Particulate organic matter (POM), dissolved organic matter (DOM), bacteria and cladoceran were sampled seasonally atZhihugang Estuary and Lake Center in Taihu Lake. The δ13C of the four organic matter fractions showed consistent temporalvariation, with heaviest values in summer and lower at other times of the year. The cladoceran δ13C showed a significantcorrelation with that of POM, reflecting a heavy dietary dependence on POM during the study period. The bacteria becameenriched in 13C compared with that of DOM throughout the sampling dates, although no significant relationship was foundbetween the two fractions. δ13C values of POM, cladoceran and bacteria were all negative significantly correlated with oxidationand reduction potential (ORP), and specific conductivity (SpCond). As for δ15N, the seasonal pattern of food web componentswas variable. The POM δ15N signature exhibited the most enriched isotope ratios during the summer months when dissolvedinorganic nitrogen (DIN) nutrients were at their lowest concentrations. The consumption of DIN in summer can explain in partthe progressive accumulation of heavy nitrogen isotopes during this period. Spatially, δ13C and δ15N of the food web componentswere all slightly depleted at Estuary than that at Lake Center during the study period, possibly due to large allochthonous inputsat Zhihugang Estuary. Relatively wide ranges of stable isotopic values from both sites suggest that seasonality should beconsidered when attempting to establish food web structures in a eutrophic lake.

A model (DALIS 1.0) of pelagic zone trophic interactions was developed using long-term, comprehensive data sets of theSulejow Reservoir. We calibrated the model using observations from the pelagic zone of the Sulejow Reservoir made between1999 and 2001. The model performed well in the description of Daphnia sp. – L. kindtii interactions when hydrologicalconditions were stable. A discrepancy between observed and simulated results was found when water inflows were high, whichwashed out the biota. We suggested that the hydrological impacts should be coupled in the updated DALIS model. Using DALIS,we also tested two scenarios: the food web model (A) without Leptodora; and (B) without YOY fish, under both good and badfood conditions for Daphnia. Results indicated that Leptodora would have a more significant impact on the reduction of Daphniabiomass than juvenile fish during some periods. As the maintenance of high Daphnia densities is recognised as a key factor intop-down effects, the DALIS model may provide frameworks that support ongoing empirical work. It is therefore recommendedthat the model be incorporated into the programme of the Sulejow Reservoir restoration.

The aim of this paper is to report the colonization process of three headwater rivers of two large trans-national Pacific riverbasins shared by Chile and Argentina, by exotic Chinook salmon (Oncorhynchus tshawytscha). To characterize the populations atthe sites, fish were analyzed in terms of length, weight, age, and stream residency patterns. Fishermen familiar with the area wereinterviewed to establish the seasonal occurrence of fish and to reconstruct the history of the colonization process. Records ofsalmon production in Chile by regions were examined to evaluate the potential origin of fish in coastal net pen aquaculture. Theregularity of spawning runs in our study sites indicates that Chinook salmon have established spawning populations in theserivers. While spawning was verified in all three rivers, only one seems to serve as a holding area for pre-spawning salmon early inspring. The correlation in the historical occurrence of Chinook salmon in the three rivers suggests that they have been colonizedas part of the same introduction event. Moreover, the temporal correlation with the development of ocean net pen production forthis species in the Chiloé region suggests that the fish may originate from escapes from these enterprises. As in all previousreports of exotic Chinook salmon in Patagonia and New Zealand, populations in the three rivers have a combination of streamand ocean ecotypes. We discuss the importance of plasticity in critical life history characteristics for the success of Chinooksalmon in Patagonia, compared to other species of anadromous salmonids.

At present, 99 species of cladocerans are known from Thailand, but up to ten more have not been identified to species,particularly in Chydorus, Ephemeroporus and Pleuroxus. Cosmopolitan species are a minority, while wide-rangingcircumtropical taxa are an important element, beside species that only occur in the tropics-subtropics of two continents. At leastthree species are suspected of a neotropical - southeast Asian disjunction, while three more are provisionally considered endemicof Thailand. Daphnia, as usual in the tropics, is rare and reduced to the single D. lumholtzi.

I examined ephippial females and males of the Palaearctic Macrothrix hirsuticornis Norman & Brady, 1867 and M.tripectinata Weisig, 1934 (Cladocera: Anomopoda: Macrothricidae). Parthenogenetic and ephippial females, and males of a thirdspecies, M. dadayi Behning, 1941, are redescribed on material from the Ciscaucasian coast of the Black Sea (Russia). A series ofmale characters, useful for species discrimination was found. Ephippia of M. tripectinata and M. dadayi are covered with smallspinules, a unique synapomorphy of these species. Recent progress in Macrothrix systematics allows us to predict that thetaxonomy will improve as more males and ephippial females (currently known only in half the species), yet especially valuablefor systematics, are described.

A key to identify the known mature larvae of the South American genera of the family Elmidae is provided. The key includesseven genera presently assigned to the subfamily Larainae and 15 genera assigned to the subfamily Elminae. New distributionaldata for all genera and a checklist of described larvae are also included. The mature larva of Macrelmis saltensis Manzo isdescribed and illustrated for the first time, and compared to other known larvae of the granigera species-group. Distributionalnotes for M. saltensis increase its known range to the north, this being the first citation of the species for Bolivia. Macrelmis isis(Hinton) is also cited for the first time for Bolivia.

Chlorophyll-a concentration and physico-chemical water quality of water bodies surrounding Santa Fe City (Argentina) wereanalyzed at 20 sampling sites during different hydroclimatic periods (August-September 2005, March-April 2006). Areas withdifferent water quality were separated by Euclidean cluster analysis, and correlation among both environmental and chlorophylldistance matrices were found (p<0.01). The areas more affected by anthropogenic influence, Los Saladillos and Salado Rivers,reached the highest trophic level as regards to chlorophyll concentration. Acceleration in the eutrophication process wasregistered in comparison with previous studies, and chlorophyll-a concentrations are similar to those encountered in othereutrophicated rivers of the world. The oligo-mesotrophic level found at the Setúbal shallow lake was lower than expected due tothe nutrient contents and human activities of its basin. However, the incoming of pristine waters from the Paraná Systemproduces a sweeping effect and a semi-lotic lake behavior that impedes eutrophication enhancement. During high-waters thisriver also improved water quality of Santa Fe and Coronda Rivers. The chlorophyll-a diminution at Setúbal Lake and Santa FeRiver in comparison to earlier studies, may be also explained by the introduction in the last decade of the bivalve Limnopernafortunei that could be responsible of important losses of algal cells. Although trophic state according to chlorophyll-aconcentration was improved with discharge increments, nitrate and total phosphorus concentration augmented in most sites as aresult of the input from polluted flooded areas. The higher ranges encountered in the present study either of chlorophyll-a ornutrient content, indicate changes in water quality and a resultant eutrophication process over a period of decades. The health ofwater bodies is not yet in danger, but it is declining due to induced man-changes.