Summer depth selection in crustacean zooplankton in nutrient-poor boreal lakes is affected by recent residential development (original) (raw)
Related papers
Influence of food quality on depth selection of Daphnia pulicaria.
We studied the habitat choice of juvenile and adult Daphnia pulicaria in thermally stratified water columns ( plankton towers) with a deep water algal maximum (DCM). The DCM consisted of either filamentous cyanobacteria (Planktothrix agardhii), non-filamentous Chlorophyceae (Scenedesmus obliquus) or a mixture of both. Adult D. pulicaria spent more time at colder temperatures in the presence of P. agardhii than in the presence of S. obliquus, either as the sole food source or when mixed with P. agardhii. Juvenile D. pulicaria did not show a different habitat choice in the three food treatments. In a fourth treatment, we also determined Daphnia distribution in the absence of food. Comparing the habitat choice of juveniles and adults in each of the four treatments, the latter spent more time at colder temperatures when food was absent or when in the sole presence of P. agardhii. Additional grazing and stable isotopic marker experiments showed that D. pulicaria ingested and assimilated Planktothrix filaments. The results suggest that the differences in habitat choice between adult D. pulicaria in the presence of different food types were influenced by food quality effects: adult Daphnia which move to colder waters in the presence of low quality P. agardhii decrease their metabolic rate and might thus be able to invest more resources into reproduction when environmental conditions improve.
Role of Daphnia (Daphnia spp.) in shallow lakes under eutrophic conditions
Eutrophication problem is common in all over the world. State of eutrophication defines the physico-chemical properties of water. Besides, it has a strong influence on the biotic communities living in that water bodies. On the flip side, grazers (species that grazes on phytoplankton) are believed to have substantial impact on the state of eutrophication. This paper testifies the effect of grazing by Daphnia spp. on the state of eutrophication therefore, physico-chemical properties of water in shallow eutrophic lake. The study was conducted with a mesocosm experimental set-up installed at the roof top of IHE Building, Delft, the Netherlands. Four experimental combinations (manipulating grazers (Daphnia spp.), nutrients and light) with six replicates were used for the experiment. Statistical test were performed to analyze the outcome of the experiment. The outcome of the experiment suggests that the grazing of Daphnia spp. significantly reduce the water turbidity under high eutrophic condition. Moreover, the experiment showed that Daphnid grazing has significant effect on DO and pH under elevated nutrient concentrations while, it failed to show any significance on NO3-N, PO4-P, electrical conductivity and water temperature under both low and higher nutrient concentrations.
Food quality influences habitat selection in Daphnia.
1. The vertical distribution of Daphnia in stratified lakes strongly depends on the depth profiles of temperature and food resources. However, ecological requirements for these factors are slightly different for juvenile and adult Daphnia.2. Here, I investigated whether food quality influences the habitat selection of Daphnia pulicaria at night and whether the habitat selection of juvenile and adult D. pulicaria is different. Daphnia were allowed to choose their optimal habitat in large, stratified water columns (plankton towers, Plön) that held either the green alga Scenedesmus obliquus (high quality) in the cold hypolimnion (Hypo-treatment) or S. obliquus in the warm epi- and cold hypolimnion (SCEN-treatment) or the non-toxic cyanobacterium Synechococcus elongatus (low quality) in the warm epilimnion and S. obliquus in the cold hypolimnion (SYN treatment).3. When food (S. obliquus) was present only in the hypolimnion (Hypo-treatment), juveniles and adults distributed similarly in the water column and spent most of their time in the interface between the warm and the food rich layer.4. When food was present in the epilimnion and hypolimnion (SCEN- and SYN-treatments), juvenile and adult D. pulicaria moved into the warm and now also food-rich epilimnion, however, the magnitude of this shift depended on the food type and age class of Daphnia. Adult and juvenile D. pulicaria spent most of their time in the epilimnion when food there was of a high quality (S. obliquus; SCEN-treatment). However, compared to the juveniles, adult Daphnia spent significantly more time in the colder hypolimnion when epilimnetic food was of a low quality (S. elongatus; SYN-treament).5. Therefore, habitat selection of adult D. pulicaria was affected by food quality whereas the habitat selection of juveniles was not.6. Additional growth and reproduction experiments show that the food quality is likely to be responsible for the different habitat selection of juveniles and adults in the SYN-treatment.7. In conclusion, my experiments show that D. pulicaria behaviourally reacts to the quality of its food source.
Ecological consequences of intraspecific variation in lake Daphnia
Freshwater Biology, 2010
1. Although populations harbour considerable diversity, most ecological studies still assume they are homogeneous. However, mounting evidence suggests that intraspecific diversity is not only common, but also important for interactions with community members. Here, intraspecific variation in Daphnia dentifera in haemoglobin content is shown to be a marker of hypolimnion use.2. Hypolimnion use differed substantially within and among D. dentifera populations. Daphnia dentifera with haemoglobin resided primarily in the hypolimnion, while D. dentifera lacking haemoglobin migrated vertically. These ‘deep’ and ‘migratory’D. dentifera had different seasonal phenologies and dynamics.3. Deep and migratory D. dentifera had qualitatively different relationships with an important competitor, Daphnia pulicaria. Deep D. dentifera density was negatively correlated with D. pulicaria density, whereas migratory density was not correlated with D. pulicaria density.4. Given that D. pulicaria tends to reside in the hypolimnion, this negative correlation probably reflects competition between D. pulicaria and the deep D. dentifera. This pattern would have been missed if only the relationship between the overall lake populations of D. dentifera and D. pulicaria had been studied.5. Abundances of deep D. dentifera and D. pulicaria were both correlated with the size of the hypolimnetic refuge from fish predation, but in opposite directions. Lakes with large refuges generally had high D. pulicaria and low deep D. dentifera densities.
Seasonal patterns in mortality of Daphnia in a shallow lake
1996
To assess the impact of predation by young-of-the-year (0+) fish on the population dynamics of Daphnia species, we made independent estimations of the mortality of Daphnia species during the year, and of the predation pressure exerted by the juvenile fish. Mortality of daphnids was computed using a model that allowed us to differentiate between different size-classes, while total fish consumption was estimated from the temperature-dependent daily weight increase and the population development of the 0+ fish. The predation pressure on the different size-classes of Daphnia species was estimated by combining the total fish consumption with estimates of the selective feeding behaviour of the fish. To make the estimates of fish consumption independent of our current (1989-1991) zooplankton data set, we estimated fish species-specific and fish length-dependent selectivity indices on zooplankton using a different data set (1976-1977). Daphnia population densities usually increased in spring and decreased rapidly in early summer. Predation by 0+ fish was not severe enough to explain the large mortality that caused the summer decline; later in the year most of the mortality in the larger size-classes of the daphnids (>1.0 mm) could be explained by fish predation. Resumé : Pour mesurer l'impact de la prédation par les jeunes poissons de l'année (0+) sur la dynamique des populations des espèces de Daphnia, nous avons fait des estimations indépendantes de la mortalité des espèces de Daphnia pendant l'année, et de la pression de prédation exercée par les jeunes poissons. Nous avons calculé la mortalité des daphnies à l'aide d'un modèle qui nous permettait de différencier les classes de taille, tandis que la consommation totale des poissons était estimée à partir de l'augmentation de poids quotidienne dépendant de la température et du développement de la population de poissons 0+. Nous avons estimé la pression de prédation sur les différentes classes de taille de Daphnia en combinant la consommation totale des poissons à des estimations du comportement d'alimentation sélective des poissons. Pour rendre les estimations de la consommation des poissons indépendantes de notre série présente (1989-1991) de données sur le zooplancton, nous avons calculé les indices de sélectivité à l'égard du zooplancton qui sont propres à l'espèce de poisson et dépendants de la longueur des poissons, en nous servant d'une série différente de données (1976-1977). Les densités de la population de Daphnia augmentaient généralement au printemps et baissaient rapidement au début de l'été. La prédation par les poissons 0+ n'était pas assez forte pour expliquer l'importante mortalité qui causait le déclin estival; pendant le reste de l'année, la majeure partie de la mortalité chez les plus grandes classes de taille des daphnies (>1,0 mm) pouvait s'expliquer par la prédation des poissons. [Traduit par la Rédaction]
Limnology and Oceanography, 1990
The ability of planktivorous fish to regulate the population dynamics of Daphnia gale&a in Lake Mendota, Wisconsin, was examined during spring and summer 1987. Low rates of consumption by yellow perch (Percaflavescens) and cisco (Coregonus artedii) allowed populations of D. galeata to expand rapidly during spring, resulting in a distinct clear-water period that lasted from mid-May until early June. A subsequent decline in D. guleatu abundance resulted from low food availability brought about by its exploitation of algal resources. Once populations of D. guleuta were reduced, predation by perch and cisco was sufficient to keep populations of D. g,lleata at low densities during July and August in spite of more abundant algal food resources, Extreme seasonal variation in the degree to which planktivorous fish can regulate daphnid population dynamics may have allowed daphnids to persist in Lake Mendota during the past century in the presence of abundant zooplanktivores.
An analysis of publications on Daphnia lumholtzi in freshwater ecosystems
Limnetica, 2018
An analysis of publications on Daphnia lumholtzi in freshwater ecosystems Biological invasions can threaten biodiversity worldwide through the loss of native species. Daphnia lumholtzi, Sars, 1885 is a native cladoceran from Australia, southwest Asia, and North Africa, and was recently recorded in the Neotropical region. We performed a scientometric analysis of scientific papers published between 1976 and 2016 to evaluate the studies that documented the occurrence of D. lumholtzi and assess the influence of local (temperature) and spatial factors (geographic distance) on the species distribution. Research articles were collected by the Thomson Reuters database (www.isiwebofknowledge.com) in December 2016. We observed that the number of articles increased over the years and that the species occurred in a great variety of environments, predominantly in reservoirs. Studies were performed using different approaches, most of them using descriptive and predictive designs. Furthermore, we observed that there was no significant relationship between D. lumholtzi abundance and both local (temperature) and spatial (geographic distance) factors. However, when we analyzed the occurrence of the species with temperature, we found that the species frequently occurred between 21 ºC and 27 ºC, and the greatest number of studies reported D. lumholtzi at 24 ºC. We observed a tendency for D. lumholtzi to occur in aquatic environments with higher temperatures. Therefore, we suggest experimental studies that evaluate the effect of temperature changes on the survival of this species, which could be impacted by climate change.
Water
The Water Framework Directive (WFD) is the European legislation on water policy that assesses water quality according to time-consuming metrics and specific taxonomic needs. In this sense, the objective of this study was to evaluate the sensitivity of Daphnia magna feeding rate assays to assess/discriminate the water quality of heavily modified and artificial water bodies. Monthly, for one year, the quality of the Crestuma-Lever reservoir (in two sampling sites: Crestuma and Marina) was assessed using physical, chemical, and biological (concentration of chlorophyll-a) elements proposed by the WFD. Additionally, D. magna was exposed to the collected water samples and the feeding rates were evaluated to include an ecosystem function evaluation in water quality assessment. The WFD metrics showed that, overall, the Crestuma-Lever reservoir has a rating of Good to Moderate Ecological Potential, regardless of site. Feeding rates varied with the sampling site and months, demonstrating that...
Influence of two Daphnia species on summer phytoplankton assemblages from eutrophic lakes
Journal of Plankton Research, 1997
We conducted grazing experiments to test whether larger-bodied Daphnia puticaria have a different effect from smaller-bodied Daphnia galeata mendotae on the composition of summer algal assemblages in eutrophic lakes. Three separate cubitainer experiments were run for 5 days in a replicated factorial design utilizing two algal community types and the two Daphnia species. Inorganic phosphorus and nitrogen were added to prevent nutrient limitation of the algae. Both edible and inedible size fractions of chlorophyll a increased in cubitainers without Daphnia spp. Grazer addition usually resulted in a reduction in edible chlorophyll; reductions were greater in D.pulicana cubitainers. Grazing by Daphnia spp. on presumed inedible chlorophyll was variable. Algal size was not always a good predictor of grazeability. The results of this study indicate that D.pulicaria, because of its greater filtration potential and ability to ingest larger particles, provides a stronger control on inedible-sized algae when compared to equal numerical densities of D.g.mendotae. However, Aphanizomenon increased as a response to heavy grazing pressure by D.pulicaria on other algal species. This suggests that biomanipulation efforts that promote large-bodied Daphnia may not produce desirable results if nutrient inputs remain high.