Factors influencing zooplankton communities in small freshwater lochs

The work contained here examined the zooplankton of small freshwater lochs in Highland Scotland. Investigations focused on zooplankton community composition based upon environmental factors and the viability of these lochs as ‘canaries’ of climate change. Sampling occurred at 30 sites which were divided into three types based upon predicted allochthonous nutrients; altitude lochs, with no input, bird lochs with loafing and roosting sites, and stock lochs located in pastoral lands. Sites were further split by fish presence and absence, yielding six terminal subtypes. Physical and chemical analysis confirmed differences between subtypes, notably salinity, conductivity, pH, area, and altitude. Of these sites, 26 were analysed for community composition; 675 Rotifers, Cladocerans and Copepods, of 68 species were identified. Zooplankton community structure and diversity were examined to determine relationships with nutrient status and to establish baseline data from which future monitoring may derive. Findings supported previous research indicating a complex fish community produces a richer assemblage than a non-complex or fishless community. The stock lochs were the only ‘type’ supported by analytical data, though it was insufficient to support the hypothesis that nutrient chemistry alone was a significant predictor of zooplankton community composition. Owing to issues with sequencing, metabarcoding techniques were unable to support morphological data, and total N was missing from the final analyses. This work recorded zooplankton communities previously uncharacterised including several indicators of warming temperature, meso- and eutrophy which may be indicative of a shift in community in response to climate change. Further investigation is necessary to establish ‘canary’ status including more thorough chemical analysis and temporal biomonitoring.