Till följd av samhällets konsumtion av psykofarmaka, återfinns rester av preparaten i utgående avloppsvatten som oförändrade eller i form av metaboliter. Avloppsvattnet utgör därför en betyd-ande källa till att vår akvatiska miljö exponeras för psykofarmaka, vars verkningsmekanismer på-verkar akvatiska organismsamhällens struktur och funktion. Det är således betydelsefullt att skapa experimentellt underlag om hur primärproducerande akvatiska system reagerar på exponering för vanligt utskriven psykofarmaka. Denna studie syftar till att undersöka eventuella effekter till följd av exponering för utvald psykofarmaka; fluoxetin och oxazepam, i planktonsamhällen från en sötvattenrecipient. Under sju dagars testperiod exponerades identifierade organismer; Mesocyclops leuckarti, Chlorella vulgaris, Monoraphidium mirabile, Monoraphidium contortum, Monoraphidium griffithii och Glaucoma scintillans, mot fluoxetin; 500 och 50 μg/l samt oxazepam; 1700 och 170 μg/l. C. vulgaris och G. scintillans visade sig vara mer känsliga mot höga halter fluoxetin än andra identifierade arter. C. vulgaris och G. scintillans minskade med 70 respektive 100 %  till följd av 500 ug/l fluoxetin. Exponeringshalten är emellertid högre än uppmätt maxvärde i utgående avloppsvatten, och bedöms därför inte utgöra akut risk för planktonsamhällen i recipienter vars förhållanden är jämförbara med denna undersökning. / As a consequence of society's consumption of psychotropic drugs, sources of these substances is detected in municipal wastewater plants as unchanged, including their metabolites. Reaching the aquatic environment, effluents contributes with a significant source of these substances which has been shown to affect the structure and function of aquatic organisms. It is important to create experimental evidence on how primary-producing aquatic ecosystems respond to the exposure of commonly prescribed psychotropic drugs. The aim of this study was to investigate possible effects of selected psychotropics; fluoxetine and oxazepam, to plankton communities from a freshwater recipient. Over an 7-day period identified organisms; Mesocyclops leuckarti, Chlorella vulgaris, Monoraphidium mirabile, Monoraphidium contortum, Monoraphidium griffithii och Glaucoma scintillans, were exposed to fluoxetine; 500 and 50 μg/l and oxazepam; 1700 and 170 μg/l. C. vulgaris and G. scintillans, turned out to be most sensitive to high levels of fluoxetine than other identified species. C. vulgaris and G. scintillans decreased by 70 and 100 % respectively, as a result of 500 ug/l fluoxetin. However, exposure levels in the experiment are much higher than measured values ​​in outgoing wastewater, and is therefore not considered to be acute toxic to non-target species comparable to those in this study.

Ce travail a porté sur l’étude de l’évolution des communautés zooplanctoniques à partir de séries temporelles de relevés effectués de 1995 à 2010 dans deux écosystèmes côtiers couplés, la Petite Rade de Toulon (PR) et Grande Rade de Toulon (GR) (Méditerranée Nord Occidentale, France) en relation avec les facteurs climatiques, les paramètres physiques et chimiques de l'eau et avec le phytoplancton. Le pas d’échantillonnage des relevés de zooplancton et du phytoplancton était d’un mois en moyenne. La maille du filet utilisé était de 90 µm, afin de cibler le mésozooplancton. La PR a différé de la GR dans son fonctionnement écologique, car elle est semi-fermée, mais aussi parce que l'activité anthropique y était beaucoup plus importante. Nos résultats ont montré que, de 1995 à 2010 dans les deux baies, l'abondance du zooplancton a sensiblement augmenté, surtout dans la PR. Il a été également établi, en utilisant différents outils statistiques, que la plus grande partie des espèces de zooplancton évolue de manière coordonnée chaque année, mais d’une manière différente d’une année à l’autre. C’est ce que nous avons appelé la signature annuelle, qui était très marquée dans la PR. Plusieurs paramètres environnementaux comme la température, l’oxygène, la salinité et l’ensoleillement, qui ont été simultanément enregistrés, expliquent cette signature annuelle. Il a été montré en effet qu’ils influencent très sensiblement la population de zooplancton, de manière instantanée ou avec un effet retardé. Les interactions responsables de cette évolution sont fort complexes, mais il a été aussi établi que ces facteurs sont plus forts lorsqu’ils agissaient de manière coordonnée. La répartition du zooplancton en groupes taxonomiques a montré que la diversité a augmenté jusqu’en 2005, puis a diminué légèrement, tout en restant à des niveaux plus élevés qu’en 1995. L’étude détaillée de la diversité, avec une classification des indices eux-mêmes, a fait l’objet du dernier chapitre. Enfin, nous émettons l’hypothèse que la diminution des stocks de poissons au cours des dernières décennies dans toute la région a entraîné une diminution des taux de prédation sur les communautés zooplanctoniques, ce qui peut expliquer l’augmentation de peuplements zooplanctoniques au cours de ces dernières années. Cet accroissement de l’abondance du zooplancton a pu entraîner à son tour une diminution de la biomasse du phytoplancton. Cette diminution a été parallèlement observée par notre équipe. Ceci suggère un système de contrôle top-down du réseau trophique. / This work focused the study of the evolution of zooplankton communities from time series of surveys conducted from 1995 to 2010 in two coastal coupled ecosystems, Little Bay (PR) and Large Bay (GR) of Toulon (North Western Mediterranean Sea, France) in relation to climatic factors, physical and chemical water parameters and phytoplankton. The samplings surveys of zooplankton, and indeed also of phytoplankton, were a month, on average. The net mesh size used was 90 µm to target Mesozooplankton. The PR differed from the GR in its ecological functioning, because it is semi-closed, but also because human activity is much more important. Our results showed that, from 1995 to 2010 in both bays, zooplankton abundance increased substantially, especially in the PR. It was also established, using statistical tools, that most zooplankton species evolved coordinated each year, but in a different way from one year to another. This is what we call the annual signature, which was more pronounced in the PR. Several environmental parameters such as temperature, oxygen, salinity and sunlight, which were simultaneously recorded, explained this annual signature. It was shown that they significantly influenced the population of zooplankton, instantly or with a delayed effect. Interactions responsible for this development are complex, but it was also established that these factors were stronger when they acted in a coordinated manner. Distribution of zooplankton taxonomic groups showed diversity increases until 2005 and then decreased slightly, while remaining at levels higher than in 1995. The detailed study of diversity, with a classification of the clues themselves was the subject of the last chapter. Finally, we hypothesize that the decline of fish stocks in recent decades throughout the region, resulting in lower rate of predation on zooplankton communities, may explain the increase of zooplankton communities in recent years. This increase in zooplankton abundance could in turn lead to a decrease in phytoplankton biomass. The decrease of phytoplankton was at the same time observed by our team. The latter hypothesis suggests a top-down control of the the food web

This research was conducted to update previous studies of the springs of the Kingdom of Saudi Arabia. Approach: Revisit every spring that was recorded previously to ascertain the current status, water quality and zooplankton communities. Results: fourteen springs out of forty six were still flowing. Several springs in the Eastern Province were structurally changed into manmade pools. Also, one new spring was located and documented in the northwestern region. Zinc and copper in several springs were the common dissolved heavy metals and have had exceeded the safe drinking water standards according to World Health Organization. Fourteen zooplankton taxa was found, seven belonged to phylum Rotifera (four Lecane spp. and three brachionids). Six belonged to subclasses Phyllopoda and Copepoda. The phyllopod, Pleuroxus sp., belongs to suborder Cladocera. The remaining five were copepods: one in the order Cyclopoida (Halicyclops sp.) and four in the order Harpacticoida (Bryocamptus sp., Schizopera sp., Euterpina sp. and Metis sp.). The remaining taxon was an unidentified species belonging to class Ostracoda. Zooplankton species were present in nine of the fifteen springs; the exceptions were Umm Al-Eyal, Abu-Dhuba and the four geothermal springs. Conclusion/ recommendation: The research concluded that the majority of the springs in the Kingdom have fallen dry between 1990 and 2013. Total dissolved solids as well as electrical conductivity, during the same period, were not significantly different. Zooplankton abundance displayed a positive correlation to Electrical Conductivity. Spring water is an important source of freshwater in the Kingdom; as such, springs must be properly maintained and conserved. More attention should be given to protect this important commodity from becoming obsolete. Groundwater protection is everyone's responsibility

I assessed the composition of zooplankton communities at the three tidal inlets connecting Lake Pontchartrain to Lake Borgne and subsequently to the Gulf of Mexico. The objectives of my research were to better understand the factors contributing to both spatial and temporal differences in zooplankton communities at the three locations. Monthly samplings of the neuston were conducted from September 2009 until April 2011 and then again from September 2012 until May 2013. Sampling consisted of triplicate tows using SeaGear “Bongo” nets. Water quality data along with water turbidity were recorded at each site and during each sampling effort. All specimens collected during the survey were quantified and identified to the lowest taxonomical unit. The results indicated that there were significant differences among the aquatic invertebrate communities composition among the three sites groups averaged across months (ANOSIM, R= 0.162, p = 0.001). The outcomes from this study could have strong implications for fisheries management and will provide a baseline for future research.

Most Australian studies on estuarine plankton have examined distribution and abundance in relation to hydrological changes, primary productivity and associated nutrient dynamics. Relatively few have examined the complex interactions between zooplankton grazers and the type and quality of food available, or the role of zooplankton grazers in structuring phytoplankton communities, or their contribution to the nutrient pool. The ecological role of zooplankton grazers in the Swan River estuary, Perth, Western Australia, was examined as part of a collaborative research project directed by the Western Australian Estuarine Research Foundation, which was established in response to concern about increasing intensity and persistence of algal blooms. The present study focussed on one component of the zooplankton, the Copepoda, as model zooplankton grazers. A regular zooplankton monitoring programme, undertaken over a two year period, provided data on seasonal patterns of abundance and distribution of zooplankton over a broad spectrum of physical conditions. Relationships were identified between habitat variables, such as algal biomass, dissolved oxygen, salinity and suspended solids and zooplankton distribution, relative abundance and species composition. Prior to the inception of this study, it was assumed that copepod species composition, abundance and richness in the Swan River estuary may have changed over time, in response to long-term declines in water quality. Comparison of historical copepod monitoring data with current data did not detect any such change and it was concluded that there was greater variation in copepod species composition, abundance and richness within years than between years and that no significant change had occurred between 1966 and 1997. / However, an absence or reduction in abundance of copepods in areas of very high algal biomass (>80 pg chlorophyll a.L-1) suggests that local loss of water quality may have an impact on copepods over a small spatial scale within the estuary. Different aspects of the interactions between zooplankton grazers and phytoplankton were studied. Zooplankton grazing rates were measured in situ during algal blooms and in the laboratory under controlled conditions to determine the potential for zooplankton grazers to reduce algal biomass. Field and laboratory experiments supported the hypothesis that copepods and other zooplankton can exert 'top-down control' over phytoplankton biomass, but that the type and biomass of phytoplankton present affected their ability to exert this control. The results of the field and laboratory grazing experiments, along with literature data, were used to provide input data for a model of zooplankton and phytoplankton dynamics during a dinoflagellate bloom in the Swan River estuary. The model was tested against biomass measurements of zooplankton and phytoplankton to determine how well it predicted actual changes in the plankton community. The simulated output closely followed the measured Page x field data and fitted regression curves and provided information about diurnal patterns of phytoplankton production, respiration and migration and hydrodynamic transport, which was not available from field data. It was shown that zooplankton grazing, particularly grazing by microzooplankton, was the process contributing most to the observed decline in dinoflagellate biomass. Nutrient availability is one of several factors determining productivity of phytoplankton. Nutrients within copepod faecal pellets are relocated by faecal deposition to sediments, where microbial activity leads to the remineralisation of these nutrients. / Quantification of metabolic excretion of nutrients by copepods and the rate at which pellets are produced by copepod grazers, the concentration of nutrients within faecal pellets and the rate at which these nutrients are released indicated that copepods may play an important role in nutrient regeneration during summer and autumn when allochthonous nutrients are unavailable. At other times of the year, it is unlikely that copepods play an important role in nutrient regeneration. The research has provided a more detailed level of understanding of the interactions between zooplankton, phytoplankton and their environment. The data is ideally suited for use in a computer model to predict the effects of management actions on the Swan River estuary. This would allow pre-emptive management strategies to be developed and lessen the focus on reactive management.

Graduation date: 1964

The species compositions and densities of the littoral and pelagic zooplankton assemblages in Crater Lake were compared. The littoral and pelagic zooplankton assemblages of most lakes are typically different due to different habitat conditions in the two zones. The littoral zone of Crater Lake lacks many of the habitat characteristics, which distinguish a typical littoral zone from the pelagic zone. In fact, none of the water quality variables measured differed significantly between the littoral zone and epilimnion of the pelagic zone in Crater Lake. The littoral and pelagic zones of Crater Lake were sampled with twelve paired sites in August and again in September of 1995. For the purposes of this study, the littoral zone was defined as lakeward from the shoreline to the 10m depth contour. At each paired site the pelagic assemblage was sampled to a depth of 120m at the 200m depth contour. Despite the almost identical water quality between the pelagic and littoral zones of Crater Lake, lack of vascular macrophytes in the littoral zone, and well-mixed epilimnion, the littoral zooplankton assemblage differed from the pelagic assemblage in both species composition and density. Several ubiquitous zooplankton taxa dominated both the littoral and pelagic zooplankton assemblages, although the density of these taxa as well as the relative abundance of these taxa differed between zones. These ubiquitous species reached their maximum densities in the metalimnion of the pelagic zone at a depth range of 10 to 60 meters below the lake surface and were considered primarily pelagic. A shift in wind direction between sampling periods influenced the distribution of pelagic zooplankton taxa in the littoral zone. Twenty-four taxa were recorded in the littoral zone, and aside from infrequent exceptions, none of these taxa were found in the pelagic zooplankton assemblage. Most of the littoral taxa were primarily adapted to the benthic zone. / Graduation date: 1999

The greater Everglades ecosystem, including Florida Bay, has undergone significant anthropogenic manipulation over the past century. These actions resulted in a series of ecologically undesirable events in the Everglades ecosystem, prompting passage of the Comprehensive Everglades Restoration Plan (CERP). It is necessary to understand the variability in, and relationship between, salinity and ecology to fully evaluate the potential effects of CERP on Florida Bay. A seven-year dataset on surface salinity along with eleven-year and eight-year datasets on mesozooplankton and planktivorous fish were analyzed. Overall, mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to 0.5 per day, whereas increases in bay-wide salinity were slower, with a maximum rate of 0.1 per day. Meteorological phenomena, such as tropical cyclones and ENSO, dramatically altered the salinity patterns of Florida Bay on interannual time scales. There was a large degree of spatial heterogeneity in salinity between sub-regions of Florida Bay due to differing freshwater sources and geomorphology. Mesozooplankton abundance displayed interannual variability and a positive correlation with salinity. Both of these features were also closely correlated with abundance of the dominant planktivorous fish, Anchoa mitchilli, indicating the importance of top-down control. The hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance during periods of increased physiological stress. The interaction between mesozooplankton and A. mitchilli, along with its correlation to salinity, was further investigated through the development of a mechanistic model of the populations in Florida Bay. The model indicated predation alone was insufficient to control mesozooplankton populations; rather, it was necessary to incorporate density-dependence utilizing a logistic prey population. With both mechanisms the model was able to replicate the observed interannual variability pattern and positive correlation between mesozooplankton and salinity. A preliminary management scenario evaluation suggests a two to six-fold difference in A. mitchilli and mesozooplankton populations between targeted and general salinity reductions. This suggests alternative freshwater management scenarios could produce drastically different ecological consequences.

AbstractPlankton samples were collected from June through October, 1970, at 5, 10, 15, and 18 m stations on transects extending into Indiana waters of Lake Michigan from Michigan City, Burns Ditch, and Gary.Bosmina longirostris, Daphnia retrocurva, and Cyclops bicuspidatus thomasi were the three dominant crustacean zooplankters in Indiana waters of Lake Michigan. Each species made up more than 10% of the total crustacean zooplankton community.The rotifer community was dominated by Polyarthra vulgaris. Other numerous rotifers included Keratella cochlearis, Synchaeta sp., and Kellicotia lonqispina.There were few consistent differences between the three transects, but, as station depth increased to 18 m, the population dynamics on the three transects tended to become more similar.In general the zooplankton community structure was made up of small microfiltrators with few macrofiltrators or predacious zooplankton present.The dominance of the microfiltrators, small size of Daphnia retrocurva sampled, seasonally late appearance of larger zooplankters, skewed sex ratios of Diaptomus, and increased numbers of zooplankton in general may all be the result of heavy alewife predation on large zooplankton forms.The dominance of less effective microfilter feeding zooplankton and the continued increase of nutrient levels in southern Lake Michigan may be combining to effect an increase in the eutrophication rate in the shallow Indiana waters of Lake Michigan.Ball State UniversityMuncie, IN 47306

The geographical distribution of the Gulf of Bothnia zooplankton species is presented together with observations of abundancies and vertical distributions. The historical development of this plankton community in the last 70 years is discussed.Spring and summer development of the plankton fauna was studiedin the Bothnian Bay. Compared to in southern parts of the Balticit could be shown that the start of development in spring formany species was only moderately later in the Bothnian Bay. Theperiod of maximal biomass was in late summer and autumn.In a study of horizontal distribution large between-station variations were found. These variations were not random as close stations formed homogenous groups. Several cases of patchiness were established. Systematically appearing differences in age-distributions were proposed as a factor in the formation of patchiness.The selective prédation on zooplankton by Baltic herring was studied in the Bothnian Bay. Besides chosing certain species herring selects the older and larger stages of these species. Egg-bearing Eurytemora females were more heavily preyed upon than the males.From literature information and own observations it was proposed that in sence of production the Bothnian Bay and the Bothnian Sea are two very different systems. Climatic effects cause a delay of primary production in spring enabling the pelagic consumers to develop in phase with the producers in the Bothnian Bay. Contrary to systems with a spring peak in phytoplankton growth this situation will lead to high pelagial efficiency leaving little to feed the benthic communities. / digitalisering@umu