Variations In Phytoplankton Community Structure Research Articles

Fine-scale variability in phytoplankton community structure and inherent optical properties measured from an autonomous underwater vehicle

The relationship between inherent optical properties (IOPs), phytoplankton community structure and the abundance of suspended particles in the size range 3–500 μm was studied near the Isles of Scilly (UK) in May 2000. Autosub, an autonomous submersible vehicle specifically designed for science missions, was used as an instrument-positioning platform. It carried a CTD system, an ac-9+ dual tube spectrophotometer, a prototype submersible flow cytometer and an Aqua-monitor water sampler. The vehicle made a 10-km transect at constant depth across a boundary between water masses with contrasting remote sensing reflectance, which was located using SeaWiFs ocean colour imagery. This boundary corresponded to a sharp (1 km) transition between one phytoplankton community consisting of coccolithophores, flagellates and dinoflagellates, and a second community dominated by diatoms and flagellates. Inherent optical properties measured along the autonomous underwater vehicle (AUV) track showed marked changes in magnitudes, ratios, spectral shapes and fine-scale spatial variability. These changes were well correlated with variations in the composition of the suspended particle assemblage measured by microscopy and in situ flow cytometry.

Changes in phytoplankton communities following logging in the drainage basins of three boreal forest lakes in northwestern Ontario (Canada), 1991–2000

The phytoplankton communities of three small boreal forest lakes (L26, L39, and L42) on Ontario's Precambrian Shield (Canada) were investigated over 10 years for possible effects of forest harvesting (logging) within their drainage basins (5 years before logging vs. 5 years after logging). During the postlogging period, higher biovolumes of several taxa were recorded, consistent with previously reported changes in nutrients, chlorophyll, light penetration, and mixing depth. Among the most dramatic changes were increases of 100 and 266% in Cyanophyceae in L39 and L42, respectively, 167% in Dinophyceae in L26, 51 and 130% in Chlorophyceae in L26 and L42, respectively, 182% in Bacillariophyceae in L26, and 53 and 73% in total phytoplankton in L26 and L42, respectively. Other effects associated with logging in the watersheds of these lakes included an increase in the numbers of taxa (in accordance with the intermediate disturbance hypothesis) and a decrease in interannual variability in phytoplankton community structure (in accordance with the ecosystem diversity–stability hypothesis). The less extensive logging of the L26 drainage basin and the maintenance of an unlogged shoreline buffer strip did not preclude apparent effects on phytoplankton comparable with some of those found in the other two lakes, where drainage basin logging was more extensive.

Phytoplankton spatial distribution patterns along the western Antarctic Peninsula (Southern Ocean)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 261:21-39 (2003) - doi:10.3354/meps261021 Phytoplankton spatial distribution patterns along the western Antarctic Peninsula (Southern Ocean) Irene A. Garibotti1,*, María Vernet2, Martha E. Ferrario3, Raymond C. Smith4, Robin M. Ross5, Langdon B. Quetin5 1Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, CRICyT, CONICET, CC 330, 5500 Mendoza, Argentina 2Scripps Institute of Oceanography, University of California, San Diego, La Jolla, California 92093-0218, USA 3Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, 1900 La Plata, Argentina 4Institute for Computational Earth System Science and 5Marine Science Institute, University of California, Santa Barbara, California 93106, USA *Email: ireneg@lab.cricyt.edu.ar ABSTRACT: This paper describes spatial distribution patterns of the phytoplankton community (composition, cell abundance and biomass concentration) in relation to local environmental conditions in the Southern Ocean. Sampling was performed during summer 1997 off the coast of the western Antarctic Peninsula between Anvers Island and Marguerite Bay. Phytoplankton was characterized by relatively low biomass throughout most of the study area and was dominated by nanoalgae (<20 µm). Phytoplankton varied along an on-offshore gradient, with decreasing total cell abundance, chlorophyll a (chl a) concentration and carbon biomass toward the open ocean. Chl a concentration showed surface or subsurface maxima in coastal and middle-shelf waters, and deep maxima between ~40 and 100 m in oceanic waters. Across-shelf variability in phytoplankton correlated with vertical stability in the water column, which appears to be the major parameter affecting phytoplankton community structure in the area. We hypothesize that the deep chl a maximum offshore may be associated with iron limitation in near-surface waters and higher iron concentration in Œwinter waters¹ (subsurface remnant of Antarctic Surface Waters). On a smaller spatial scale, a cluster analysis showed great regional variability in phytoplankton assemblages. The area was divided into 4 main regions based on differences in the phytoplankton composition and concentration. Three peaks in phytoplankton abundance were found on a north-to-south gradient in near-shore waters: a Cryptomonas spp. bloom near Anvers Island, a small unidentified phytoflagellate bloom in Grandidier Channel, and a diatom bloom in Marguerite Bay. These assemblages resemble different stages of the phytoplankton seasonal succession, and may be related to the progressive sea-ice retreat, which might have regulated the timing of the onset of the phytoplankton seasonal succession in a north-south gradient. Biological environmental factors, such as seeding of the water column by epontic algae and selective zooplankton herbivory, are hypothesized to affect community composition in coastal regions. We conclude that large-scale variability in phytoplankton community structure is related to water column physical conditions and possibly iron availability, while mesoscale variability, as seen in coastal waters, is more likely due to seasonal succession of different algae groups. KEY WORDS: Western Antarctic Peninsula · Phytoplankton spatial variability · Seasonal progression · Environmental gradients · Palmer LTER Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 261. Online publication date: October 17, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

Spatial Variability of Phytoplankton Community Structure in Western Pacific Ocean Estimated by Phytoplankton Pigments

Spatial Variability of Phytoplankton Community Structure in Western Pacific Ocean Estimated by Phytoplankton Pigments

Seasonal variation of phytoplankton community structure and nitrogen uptake regime in the Indian Sector of the Southern Ocean

This study investigates the dynamics of phytoplankton communities and nitrogen uptake in the Indian sector of the Southern Ocean during spring and summer. The study area is oligotrophic (Chl a stocks <50 mg m−2); nevertheless, a large spatial variation of phytoplankton biomass and community structure was observed. During both seasons the phytoplankton community in the seasonal ice zone showed higher biomasses and was mainly composed of large diatom cells. However, in the permanently open ocean zone the community had low biomass and was chiefly composed of nano- and picoflagellates. In the polar front zone, although biomass was higher, the community structure was similar to the open ocean zone. The results suggest that the variation in phytoplankton community structure on a larger scale resonates with gradients in water column stability and nutrient distribution. However, significant changes in biomass and nutrient stocks but little change in community structure were observed. Absolute nitrogen uptake rates were generally low, but their seasonal variations were highly significant. During spring the communities displayed high specific nitrate uptake (mean rate = 0.0048 h−1), and diatoms (in the seasonal ice zone) as well as nano- and picoflagellates (in the permanently open ocean zone and polar front zone) were mainly based on new production (mean ƒ-ratio = 0.69). The transition to summer was accompanied by a significant reduction in nitrate uptake rate (0.0048 h−1 → 0.0011 h−1) and a shift from predominantly new to regenerated production (ƒ-ratio 0.69 → 0.39). Ammonium played a major role in the seasonal dynamics of phytoplankton nutrition. The results emphasize that, despite a large contrast in community structure, the seasonal dynamics of the nitrogen uptake regime and phytoplankton community structure in all three subsystems were similar. Additionally, this study supports our previous conclusion that the seasonal shift in nitrogen uptake regime can occur with, as well as without, marked changes in community structure.

Spatial variations of phytoplankton community structure in a highly eutrophicated coast of the Western Mediterranean Sea

Pinedo is a small beach placed at the southern side of Valencia (Eastern Spain). This coastal area has became highly eutrophicated because of the discharge of a large flow of urban wastewaters at the shore line. In order to assess the environmental impact of a new sea outfall and to study the phytoplankton and nutrients dynamics of this eutrophicated system a broad survey was conducted between May 1989 and April 1990. Physical and chemical parameters were measured through a transect laying between the wastewater discharge point and the open sea. In this paper we report preliminary results about the variations observed in the phytoplankton community along this sharp environmental gradient. Three main zones with particular phytoplankton structure appear well differentiated. The first is an inshore zone very influenced by continental loadings where brackish and polluted waters were found. Phytoplankton shows relatively low numbers being dominated by Chlorophyceae and a few other eurihaline species. An intermediate zone has salinities close to sea water but nutrient concentrations are high enough to allow maximum development of phytoplankton, which reaches its highest abundance and diversity values. Diatoms, dinoflagellates and some flagellates (Prymnesiophyceae and Cryptophyceae) dominate the eukaryotic community of this zone. Gradual impoverishment of sea water is accompanied by a rapid decrease of phytoplankton biomass, which is reduced to scarce flagellates populations at the open sea stations.

Spatial variations of phytoplankton community structure in a highly eutrophicated coast of the Western Mediterranean Sea

Pinedo is a small beach placed at the southern side of Valencia (Eastern Spain). This coastal area has became highly eutrophicated because of the discharge of a large flow of urban wastewaters at the shore line. In order to assess the environmental impact of a new sea outfall and to study the pbytoplankton and nutrients dynamics of this eutrophicated system a broad survey was conducted between May 1989 and April 1990. Physical and chemical parameters were measured through a transect laying between the wastewater discharge point and the open sea. In this paper we report preliminary results about the variations observed in the pbytoplankton community along this sharp environmental gradient Three main zones with particular pnytoplankton structure appear well differentiated. The first is an inshore zone very influenced by continental loadings where brackish and polluted waters were found. Pbytoplankton shows relatively low numbers being dominated by Chlorophyceae and a few other eurihaline species. An intermediate zone has salinities close to sea water but nutrient concentrations are high enough to allow maximum development of pbytoplankton, which reaches its highest abundance and diversity values. Diatoms, dinoflagellates and some flagellates (Prymnesiophyceae and Cryptophyceae) dominate the eukaryotic community of this zone. Gradual impoverishment of sea water is accompanied by a rapid decrease of pbytoplankton biomass, which is reduced to scarce flagellates populations at the open sea stations.

Temporal variability of phytoplankton community structure based on pigment analysis

Algal chlorophyll and carotenoid distributions were measured periodically in the euphotic zone of Sta. ALOHA (22°45'N, 158°00'W) between February 1989 and October 1991 to document the variability in phytoplankton abundance and composition. The annual mean depth‐integrated (0–200 db) concentration of Chl a displayed significant interannual variability. Seasonal patterns in Chl a concentration were found to be depth‐dependent. Elevated Chl a in the mixed layer is the result of photoadaptation as the mixed layer deepens in winter. Increases in Chl a at the deep chlorophyll maximum layer (DCML) in spring are explained by increased nutrient availability caused by a deepening of the DCML relative to the σθ = 24.25 density surface.An algorithm based on the ratios of Chl a to diagnostic pigments present in specific algal taxa was used to estimate the contribution to total Chl a by the major algal groups represented within the DCML. Results indicate the presence of a phytoplankton community at the DCML with the following mean composition: Prochlorococcus spp. (39%), cyanobacteria (24%), prymnesiophytes (22%),and chrysophytes (13%). No single taxon is responsible for the springtime increase in Chl a observed in this habitat. Results from size fractionation and normal‐phase high performance liquid chromatography confirm that Prochlorococcus spp. are the principal contributors of Chl a to the DCML.

Response of Phytoplankton in Acidic Lakes in Ontario to Whole-Lake Neutralization

Changes in phytoplankton community composition were examined in two acidic lakes in Ontario, Bowland and Trout Lakes, to determine whether neutralization (and subsequent stocking with lake trout (Salvelinus namaycush) in the case of Bowland Lake) would reverse acidic characteristics. Miskokway Lake was monitored as an untreated reference lake. Analysis of community percentage similarity showed that year-to-year variability in phytoplankton community structure would have been low in the absence of neutralization. While changes in phytoplankton biovolumes or chlorophyll a concentrations after neutralization were not significant, there were several taxonomic changes: (1) the shift in the Bowland Lake phytoplankton community away from dominance by the cyanophyte, Rhabdoderma, and (2) the dominance of the prymnesiophyte Chrysochromulina breviturrita in the Bowland Lake phytoplankton community in 1985 2 yr after neutralization. It is likely that the major phytoplankton taxonomic changes were direct responses to chemical changes. These results suggest that structural changes (taxonomic) maintained stability of the phytoplankton communities under chemical stress (in terms of standing crop).

Spatial, temporal, and storm runoff-related variations in phytoplankton community structure in a small, suburban reservoir

Phytoplankton abundance and community structure were determined routinely over an annual period and intensively during two storm-runoff events in a small suburban reservoir in northern Virginia, U.S.A. Traditional graphical techniques and a multivariate approach (Principal Components Analysis) were used to demonstrate a seasonal pattern of phytoplankton succession with greens and blue-greens dominant in summer, diatoms and chrysophytes in spring and fall, and cryptophytes in winter. Spatial variations were minor over horizontal and vertical dimensions during spring mixis, but depth variations were substantial during summer stratification. Storm runoff had little effect on phytoplankton composition during the stable summer period, but was associated with a substantial perturbation in community structure during the spring to summer transition.