Lubomira Burchardt

Assessment and significance of phytoplankton species composition within Chesapeake Bay and Virginia tributaries through a long-term monitoring program

Phytoplankton and water quality long term trends are presented from a 20-year monitoring program of Chesapeake Bay and several of its major tributaries. Increasing phytoplankton biomass and abundance are ongoing within this estuarine complex, with diatoms the dominant component, along with chlorophytes and cyanobacteria as sub-dominant contributors in the tidal freshwater and oligohaline regions. Diatoms, dinoflagellates, and cryptomonads are among the major flora downstream in the tributaries and within the Chesapeake Bay. Water quality conditions within the three tributaries have remained rather stable over this time period; while there are long term trends of reduced nutrients, increasing bottom oxygen, and decreasing water clarity for the lower Chesapeake Bay. Of note is an increasing trend of cyanobacteria biomass at 12 of the 13 stations monitored at tributary and Chesapeake Bay stations, plus the presence of 37 potentially harmful taxa reported for these waters. However, the overall status of the phytoplankton populations is presently favorable, in that it is mainly represented and dominated by taxa suitable as a major food and oxygen source within this ecosystem. Although potentially harmful taxa are present, they have not at this time exerted profound impact to the region, or replaced the diatom populations in overall dominance.

Neuston : Its definition with a historical review regarding its concept and community structure

Since NAUMANN (1917) introduced the term neuston, various criteria and descriptions have been used to identify the habitat and its populations. Dissimilar methods of collection protocols have contributed to these different interpretations. To more fully identify the restricted ecological niche occupied by this unique community, papers from the original and more recent freshwater and marine neuston studies are discussed along with the common sampling methods for neuston. Characteristics of the neuston habitat are also presented, with definitions for neuston, epineuston, and hyponeuston. Attachment to the surface layer by its floral or faunal populations is not considered a requirement, and the neuston community includes organisms that move directly on or below the water surface. The depth of the neuston (hyponeuston) community below the waters surface can be determined by noting statistically significant changes within the populations with increasing depth below the surface layer. This depth would be expected to change diurnally and seasonally, and also to differ between freshwater and marine habitats. The horizontal patchiness of the neuston should also be anticipated and resolved through an adequate sampling protocol.

Phytoplankton Composition Within the Tidal Freshwater-Oligohaline Regions of the Rappahannock and Pamunkey Rivers in Virginia

Abstract The Rappahannock River is a major river system across north central Virginia prior to entering the Chesapeake Bay. In contrast, the Pamunkey River is smaller in size and joins the Mattoponi River to form the York River, which flows parallel to the Rappahannock before it also flows into Chesapeake Bay. A unique mixing area for both flora and environmental conditions exists in the tidal freshwater-oligohaline region of both rivers. This is a dynamic mixing section where freshwater and estuarine species are subject to the interaction of river flow and daily tidal rhythms. The phytoplankton composition in this region of the two rivers was identified over a 13.5-year period (July 1986–December 1999). The results indicated freshwater and estuarine populations forming a diverse assemblage of 268 taxa, with diatoms, chlorophytes, and cyanoprokaryotes the dominant flora. Phytoplankton in this region were predominantly freshwater taxa (e.g., >70%), with a diverse diatom assemblage representing >90% of the estuarine flora at these sites.

Habitat requirements of the Charetum intermediae phytocoenoses in lakes of western Poland

The study presents habitat and phytosociological analyses of the Chara intermedia phytocenoses, rare described in Europe. 16 physico-chemical water parameters were analysed, coming from the samples taken in 20 phytocenoses of 13 lakes located in western Poland. The analysed community appeared in naturally shallow lakes representing last stages of the disappearance of glacial water basins. The study attempts to estimate the bioindicative value of the charophyta meadow Charetum intermediae in relation to its habitat. A particular attention has been paid to the determination of the habitat trophic condition, and to the concentration of elements connected with the hardness of water and the content of humic substances. The study shows crucial habitat gradients of the C. intermediae association, taking into account also the species composition of phytocenoses.

Interrelationships between macrophytes (including charophytes) and phytoplankton and the ecological state of lakes

Abstract Multidisciplinary investigations of 30 lakes (mid-Western Poland) were carried out in the years 2001–2004. Micro- and macrophyte vegetation was studied against the background of abiotic conditions. Significantly higher biomass of phytoplankton was found in nutrient rich shallow lakes without both charophyte and vascular submersed vegetation as well as in lakes with only poorly developed vascular communities. Visibly better abiotic conditions and the lowest phytoplankton biomass were observed in deeper lakes with diverse macrophyte (and particularly charophyte) vegetation. Lakes with poorly developed charophyte vegetation represented transitional conditions and biomass. Nevertheless, in some (mostly shallow) lakes, where submersed vegetation and particularly charophyte communities were well developed, phytoplankton biomass was rather low and the transparency was high despite eutrophic conditions. Additionally, in those lakes macrophyte vegetation was not only abundant but also diverse with rare, valuable or even unexpected communities of high bioindicator value. Interestingly, an opposing situation with abundant phytoplankton and bad light conditions was also documented in shallow lakes with submersed vegetation. In those lakes, however, only vascular macrophytes developed dense but homogeneous (monospecific) beds. The results are discussed regarding interrelationships between macrophyte vegetation and phytoplankton assemblages.

Spring phytoplankton and periphyton composition: case study from a thermally abnormal lakes in Western Poland.

Abstract Getting to know the response of different groups of aquatic organisms tested in altered thermal environments to environmental conditions makes it possible to understand processes of adaptation and limitation factors such as temperature and light. Field sites were located in three thermally abnormal lakes (cooling system of power plants), in eastern part of Wielkopolska region (western Poland): Pątnowskie, Wąsosko-Mikorzyńskie and Licheńskie. Water temperatures of these lakes do not fall below 10°C throughout the year, and the surface water temperature in spring is about 20˚C. In this study, we investigated the species structure of the spring phytoplankton community in a temperature gradient and analyzed diversity of periphyton collected from alien species (Vallisneria spiralis) and stones. 94 taxa belonging to 56 genera of algae (including phytoplankton and periphyton) were determined. The highest number of algae species were observed among Chlorophyta (49), Bacillariophyceae (34) and Cyanobacteria (6). In spite of important differences in temperature in the investigated lakes, taxonomic composition of phytoplankton was comparable. Thermophilic species: Glochidinium penardiforme and Cylindrospermopsis raciborskii were found in the species structure (blooms were not observed). The obtained data also showed that the biotic surface of Vallisneria spiralis was a better substrate for Bacillariophyceae colonization than stones. The examination in the spring season of these thermally altered lakes, indicated the taxonomic composition of phytoplankton typical for eutrophic reservoirs (not heated). There was no replacement of any phytoplankton groups which are characteristic for spring conditions, even if there were changes in the competition dynamics.

Phytoseston and heterotrophic bacteria in the assessment of the waters in the Wełna and Nielba Rivers

Phytoseston and heterotrophic bacteria in the assessment of the waters in the Wełna and Nielba Rivers The phytoseston flora and heterotrophic bacteria from the two intersecting rivers were studied during the intensive water flow (from October 2006 to May 2007). The physical and chemical measurements indicated that the water quality in the rivers regarding their purity, had slightly improved in the Nielba River and deteriorated in the Wełna River, at the sites behind the intersection zone. It was in the agreement with the studied phytoseston diatom communities (dominated by eutraphentic taxa). Phytoplankton during the winter months was dominated by Aulacoseira granulata. The importance of species from the genera Oscillatoria, Planktolyngbya, Tychonema, Planktothrix, Scenedesmus/Desmodesmus, Nitzschia and Fragilaria increased in spring and autumn. Heterotrophic bacteria occurred in considerably higher numbers in the Wełna River than in the Nielba River, with a significant decrease in the waters of the Wełna River behind the river-intersection. All analyses revealed that the waters in the Wełna River were more polluted with organic compounds than in the Nielba River locations.