Phytoplankton Succession and Primary Production in Babine Lake, British Columbia

1975 ◽  
Vol 32 (12) ◽  
pp. 2413-2427 ◽  
Author(s):  
John G. Stockner ◽  
K. R. S. Shortreed
Keyword(s):  
Primary Production ◽  
Sockeye Salmon ◽  
Mixed Layer Depth ◽  
Carbon Assimilation ◽  
Annual Production ◽  
Phosphate Limitation ◽  
The South ◽  
South Basin ◽  
The North ◽  
Principal Factors

Ten stations located in six zones (subbasins) were sampled biweekly from May to October 1973 to detect possible regional differences in production in this large, 155 km long, dystrophic lake. The spring bloom occurred in all zones while a fall bloom occurred only in Zones 5 and 6. Carbon assimilation showed two peaks in south basin zones, but only one (spring) at zones north of Topley Landing. Seasonal variation in phytoplankton numbers and volume, seston, and chlorophyll a followed a pattern similar to that noted for primary production. Mean production was 100 mg C∙m−2∙day−1 in Zones 1–4, but was 145 in Zones 5 and 6. Annual production was estimated at 25 g C∙m−2 in the north basin and 40 in the south basin. Reasons for the regional disparities are discussed, with greatest significance given to regional variations in mixed layer depth, surface inflows (loading), and basin mean depth. The development and sustainment of the autumnal bloom of Tabellaria fenestrata is thought to be one of the principal factors responsible for greater production in the south basin.An estimated 0.05 g TP∙m−2 enters the lake yearly. This can vary depending on the return of adult sockeye salmon (Oncorhynchus nerka), whose carcasses contribute up to 20% of the total. An estimated 30% is lost via the Babine River, and it is speculated that of the remaining 70%, most is lost to the sediments. Phosphate limitation is implied as a chief factor limiting primary production in the north basin stations, but not in the south basin. On the basis of total phosphorus load the lake is classed as oligotrophic, but in terms of annual production and its humic stained waters it is more correctly considered mixotrophic.

Production of Chironomus, Procladius, and Chaoborus at Different Levels of Phytoplankton Biomass in Lake Memphremagog, Quebec–Vermont

1977 ◽  
Vol 34 (11) ◽  
pp. 2001-2007 ◽  
Author(s):  
R. M. Dermott ◽  
J. Kalff ◽  
W. C. Leggett ◽  
J. Spence
Keyword(s):  
Phytoplankton Biomass ◽  
Standing Stock ◽  
Dry Weight ◽  
Annual Production ◽  
The South ◽  
Algal Production ◽  
The North ◽  
Chaoborus Punctipennis ◽  
The Mean ◽  
Different Levels

In Lake Memphremagog a north–south gradient in algal production and biomass exists during the ice-free period, with highest production in the southern areas. In response, the mean annual benthic standing stock (dry weight) in the south basin was 2.8 times greater than in the north basin at comparable depth. Mean annual standing stock of Procladius denticulatus and Chironomus anthracinus were significantly (5.8 and 3.1 times, respectively) higher in the south, while that of Chaoborus punctipennus did not differ significantly between areas. Annual production of P. denticulatus was greater in the south (0.861 g/m2) than in the north (0.143 g/m2). Similarly for Chironomus anthracinus annual production was greater in the south (3.393 g/m2) than in the north (1.264 g/m2). Production of Chaoborus punctipennis was greater in the north (0.066 g/m2) than in the south (0.348 g/m2). P:B ratios were less variable. Key words: Lake Memphremagog, benthos, production, nutrient gradient, mortality

Growth rate and condition of walleye (Sander vitreus), sauger (Sander canadensis), and dwarf walleye in a large Canadian lake

2018 ◽  
Vol 96 (7) ◽  
pp. 739-747 ◽  
Author(s):  
K.T. Sheppard ◽  
B.J. Hann ◽  
G.K. Davoren
Keyword(s):  
Dreissena Polymorpha ◽  
Sander Vitreus ◽  
Osmerus Mordax ◽  
Bythotrephes Longimanus ◽  
The South ◽  
Rainbow Smelt ◽  
Lake Winnipeg ◽  
South Basin ◽  
The North ◽  
North And South

The second largest inland walleye (Sander vitreus (Mitchill, 1818)) and sauger (Sander canadensis (Griffith and Smith, 1834)) fishery in Canada is found in Lake Winnipeg, Manitoba. To manage the fishery for a sustainable future, the growth and condition of these fish must be understood. Objectives were to (1) examine baseline growth and condition of walleye and sauger in Lake Winnipeg, (2) evaluate variation between the North and South basins, and (3) contribute observational findings on the distribution of dwarf walleye. Gill nets were set to catch walleye, sauger, and dwarf walleye throughout both basins at various locations and in all seasons during 2010 and 2011. North Basin walleye and sauger had higher growth rates and condition relative to the South Basin. This may be due to differential exploitation rates or diets such as the consumption of invasive rainbow smelt (Osmerus mordax (Mitchell, 1814)) in the North Basin and not in the South Basin. Dwarf walleye were observed more frequently in the South Basin than in the North Basin. Overall, this study provides important baseline data on the growth and condition of walleye and sauger populations prior to invasion of the spiny waterflea (Bythotrephes longimanus Leydig, 1860) and zebra mussels (Dreissena polymorpha (Pallas, 1771)).

The ecological impact of the sea urchin Paracentrotus lividus (Lamarck) in Lough Ine, Ireland

1983 ◽  
Vol 300 (1101) ◽  
pp. 513-552 ◽  
Keyword(s):  
Sea Urchin ◽  
Animal Species ◽  
Paracentrotus Lividus ◽  
Coralline Algae ◽  
Diurnal Fluctuation ◽  
Tide Pool ◽  
Crustose Coralline Algae ◽  
The South ◽  
South Basin ◽  
The North

An ecological account is given of the rocky shallow sublittoral of Lough Ine, County Cork, Republic of Ireland, from low water level to about 1 m below this level. With increasing distance from the Rapids mouth a forest of laminarian algae gives way to low algal bush, and still further into the lough the sea urchin Paracentrotus lividus destroys all soft upstanding algae. Much of the grazed area becomes overgrown by crustose coralline algae. Patches of the green algae Codium fragile ssp. tomentosoides and Enteromorpha clathrata fringe the Paracentrotus graze patches. An account is given of the effects of Paracentrotus on the shallow sublittoral community. Algae in the ungrazed areas accommodate large numbers of individuals and many species of invertebrates, especially amphipods, small gastropods and small polychaetes. In grazing, Paracentrotus destroys this population and its habitat. However, the removal of these algae, and of the sediment that they trap, provides a new habitat, suitable for plant and animal species that can resist Paracentrotus . Crustose coralline algae cover much of the rock, and are burrowed into or enclose the tubes of a characteristic and entirely different polychaete fauna. On the surface of the rocks are found saddle oysters ( Anomia ephippium ), limpets ( Patella aspera ) and other hard- shelled animal species. The relations between Codium and Paracentrotus have been investigated by transfer experiments in the ‘field’ and by observations with an aquarium tank. Paracentrotus readily eats Codium , especially when the urchins are at a high population density; but Codium benefits from the clearance of other algae, and is a quick recolonist, so that on balance it benefits from the presence of the urchin. Paracentrotus feeds mainly by day, and on a steep shore some wander up into the littoral region as the tide rises and destroy Fucus serratus . This accounts for the almost complete absence of F. serratus from the North Basin. Paracentrotus does not move upwards by night. The hard-shelled animal species Anomia, Patella, Chlamys varia , adult Gibbula cineraria and Pomatoceros , found plentifully on graze patches in the North Basin, diminish in abundance southwards even within grazed areas, while the numbers of the starfish Marthasterias glacialis under the rocks increase. Experiments show that Marthasterias readily eats Anomia . These Marthasterias are quite small. As they grow bigger they move away onto muddy areas and extend their diet to include large buried lamellibranchs. Small Paracentrotus are usually found in larger numbers underneath boulders than above, while larger ones tend to come up by day onto the tops, where they form graze patches. From a study of growth lines in the interambulacral plates and from growth in cages we conclude that a horizontal diameter of 30-40 mm (with considerable variation) is reached in 3-4 years from settlement. The peak in numbers of Paracentrotus visible in the South Basin in 1979 might perhaps be ascribed to a good settlement in the warm summers of 1975 and 1976. Temperature of the shallow marginal water of the lough is subject to diurnal fluctuation, as in a tide pool, and can reach high levels in summer. This might favour Paracentrotus . However, numbers of Paracentrotus are probably severely reduced by predators in the South Basin. Crabs have already been implicated. It is possible that the small or half grown Marthasterias under shallow sublittoral rocks might destroy newly settled Paracentrotus , although this still has to be demonstrated.

scholarly journals Phosphate availability and the ultimate control of new nitrogen input by nitrogen fixation in the tropical Pacific Ocean

2007 ◽  
Vol 4 (4) ◽  
pp. 2407-2440 ◽  
Author(s):  
T. Moutin ◽  
D. M. Karl ◽  
S. Duhamel ◽  
P. Rimmelin ◽  
P. Raimbault ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
N2 Fixation ◽  
Cold Water ◽  
Austral Summer ◽  
Deep Ocean ◽  
South Pacific ◽  
Phosphate Limitation ◽  
The South ◽  
Carbon Export ◽  
The North

Abstract. Due to the low atmospheric input of phosphate into the open ocean, it is one of the key nutrients that could ultimately control primary production and carbon export into the deep ocean. The observed trend over the last 20 years, has shown a decrease in the dissolved inorganic phosphate (DIP) pool in the North Pacific gyre, which has been correlated to the increase in di-nitrogen (N2) fixation rates. Following a NW-SE transect, in the Southeast Pacific during the early austral summer (BIOSOPE cruise), we present data on DIP, dissolved organic phosphate (DOP), and particulate phosphate (PP) pools and DIP turnover times (TDIP) along with N2 fixation rates. We observed a decrease in DIP concentration from the edges to the centre of the gyre. Nevertheless the DIP concentrations remained above 100 nmol L−1 and TDIP were more than a month in the centre of the gyre: DIP availability remained largely above the level required for phosphate limitation. This contrasts with recent observations in the western Pacific Ocean at the same latitude (DIAPALIS cruises) where lower DIP concentrations (<20 nmol L−1) and TDIP<50 h were measured during the summer season. During the BIOSOPE cruise, N2 fixation rates were higher within the cold water upwelling near the Chilean coast. This observation contrasts with recently obtained model output for N2 fixation distribution in the South Pacific area and emphasises the importance of studying the main factors controlling this process. The South Pacific gyre can be considered a High P Low Chlorophyll (HPLC) oligotrophic area, which could potentially support high N2 fixation rates, and possibly carbon dioxide sequestration, if the primary ecophysiological controls, temperature and/or iron availability, were alleviated.

scholarly journals Water column stability as an important factor controlling nitrite-dependent anaerobic methane oxidation in stratified lake basins

2021 ◽  
Author(s):  
Guangyi Su ◽  
Moritz Lehmann ◽  
Jana Tischer ◽  
Yuki Weber ◽  
Jean-Claude Walser ◽  
...  
Keyword(s):  
Water Column ◽  
Electron Acceptor ◽  
Nitrite Reduction ◽  
Redox Conditions ◽  
Series Data ◽  
Anaerobic Oxidation Of Methane ◽  
The South ◽  
South Basin ◽  
Water Column Stability ◽  
The North

Anaerobic oxidation of methane (AOM) with nitrate/nitrite as the terminal electron acceptor may play an important role in mitigating methane emissions from lacustrine environments to the atmosphere. We investigated AOM in the water column of two connected but hydrodynamically contrasting basins of a south-alpine lake in Switzerland (Lake Lugano). The North Basin is permanently stratified with year-round anoxic conditions below 120 m water depth, while the South Basin undergoes seasonal stratification with the development of bottom water anoxia during summer. We show that below the redoxcline of the North Basin a substantial fraction of methane was oxidized coupled to nitrite reduction by Candidatus Methylomirabilis. Incubation experiments with 14CH4 and concentrated biomass from showed at least 43-52%-enhanced AOM rates with added nitrate/nitrite as electron acceptor. Multiannual time series data on the population dynamics of Candidatus Methylomirabilis in the North Basin following an exceptional mixing event in 2005/2006 revealed their requirement for lasting stable low redox-conditions to establish. In the South Basin, on the other hand, we did not find molecular evidence for nitrite-dependent methane oxidizing bacteria. Our data suggest that here the dynamic mixing regime with fluctuating redox conditions is not conducive to the development of a stable population of relatively slow-growing Candidatus Methylomirabilis, despite a hydrochemical framework that seems more favorable for nitrite-dependent AOM than in the North Basin. We predict that the importance of N-dependent AOM in freshwater lakes will likely increase in future because of longer thermal stratification periods and reduced mixing caused by global warming.

“Guns Plus Interest”

2019 ◽  
pp. 64-96
Author(s):  
Yelena Biberman
Keyword(s):  
Balance Of Power ◽  
The State ◽  
Local Power ◽  
Kashmir Valley ◽  
The South ◽  
Jammu And Kashmir ◽  
Security Forces ◽  
The North ◽  
Principal Factors ◽  
Defense Committees

This chapter shows that the principal factors driving the state-nonstate alliances in Kashmir (1989–2003) were the local balance of power and actors’ interests. It was only when the Indian army demonstrated force employment prowess through a string of military victories that it was able to attract opportunists. These were former rebels seeking local power, profit, and security. The proxies—most notably the Ikhwan-ul-Muslimoon in the north, as well as the Jammu and Kashmir Ikhwan and Muslim Mujahideen in the south of the Kashmir Valley—helped to shift the balance of power in India’s favor. This prompted the insurgency to move to the mountainous Jammu region. There, the security forces turned to local activists. These, mostly Hindu, villagers formed the so-called Village Defense Committees.

High resolution sediment microfabric and geochemical analysis reveals seasonal scale redox mineralisation, anthropogenic environmental change and pollution in England's largest natural lake - Windermere

2020 ◽  
Author(s):  
James Fielding ◽  
Alan Kemp ◽  
Ian Croudace ◽  
Peter Langdon ◽  
Richard Pearce ◽  
...  
Keyword(s):  
Toxic Elements ◽  
Slope Failure ◽  
Sediment Quality ◽  
Quality Standards ◽  
Potentially Toxic Elements ◽  
The South ◽  
South Basin ◽  
The North ◽  
Natural Lake ◽  
Sediment Anoxia

&lt;p&gt;Many lakes in industrialised areas have undergone anthropogenically driven eutrophication and increases in pollution leading to decreased water and sediment quality. In some cases, these effects are enhanced by seasonally changing lake redox conditions that may act to concentrate potentially toxic elements sufficiently to exceed internationally recognised Sediment Quality Standards, impacting key species and jeopardizing water supply.&amp;#160; A combined, geochemical and sediment microfabric analysis is applied to reconstruct the history of cultural eutrophication and pollution in the North and South Basins of Windermere, England&amp;#8217;s largest natural lake. We also document a record of seismicity and link increased sedimentation rates and sediment instability. The onset and development of eutrophication in Windermere occurred from the mid-19th to the early 20th centuries.&amp;#160; Raised lake productivity is indicated by an increase in sedimentary &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C, and increased pollution by elevated sedimentary trace metals (Pb, Zn, Cu, Hg, and As), likely enhanced by incorporation and adsorption to settling diatom aggregates, preserved as sedimentary laminae. In the South Basin of the lake, contemporaneous increasing sediment &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N values also occur in step with increasing Zn, Hg, Cu from this time, linking metal enrichment to the input of isotopically heavy nitrate (N) from anthropogenic sources including sewage. From around 1930, a decrease in Mn and Fe-rich laminae indicate reduced deep water ventilation, and increased incidence of sediment anoxia, being most intense in the deeper North Basin where benthic activity intermittently ceased. Strongly reducing conditions in the sediment promoted Fe and Mn reduction and the formation of unusual Pb-bearing barite, hitherto only described from toxic mine wastes and contaminated soils. In the North Basin cores a clay rich laminae dated 1979-1980 is shown to be a mass transport deposit linked to large scale slope failure likely caused by the 4.7 ML 1979 Carlisle earthquake. Slope failure was exacerbated by preconditioning principally by increased sedimentation as a result of anthropogenic activities. From 1980 there was a partial recovery in oxygenation with Mn and Fe rich laminae returning in some parts. But in the South Basin, the continued impacts of sewage discharge is indicated by elevated &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N of organic matter. Imaging and X-ray microanalysis using scanning electron microscopy has enabled the identification of seasonal-scale redox mineralisation of Mn, Fe and Ba related to intermittent sediment anoxia. Elevated concentrations of Mn, Fe, Ba, and As also occur in the surficial sediment and provide evidence for dynamic redox mobilisation of potentially toxic elements that may be released to the lake waters. Concentrations of As, in particular, exceed international Sediment Quality Standards. These surface enrichments in As and other toxic elements may become more prevalent in the future with climate change driving lengthened summer stratification in the lake.&lt;/p&gt;

phytoplankton Communities of Lakes Experimentally Acidified with Sulfuric and Nitric Acids

1990 ◽  
Vol 47 (7) ◽  
pp. 1378-1386 ◽  
Author(s):  
D. L. Findlay ◽  
S. E. M. Kasian
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Species Diversity ◽  
Species Composition ◽  
Phytoplankton Species ◽  
The South ◽  
South Basin ◽  
The North ◽  
Late Fall ◽  
Phytoplankton Communities

Additions of sulfuric acid to the South Basin and nitric acid to the North Basin of Lake 302 caused major changes in the phytoplankton communities. The basins were separated by a nylon-reinforced vinyl sea curtain. In the South Basin, below pH 5.6, species composition shifted from chrysophycean dominance to one of Dinophyceae. Diatoms and cyanophytes were eliminated below pH 5.3. Phytoplankton species diversity decreased as pH decreased. Total epilimnetic biomass was unchanged, except in late fall, when entrainment of dense layers of hypolimnetic species caused increases. The assemblage in the North Basin changed immediately upon additions of HNO3 to resemble systems experimentally fertilized with nitrogen. Chrysophycean dominance gave way to chlorophytes and dinoflagellates. Once pH decreased below 6.0, diatoms and cyanophytes were eliminated from the assemblage, as in the South Basin. Phytoplankton species diversity decreased, but total epilimnetic biomass remained unaffected.

scholarly journals Ecophysiological response and morphological adjustment of Argania spinosa L. Skeels under contrasting climates: case study of marginal populations

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohamed Ait Bihi ◽  
Fatima Ain-Lhout ◽  
Abdelhakim Hatimi ◽  
Fadma Fahmi ◽  
Saida Tahrouch
Keyword(s):  
Stomatal Density ◽  
Photochemical Efficiency ◽  
Carbon Assimilation ◽  
Distribution Area ◽  
Summer Drought ◽  
The South ◽  
Marginal Populations ◽  
Southern Limit ◽  
Argania Spinosa ◽  
The North

In this paper, we investigated the seasonal physiological performance and morphological adjustment of Argania spinosa growing under contrasting climatic and biogeographic conditions.Two marginal populations were selected in the main distribution area of the species, one at the Northwest and the other one at the South-west. Trees from the North showed a Mediterranean pattern in Photosynthetic performances, exhibiting maximal carbon assimilation during spring and minimum in summer. In contrast, trees from the South showed a different pattern with maximum values recorded in winter and minimum in spring. Photochemical efficiency of PSII results evidenced the absence of damage to PSII in both sites, probably due to an efficient energy dissipation processed by carotenoid pigments. We recorded increased LMA values in the South, which improves drought resistance. Increasing stomatal length and decreasing stomatal density were registered during the drought season in both populations. A. Spinosa is sensitive to changes in the length of drought stress at its Southern limit. The scarcity of rainfall leading to persistent drought has limited the distribution of the species to the banks of dry Wadis and depressions, where it finds some water compensations during summer. In the North, the summer drought severely impacted the species carbon assimilation.

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