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The location of Lake Simcoe in southern Ontario, Canada. The 10, 20, 30 and 40 m depth contours, the locations of 12 sampling stations and some morphometric data are also shown (A = lake area excluding islands; V = lake volume; z = mean depth).
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Consensus-building univariate and multivariate data analyses were used to identify patterns in space and time over seven years among 12 sampling stations in a 720 km2 hardwater Canadian lake (Lake Simcoe, Ontario, Canada). There were 15 copepods and 26 cladoceran species identified in samples collected throughout the May-October periods of 1986-199...
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... poly- morpha) in 1994-95, both of which have potential to alter zooplankton community structure, either directly or indirectly (Yan & Pawson 1997;MacIsaac 1996). Because of the heterogenous morphometry and large size of Lake Simcoe [relatively shallow Cook's Bay, relatively deep Kempenfelt Bay and the large moder- ately deep main lake ( Fig. 1)], zooplankton data col- lected regularly over several years from many locations on the lake are well-suited to multivariate methods of analysis. Nicholls & Tudorancea (2001a) have previ- ously shown how fuzzy cluster membership coefficients could be used for ranking the importance of crustacean zooplankton species for their ...
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... samples were collected at approxi- mately bi-weekly intervals at each of 12 Lake Simcoe stations ( Fig. 1) during the May through October peri- ods of 1986 to 1992. Samples were taken from vertical tows from one meter above bottom to the lake surface with a modified conical Clarke-Bumpus net (1 m long, 12.5 cm mouth diameter, 80 µm Nitex mesh, net bucket 5.1 cm diameter) equipped with a flow meter for esti- mation of net efficiencies. ...
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... to this was Station C1, all seven years of which, along with C6-91, formed Group I of the 7-group solution. Excluding Group I, eight of the 11 remaining 1990 SUs were found in Group II (Fig. 6). All of the remaining 1992 SUs were found with six of the remaining 1991 stations in Group III. Group IV was comprised of deep-water stations (see Fig. 1) including half of the 1988 SUs. Groups V and VI were comprised predominantly of the 1987, 1988 and 1989 SUs, 83% of which were from deep-water locations. Group VII con- tained all of the 1986 SUs (again with the exception of Station C1), and included both deep-water and shallow- water locations (Fig. ...
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... community structure during 1992 and 1986 was significantly different from all other years (Fig. 10). On average, community structures during 1988 and 1990 were not significantly different, as was the case for 1989 and 1990. Similarly, average zoo- plankton community structures measured during 1987, 1989 and 1991 could not be distinguished statistically (Fig. ...
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... structure during 1992 and 1986 was significantly different from all other years (Fig. 10). On average, community structures during 1988 and 1990 were not significantly different, as was the case for 1989 and 1990. Similarly, average zoo- plankton community structures measured during 1987, 1989 and 1991 could not be distinguished statistically (Fig. ...
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... dissimilarity was not significantly different from those determined for each separate year. Cophenetic correlation analyses of all seven inter-station CY dissimilarity matrices (one for each of the years 1986-1992) produced correlation coef- ficients (r) ranging from 0.525, for the 1989 and 1991 pair of matrices, to 0.839, for the 1987-1992 pair (Fig. ...
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... cumu- lative percentage of the first two eigenvalues was only 58%, so it is doubtful if this two-dimensional ordination adequately portrayed the inter-year distances. Permuta- tion tests of each pair of annual matrices more conclu- sively established the lack of significant difference be- tween any of the annual pairings at probability levels <5% (Fig. 11). It is important to emphasize that this simply means that the patterns of inter-station dissimilarity (all 66 possible pairs of stations) were consistent between years, not necessarily that year-to-year dissimilarities in specific inter-station pairings were not significantly different; these temporal effects are explored ...
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... which all subsequent years were compared within stations revealed that 1987 had the lowest CY-dissimilarity with the baseline at six of the 12 stations, while 1992 had the highest dissimilarity with the 1986 baseline at 10 of the 12 stations. Aver- aged over all stations, the yearly intra-station dissimi- larities steadily increased 78% by 1992 (Fig. 12). The greatest rates of increase in yearly intra-station dissimi- larity with 1986 baselines were found for Stations K42 and E51 (281% and 224% increases, respectively; Fig. 12). Trends were least evident at the Cook's Bay sta- tions; Spearman's Rank correlation coefficients of 0.543, 0.429 and 0.600 (n = 6), relating Stations C1, C6 ...
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... aged over all stations, the yearly intra-station dissimi- larities steadily increased 78% by 1992 (Fig. 12). The greatest rates of increase in yearly intra-station dissimi- larity with 1986 baselines were found for Stations K42 and E51 (281% and 224% increases, respectively; Fig. 12). Trends were least evident at the Cook's Bay sta- tions; Spearman's Rank correlation coefficients of 0.543, 0.429 and 0.600 (n = 6), relating Stations C1, C6 and C9 1986 baseline CY-dissimilarities to subsequent years, were not significant (P >0.1). ...
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... CY-dissimilarities to subsequent years, were not significant (P >0.1). These trends in community structure were the net re- sults of many different patterns of change for many taxa. Such patterns included increasing densities over the 7-year period of Daphnia longiremis, Diaphano- soma birgei and declining densities of Daphnia puli- caria (Fig. 13). Several taxa including Daphnia g. men- dotae (especially in Kempenfelt Bay), immature stages of cyclopoid copepods, an unidentified Daphnia spe- cies, D. parvula, Mesocyclops edax (especially in Kem- penfelt Bay), Leptodiaptomus sicilis (in the main lake), Sida crystallina and Leptodora kindtii (especially in Cook's Bay) showed ...
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... Daphnia spe- cies, D. parvula, Mesocyclops edax (especially in Kem- penfelt Bay), Leptodiaptomus sicilis (in the main lake), Sida crystallina and Leptodora kindtii (especially in Cook's Bay) showed highest values in the middle years of the study. Ceriodaphnia spp. in Kempenfelt Bay and Cook's Bay were at their lowest densities during this time (Fig. 13). Fig. 13. May-October average densities of selected crustacean zooplankton taxa demonstrating trend patterns over the 7-year period (increasing, decreasing, mid-study peaks, or mid-study lows). The stations used to compile the averages for Kempenfelt Bay were: K38, K39 and K42; for Cook's Bay: C1, C6 and C9; for the main lake: S15, ...
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... spe- cies, D. parvula, Mesocyclops edax (especially in Kem- penfelt Bay), Leptodiaptomus sicilis (in the main lake), Sida crystallina and Leptodora kindtii (especially in Cook's Bay) showed highest values in the middle years of the study. Ceriodaphnia spp. in Kempenfelt Bay and Cook's Bay were at their lowest densities during this time (Fig. 13). Fig. 13. May-October average densities of selected crustacean zooplankton taxa demonstrating trend patterns over the 7-year period (increasing, decreasing, mid-study peaks, or mid-study lows). The stations used to compile the averages for Kempenfelt Bay were: K38, K39 and K42; for Cook's Bay: C1, C6 and C9; for the main lake: S15, E50, E51 and ...
Citations
... The invasive zooplanktivore Bythotrephes longimanus (Cercopagididae; the spiny water flea, hereafter called Bythotrephes) was first detected in routine zooplankton monitoring samples in the autumn of 1993, and has since become well established in the lake (Kelly et al., 2013;MOECC, 2015). From 1986 to 1992, four cladocerans and three copepods dominated the zooplankton community, while species richness varied from 14 to 31 across 12 lake stations (Nicholls & Tudorancea, 2001a). Declines in the total abundance of zooplankton, as well as cladoceran species richness, coincided with the establishment of Bythotrephes in 1994, although beginning in 2000, cladoceran species richness has been slowly increasing (MOECC, 2015). ...
Predicting how freshwater biota respond to multiple stressors is currently a major challenge facing aquatic ecologists and environmental managers. Lake Simcoe is an ideal location to test the impact of multiple stressors on aquatic biota over time, as changes in climate warming, species invasions, nutrient loading, and human population growth have occurred throughout the last three decades.
In this study, we used a suite of multivariate analyses to quantify the unique and interactive effects of physico‐climatic, water quality, and biological variables in explaining phytoplankton community composition from 1986 to 2012.
Changes in water quality, zooplankton abundance and community composition (following the invasion of Bythotrephes longimanus ), euphotic zone temperature and thermal stability, and the invasion of zebra mussels ( Dreissena polymorpha ) acting at different times throughout the period of record, were associated with major shifts in the phytoplankton community of Lake Simcoe: dominance of eutrophic diatoms and cyanobacteria from 1986 to 1997 shifted to chlorophytes after 1998, then again to a diverse mix of taxa represented by all major categories of algae after 2004.
Contrary to expectation, we found little evidence that interactions between multiple stressors are taking place in Lake Simcoe. Instead, our results demonstrated the sequential nature of multiple stressors in influencing interannual variation in phytoplankton community structure. By occurring consecutively over time, we propose a “sequence of stressors” has influenced the ecological health of the lake over the preceding three decades.
Considered by category, biological stressors, followed by water quality, then temperature and climate, explained the largest amount of total variance in the phytoplankton data. The prominence of zooplankton community changes as significant predictors of phytoplankton community change throughout the period of record suggests the top‐down effect of these herbivores are also very important.
Our results highlight the importance of extensive ecosystem monitoring in determining ecosystem health. Our approach may assist in the management of other aquatic systems, where identifying when multiple stressors are not operating may simplify the management process, allowing remediation efforts to focus on the most impactful stressors as primary targets for ecosystem restoration.
... The ratio between calanoid and cyclopoid copepods can give valuable information on the trophic state of the water body. Nicholls and Tudorancea (2001) correlated the disappearance of calanoid species to oxygen concentration depletion and significant nutrient loads in the system. In Lake Iezerul Ighiel however, the ratio between calanoids (Acanthodiaptomus denticornis) and cyclopoids (Cyclops vicinus; Eucyclops serrulatus proximus) had a general value of 5:1, thus showing good trophic conditions. ...
The worldwide consumption of energy drinks has grown globally during the last few decades among athletes and youth, because of their stimulant properties. Although these beverages are consumed in order to improve concentration, physical and cognitive performance, there is insufficient evidence or studies to confirm these claims. The aim of our study was to investigate if acute administration of Red Bull energy drink influences some biochemical parameters of the blood as well as blood pressure and heart rate, under physical activity in trained and untrained healthy males.
Thirteen healthy voluntary males between the ages 20-25 years participated in this study. They were organized in two groups: trained and untrained. Blood samples were drawn and certain hemodynamic parameters were measured before and after physical activity/Red Bull administration. Anthropometrical measurements were also determined.
A significant increase of blood pressure and heart rate were noticed after Red Bull administration in all subjects, while the glucose concentration decreased. The concentration of total protein increased significantly after Red Bull administration, as did the activities of serum LDH, AST and ALT. These results indicate that acute consumption of energy drinks can affect biochemical blood parameters as well as the hemodynamic parameters.
... The ratio between calanoid and cyclopoid copepods can give valuable information on the trophic state of the water body. Nicholls and Tudorancea (2001) correlated the disappearance of calanoid species to oxygen concentration depletion and significant nutrient loads in the system. In Lake Iezerul Ighiel however, the ratio between calanoids (Acanthodiaptomus denticornis) and cyclopoids (Cyclops vicinus; Eucyclops serrulatus proximus) had a general value of 5:1, thus showing good trophic conditions. ...
The present study represents the first limnological survey made in Lake Iezerul Ighiel, considering the most important biotic communities in the water column (phyto-and zooplankton) and from the bottom (phyto-and zoobenthos). No data was collected on ichthyofauna, since the species existing in the lake were introduced. The lake was sampled in 2014 in three seasons, from three sampling sites located in different regions of the water body, having different characteristics. Physical and chemical parameters were also analysed. The biotic communities considered for the study depicted a generally good ecological status of the lake. However, moderate organic pollution, together with initial phases of eutrophication were indicated by the algal and invertebrate communities considered for the present study, both planktonic and benthic.
... Invasions of nonindigenous species that negatively impact the biology and ecology of zooplankton have the potential to simultaneously influence the dynamics of multiple trophic levels (e.g., primary producers, herbivores, top predators), with cascading consequences for primary and secondary production, nutrient cycling, and water quality, and potentially impacting overall ecosystem functioning (Mack et al. 2000, Barbiero et al. 2006). Historical changes in zooplankton community structure and diversity in Lake Simcoe were linked to changes in water quality and planktivorous fish abundances (Nicholls and Tudorancea 2001), but recent species invasions in the lake may also threaten zooplankton populations (J.D. Young, unpubl.). For example, zebra mussels (Dreissena polymorpha) became established in Lake Simcoe around 1996 (Evans et al. 2011), and their invasion coincided with significant changes in phytoplankton community composition and likely contributed to increases in water clarity (Eimers et al. 2005). ...
The invasion of the nonindigenous zooplankter Bythotrephes longimanus in Lake Simcoe has the potential to impact overall ecosystem functioning, yet there is currently no information regarding the status and dynamics of its population. We used a combination of uni-and multivariate analyses to examine variation in Bythotrephes interannual and seasonal abundance, and life-history characteristics in Lake Simcoe from 1999 to 2007, and we explored the biotic (predators, prey) and/or abiotic (water quality, temperature) factors that may have regulated its population over this period. The mean annual abundance of Bythotrephes varied by an order of magnitude over the period of study and was significantly associated with epilimnetic temperature and prey and predator abundance. Bythotrephes typically appeared in early summer and had 2 seasonal abundance peaks, which varied in magnitude and timing within and among years. August and September Secchi depth and total phosphorus concentration predicted groups of years with similar Bythotrephes phenologies, lending further support to the role of water clarity as a significant component of this visual predator's habitat in its invaded range. Bythotrephes body size and reproductive patterns also varied seasonally, possibly reflecting the seasonal availability of cladoceran prey, predation pressure from planktivorous fish, or adaptations to avoid unfavourable conditions. Overall, a complex interaction of fish predation, food availability, temperature, and water clarity controlled the dynamics of Bythotrephes in Lake Simcoe. Changes to the Lake Simcoe ecosystem due to Bythotrephes invasion may have important consequences for the ecosystem services provided by the lake and merit further investigation.
... Among the copepods, juveniles (nauplii and copepodites) dominate. In eutrophic water bodies, the life time of dominant species is short and young individuals prevail, while the adults are strongly decimated by predators (Ponyi & Zankai 1982;Nicholls & Tudorancea 2001). Metazooplankters inhabit mainly the epilimnion and metalimnion, where they find suitable living conditions. ...
The response of Daphnia populations to invertebrate predators involves morphological or behavioural changes. Few studies
suggest that contaminant aqueous metals, like Cu or Ni at environmentally relevant concentrations, interfere with invertebrate
chemical communication systems, such as that which operates between Daphnia and Chaoborus. The objective of our study was to
determine if this interference could be also observed in lakes naturally rich in dissolved metals, such as volcanic lake (Lago Grande
di Monticchio). This study aimed to assess if natural dissolved metals (e.g., Fe, Mn and Sr) could impair the ability of Daphnia pulex
and D. galeata × hyalina × cucullata 'complex' populations to respond to Chaoborus kairomones by producing morphological
defenses against potential predation, and to understand how Chaoborus predation might affect zooplankton community composition
and overall zooplankton density. The predator impact did not result in: i) any morphological changes; ii) any apparent shift in body
size pattern of the prey population; iii) any shift in life history traits. Chaoborus accounted for high mortality rates in Cladocera and
strongly reduced the chance of individuals to reach maturity. Moreover, highly significant negative correlations between abundance
of dominant taxa of zooplankton and C. flavicans were found. The last larval instars of C. flavicans seem to reduce the number of
crustaceans, particularly cladocerans and copepod adults and could play an important role in structuring zooplankton communities.
Our results suggest that metal inhibition of defence strategies induction probably occurs along the signal transduction pathway in
Lake Grande di Monticchio. Impairment of chemosensory response to predatory chemical cues may have widespread ecological
consequences in aquatic systems. Chaoborus predation effects can greatly affect both zooplankton biomass and community
composition, impact interactions at lower trophic levels and generate an ecological cascade leading to a rapid eutrophication.
... Among the copepods, juveniles (nauplii and copepodites) dominate. In hypertrophic water bodies, the life cycle of dominant species is short, and young individuals prevail, while the adults are strongly decimated by fish (Ponyi & Zankai, 1982;Haberman, 1998;Nicholls & Tudorancea, 2001). ...
The vertical and temporal distribution of metazooplankton in the small hypertrophic, strongly stratified, temperate Lake Verevi
(Estonia) was studied during 1998–2001. The zooplankton of Lake Verevi is characteristic of hypertrophic lakes, with a small
number of dominant species, rotifers being the main ones, and juveniles prevailing among copepods. In 1999–2001, the average
abundance of metazooplankton in the lake was 1570 × 103 ind m−3; in the epilimnion 2320 × 103 ind m−3, in the metalimnion 2178 × 103 ind m−3, and in the hypolimnion 237 × 103 ind m−3. The average biomass of metazooplankton was 1.75 g m−3; in the epi-, meta- and hypolimnion, accordingly, 2.16, 2.85 and 0.26 g m−3. The highest abundances — 19,136 × 103 ind m−3 and 12,008 × 103 ind m−3 — were registered in the lower half of the metalimnion in 24 May and 5 June 2001, respectively. Rotifer Keratella cochlearis f. typica (Gosse, 1851) was the dominating species in abundance. In biomass, Asplanchna priodonta Gosse, 1850, among the rotifers, and Eudiaptomus graciloides (Lilljeborg, 1888), among the copepods, dominated. According to the data from 2000’2001, the abundance and biomass of both
copepods and rotifers were highest in spring. Zooplankton was scarce in the hypolimnion, and no peaks were observed there.
During the summers of 1998 and 1999, when thermal stratification was particularly strong, zooplankton was the most abundant
in the upper half of the metalimnion, and a distinct peak of biomass occurred in the second fourth of the metalimnion. Probably,
the main factors affecting the vertical distribution of zooplankton in L. Verevi are fish, Chaoborus larvae, and chemocline, while food, like phytoplankton, composition and abundance may affect more the seasonal development
of zooplankton.
... Among the copepods, juveniles (nauplii and copepodites) dominate. In hypertrophic water bodies, the life cycle of dominant species is short, and young individuals prevail, while the adults are strongly decimated by fish (Ponyi & Zankai, 1982;Haberman, 1998;Nicholls & Tudorancea, 2001). ...
The present book summarises investigations on Lake Verevi (surface 12.6 ha, mean depth 3.6 m), located in the Estonian town of Elva, initiated since 1929. The seventeen articles in this issue deal with a wide range of questions, starting with a holistic overview of the ecological status, over assessments of long-term changes in biotic and abiotic conditions and finishing with proposed restoration plans. Abiotic chapters provide calculations on water and mass balance, distribution and fractions of phosphorus in the sediment, optical properties and penetration of radiation in the water column, sedimentation rate during the formation of stratification, and nitrogen circulation characteristics. All of these phenomena explain the special environmental features of this highly stratified lake. Long-term changes, seasonal development, primary production and resource ratios inducing the distribution of species composition of various biota (bacterio-, phyto and zooplankton, macrozoobenthos, fish) are discussed. The most important issues in this book are long-term investigations on a complex ecosystem, the phenomenon of partial meromixis, the description of restoration methods, and the existence of narrow microniches for plankton in the water column.
The book aims at a large audience, including researchers and students of complex limnological questions and of intricate ecological systems, but also to managers and decision makers. The present volume firmly establishes Lake Verevi as a model system of a natural aquatic habitat, experiencing a multitude of anthropogenic pressures, but for which restoration plans aim to provide sustainable management in the future.
Reprinted from Hydrobiologia volume 547 (2005)
Large lakes, such as Lake Simcoe, Ontario, Canada, are undergoing significant change due to local and global stressors. Uni- and multivariate analyses of Lake Simcoe’s zooplankton community from 1986 to 2012 indicated multiple events of ecosystem change that were synchronous across three lake stations. In the mid-1990s, shifts in zooplankton species abundance and richness, and total cladoceran body size were strongly correlated with the invasion of the zooplanktivore, Bythotrephes cederstroemii. In the early 2000s, additional shifts in zooplankton abundance, as well as copepod body size, coincided with increased water clarity (linked to filter feeding by the invader Dreissena polymorpha) and hypolimnetic water temperature. Further community changes occurred in the 2000s when Bythotrephes declined and many vulnerable cladoceran species recovered. However, the Lake Simcoe community did not fully return to its pre-invasion state as the cold-water herbivores, Daphnia longiremis and Daphnia pulicaria, remained absent. The Lake Simcoe zooplankton community illustrates ongoing ecosystem change that propagated throughout the lake food web, and may be reflected in other lakes experiencing global stressors of climate change and species invasions.
Lake Simcoe has had many stressors in the past decades. High total phosphorus (TP) loads into the lake led to end-of-summer volume-weighted hypolimnetic dissolved oxygen (MVWHDO) levels that were lethal to coldwater fish species. Additionally, dreissenid mussels became established in the lake around 1996, and may have affected nutrient cycling and phytoplankton abundance. Using data averaged over two time periods following dreissenid mussel establishment, we re-evaluated empirical relationships connecting TP loading rate and MVWHDO concentration that were developed with pre-dreissenid data. Oxygen depletion rate predicted chlorophyll (Chla) well within the range of other Ontario lakes. Measured Chla corresponded well with Chla predicted from lake TP concentration except at the shallowest station, indicating that the lake may becoming more spatially heterogeneous. Interestingly though, the Chla:TP temporal trend increased post-dreissenids when it is often observed to decrease (e.g., Great Lakes). Measured lake TP concentration was better predicted by TP loads when averaged over the ice-free season compared with the spring. The final model predicted MVWHDO directly from TP load very closely except for the 2002–2006 time period when the end-of-summer date was September 15 rather than September 30, suggesting that the date when MVWHDO is determined should be continuously re-evaluated. Additionally, trend analyses on each variable from 1980 to 2008 did not identify any changes that coincided with dreissenid establishment. Given that this model appears to be sound for the post-dreissenid period, an estimated TP load of 44 tonnes/yr was predicted that would yield the current MVWHDO target level of 7mg/L.
