Macrofossil Analysis

At Henderson Ecology we analyse the macro-remains of aquatic plants (seeds, leaves, oospores, spines etc.) and animal parts (invertebrate parts, molluscs and fish remains) preserved in lake sediment cores using light microscopy. Remains are identified to species and their changing abundance through time is reported using stratigraphic diagrams.

Analysis of the macrofossil record allows the structural and functional characteristics of pre- pollution ecosystems to be reconstructed and macrophyte reference conditions to be defined. Macrofossils are often used, in conjunction with preserved diatoms and cladocera, in multi- proxy projects to assess any deviation away from past conditions and inform ecological classification of a water body as required by the Water Framework Directive. Some recent projects Gina Henderson has worked on using macrofossils are listed below:

  • 2013, Reference conditions for phosphorus runoff from forested areas with arable soil properties (Norwegian Research Council, led by Bioforsk).

  • 2011-2014, BIOFRESH project (European Union).

  • 2008, Palaeoecological assessment of fresh waters in SACs and ASSIs in Northern Ireland.

  • 2007, Palaeoecological Investigation of the Past Biological Structure and Function in the Trinity Broads (Essex and Suffolk Water with the Broads Authority).

  • 2007, Palaeoecological Investigation of Rockland Broad (Broads Authority).

  • 2006-2008, Environmental Improvement Plan (EIP) for impacted mesotrophic lochs, Palaeoecological study, (SEPA).

Case Study- Green Plantation Pond, North Norfolk

The Green Plantation Pond project explored the spatial relationship between contemporary aquatic vegetation and surface sediment macrofossil remains as part of the BIOFRESH project (European Union). By comparing macrophyte and plant macrofossil distributions at multiple, closely-spaced points in Green Plantation Pond for 2000 and 2008-2009, the study sought to advance our understanding of how well macrofossils track aquatic vegetation change in shallow lakes.  The aquatic vegetation of Green Plantation Pond has undergone marked compositional change since 2000, with, among other lesser changes, a dramatic shift from a community dominated by Elodea spp., Potamogeton pusillus and Chara spp. to one dominated by Ceratophyllum demersum, Ceratophyllum submersum, Chara spp. and Potamogeton crispus after 2005.

The plots below compare macrophyte %PVI distribution for 2000 and 2008 with macrofossil density distribution for 2000 and 2009 represented by plant macro-remains extracted from surface sediment samples. The plots demonstrate that the macrofossils retrieved represent a large proportion of the contemporary flora.

The macrofossils reliably recorded both the main shift in the contemporary vegetation (e.g. especially the increase in Ceratophyllum spp. and P. crispus dominance) and lesser, more subtle changes (e.g. increase in M. spicatum and Lemna species) exceptionally well. This study highlights the huge potential of macrofossils for providing reliable records of subdecadal changes in aquatic vegetation in small, shallow lakes. For more information on this study see Publications or contact us to discuss further how macrofossils can be used to inform ecological restoration targets.

Clarke et al., (2016) The representation of aquatic vegetation change by plant macrofossils in a small and shallow freshwater lake. Vegetation History and Archaeobotany 23, 265-276.

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