Response of diatom assemblages to the disruption of the running water continuum in urban areas, and its consequences on bioassessment

The possibilities and limitations of comparative diatomaceous analysis for confirming or excluding the site of an incident - Case studies

Diatoms (Bacillariophyta) are unicellular photosynthetic organisms commonly occurring in aquatic habitats on Earth. Their autecology makes them almost perfect indicators of environmental conditions and so have high potential for use in forensics. Both eurytopic and stenotopic species are important in site identification: eurytopic forms due to their abundance, and stenotopic forms due to their narrow range of tolerance to environmental conditions. Their presence can hence provide a clear insight into an ecosystem and its microhabitats. The diatoms are useful as significant indicator in diagnosing of drowning. However, to definitively link a corpse with the place where it was found and to indicate whether this was also the crime scene, it is essential that any comparative diatomaceous analyses are performed correctly. The following study presents selected cases in which a comparative diatomaceous analysis was performed. In all cases, the biological samples secured during the autopsy were compared with environmental samples collected from the site of the cadaver disclosure. Our findings show both the possibilities and limitations of using this method in forensics. These forensic investigations need close collaboration between coroners and diatomology experts. It is crucially important to reveal whether the place of corpse finding is the same as the place of drowning.

Persistent Cyanobacteria Blooms in Artificial Water Bodies-An Effect of Environmental Conditions or the Result of Anthropogenic Change

Algal blooms are an emerging problem. The massive development of phytoplankton is driven partly by the anthropogenic eutrophication of aquatic ecosystems and the expansion of toxic cyanobacteria in planktonic communities in temperate climate zones by the continual increase in global temperature. Cyanobacterial harmful algal blooms (CyanoHABs) not only disturb the ecological balance of the ecosystem, but they also prevent the use of waterbodies by humans. This study examines the cause of an unusual, persistent bloom in a recreational, flow-through reservoir; the findings emphasize the role played by the river supplying the reservoir in the formation of its massive cyanobacterial bloom. Comprehensive ecosystem-based environmental studies were performed, including climate change investigation, hydrochemical analysis, and bio-assessment of the ecological state of the river/reservoir, together with monitoring the cyanobacteria content of phytoplankton. Our findings show that the persistent and dominant biomass of Microcystis was related to the N/P ratio, while the presence of Aphanizomenon and Dolichospermum was associated with the high-temperature end electric conductivity of water. Together with the increase in global temperature, the massive and persistent cyanobacterial bloom appears to be maintained by the inflow of biogenic compounds carried by the river and the high electric conductivity of water. Even at the beginning of the phenomenon, the reservoir water already contained cyanobacterial toxins, which excluded its recreational use for about half the year.