Biological Environmental Proxies in Ireland

Published:February 2025

Using biological indicators to reconstruct past environments

Biological environmental proxies are one of the main tools used in palaeoecology to reconstruct past environments. In Ireland, indicators such as pollen, chironomids and testate amoebae provide detailed insights into past climate, vegetation and ecological change.

One of the key advantages humans have — and one that has driven our extraordinary technological progress — is our ability to communicate in detail. Knowledge gained through experience, experiment, or inspiration can be passed on, meaning the wheel does not have to be continually reinvented.

This is the foundation of scientific progress. Research builds on what has gone before, and this process continues today through the publication of thousands of scientific papers describing new discoveries and developments.

Publishing, however, is only one end of the chain. A research project may take years to complete, but once published, the next challenge is finding that information.

The Challenge of Finding Information

Scientific papers are published across thousands of journals. Where a paper is published often depends on the perceived prestige of the journal — higher prestige often means higher academic “scores.” But this does not necessarily make new research easier to find.

There are bibliographical databases that catalogue published work, allowing searches by:

• subject
• keywords
• author
• research field

However, there are many such databases, and no guarantee that any given paper will appear in all — or even any — of them. Search tools vary in quality, and the underlying data can be surprisingly inconsistent.

This means that one of the first tasks in any research project is simply to find out what has already been done.

The Need for a Review

Beyond individual papers, what is particularly valuable is a review — a synthesis of existing work that shows:

• what has been studied
• where it has been studied
• and how useful those studies have been

In the case of the Three Lakes project, it quickly became clear that there is no comprehensive review of palaeoecological work carried out across Ireland.

This is significant, because the Three Lakes project aims to contribute new knowledge and potentially fill important gaps.

The Scoping Review

As a result, a scoping review is now underway. Its purpose is to assess how biological environmental proxies have been used across the island of Ireland, with a particular focus on:

• their geographical distribution
• the time periods they cover

It is already clear that a great deal of palaeoecological work has been carried out by Irish researchers. But how much of that work was conducted in Ireland itself? And when? And using which proxies?

The Proxies

The Three Lakes project will make use of several key biological proxies:

• Chironomids — indicators of summer air temperature
• Testate amoebae — indicators of water table depth and precipitation
• Sedimentary ancient DNA (sedaDNA) — evidence of past biological communities

However, for the purposes of the scoping review, this list was expanded to include a broader set of commonly used proxies:

• Pollen — proxy for vegetation and climate
• Cladocera — indicators of water quality
• Diatoms — also indicators of water quality

Water quality itself can reveal a great deal about past environments, including:

• nutrient levels
• possible pollution
• flooding events
• broader ecological changes

What the Review Will Do

The aim of the review is to identify:

• the number of relevant studies
• the sites included in those studies
• the proxies used
• the time periods represented

Only studies carried out on the island of Ireland (in the geographical sense) are included.

A heatmap with the occurrence of biological proxies in Ireland (this is a first draft and may be subject to change)

Six charts showing the number of studies and years of occurrence of biological palaeoenvironmental proxies(this is a first draft and may be subject to change)

Six charts showing the number of sites and years of occurrence of studies of biological palaeoenvironmental proxies(this is a first draft and may be subject to change)

This approach will also allow us to explore how the use of these proxies has evolved over time — as their value became better understood, as methods improved, and perhaps as some fell out of favour.

Palaeoecology as Investigation

Palaeoecology is, in many ways, like detective work.

The aim is to reconstruct a picture of the environment at a particular place and time in the past. Given a set of clues, what can we infer?

The proxies are those clues. Each has a known relationship to environmental conditions. By combining them, we can build up a more complete picture of what was happening.

The “scene” of the investigation is the study site — in this case, Three Lakes — but the question naturally arises:

Can what we learn at one site be applied elsewhere?

One way to address this is to carry out similar studies across many locations. By comparing and combining results, it becomes possible to build a broader picture of how Ireland’s landscapes and ecosystems developed after the last glaciation.

This scoping review is a first step in that direction — helping to identify where the gaps are, and where new work can make the greatest contribution.