Biodiversity assessment of groundwater-dependent ecosystems in Malta : evaluating copepods as bioindicators of groundwater health

Abstract

This study investigates the biodiversity of groundwater-dependent ecosystems (GDEs) in Malta, focusing on copepods as bioindicators of groundwater health. Groundwater is essential in sustaining GDEs, yet these ecosystems remain underexplored, particularly in terms of local biodiversity. The aim of this research is to assess the biodiversity of groundwater organisms, with particular attention to copepods, in order to evaluate the ecological status of GDEs and their associated groundwater bodies. Groundwater samples were collected from a range of sites, including hand-dug wells (Maltese: Spejjer), groundwater-fed springs, and boreholes. The sampling process involved the use of a bucket in conjunction with a plankton net. Boreholes were sampled using a bailer. Copepod assemblages were examined microscopically to determine community composition in terms of abundance and life-stages. The study also examined the influence of chemical stressors, particularly salinity, nitrates, nitrites, and phosphates, on copepod populations. Typical morphological traits strongly point towards the organism being a copepod (cyclopoid or harpacticoid). The results reveal copepod presence across three groundwater bodies, two coastal aquifers and one perched, however a clear indication of which physicochemical factors affect their presence was not concluded. Presence of copepods was strongly linked to coastal aquifers, and collection methods could influence the life-stages at which copepods are sampled. This research emphasises the value of copepods as bioindicators for monitoring GDEs. The need for further investigation on a taxonomical level would be required to understand the ecosystem relationship and dynamics within a more representative and consistent source for the sample. More data needs to be analysed across a broader region of the country to better understand how to exploit copepod analysis into groundwater monitoring. This would be a first step towards an effective policy that can be developed to protect Malta’s groundwater resources in a rather cost-effective and efficient way.