, and constraint if prevented from securing an optimal diet.     

Population genetic consequences of larval dispersal mode and hydrography: a case study with bryozoans

Genetic analysis of the marine bryozoans Celleporella hyalina and Electra pilosa using the RAPD technique revealed population structuring corresponding to the contrasting modes of larval dispersal. Samples of C. hyalina exhibited genetic differentiation over distances as small as 10 m, concordant with the limited dispersal predicted by a simulation model, based on the short pelagic phase of the lecithotrophic larvae and the local hydrography. In contrast, E. pilosa showed high levels of genetic heterogeneity only over much larger spatial scales, commensurate with its production of comparatively long-lived planktotrophic larvae. The population differentiation observed between samples of E. pilosa, collected from sites 70 km apart, is reconcilable with coastal water currents and frontal systems that restrict the exchange of water masses between the two sites. Hydrographic conditions and discontinuous distribution of suitable substrata therefore are seen to constrain gene flow, creating opportunities for local genetic differentiation despite the high dispersal potential of pelagic larvae. Received: 9 August 2000 / Accepted: 18 November 2000