Paper Authors and Title

Denise Davey (Atlantic Technological University), Paul Hamilton, “Assessment of the Water Quality of Ash Lane Stream, Co. Sligo using the Q Biotic Index and its relevance to Forensic Science”


This study was performed to determine the water quality of Ash Lane Stream in County Sligo in the Northwest of Ireland, by utilising the Q. Biotic Index system. Highlighted in this report are key findings and their relevance to forensic crime scene investigation. Caddisflies (Trichoptera), and water beetles (Coleoptera) were the primary macroinvertebrates retrieved of forensic significance. Identification of aquatic macroinvertebrates is a step toward a basic understanding of the role these organisms play in death scene investigations (Merritt and Wallace, 2007). Entomology can be very useful to determine the manner of death, length of the post-mortem interval and if a cadaver may have been moved from one site to another (Lord and Rodriguez, 1989). Benthic macroinvertebrates can also be useful measures or indicators of water pollution, telling us how oxygen rich or polluted a water source may be. The data was collected by taking samples in the freshwater stream using the kick sampling method and performing electrochemical analysis in situ. From the diversity encountered and relative proportions of the various organisms (Clabby, Lucey, and McGarrigle, 2003) it was determined that the water quality of Ash Lane stream has a Biotic Index value of Q3, with the water in an unsatisfactory condition. The result of this study compares with the most recent published literature on water quality surveys by the EPA and by a consultancy firm who have completed a similar survey on this stream. It is recommended that further investigation be conducted in this area of research.


Clabby, K.J., Lucey, J. and McGarrigle, M.L. (2003) Interim Report on The Biological Survey of River Quality: Results of the 2003 Investigations, available here.

Lord WD, Rodriguez WC. Forensic entomology: the use of insects in the investigation of homicide and untimely death. The Prosecutor Winter, (1989); 41-48.

Merritt RW, Wallace JR. The role of aquatic insects in forensic investigations. In: Byrd JH, Castner JL, editors. Forensic Entomology: The Utility of Arthropods in Legal Investigations. Boca Raton: CRC Press, 3 2007.


Figure 1: Caddisfly (Trichoptera), retrieved at Ash Lanse stream, Co. Sligo