Herbivory in variable environments: an experimental test of the effects of vertical mixing and Daphnia on phytoplankton community structure

2001 ◽  
Vol 58 (7) ◽  
pp. 1371-1379 ◽  
Author(s):  
Beatrix E Beisner
Keyword(s):  
Community Structure ◽  
Phytoplankton Community ◽  
Size Structure ◽  
Vertical Mixing ◽  
Community Diversity ◽  
Temporal Heterogeneity ◽  
Phytoplankton Community Structure ◽  
Phytoplankton Composition ◽  
Encounter Rates ◽  
Phytoplankton Communities

Phytoplankton communities in lakes are exposed to different within-season frequencies of heterogeneity in resource supply because of wind-induced vertical mixing. Effects of such heterogeneity, in conjunction with herbivory, on phytoplankton community structure have rarely been simultaneously examined, despite the fact that each factor can have large effects on phytoplankton composition and diversity. This study uses replicated oligotrophic mesocosms to examine the effects of herbivory and different scales of temporal heterogeneity in deepwater mixing. The pattern of vertical mixing alone had minor effects on phytoplankton community diversity and composition. The herbivore Daphnia caused a shift in phytoplankton composition to less edible types, based mainly on morphological features (spiny shapes and trichomes on cell walls) rather than size structure alone. Phytoplankton richness depended jointly on mixing frequency and large Daphnia biomasses. When systems were well mixed, with high encounter rates between predator and prey populations, phytoplankton community richness was lowest. By contrast, the systems that were least often mixed had highest richness. These results are related to limited encounter rates with infrequent mixing and to the availability of refuges from predation. Responses to different scales of temporal heterogeneity in these oligotrophic phytoplankton communities depend more on Daphnia feeding than on resource pulsing.

scholarly journals Response of ocean phytoplankton community structure to climate change over the 21st century: partitioning the effects of nutrients, temperature and light

2010 ◽  
Vol 7 (12) ◽  
pp. 3941-3959 ◽  
Author(s):  
I. Marinov ◽  
S. C. Doney ◽  
I. D. Lima
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Sea Ice ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Vertical Mixing ◽  
Phytoplankton Community Structure ◽  
Marginal Sea ◽  
Small Phytoplankton ◽  
The Impact

Abstract. The response of ocean phytoplankton community structure to climate change depends, among other factors, upon species competition for nutrients and light, as well as the increase in surface ocean temperature. We propose an analytical framework linking changes in nutrients, temperature and light with changes in phytoplankton growth rates, and we assess our theoretical considerations against model projections (1980–2100) from a global Earth System model. Our proposed "critical nutrient hypothesis" stipulates the existence of a critical nutrient threshold below (above) which a nutrient change will affect small phytoplankton biomass more (less) than diatom biomass, i.e. the phytoplankton with lower half-saturation coefficient K are influenced more strongly in low nutrient environments. This nutrient threshold broadly corresponds to 45° S and 45° N, poleward of which high vertical mixing and inefficient biology maintain higher surface nutrient concentrations and equatorward of which reduced vertical mixing and more efficient biology maintain lower surface nutrients. In the 45° S–45° N low nutrient region, decreases in limiting nutrients – associated with increased stratification under climate change – are predicted analytically to decrease more strongly the specific growth of small phytoplankton than the growth of diatoms. In high latitudes, the impact of nutrient decrease on phytoplankton biomass is more significant for diatoms than small phytoplankton, and contributes to diatom declines in the northern marginal sea ice and subpolar biomes. In the context of our model, climate driven increases in surface temperature and changes in light are predicted to have a stronger impact on small phytoplankton than on diatom biomass in all ocean domains. Our analytical predictions explain reasonably well the shifts in community structure under a modeled climate-warming scenario. Climate driven changes in nutrients, temperature and light have regionally varying and sometimes counterbalancing impacts on phytoplankton biomass and structure, with nutrients and temperature dominant in the 45° S–45° N band and light-temperature effects dominant in the marginal sea-ice and subpolar regions. As predicted, decreases in nutrients inside the 45° S–45° N "critical nutrient" band result in diatom biomass decreasing more than small phytoplankton biomass. Further stratification from global warming could result in geographical shifts in the "critical nutrient" threshold and additional changes in ecology.

scholarly journals Timing of sea ice retreat can alter phytoplankton community structure in the western Arctic Ocean

2014 ◽  
Vol 11 (7) ◽  
pp. 1705-1716 ◽  
Author(s):  
A. Fujiwara ◽  
T. Hirawake ◽  
K. Suzuki ◽  
I. Imai ◽  
S.-I. Saitoh
Keyword(s):  
Community Structure ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
Western Arctic Ocean ◽  
Phytoplankton Communities ◽  
Ice Retreat ◽  
Western Arctic ◽  
Sea Ice Retreat

Abstract. This study assesses the response of phytoplankton assemblages to recent climate change, especially with regard to the shrinking of sea ice in the northern Chukchi Sea of the western Arctic Ocean. Distribution patterns of phytoplankton groups in the late summers of 2008–2010 were analysed based on HPLC pigment signatures and, the following four major algal groups were inferred via multiple regression and cluster analyses: prasinophytes, diatoms, haptophytes and dinoflagellates. A remarkable interannual difference in the distribution pattern of the groups was found in the northern basin area. Haptophytes dominated and dispersed widely in warm surface waters in 2008, whereas prasinophytes dominated in cold water in 2009 and 2010. A difference in the onset date of sea ice retreat was evident among years–the sea ice retreat in 2008 was 1–2 months earlier than in 2009 and 2010. The spatial distribution of early sea ice retreat matched the areas in which a shift in algal community composition was observed. Steel-Dwass's multiple comparison tests were used to assess the physical, chemical and biological parameters of the four clusters. We found a statistically significant difference in temperature between the haptophyte-dominated cluster and the other clusters, suggesting that the change in the phytoplankton communities was related to the earlier sea ice retreat in 2008 and the corollary increase in sea surface temperatures. Longer periods of open water during the summer, which are expected in the future, may affect food webs and biogeochemical cycles in the western Arctic due to shifts in phytoplankton community structure.

scholarly journals Phytoplankton community structure in Menjer Lake, Central Java

2021 ◽  
Vol 869 (1) ◽  
pp. 012037
Author(s):  
F Sulawesty ◽  
G P Yoga ◽  
L Subehi ◽  
R Rosidah
Keyword(s):  
Community Structure ◽  
Phytoplankton Community ◽  
Diversity Index ◽  
Nutrient Content ◽  
Cell Counting ◽  
Phytoplankton Community Structure ◽  
Nitrogen And Phosphorus ◽  
Central Java ◽  
Phytoplankton Communities ◽  
Ecological Pressure

Abstract The occurrence of land changes around Lake Menjer, Central Java Province will affect the condition of water quality subsequently will affect biota, including phytoplankton. The purposes of study was to analyze the composition and abundance of phytoplankton in Menjer Lake regarding to nutrient content i.e. nitrogen and phosphorus. Observations on the phytoplankton community were conducted in July and October 2019 at six locations in Menjer Lake. Water samples were taken at the water surface as much as 10 L filtered using plankton net. Identification was carried out under the inverted microscope Diaphot 300. The abundance was calculated using the Sedgwick Rafter cell counting (SRCC) method. Analysis of the phytoplankton community structure was derived by calculating the Diversity Index, Evenness Index, and Simpson Dominance Index. The nutrient content in Menjer Lake influences the structure of phytoplankton communities quantitatively and qualitatively. Observation showed that the diversity of phytoplankton was low and there was one species dominanted, the result explained that the phytoplankton community in Menjer Lake is unstable and there is ecological pressure on the community. It can be concluded that the improvement of environmental conditions around Menjer Lake is the basis for the sustainable management of Menjer Lake.

Deep chlorophyll-a maximum at one station in the middle Adriatic Sea

2002 ◽  
Vol 82 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Živana Ninčević ◽  
Ivona Marasović ◽  
Grozdan Kušpilić
Keyword(s):  
Community Structure ◽  
Phytoplankton Community ◽  
Adriatic Sea ◽  
Vertical Mixing ◽  
Size Fraction ◽  
Phytoplankton Community Structure ◽  
Phytoplankton Blooms ◽  
Chemical Factors ◽  
Phytoplankton Size ◽  
Physical And Chemical

Deep or subsurface chlorophyll-a maximum (DCM) was studied at one station in the middle Adriatic from December 1996 to June 1998. Chlorophyll-a concentration, abundance, volume carbon concentration, size-fraction of phytoplankton and phytoplankton community structure were determined. In addition, physical and chemical factors as well as nutrients were determined. The DCM occurs during both the vertical mixing and stratification period in the middle Adriatic Sea. It is most frequent between 50 and 75 m. It is located below the pycnocline and it is associated with the nutricline. Phytoplankton size-fraction and community structure vary seasonally. The DCM is most pronounced during spring phytoplankton blooms with diatom dominance. Procaryotic picoplankton Synechococcus sp. was abundant in DCM during summer stratification. The DCM represents both a biomass maximum and a phytoplankton adaptation to low irradiance.

scholarly journals Pigments, elemental composition (C, N, P, Si) and stoichiometry of particulate matter, in the naturally iron fertilized region of Kerguelen in the Southern Ocean

2014 ◽  
Vol 11 (6) ◽  
pp. 8259-8324 ◽  
Author(s):  
M. Lasbleiz ◽  
K. Leblanc ◽  
S. Blain ◽  
J. Ras ◽  
V. Cornet-Barthaux ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Community Structure ◽  
Elemental Composition ◽  
Phytoplankton Community ◽  
Reference Station ◽  
Phytoplankton Community Structure ◽  
Iron Fertilization ◽  
Phytoplankton Communities ◽  
Natural Iron ◽  
Fertilization Experiments

Abstract. The particulate matter distribution and phytoplankton community structure of the iron-fertilized Kerguelen region were investigated in early austral spring (October–November 2011) during the KEOPS2 cruise. The iron-fertilized region was characterized by a complex mesoscale circulation resulting in a patchy distribution of particulate matter. Integrated concentrations over 200 m ranged from 72.2 to 317.7 mg m−2 for chlorophyll a, 314 to 744 mmol m−2 for biogenic silica (BSi), 1106 to 2268 mmol m−2 for particulate organic carbon, 215 to 436 mmol m−2 for particulate organic nitrogen, and 29.3 to 39.0 mmol m−2 for particulate organic phosphorus. Three distinct high biomass areas were identified: the coastal waters of Kerguelen Islands, the easternmost part of the study area in the Polar Front Zone, and the southeastern Kerguelen Plateau. As expected from previous artificial and natural iron-fertilization experiments, the iron-fertilized areas were characterized by the development of large diatoms revealed by BSi size–fractionation and HPLC pigment signatures, whereas the iron-limited reference area was associated to a low biomass dominated by a mixed (nanoflagellates and diatoms) phytoplankton assemblage. A major difference from previous artificial iron fertilization studies was the observation of much higher Si : C, Si : N, and Si : P ratios (respectively 0.31 ± 0.16, 1.6 ± 0.7 and 20.5 ± 7.9) in the iron-fertilized areas compared to the iron-limited reference station (respectively 0.13, 1.1, 5.8). A second difference is the patchy response of the elemental composition of phytoplankton communities to large scale natural iron fertilization. Comparison to the previous KEOPS1 cruise also allowed to address the seasonal dynamics of phytoplankton bloom over the southeastern plateau. From POC, PON, and BSi evolutions, we showed that the elemental composition of the particulate matter also varies at the seasonal scale. This temporal evolution followed changes of the phytoplankton community structure as well as major changes in the nutrient stocks progressively leading to silicic acid exhaustion at the end of the productive season. Our observations suggest that the specific response of phytoplankton communities under natural iron fertilization is much more diverse than what has been regularly observed in artificial iron fertilization experiments and that the elemental composition of the bulk particulate matter reflects phytoplankton taxonomic structure rather than being a direct consequence of iron availability.

scholarly journals Impact of the 2009 extreme water level variation on phytoplankton community structure in Lower Amazon floodplain lakes

2012 ◽  
Vol 23 (3) ◽  
pp. 260-270 ◽  
Author(s):  
Simone Casali ◽  
Maria do Carmo Calijuri ◽  
Bernard Barbarisi ◽  
Vivian Fróes Renó ◽  
Adriana Gomes Affonso ◽  
...  
Keyword(s):  
Community Structure ◽  
Water Level ◽  
Phytoplankton Community ◽  
Diversity Index ◽  
Water Level Fluctuations ◽  
Phytoplankton Community Structure ◽  
Extreme Water Level ◽  
Hydrological Conditions ◽  
Amazon Floodplain ◽  
Phytoplankton Communities

AIM: This paper examines the effect of the extreme water level change in 2009 on the structure and diversity of the phytoplankton communities in lakes of the Lower Amazon Floodplain, and compares it to phytoplankton community structure data reported in the literature for 2002 and 2003 high water periods, closer to the normal hydrological conditions. METHODS: Sub-surface integrated water samples for phytoplankton and chlorophyll-a analyses were collected during high and low water phases in 2009. Water temperature (°C), pH, turbidity (NTU) and electrical conductivity (µS.m-1) were measured, and the Shannon diversity index was calculated. RESULTS: The results showed striking differences in taxonomic composition between phases (high and low) and also between normal (2002 and 2003) and extreme (2009) hydrological conditions, all related to the flood pulse intensity. CONCLUSIONS: Extreme water level fluctuations can result in shifts in phytoplankton community structure and diversity. This work represents a valuable contribution to phytoplankton research since presents the community structure under extreme hydrological events in the Amazon floodplain.

scholarly journals Variation of phytoplankton community structure in Quang Ngai coastal waters during 2015–2019

2021 ◽  
Vol 20 (4A) ◽  
pp. 21-33
Author(s):  
Huynh Thi Ngoc Duyen ◽  
Tran Thi Minh Hue ◽  
Tran Thi Le Van ◽  
Phan Tan Luom ◽  
Nguyen Ngoc Lam ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Impacts ◽  
Coastal Waters ◽  
Phytoplankton Community ◽  
Environmental Changes ◽  
Diversity Indices ◽  
Species Number ◽  
Phytoplankton Community Structure ◽  
Phytoplankton Diversity ◽  
Phytoplankton Communities

Phytoplankton in coastal waters are important for the evaluation of either biodiversity or environmental impacts because of this highly vulnerable ecosystem. Seasonal and annual changes in the phytoplankton community structure in Quang Ngai waters during the period 2015 to 2019 were analyzed to assess the phytoplankton diversity and reveal possible causes of these changes. A total of 366 phytoplankton taxa belonging to 10 classes were identified throughout this present study. The highest species number was found in 2019 with 295 taxa, followed by those in 2015 (247), 2017 (185), and 2018 (99). The waters of Ly Son transect showed the highest diversity and most stable phytoplankton communities in both dry and rainy seasons, whereas the stations of Quang Ngai coast revealed high variability of the communities. All diversity indices including Margalef, Pielou, Shannon, Simpson did not reflect well differences in average values but a certain degree of variances, indicating possible environmental impacts. During the study time, there were blooms of certain diatom species including Skeletonema spp. in 2015 and Pseudo-nitzschia spp. in 2019. Analysis of a diatoms index, Centric/Pennate ratio, indicated that the waters were in eutrophic status with a decreasing trend from the coast area to Ly Son island in 2015 and 2019. This research built up fundamental data on phytoplankton communities for Quang Ngai province. The Centric/Pennate diatom index and diversity would be used as indicators for environmental changes and their values provided warning of eutrophication in this coastal waters including the water surrounding Ly Son island.

scholarly journals Timing of sea ice retreat can alter phytoplankton community structure in the western Arctic Ocean

2013 ◽  
Vol 10 (9) ◽  
pp. 15153-15180 ◽  
Author(s):  
A. Fujiwara ◽  
T. Hirawake ◽  
K. Suzuki ◽  
I. Imai ◽  
S.-I. Saitoh
Keyword(s):  
Community Structure ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
Western Arctic Ocean ◽  
Phytoplankton Communities ◽  
Ice Retreat ◽  
Western Arctic ◽  
Sea Ice Retreat

Abstract. This study assesses the response of phytoplankton assemblages to recent climate change, especially with regard to the shrinking of sea ice in the northern Chukchi Sea of the western Arctic Ocean. Distribution patterns of phytoplankton groups in the late summers of 2008–2010 were analyzed based on HPLC pigment signatures and, the following four major algal groups were inferred via multiple regression and cluster analyses: prasinophytes, diatoms, haptophytes and dinoflagellates. A remarkable interannual difference in the distribution pattern of the groups was found in the northern basin area. Haptophytes dominated and dispersed widely in warm surface waters in 2008, whereas prasinophytes dominated in cold water in 2009 and 2010. A difference in the onset date of sea ice retreat was evident among years – the sea ice retreat in 2008 was 1–2 months earlier than in 2009 and 2010. The spatial distribution of early sea ice retreat matched the areas in which a shift in algal community composition was observed. Steel-Dwass's multiple comparison tests were used to assess the physical, chemical and biological parameters of the four clusters. We found a statistically significant difference in temperature between the haptophyte-dominated cluster and the other clusters, suggesting that the change in the phytoplankton communities was related to the earlier sea ice retreat in 2008 and the corollary increase in sea surface temperatures. Longer periods of open water during the summer, which are expected in the future, may affect food webs and biogeochemical cycles in the western Arctic due to shifts in phytoplankton community structure.

Temporal Distribution Patterns of Phytoplankton Community Structure in a Large Shallow Lake, Lake Taihu, China

2014 ◽  
Vol 955-959 ◽  
pp. 1363-1367 ◽  
Author(s):  
Rui Ye ◽  
Xin Qian ◽  
Kun Shan ◽  
Hai Long Gao
Keyword(s):  
Community Structure ◽  
Shallow Lake ◽  
Phytoplankton Community ◽  
Lake Taihu ◽  
Cyanobacterial Bloom ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Phytoplankton Community Structure ◽  
Monthly Basis ◽  
Phytoplankton Communities

Temporal distribution phytoplankton community structure in a shallow lake, Lake Taihu, China, was investigated from 2010 to 2011 on a monthly basis at 9 sampling stations. The results showed that phytoplankton communities primarily consist of cyanobacteria, chlorophyta and bacillariophyta in Lake Taihu. A significant change in phytoplankton community was observed in both years: cyanobacteria hold an overwhelming dominance in summer and autumn, chloraphyta and bacillariophyta occupied the certain proportion only when the cyanobacterial bloom was declined in winter and early spring. The maximum abundance value of cyanobacteria, chlorophyta and bacillariophyta appeared at June, 2010, July, 2011 and Feb, 2011, respectively. The present study is a continuation and complement in long-term research of Lake Taihu, which provides scientific foundation for further research of the lake.

scholarly journals Response of ocean phytoplankton community structure to climate change over the 21st century: partitioning the effects of nutrients, temperature and light

2010 ◽  
Vol 7 (3) ◽  
pp. 4565-4606 ◽  
Author(s):  
I. Marinov ◽  
S. C. Doney ◽  
I. D. Lima
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Vertical Mixing ◽  
Lower Surface ◽  
Nutrient Concentrations ◽  
Phytoplankton Community Structure ◽  
Small Phytoplankton ◽  
The Impact

Abstract. The response of ocean phytoplankton community structure to climate change depends upon species competition for nutrients and light, as well as the increase in surface ocean temperature. We propose an analytical framework linking changes in nutrients, temperature and light with changes in phytoplankton growth rates, and we assess our theoretical considerations against model projections (1980–2100) from a global Earth System model. Our proposed ''critical nutrient theory'' suggests that there is a critical nutrient threshold below (above) which a nutrient change will affect more (less) small phytoplankton biomass than diatom biomass, i.e. the phytoplankton with lower half-saturation coefficient K are influenced more strongly in low nutrient environments. This nutrient threshold broadly corresponds to 45° S and 45° N, poleward of which high vertical mixing and inefficient biology maintain higher surface nutrient concentrations and equatorward of which reduced vertical mixing and more efficient biology maintain lower surface nutrients. In the 45° S–45° N low nutrient region, decreases in limiting nutrients – associated with increased stratification under climate change – are predicted analytically to limit more strongly the net growth of small phytoplankton than the growth of diatoms. In high latitudes, the impact of nutrient decrease on phytoplankton biomass is more significant for diatom biomass than for small phytoplankton biomass, and contributes to diatom declines in the northern marginal sea ice and subpolar biomes. Climate driven increases in surface temperature and changes in light are predicted to have a stronger impact on small phytoplankton than on diatom biomass in all ocean domains. Our analytical predictions explain reasonably well the shifts in community structure under a modeled climate-warming scenario. Further stratification from global warming could result in geographical shifts in the ''critical nutrient'' threshold and additional changes in ecology.

Sign in / Sign up

Export Citation Format

Share Document