Two new marine species of Cocconeis (Bacillariophyceae) from the west coast of Sweden

This paper is part of a project of studying benthic diatom biodiversity on marine coastal regions of Sweden with focus on rare and less known species. Two new species of Cocconeis Ehrenb. are described from Vrångö, a small island in the west coast of Sweden. Both species were found as epiphytic on the green alga Ulva intestinalis L. Cocconeis magnoareolata Al-Handal, Riaux-Gob., R.Jahn & A.K.Wulff sp. nov. is a small species not exceeding 9 µm in length and characterized by having large subquadrangular areolae on the sternum valve. Cocconeis vrangoensis Al-Handal & Riaux-Gob. sp. nov. appears similar to some taxa of the ‘Cocconeis scutellum complex’, but differs by its stria density on both valves and variable features of the areola and valvocopula ultrastructure. Detailed descriptions based on light and electron microscopy examination, a comparison with closely related taxa, as well as a description of the habitat of both species are here presented

The novel species Navicula eileeniae (Bacillariophyta, Naviculaceae) and its recent expansion in the Central Appalachian region of North America

Background and aims – A novel species of Navicula has been recently discovered in rivers of the central Appalachian Mountains, USA. The purpose of this paper is to formally establish this new species and to determine whether it had been overlooked in the past or is a recent arrival to the area.Methods – We studied historical collections made in Pennsylvania, Virginia and adjacent areas since the 1940s and housed at the ANSP Diatom Herbarium. Light and scanning electron microscopy was employed to study the morphology of the new species and similar Navicula taxa, including those commonly reported at the same locations, or originally described from the rivers of the eastern United States, such as N. radiosafallax, initially established as N. radiosa var. parva by J.H. Wallace.Key results – The new species has an unusual shape of the external raphe slit, which is undulate toward the proximal ends. This character was so far found in a single other Navicula species known only from Europe. Examination of historical materials confirmed that N. eileeniae was absent from collections made in the eastern United States before 2007, but has become progressively more common and abundant in the last decade. The prevalence of this species in streams of low to moderate mineral and nutrient content suggests that its recent expansion cannot be explained by pollution. Climate change is also unlikely to have caused the northward expansion of N. eileeniae, as it has never been recorded south from central Appalachia.Conclusions – The results of this study confirm that a population of previously unknown Navicula species has been expanding in Central Appalachia and suggest that rapid shifts of distributional ranges not readily explainable by environmental changes may occur in protists

Fig. 1 in Two new marine species of Cocconeis (Bacillariophyceae) from the west coast of Sweden

Fig. 1. Map of the west coast of Sweden and location of sampling site, Vrångö Island (black circle)

Ecoregion, land use and phytoplankton relationships in productive Ohio reservoirs

We describe characteristics of phytoplankton communities of Ohio reservoirs with emphasis on the interrelationships among cyanobacterial populations, land use within 3 ecoregions, and associated environmental variables. We collected 59 phytoplankton samples from 25 mostly productive reservoirs located within 3 distinct ecoregions corresponding to intense agricultural land use (Eastern Corn Belt Plains), intermediate forestation and intermediate agricultural land use (Erie Drift Plain), and heavily forested land (Western Allegheny Plateau) between May and October 2008–2010 and May and June 2011. Cyanobacteria populations peaked in late summer months and were dominated by nitrogen-fixing taxa only in Western Allegheny Plateau and Erie Drift Plain sites, which commonly included Anabaena, Anabaenopsis, Aphanizomenon, and Cylindrospermopsis. Canonical correlation analysis suggests that the qualitative and quantitative characteristics of phytoplankton populations in Ohio reservoirs are strongly influenced by underlying land use practices. Coarse resolution at the ecoregion scale can be valuable in describing potential cyanobacteria composition where detailed nutrient budgets are not available for particular reservoirs and lakes

Response of phytoplankton and zooplankton communities in six reservoirs of the middle Missouri River (USA) to drought conditions and a major flood event

We assessed if the qualitative and quantitative aspects of plankton composition in reservoirs of the middle Missouri River were influenced by hydrologic variability. Phytoplankton and zooplankton communities in six reservoirs of this highly regulated system were sampled between 2004 and 2011 during historic drought, subsequent recovery, and a 100-year flood event. The reservoir system encompasses a broad latitudinal gradient of decreasing depth, decreasing water residence time and increasing trophic state. Phytoplankton communities of the upper three reservoirs were co-dominated by planktonic and meroplanktonic diatoms during the drought, recovery, and flood periods, but the proportion of more silicified meroplanktonic diatoms increased in the lower three reservoirs as water residence time decreased. Peak phytoplankton biovolume usually occurred during spring/early summer and was associated with increased hydrologic inflows and outflows. Zooplankton biomass of the reservoir system was dominated by Daphnia spp., but all zooplankton groups decreased as inflows and outflows accelerated during the recovery and flood periods. Rotifer abundances were higher under turbulent conditions associated with dam operations. Canonical correlation analyses suggested that temperature, water residence time, station depth, and water clarity explained more variance in the structures of phytoplankton and zooplankton communities than bioavailable nutrient parameters. © 2012 Springer Science+Business Media Dordrecht