Lake Name or Name Lake? The etymology of lake nomenclature in the United States

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Lake Pátzcuaro fishery management plan

Lake Pátzcuaro, a97.5 km² lake in central México, has animportant artisanal multi-species fishery thatis currently overexploited. Twelve fishes andone amphibian are important in the fishery,which is conducted largely from small woodenboats using seines, gill nets, and thetraditional butterfly net. Fishery yields fromthe lake peaked in 1988, but have declined tonear record lows since then. We propose amanagement plan to restore the fishery. Keycomponents of the plan include: 1) licensingand restricting the number of fishermen; 2)continuing a recent ban on seines andimplementing limits on the number and meshsizes of gill nets to allow fish to complete atleast one spawning before they are vulnerableto harvest; 3) establishing a closed season andareas closed to fishing to protect spawningfish; 4) increased education for fishermen inbasic skills, fishing technology, andalternative jobs; 5) continued monitoring andresearch to assess trends in the fishery and todevelop culture techniques to help restore fishpopulations; and 6) compliance and enforcementmechanisms to make the plan effective,including perhaps establishment of propertyrights for particular areas of the lake forspecific groups of fishermen and more generallyan equitable assignment of lake ecosystem usesbetween fishery and non-fishery users. Werecommend the plan be implemented in anadaptive fashion with provisions for adjustingregulations as conditions warrant. If at leastsome elements of this plan are not adopted thenthe Lake Pátzcuaro fishery is likely tocollapse.     

Lake Superior: an invasion coldspot?

Lake Superior receives a disproportionate number of ballast water discharges from transoceanic ships operating on the Laurentian Great Lakes. Although this provides dispersal opportunities for nonindigenous species (NIS), relatively few NIS were initially discovered in this lake prior to being recorded elsewhere in the basin. A lack of NIS records from this lake may be an artefact of sampling bias. We tested this hypothesis by sampling benthos and plankton from littoral and deepwater habitats around the perimeter of Lake Superior during June and August 2001. Using morphological analysis techniques, we identified a total of 230 invertebrate taxa representing planktonic, benthic and nektonic lifestyles. Five species with invasion histories in the lower Great Lakes, the bivalves Sphaerium corneum, Pisidium amnicum and P. moitessierianum, gastropod Potamopyrgus antipodarum and amphipod Echinogammarus ischnus, were identified for the first time in Lake Superior. In addition, records of expanded distributions within this lake are presented for the amphipod Gammarus fasciatus and oligochaetes Ripistes parasita and Vejdovskyella intermedia. Recently introduced NIS in Lake Superior were found near international ports, implicating shipping as the vector of their introduction. Intrinsic physical-chemical aspects of Lake Superior may account for the scarcity of NIS in this lake as compared to the lower Great Lakes.     

Schistosomiasis in Lake Mala?i Villages

Historically, open shorelines of Lake Malaŵi were free from schistosome, Schistosoma haematobium, transmission, but this changed in the mid-1980s, possibly as a result of over-fishing reducing density of molluscivore fishes. Very little information is available on schistosome infections among people in lake-shore communities and therefore we decided to summarise data collected from 1998 to 2007. Detailed knowledge of the transmission patterns is essential to design a holistic approach to schistosomiasis control involving the public health, fisheries and tourism sectors. On Nankumba Peninsula, in the southern part of the lake, inhabitants of villages located along the shores of Lake Malaŵi have higher prevalence of S. haematobium infection than those living in inland villages. Overall prevalence (all age classes combined) of urinary schistosomiasis in 1998/1999 ranged from 10.2% to 26.4% in inland villages and from 21.0% to 72.7% in lakeshore villages; for school children prevalence of infection ranged from 15.3% to 57.1% in inland schools and from 56.2% to 94.0% in lakeshore schools. Inhabitants on the islands, Chizumulu and Likoma, also have lower prevalence of infection than those living in lakeshore villages on Nankumba Peninsula. This increased prevalence in lakeshore villages is not necessarily linked to transmission taking place in the lake itself, but could also be due to the presence of more numerous typical inland transmission sites (e.g., streams, ponds) being close to the lake. Temporal data witness of intense transmission in some lakeshore villages with 30–40% of children cleared from infection becoming reinfected 12 months later (also lakeshore village). The level of S. mansoni infection is low in the lakeshore communities. Findings are discussed in relation to fishing in the lake.     

Long-term Patterns of Shifts between Clear and Turbid States in Lake Krankesjön and Lake Tåkern

During the past century, Lake Tåkern and Lake Krankesjön, southern Sweden, have shifted repeatedly between a state of clear water and abundant submerged vegetation, and a state of turbid water and sparse vegetation. Long-term empirical data on such apparently alternative stable state dynamics are valuable as complements to modeling and experiments, although the causal mechanisms behind shifts are often difficult to identify in hindsight. Here, we summarize previous studies and discuss possible mechanisms behind the shifts. The most detailed information comes from monitoring of two recent shifts, one in each lake. In the 1980s, L. Krankesjön shifted to clear water following an expansion of sago pondweed, Potamogeton pectinatus. Water clarity increased when the pondweed was replaced by characeans. Zooplankton biomass in summer declined and the concentration of total phosphorus (TP) was reduced to half the previous level. The fish community changed over several years, including an increasing recruitment of piscivorous perch (Perca fluviatilis). An opposite directed shift to turbid water occurred in Lake Tåkern in 1995, when biomass of phytoplankton increased in spring, at the expense of submerged vegetation. Consistent with the findings in L. Krankesjön, phyto- and zooplankton biomass increased and the average concentration of TP doubled. After the shift to clear water in L. Krankesjön, TP concentration has increased during the latest decade, supporting the idea that accumulation of nutrients may lead to a long-term destabilization of the clear water state. In L. Tåkern, data on TP are inconclusive, but organic nitrogen concentrations oscillated during a 25-year period of clear water. These observations indicate that intrinsic processes cause gradual or periodic changes in system stability, although we cannot exclude the possibility that external forces are also involved. During such phases of destabilization of the clear water state, even small disturbances could possibly trigger a shift, which may explain why causes behind shifts are hard to identify even when they occur during periods of extensive monitoring.     

Zooplankton of Lake Peipsi-Pihkva in 1909–1987

164 taxa were identified in the net zooplankton of the pelagial of L. Peipsi-Pihkva in 1909–1987, including 3 species of protozoans, 74 species of rotifers, 58 species of cladocerans, 28 species of copepods and 1 mollusc. One rotifer species, Ploesoma peipsiense Mäemets et Kutikova, has been described as new for science here. The zooplankton of L. Peipsi-Pihkva is remarkably rich in species including rarities in Estonia: Limnosida frontosa, Drepanothrix dentata, Bythotrephes longimanus, B. cederstroemi etc. Due to its large surface area, L. Peipsi-Pihkva provides a large scale of biotopes of a diverse trophic state and humic content, which support species with different ecological requirements. Most of the aquatory of the lake has lately been mesotrophic, favouring the coexistence of indicators of oligo- and mesotrophic state and species preferring a higher trophic state. The occurrece of 10 species of the genus Bosmina including B. berolinensis, B. gibbera, B. lilljeborgi, B. thersites and B. crassicornis, sparse in Estonian lakes, is the most noteworthy feature of the zooplankton of L. Peipsi-Pihkva. The coexistence of B. coregoni and B. berolinensis, B. gibbera, B. lilljeborgi etc. which were earlier regarded as subspecies of B. c. coregoni proves that they are different species producing usually no hybrids. The species composition was subjected to certain changes during the years under consideration. Larvae of Dreissena were first found in zooplankton in 1962. The oligo-mesotrophic indicator Holopedium gibberum occurred in the lake in 1909–1964, but was lacking in later samples.     

Winter microbial activity in Lake Tuusulanjärvi

Microbial heterotrophic activity, dark CO₂ assimilation, primary productivity and microbial ATP were measured monthly in the extremely eutrophic Lake Tuusulanjärvi during the winter of 1979–1980. Because of continuous water circulation caused by low temperature and artificial aeration of the lake, no winter stratification developed. Very low summertime ³H-glucose turnover times of 5 h increased to a level of 10–20 h from August to January. Winter maximum of 110 h was measured in March, and turnover times returned to 10–20 h in April, before the vernal bloom of algae occured. Oxygen saturation remained over 46% during the winter.High primary productivity was observed in November (400–500 mg C m^–3 day^–1), and measurable productivity was detected under ice in January (80 mg C m^–3 day^–1). Dark CO₂ assimilation increased to 14% of primary productivity in March. No correlation was found between ³H-glucose turnover rate and dark CO₂ assimilation. ATP correlated slightly better with primary productivity than with turnover rate. The single concentration method proved to be sensitive for winter heterotrophic activity measurement.     

The major anions in Lake Maryût waters

Summary Determinations for sulphate, bromide content and the alkalinity of Lake Maryût water were carried out at six stations during the four seasons of 1966. The sulphate chlorinity ratio increases with the decrease of chlorinity. It has an average of 0.2649 which is higher than the ratio of 0.1395 for sea water and lower than the ratio for river waters. Regional variations in the SO₄/Cl ratio are attributed to the effect of drainage water which have a high sulphate content. The average bromine chlorinity ratio 0.00360 is compared with 0.00348 for sea water. The seasonal and regional variation of the Br/Cl ratio is less significant than the SO₄/Cl ratio. The specific alkalinity decreases with the increase of chlorinity. The average specific alkalinity for the lake water is 3.20 which is higher than that for sea water, (0.126), and lower than that for river waters.     

Coliform concentrations in Lake Erie — 1966 to 1970

Total coliform concentrations obtained from cruises of Lake Erie, conducted from the Canada Centre for Inland Waters between 1966 and 1970, have been analysed to determine the spatial and temporal distribution of total coliforms in the lake. Although year to year comparisons were made on a qualitative level due to the limitations in the data, some consistent seasonal features of the spatial distribution are evident. The location of zones of higher concentration have been attributed to proximity to large urban areas and lake currents. The contribution of fecal coliforms to the total coliform concentration has been examined with the conclusion that, at the low total coliform concentrations ( 30 per 100 ml) observed in much of the lake, there is no relationship between the two concentrations but, over a broader range, fecal coliforms increase with total coliform concentrations and, at very high total coliform concentrations (1000 per 100 ml), fecal coliforms are always present. The analysis demonstrates 1) the value of examining observed and fitted distributions to compare subsets of a large collection of data and 2) a clustering procedure which is generally applicable to data consisting of counts.     

Underwater sinkhole sediments sequester Lake Huron’s carbon

Lake Huron’s submerged sinkhole habitats are impacted by high-conductivity groundwater that allows photosynthetic cyanobacterial mats to form over thick, carbon-rich sediments. To better understand nutrient cycling in these habitats, we measured the stable isotopic content of carbon and nitrogen in organic and inorganic carbon pools in Middle Island sinkhole, a ~23 m deep feature influenced by both groundwater and overlying lake water. Two distinct sources of dissolved CO₂ (DIC) were available to primary producers. Lake water DIC (δ ¹³C = ?0.1 ‰) differed by +5.9 ‰ from groundwater DIC (δ ¹³C = ?6.0 ‰). Organic carbon fixed by primary producers reflected the two DIC sources. Phytoplankton utilizing lake water DIC were more enriched in ¹³C (δ ¹³C = ?22.2 to ?23.2 ‰) than mat cyanobacteria utilizing groundwater DIC (δ ¹³C = ?26.3 to ?30.0 ‰). Sinkhole sediments displayed an isotopic signature (δ ¹³C = ?23.1 ‰) more similar to sedimenting phytoplankton than the cyanobacterial mat. Corroborated by sediment C/N ratios, these data suggest that the carbon deposited in sinkhole sediments originates primarily from planktonic rather than benthic sources. ²¹⁰Pb/¹³⁷Cs radiodating suggests rapid sediment accumulation and sub-bottom imaging indicated a massive deposit of organic carbon beneath the sediment surface. We conclude that submerged sinkholes may therefore act as nutrient sinks within the larger lake ecosystem.     

Acoustic diversity in Lake Malawi’s rock-dwelling cichlids

The cichlids of Lake Malawi are one of the world’s most species rich and phenotypically diverse groups of extant vertebrates. The extraordinary variability of this group’s color patterns, reproductive behaviors, and trophic morphologies are well documented. More recently, an additional axis of phenotypic diversity has been identified. Lake Malawi cichlids have been shown to use species-specific acoustic communication in both aggressive and reproductive encounters. However, documentation of acoustic signals used by this group is limited to a small number of taxa observed within the confines of the laboratory. This study examines the acoustic signals produced by six species spanning four genera of rock-dwelling cichlids recorded in their natural habitat, the shallow waters surrounding Thumbi West Island, Lake Malawi. Four acoustic parameters were quantified and compared between species: trill duration, number of pulses per trill, pulse duration, and pulse period. Using these characteristics, sympatric species within the genus Maylandia were easily distinguished. Furthermore, a comparison of this data to previously published acoustic data reveals possible geographic dialects within species.     

Zooplankton in Lake Atnsjøen 1985–1997

The aim of this paper is to study long-term changes in the zooplankton of a subalpine locality unaffected by direct anthropogenic disturbances. The material has been collected during the period 1985–1997; since 1988 a standardised sampling program has been followed, with five sampling dates during the ice free period (June–October) at three fixed stations. Altogether 17 species of Rotatoria, 9 species of Copepoda and 11 species of Cladocera were recorded. Of these 10 species of Rotatoria, two species of Copepoda and five species of Cladocera occur regularly in the plankton. Polyarthra vulgaris dominate among the rotifers together with Kellicottia longispina and Conochilus unicornis. The crustacean community is dominated by the copepod Cyclops scutifer, and the cladocerans Bosmina longispina, Holopedium gibberum and Daphnia longispina. The cladocerans Bythotrephes longimanus, Polyphemus pediculus,and the copepodsArctodiaptomus laticeps and Heterocope saliens all occur regularly, but at low densities. The zooplankton density is low in May/June and peaks in August and September, but the timing of maximum densities varies from year to year. By numbers, the rotifers strongly dominate with densities 10–15 times higher than the crustaceans. The annual maximum density (rotifers plus crustaceans) ranged from 50 ind. l^?1 (1985, 1988) to 450 ind. l^?1 (1995). Mean density is about 140–150 ind. l^?1. By biomass (dry weight), the cladocerans constitute 60%, while the copepods and rotifers constitute 30% and 10% of the zooplankton, respectively. The annual maximum has varied between 70 and 260 μg dw l^?1, with 170 μg dw l^?1 as the mean level. C. scutifer usually has a one-year lifecycle without diapause, but a small fraction of the population has a two-year lifecycle. The life cycle in 1989 and 1990 differed strongly from the other years. The life cycles of B. longispina, D. longispina and possibly also H. gibberum and A. laticeps, indicate two generations during the summer. H. gibberumandH. saliens pass the winter as resting eggs. The other crustacean species, except C. scutifer, pass the winter mainly as resting eggs, but all have a small winter population in the water mass. C. scutifer is the only species without resting eggs. The vertical distribution normally shows highest density between 5 and 10 m depth. However, during some periods maximum density is observed close to the surface, while at other times it is seen deep in the hypolimnion. The vertical distribution is most pronounced when the thermocline is sharp, and less pronounced during the full circulation in autumn. The vertical migration may also be pronounced, especially in B. longispina, with high density near the surface during the night. The vertical migration is less pronounced among the rotifers and copepods. The degree of vertical migration varies with temperature and food conditions. There is little variation from year to year in species composition, but large variation in species dominance, seasonal development, population density, and vertical and horizontal distribution during the sampling period. Variations in temperature, food condition, predation, and water through-flow are possible causes for the observed differences between the years. Input of allochthonous material is especially important. However, no clear correlation have been found between the development of the plankton community and these environmental factors. Hence, these interactions are complex and multifactorial.     

From foraging to farming in the Great Mazurian Lake District: palynological studies on Lake Miłkowskie sediments, northeast Poland

Early and mid Holocene local vegetational history, with special reference to woodland communities, was revealed by pollen analysis of a radiocarbon dated lake sediment profile from Lake Miłkowskie (Jezioro Miłkowskie) in northeastern Poland. The main factor controlling the dynamics of woodland composition changes until ca. 1950 b.c. was climate. After that, the role of human activity became increasingly important. The results of high-resolution pollen analyses provide evidence for early woodland disturbances caused by Mesolithic people at ca. 6950 b.c. Several episodes of human impact, differing in scale, and separated by subsequent episodes of woodland regeneration/stabilization were noted. The first traces of local crop farming, shown by the presence of Cerealia pollen, were recorded at ca. 3800 b.c. in the Paraneolithic/Neolithic period. Animal husbandry as well as cereal cultivation played only a marginal role in the economy, which was traditionally based on hunting, fishing and gathering through the Neolithic and the early Bronze Age. The change in economic strategies from foraging towards farming, starting around 3750 b.c., was a long-lasting process. An increase of productive economy took place in the middle Bronze Age at ca. 1400 b.c.     

The Origin and Evolution of Lake Vähä-Pitkusta, SW Finland – A Multi-Proxy Study of a Meromictic Lake

Lake Vähä-Pitkusta is a 35-m deep meromictic kettle-hole lake in SW Finland. The topmost 15cm of the sediment stratigraphy consists of black gyttja, representing the last ca. 600years. A sediment core from the deepest point was examined with multi-proxy methods to determine the origin and evolution of the basin, the onset of the meromictic conditions and the primary factors that initiated the meromictic processes. The results indicate that Lake Vähä-Pitkusta became isolated from the Baltic basin during the Yoldia Sea stage. After initial unstable sedimentary conditions the development continued steadily until ca. 2500–2300 cal.BP when there is indication of lake level rise and/or increased surface runoff, probably resulting from a cooler and moister climate. The diatom and cladoceran results indicate only a slight rise in the trophic state following the increased erosion. Pollen evidence suggests weak anthropogenic activity in the catchment during the last 1000 years, and this had only little effect on the trophic state, which remained rather low. Thus, it is most unlikely that the trophic state was the primary reason for the origin of meromixis, although it may have contributed to it. We tentatively suggest that the primary reason was the peculiar morphometric dimensions of Lake Vähä-Pitkusta (small, deep, sheltered from winds) which made it very sensitive and that even a very slight increase in soluble electrolytes may push it over the edge into meromixation. It is possible that this did not occur during the cold/moist period around ca. 2300 cal.BP but during the Medieval Climate Anomaly. Studies on sediment geochemistry are needed to verify this assumption.     

Lake Level Changes Recorded by Tree Rings of Lakeshore Shrubs： A Case Study at the Lake West-Juyan, Inner Mongolia, China

Variation in water resources is a main factor influencing ecohydrological processes and sustainable development in arid regions. Lake level changes are a useful indicator of the variability in water resources. However, observational records of changes in lake levels are usually too short to give an understanding of the long-term variability. In the present study, we investigated the tree rings of shrubs growing on the lakeshore of Lake West-Juyan, the terminus of the Heihe River in western China, and found that Lake West-Juyan had undergone degradation three times over the past 200 years. The lake level decreased from 904.3 to 896.8 m above sea level （a.s.1.） during the period 1800-1900, to 892.0 m a.s.1, from around 1900 to the late 1950s, and the lake dried out in 1963. The trend for changes in lake levels, which was represented by the composite chronology of three beach bars, showed that the phases of increasing lake levels over the past 150 years were during the periods 1852-1871, 1932-1952, 1973-1982, and 1995-1999. Comparison with the history of regional economic development showed that human activity has played an important role in regulating the water resources of the lower reaches of the Heihe watershed over the past 200 years.     

Changing Abundance of Hexagenia Mayfly Nymphs in Western Lake Erie of the Laurentian Great Lakes: Impediments to Assessment of Lake Recovery?

After an absence of 40 years, mayfly nymphs of the genus Hexagenia were found in sediments of western Lake Erie of the Laurentian Great Lakes in 1993 and, by 1997, were abundant enough to meet a mayfly‐density management goal (ca. 350 nymphs m^—2) based on pollution‐abatement programs. We sampled nymphs in western Lake Erie and Lake St. Clair, located upstream of western Lake Erie, to determine the importance of seasonal abundance and life‐history characteristics of nymphs (e.g., emergence and recruitment) on density estimates relative to the mayfly‐density management goal. Two types of density patterns were observed: (1) densities were relatively high in spring and gradually decreased through late summer (observed in Lake Erie and Lake St. Clair in 1997 and Lake St. Clair in 1999) and (2) densities were relatively high in spring, gradually decreased to mid summer, abruptly decreased in mid summer, and then increased between summer and late fall (Lake Erie and Lake St. Clair in 1998 and Lake Erie in 1999). Length‐frequency distributions of nymphs and observations of adults indicate that the primary cause for the two density patterns was attributed to failed (first pattern) and successful (second pattern) reproduction and emergence of nymphs into adults in mid summer. Gradual declines in densities were attributed to mortality of nymphs. Our results indicate that caution should be used when evaluating progress of pollution‐abatement programs based on mayfly densities because recruitment success is variable both between and within years. Additionally, the interpretation of progress toward management goals, relative to the restoration of Hexagenia populations in the Great Lakes and possibly other water bodies throughout the world, is influenced by the number of years in which consequtive collections are made.     

Fishery of Lake Ladoga — past, present and future

The post-war fishery of Lake Ladoga can be divided according to its catch level into four periods. In the years 1945–1954 the total annual catch increased, and reached the level of 4000 tonnes. In this period the fish stocks that had increased during the war years were intensively exploited. However, this fishery was not in balance with the stocks during the period 1955–1963. As a consequence, the catch decreased drastically, being sometimes less than 2000 tonnes.Controlling the fishery restored the abundance of whitefish Coregonus lavaretus (L.) and zander Stizostedion lucioperca (L.). This increased the total annual catch to about 5500 tonnes in 1964–1989. However, the fishery control measures have not been sufficient to achieve the conservation of salmon Salmo solar L. m. sebago, brown trout Salmo trutta L. and the migratory lake whitefish stocks.A decrease in the total fish catch has been observed since 1990. This decrease may be related to the deterioration of the environment of Lake Ladoga, caused by anthropogenic factors. The unfavourable state of the ecosystem has led to decline of the whitefish stocks and, especially during the last few years, to drastical decline of zander.Acute problems, to be faced in the near future, are connected with the hatchery maintenance of several river-spawning stocks, e.g. salmon, brown trout and migratory whitefish, because the existing fish hatcheries are insufficient in capacity and technically outdated.     

Mercury contamination in Lake Xolotlán (Managua)

Total mercury was measured in different compartments of Lake Xolotlán's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 g Hg.g^–1±0.46 at the surface, with extreme values of 0.16 and 1.8 g.g^–1. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 g.Hg^–1 in January and 506 g.g^–1 in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 g.g^–1±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 g.g^–1±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 g.g^–1±1.29 inC. managuense and 0.62 g.g^–1±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 g.g^–1±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 g.g^–1±6.34 (n=58), and in women 3.39 g.g^–1±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 g.g^–1±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.     

Spatial–temporal patterns of methane dynamics in Lake Taihu

Many European lakes are monitored according to the EU Water Framework Directive (WFD), with focus on phytoplankton biomass and species composition. However, the low-frequency WFD monitoring may miss short-term phytoplankton changes. This is an important issue because short-term extreme meteorological events (heat waves and heavy rain) are predicted to increase in frequency and intensity with climate change. We used records from Lake Mondsee (Austria) from 2009 to 2015 to test if a reduction from monthly to seasonal sampling affected the average annual phytoplankton biovolume. Furthermore, we combined inverted light microscopy, FlowCAM and flow cytometry to estimate the effect of sampling during extreme events on average phytoplankton biovolume. Relative to monthly sampling, seasonal sampling significantly overestimated phytoplankton biomass. A heat wave in 2015 and two episodes of heavy rain in 2015 and 2016 caused species-specific changes; biovolumes of chlorophytes and the filamentous cyanobacterium Planktothrix rubescens (De Candolle ex Gomont) Anagnostidis & Komárek increased significantly during the heat wave. Using live material with FlowCAM and flow cytometry, we detected small and fragile cells and colonies that were either ignored or underrepresented by analysing fixed samples with light microscopy. We suggest a modified sampling and analysis strategy to capture short-term changes within the phytoplankton community.