Academic literature on the topic 'Goldsborough'

The Australian species of the water beetle genus Hydraena Kugelann, 1794, are revised, based on the study of 7,654 specimens. The 29 previously named species are redescribed, and 56 new species are described. The species are placed in 24 species groups. High resolution digital images of all primary types are presented (online version in color), and geographic distributions are mapped. Male genitalia, representative female terminal abdominal segments and representative spermathecae are illustrated. Australian Hydraena are typically found in sandy/gravelly stream margins, often in association with streamside litter; some species are primarily pond dwelling, a few species are humicolous, and one species may be subterranean. The areas of endemicity and species richness coincide quite closely with the Bassian, Torresian, and Timorian biogeographic subregions. Eleven species are shared between the Bassian and Torresian subregions, and twelve are shared between the Torresian and Timorian subregions. Only one species, H. impercepta Zwick, is known to be found in both Australia and Papua New Guinea. One Australian species, H. ambiflagellata, is also known from New Zealand. New species of Hydraena are: H. affirmata (Queensland, Palmerston National Park, Learmouth Creek), H. ambiosina (Queensland, 7 km NE of Tolga), H. antaria (New South Wales, Bruxner Flora Reserve), H. appetita (New South Wales, 14 km W Delagate), H. arcta (Western Australia, Synnot Creek), H. ascensa (Queensland, Rocky Creek, Kennedy Hwy.), H. athertonica (Queensland, Davies Creek), H. australula (Western Australia, Synnot Creek), H. bidefensa (New South Wales, Bruxner Flora Reserve), H. biimpressa (Queensland, 19.5 km ESE Mareeba), H. capacis (New South Wales, Unumgar State Forest, near Grevillia), H. capetribensis (Queensland, Cape Tribulation area), H. converga (Northern Territory, Roderick Creek, Gregory National Park), H. cubista (Western Australia, Mining Camp, Mitchell Plateau), H. cultrata (New South Wales, Bruxner Flora Reserve), H. cunninghamensis (Queensland, Main Range National Park, Cunningham's Gap, Gap Creek), H. darwini (Northern Territory, Darwin), H. deliquesca (Queensland, 5 km E Wallaman Falls), H. disparamera (Queensland, Cape Hillsborough), H. dorrigoensis (New South Wales, Dorrigo National Park, Rosewood Creek, upstream from Coachwood Falls), H. ferethula (Northern Territory, Cooper Creek, 19 km E by S of Mt. Borradaile), H. finniganensis (Queensland, Gap Creek, 5 km ESE Mt. Finnigan), H. forticollis (Western Australia, 4 km W of King Cascade), H. fundaequalis (Victoria, Simpson Creek, 12 km SW Orbost), H. fundata (Queensland, Hann Tableland, 13 km WNW Mareeba), H. hypipamee (Queensland, Mt. Hypipamee National Park, 14 km SW Malanda), H. inancala (Queensland, Girraween National Park, Bald Rock Creek at "Under-ground Creek"), H. innuda (Western Australia, Mitchell Plateau, 16 mi. N Amax Camp), H. intraangulata (Queensland, Leo Creek Mine, McIlwrath Range, E of Coen), H. invicta (New South Wales, Sydney), H. kakadu (Northern Territory, Kakadu National Park, Gubara), H. larsoni (Queensland, Windsor Tablelands), H. latisoror (Queensland, Lamington National Park, stream at head of Moran's Falls), H. luminicollis (Queensland, Lamington National Park, stream at head of Moran's Falls), H. metzeni (Queensland, 15 km NE Mareeba), H. millerorum (Victoria, Traralgon Creek, 0.2 km N 'Hogg Bridge', 5.0 km NNW Balook), H. miniretia (Queensland, Mt. Hypipamee National Park, 14 km SW Malanda), H. mitchellensis (Western Australia, 4 km SbyW Mining Camp, Mitchell Plateau), H. monteithi (Queensland, Thornton Peak, 11 km NE Daintree), H. parciplumea (Northern Territory, McArthur River, 80 km SW of Borroloola), H. porchi (Victoria, Kangaroo Creek on Springhill Rd., 5.8 km E Glenlyon), H. pugillista (Queensland, 7 km N Mt. Spurgeon), H. queenslandica (Queensland, Laceys Creek, 10 km SE El Arish), H. reticuloides (Queensland, 3 km ENE of Mt. Tozer), H. reticulositis (Western Australia, Mining Camp, Mitchell Plateau), H. revelovela (Northern Territory, Kakadu National Park, GungurulLookout), H. spinissima (Queensland, Main Range National Park, Cunningham's Gap, Gap Creek), H. storeyi (Queensland, Cow Bay, N of Daintree River), H. tenuisella (Queensland, 3 km W of Batavia Downs), H. tenuisoror (Australian Capital Territory, Wombat Creek, 6 km NE of Piccadilly Circus), H. textila (Queensland, Laceys Creek, 10 km SE El Arish), H. tridisca (Queensland, Mt. Hemmant), H. triloba (Queensland, Mulgrave River, Goldsborough Road Crossing), H. wattsi (Northern Territory, Holmes Jungle, 11 km NE by E of Darwin), H. weiri (Western Australia, 14 km SbyE Kalumburu Mission), H. zwicki (Queensland, Clacherty Road, via Julatten).

The role of communities associated to a substrate as fundamental components of an aquatic system has been recognized by many authors. Although periphyton has been considered of great importance in shallow lakes, its inclusion in different ecological models has been unusual. Phillips et al. (1978) were the first in considering epiphyton as an internal mechanism leading the system to a change in its state from greater water transparecy to more turbid conditions. In contrast, Scheffer et al. (1993) proposed the Alternative Equilibria Hypothesis (AEH), which considers that a shallow lake can alternate between two states, a Clear Water State (stabilized by the presence of submerged macrophytes) and a Turbid Water State (stabilized by an elevated phytoplankton biomass), excluding in this scheme the periphytic communities. Later only the conceptual model coined by Goldsborough and Robinson (1996, G&R model) emphasizes again the importance of epiphyton as well as that of epipelon and metaphyton by establishing the possibility of occurrence of four states according to the contributions to the total algal biomass of each of the algal taxocenosis. Some analyses of the system’s dynamics have been performed in pampean lakes in the context of the AEH. On the other hand, knowledge regarding periphytic and benthic communities is still poor. We propose as an hypothesis that phytoperiphyton will respond to the occurrence of different equilibria states, displaying, at the same time, strong interrelationships with the phytobenthos as well as with the phytoplankton. On the other hand, we consider the possibility that the phytoperiphytic and phytobenthic assemblages may function as internal mechanisms both, as state change or as state stability factors. Finally, we assess the importance of phytoperiphyton as regards its contributions to the total algal biomass in the context of the G&R model, comparing then the results with those obtained in the case of the AEH. The general objectives of the present investigation are to gather information about the structure and dynamics of the phytoperiphyton and its relationships with environmental factors as well as with the phytobenthon and phytoplankton in a pampean shallow lake; and to analyze phytoperiphytic dynamics under the AEH and the G&R model contexts, evaluating periphytic contributions to the total algal biomass. This investigation was carried out in an seepage shallow lake, Lacombe Lake, which is included in the “Grupo Marginal de lagunas” group in the pericoastal region of Provincia de Buenos Aires. Sampling was performed from July 2001 to June 2002 at four sites according to their exposure to environmental factors and the presence of macrophytes: bulrush beds, (JP and JC); and sites devoided of emergent vegetation but with stands of submerged macrophytes during the growing season (ALe and ALr). J sites and ALe were also representative of deeper zones and ALr of a site near the shore. Environmental variables were measured in situ and water samples were collected for chemical analysis and for plankton identification and quantification, following a vertical profile (excepting in ALr). In the case of phytoperiphyton, bulrush epiphyte samples (epiphyton) were taken following a vertical profile and those of submerged macrophytes were collected from the first 25 cm of the stems. Benthon (epipelon) was sampled using a corer. Aliquots for chemical analysis were also extracted from those samples. Vegetal substrate dynamics was also evaluated during sampling. At the laboratory, concentrations of algal nutrients, of the eight principal ions and of soluble polyphenols, as well as alkalinity and total hardness were measured. Phytoplanktonic, epiphytic and epipelic samples were treated for active a chlorophyll and pheopigment determinations. Organism identification and quantification were made according to standardized and own developed methods. First, variations in biotic and abiotic variables were analyzed for the determination of different equilibrium states occurrence. Three perturbation events were registered: precipitations in August, October and March. All of them involved water level increases and conductivity diminutions. Especially in the first two events, nutrient input from runoff was observed; meanwhile in March the input of water determined the dilution in nutrients concentrations. On the other hand, light conditions improved, particularly from October onwards, when stands of submerged macrophytes developed and a decrease of phytoplankton density and a change in its specific composition was detected. The latter being generated by the dilution effects of water input, the shading of the aquatic plants and algal consumption by cladocerans. March event also involved an improvement of light underwater climate but the increase in the water level affected macrophyte stands which mainly withdrawed to the shallowest zones. As regards phytoplankton, changes in the specific composition were recorded again. The statistic evaluation of these facts in conjunction with the analysis of permanence, resiliency and resistance properties of the dominating taxocenosis leads to interpret in the context of the AEH that two equilibria states occurred in the shallow lake. During the first three months a Turbid Water State developed, given by the phytoplankton domination given by an oscilatorial cyanophyte, minor transparency and relatively higher nutrient concentrations. In October and November the passage between states occurred, thus considering these months as transitional. From December onwards a Clear Water State established given by extended development of stands of submerged macrophytes, greater water transparency and minor nutrient concentrations. Finally, from March to May, given the submerged macrophyte withdrawal to shallowest sectors it can be interpreted that the system oscillated around a clear water state, or else, taking into account changes in the planktonic community, it is suggested that a third different state established, the “mixed phytoplankton” state. It is also suggested that states developed in Lacombe could be alternative. Next, the structure and dynamics of phytoperiphyton on bulrush and submerged macrophytes was analyzed. Vertical spatial and temporal variations of bulrush epiphyton showed to be more important than differences between sites. These variations involved smaller biomass values and a simpler physiognomy during turbid water phase and along the vertical gradient in all sampling occasions. In October, related to better light underwater conditions and the nutrient input, epiphytic biomass increased, principally promoted by species typical of the turbid phase. Nonetheless, a structural change started in this month, driven by herbivores but also by the modification of internal relationships between members of the same taxocenosis (shading and less bare substrate to be colonized). This resulted in the establishment of the characteristic assemblages of the clear water phase. During the first three months domination by stalked diatoms structured the community in a unique stratum, resistant to the less favourable light conditions and resilient to August perturbations. From December onwards Spirogyra species dominated, constituting the upper stratum, followed by Oedogonium species in the middle stratum and diatoms in the lower one. These assemblages were stabilized by mechanisms mainly displayed by the zignematalean taxon (shading, epifitism inhibition), allowing to considerer that they were resilient to March perturbation event (de novo establishment on non previously colonized surfaces). In face of the permanence, resistance and resilience properties showed by the taxocenosis, two different states of bulrush phytoperiphyton are considered: turbid water and clear water assemblages. This temporal pattern appeared less well delimited with depth and showed up later in time. Epiphyton data suggested that both states could be alternative. Differences between sites could be observed in respect to phytoperiphyton growing on submerged macrophytes, but the same temporal pattern showed by bulrush periphyton couldn’t be detected due to a great variability in the data gathered. In the next section, the analysis of the structure and dynamics of the phytobenton was carried out. It was showed that differences between the deepest sampling points and the shallowest site were greater than temporal ones. The composition of the assemblages was scarcely variable in time. The taxocenosis was principally related to the poor light conditions recorded on the sediment surface throughout the entire sampling period, even during the clear water phase. The examination of the specific composition in function of its origin evidenced the influence that the epipelon receives from other taxocenosis, constituting a refuge site for allochthonous taxa during unfavourable situations. The scarce variability of the epipelic fraction is also showed. In this way, it is considered that the taxocenosis maintained itself in only one state, indifferent to state changes in the lake and principally resisting the darkness and bearing to live in the unstable sediments. Subsequently, first the roles of the phytoperiphyton and complementary those of phytobenton, as state change or state stability agents were evaluated. The harmful effect of the phytoperiphyton on submerged macrophytes was probably counteracted by plant ramification production and allelopathy. The evidence suggested that its role as nutrient sequestrator is of minor importance in this case, due to other factors that might have disturbed phytoplankton more intensely than competition with phytoperiphyton. Much evidence supported the role of phytobenton as a source of epiphytic and planktonic species belonging either to turbid and clear water state assemblages. The results did not support the hypothesis that phytobenton may play a role as a sediment-stabilizing factor. On the contrary, it may be perturbating agent. Next, an analysis of the contributions of each community to the total algal biomass in the context of the G&R model was performed. Comparisons with AEH results were also carried out. This leaded to the consideration of the occurrence of the following states in Lacombe Lake: a Lake State consistent with the Turbid Water phase, an Open State consistent with the Clear Water phase and local Dry States in ALr site occurred both during the turbid water phase (July) or the clear water situation (March-April). The substantial contribution of epiphyton especially, that growing on submerged macrophytes, is emphasized. The importance of the discrimination of different fractions of epipelon material according to its origin when evaluating the contributions of each community to total algal biomass is also highlighted. Finally, a new interpretation is presented based on algal taxocenosis dynamics, which incorporates elements from both, the AEH and the G&R model. In conclusion, phytoperiphyton in this pampean shallow lake is strongly affected by the factors that determine the establishment or passage from one equilibrium state to another. These assemblages respond to changes through modifications in their own internal structure. These structures gradually alter with depth, remaining these changes more fully explained by the comparison with phytobenton dynamics. Besides the possible roles that the taxocenosis might undertake as an internal mechanism in the change or stabilization of systems states in different situations other than those encountered during this study, epiphyton importance in the systems context, is principally evidenced by the great contribution that these taxocenosis make to the total algal biomass, constituting the dominant compartment during clear water states.
El rol de las comunidades relacionadas a un sustrato como componentes fundamentales dentro de un sistema acuático ha sido reconocido por varios autores. A pesar de la importancia dada al perifiton en lagos someros, su inclusión dentro de diferentes modelos ecológicos ha sido inusual. Phillips et al. (1978) son los primeros en considerar al epifiton como un mecanismo interno en el pasaje de un estado de aguas transparentes a otro más turbio. En contraste, Scheffer et al. (1993), proponen la Hipótesis de Estados de Equilibrio Alternativos (HEEA) que considera que un lago somero puede alternar entre dos estados, uno de Aguas Claras, (estabilizado por la presencia de macrófitas sumegidas) y otro de Aguas Turbias (estabilizado por la elevada biomasa de fitoplancton), no tomando en consideración a las comunidades perifiticas. Sólo el marco conceptual propuesto por Goldsborough y Robinson (1996, modelo G&R) da nuevamente relevancia al epifiton, incluyendo al epipelon, al metafiton y al fitoplancton dentro de un modelo ecológico, discriminando cuatro estados de acuerdo a la dominancia en la biomasa algal total de alguna de estas taxocenosis. En las lagunas pampeanas se han realizado algunos análisis de la dinámica de los sistemas en el marco de la HEEA. Por otro lado, el conocimiento acerca de las comunidades perifíticas y bentónicas todavía es escaso. Se propone como hipótesis que el fitoperifiton variará de acuerdo a la ocurrencia de los diferentes estados en la laguna (según HEEA), interrelacionándose al mismo tiempo con el fitobenton y el fitoplancton. Por otro lado, también se considera la posibilidad de que tanto los ensambles fitoperifíticos como fitobentónicos sean mecanismos internos en el pasaje o en la estabilización de un estado. Por último, se valora la importancia del fitoperifiton en cuanto a sus aportes a la biomasa algal total en el marco del modelo G&R, realizando comparaciones con los resultados obtenidos en el caso de la HEEA. Los objetivos generales de esta investigación son: obtener información acerca de la dinámica y estructura del fitoperifiton y su relación con factores ambientales así como, también, acerca de sus interrelaciones con el fitobenton y el fitoplancton en una laguna pampeana; y analizar su dinámica en el marco de la HEEA y del modelo G&R valorando los aportes del fitoperifiton a la biomasa algal total. El estudio se realizó en la laguna Lacombe comprendida en el Grupo Marginal de lagunas en la región pericostera de la Provincia de Buenos Aires. Los muestreos se realizaron desde julio 2001 a junio 2002 en cuatro sitios de acuerdo a su grado de exposición a las variables ambientales y la presencia de macrófitas: Juncales (JP y JC); sitios de Aguas Libres con o sin macrófitas sumergidas durante la época de crecimiento (ALe y ALr). Los sitios J y ALe representan, puntos de mayor profundidad y ALr un sitio cercano a la orilla. Siguiendo un perfil vertical (con excepción del sitio cercano a la orilla, ALr) se midieron variables ambientales in situ y se tomaron muestras de agua para realizar análisis químicos del agua y la identificación y la cuantificación del plancton. En el caso del fitoperifiton se tomaron muestras de epifitos sobre junco (epifiton) también en un perfil vertical y en los 25 cm apicales del tallo de plantas sumergidas. El benton (epipelon) fue muestreado con un corer, extrayendo muestras también para realizar análisis químicos de los sedimentos. En el campo también se evaluaron las dinámicas de los sustratos vegetales. En el laboratorio se midieron las concentraciones de nutrientes algales, de los ocho iones principales, de los polifenoles solubles así como también la reserva alcalina y la dureza total. Las muestras de fitoplancton, epifiton y epipelon fueron tratadas para la estimación de clorofila a activa y feopigmentos, y la identificación y cuantificación de organismos según métodos estandarizados y propios. En principio, se analizaron las variables bióticas y abióticas para determinar la ocurrencia de estados de equilibrio en la laguna. Tres eventos principales de perturbación ocurrieron durante el período de estudio: las precipitaciones en agosto, octubre y marzo. Todas ellas involucraron aumentos del nivel hidrométrico y disminuciones en la conductividad. En los dos primeros, especialmente en octubre, se produjo la entrada de nutrientes por escorrentía, en tanto que en marzo el aporte de agua resultó en la dilución de los mismos. Por otro lado, las condiciones lumínicas mejoraron especialmente a partir de octubre, lo que se relacionó con el desarrollo de manchones de macrófitas sumergidas y una menor densidad y composición diferente del fitoplancton. Esto último se produjo por los efectos de dilución de la entrada de agua, el sombreado de las plantas acuáticas y por el pastoreo de cladóceros. El evento de marzo involucró también un mejoramiento de las condiciones de luz en la columna de agua pero, paralelamente, determinó la retracción de los manchones de macrófitas sumergidas hasta zonas más cercanas a la orilla. En el fitoplancton se operaron cambios en la composición específica. La evaluación estadística de estos hechos junto con el análisis de las características de permanencia, resiliencia y resistencia de las taxocenosis dominantes condujeron a interpretar que durante el período de estudio se establecen dos estados de equilibrio según la HEEA. Durante los tres primeros meses se desarrolló un estado de aguas turbias definido por la dominancia del fitoplancton con el predominio de una oscilatorial, menor transparencia y concentraciones de nutrientes relativamente más elevadas. En octubre y noviembre se produjo el pasaje entre estados, considerándose a estos meses como transicionales. De diciembre hasta el final del estudio, se desarrolló un estado de aguas claras definido por la presencia de manchones de macrófitas, mayor transparencia del agua y menores concentraciones de nutrientes. Finalmente, de marzo hasta mayo, dada la retracción de los manchones de macrófitas sumergidas, se puede interpretar que ocurrió una oscilación del sistema alrededor de un estado de aguas claras o, dados los cambios operados en el plancton, un tercer estado “mixed phytoplankton”. Se evidenció que los estados establecidos podrían ser alternativos. Seguidamente se analizaron la estructura y dinámica del fitoperifiton sobre junco y las macrófitas sumergidas. Las variaciones espaciales verticales y temporales en la dinámica del perifiton sobre junco resultaron más marcadas que las espaciales horizontales (entre sitios). Estas variaciones implicaron una menor biomasa y una fisonomía más simple durante la fase de aguas turbias y a lo largo del perfil vertical en todas las fechas. Relacionado con el incremento de la luz en la columna de agua y por la entrada de nutrientes en octubre, la biomasa epifítica aumentó, impulsada por las especies características de la fase turbia. Sin embargo, a partir de ese mes se dió un cambio estructural, generado por el pastoreo pero, también, por la modificación en las relaciones entre los componentes de la taxocenosis (autosombreado y menor disponibilidad de sustrato libre) que desembocó en el establecimiento de los ensambles característicos de la fase clara. Durante los tres primeros meses el predominio de diatomeas pedunculadas conformó una comunidad uniestrato, resistente a una menor disponibilidad de la luz y resiliente frente a las perturbaciones de agosto. De diciembre a febrero se desarrolló un ensamble donde predominan las especies de Spirogyra formando un estrato superior, las de Oedogonium en un estrato medio y las diatomeas en un estrato inferior. Estos ensambles presentaron mecanismos de estabilización dados por los talos de la zignematal (sombreado, inhibición del crecimiento de epifitos secundarios), considerándose resilientes frente a las perturbaciones de marzo (desarrollo de los ensambles en sitios previamente no colonizados). En función de las características de permanencia, resistencia y resiliencia, se diferenciaron dos estados en el fitoperifiton de junco: ensambles de fase turbia y ensambles de fase clara. Este patrón temporal se hizo menos marcado en profundidad y aparece en forma retrasada en el tiempo. Los datos habrían indicado la posibilidad de que ambos estados fuesen alternativos. El fitoperifiton sobre macrófitas sumergidas presentó variaciones definidas en el sentido espacial horizontal (mayor biomasa en sitios más profundos) pero no se detectó un patrón temporal, similar al del perifiton sobre junco, dada la gran variabilidad de los datos obtenidos. En el apartado siguiente se analizaron la estructura y dinámica del fitobenton. Se estableció que las variaciones entre sitios de muestreo fueron más marcadas que las temporales. Los ensambles epipélicos presentaron en general una composición escasamente variable a lo largo del tiempo relacionándose principalmente con la disponibilidad de luz. Ésta fue escasa durante todo el período de estudio por lo que las condiciones de crecimiento para las algas béntonicas no fueron favorables, aún con los cambios de estado en la laguna. El análisis del material en función de su origen evidenció las influencias que esta comunidad recibe desde otros ensambles, siendo un sitio de refugio para organismos alóctonos durante épocas desfavorables. También se evidenció la escasa variabilidad de la fracción epipélica propiamente dicha durante todo el período de estudio. Así, se considera que esta taxocenosis se mantuvo en un solo estado, ajena al pasaje de estado en la laguna, principalmente resistiendo la falta de luz y la inestabilidad de los sedimentos. Posteriormente, se evaluó primeramente el papel del fitoperifiton y, en forma complementaria, el del fitobenton como impulsores del pasaje de estados o como estabilizadores de los mismos en la laguna. El efecto de sombreado del fitoperifiton sobre macrófitas sumergidas probablemente fue contrarrestado por la producción de nuevas ramificaciones de las macrófitas y por alelopatía. Las evidencias señalaron que su rol como secuestradores de nutrientes disponibles para el fitoplancton fue menor en este caso, dado que éste último se halla perturbado por otros factores más que por la competencia con el epifiton. Las evidencias señalaron al epipelon como simiente de especies del epifiton y del fitoplancton tanto pertenecientes a la fase turbia como a la clara. En cambio, los resultados no avalaron su rol como estabilizador de los sedimentos. Al contrario, podría ser una perturbación de éstos. A continuación, se examinaron las contribuciones de las taxocenosis a la biomasa algal total en el marco del modelo G&R. También se realizó la comparación de los resultados con aquellos obtenidos a partir de la HEEA. Se consideró la ocurrencia de un estado Lake State congruente con la fase turbia en la laguna, un estado Open State congruente con la fase clara y estados locales Dry State en ALr tanto en la fase turbia (julio) como en la clara (marzo-abril). Se destacó la substancial contribución del epifiton sobre macrófitas sumergidas. También, se subrayó la importancia de discriminar, en relación con el epipelon, los aportes de cada una de las taxocenosis cuando se evalúan las contribuciones a la biomasa algal total. Finalmente, se ofreció una interpretación basada sobre la dinámica de las taxocenosis algales considerando elementos de la HEEA y del modelo G&R. En conclusión, el fitoperifiton en las lagunas pampeanas fue fuertemente influido por los factores que determinan los estados de equilibrio, respondiendo al cambio de los mismos con la modificación en su estructura interna. Ésta se alteró gradualmente con la profundidad, quedando estos cambios más completamente explicados a través de la comparación con la dinámica del fitobenton. Además de los posibles roles que podría desempeñar como mecanismo interno de pasaje o como estabilizador de estados en situaciones diferentes a las halladas en Lacombe, su importancia en el contexto del sistema se manifiesta en el gran aporte que realiza a la biomasa algal total, constituyendo el compartimiento dominante en los estados de aguas claras.

The development of the World Wide Web has created new opportunities for interpersonal interaction. The Internet allows one-to-one (e-mail), one-to-many (Web sites, e-mail lists) or many-to-many (online discussion forums) interaction, which represent a unique feature in comparison with traditional communication channels (Armstrong & Hagel, 1996). On the other hand, the Internet has specific characteristics, such as: • Interactivity: The Internet offers multiple possibilities of interactive communication, acting not only as an interface, but also as a communication agent (allowing a direct interaction between individuals and software applications) • Transparency: The information published online can be accessed and viewed by any Internet user, unless this information is specifically protected • Memory: The Web is a channel not only for transmitting information, but also for storing information¾in other words, the information published on the Web remains in the memory of the network until it is erased. These characteristics permit the development of online or virtual communities¾groups of people with similar interests who communicate on the Web in a regular manner (Armstrong & Hagel, 1996; Goldsborough, 1999a, 1999b; Gordon, 2000). Many studies deal with the ethics of research in Cyberspace and Virtual Communities (Bakardjieva, Feenberg, & Goldie, 2004), but very few publications relate with the Codes of Ethics used in Public Discussion Forums (Belilos, 1998; Johnson, 1997). Other specialists have analyzed specific categories or uses of online discussion forums, such as online learning (Blignaut & Trollip, 2003; DeSanctis, Fayard, Roach, & Jiang, 2003) or the creation of professional communities of practice (Bickart & Schindler, 2001; Kling, McKim & King, 2003; Millen, Fontaine, & Muller, 2002), and in this context, have also discussed briefly the importance of netiquette and forum monitoring (Fauske & Wade, 2003, 2004). The difference between these online communities and public discussion forums is the degree of control exercised on the functioning and purpose of the forum by a specific individual or organization. This article attempts to investigate, analyze and present the main patterns of the codes/rules of ethics used in the public discussion forums, otherwise known as Newsgroups, and their influence on the profile and functioning of the community.

The development of the World Wide Web has created new opportunities for interpersonal interaction. The Internet allows one-to-one (e-mail), one-to-many (Web sites, e-mail lists) or many-to-many (online discussion forums) interaction, which represent a unique feature in comparison with traditional communication channels (Armstrong & Hagel, 1996). On the other hand, the Internet has specific characteristics, such as: • Interactivity: The Internet offers multiple possibilities of interactive communication, acting not only as an interface, but also as a communication agent (allowing a direct interaction between individuals and software applications) • Transparency: The information published online can be accessed and viewed by any Internet user, unless this information is specifically protected • Memory: The Web is a channel not only for transmitting information, but also for storing information¾in other words, the information published on the Web remains in the memory of the network until it is erased. These characteristics permit the development of online or virtual communities¾groups of people with similar interests who communicate on the Web in a regular manner (Armstrong & Hagel, 1996; Goldsborough, 1999a, 1999b; Gordon, 2000). Many studies deal with the ethics of research in Cyberspace and Virtual Communities (Bakardjieva, Feenberg, & Goldie, 2004), but very few publications relate with the Codes of Ethics used in Public Discussion Forums (Belilos, 1998; Johnson, 1997). Other specialists have analyzed specific categories or uses of online discussion forums, such as online learning (Blignaut & Trollip, 2003; DeSanctis, Fayard, Roach, & Jiang, 2003) or the creation of professional communities of practice (Bickart & Schindler, 2001; Kling, McKim & King, 2003; Millen, Fontaine, & Muller, 2002), and in this context, have also discussed briefly the importance of netiquette and forum monitoring (Fauske & Wade, 2003, 2004). The difference between these online communities and public discussion forums is the degree of control exercised on the functioning and purpose of the forum by a specific individual or organization. This article attempts to investigate, analyze and present the main patterns of the codes/rules of ethics used in the public discussion forums, otherwise known as Newsgroups, and their influence on the profile and functioning of the community.