Histories of bioinvasions in the Mediterranean

Dr Simon Pooley, Lambert Lecturer in Environment (Applied Herpetology) at Birkbeck discusses ‘bioinvasions’  – the phenomenon of plants, animals and microbes being introduced more frequently into new regions – which is the subject of his new book, co-edited with Ana Isabel Queiroz.

Bioinvasions, a global environmental problem of anthropogenic origin, have been studied mainly by the natural sciences. However, it is widely acknowledged that it is also important to understand the human dimensions of bioinvasions. The book brings together environmental historians and natural scientists to produce historical narratives of bioinvasions, drawing on a bricolage of sources and methods. Central to our endeavours is our recognition that temporal and spatial scales are crucial variables in all narratives which attempt to explain the movement of invasive species across ecosystems and landscapes.

This book has three overarching aims: first, to provoke natural scientists working on bioinvasions to think more historically; second, to convince environmental historians to engage with the science of bioinvasions; and third, through sharing the research presented in this book, to convince them all of the richness of the research materials and themes and the importance of the issues, and so stimulate interdisciplinary collaborations on bioinvasions.

So, why focus on the Mediterranean region? Primarily, it is because of the antiquity of human and ecological relations in the region, notably regional (and from the fifteenth century, global) maritime communications and trade. While historians have studied the impacts of European trade and invasive plants, animals and diseases elsewhere on the planet, they have paid less attention to the reverse flow. The introductions of some well-known naturalised (non-invasive) plants such as tomatoes, potatoes, tobacco and citrus, are better known.

Of course, as the eminent environmental historian J. Donald Hughes has remarked, the Mediterranean region is a somewhat fuzzy concept, and has been defined differently depending on whether scholars have chosen biophysical, political or cultural variables and definitions. In our usage, it includes the entirety of the Mediterranean Sea, and terrestrially, the Mediterranean-type climate (MTC) region surrounding this sea.

This biophysical framework should not obscure how this region has been transformed by human actions—from agriculture to herding, burning to hunting and deforestation. Such is the scale and diversity of such influences, over millennia, that the region represents an archetypal landscape where humans and their physical and biotic environments have coevolved.

Our book includes historical case studies which collectively contribute towards a history of bioinvasions in the Mediterranean region. The histories of marine invasions best fit this aspiration, in taking in the full sweep of the Mediterranean Sea. Some of the remaining chapters are perhaps more histories in than of the region, but they all offer insights into the histories and processes of invasion in the region which share commonalities across a diversity of ecological and cultural contexts. In addition to climatic and topographical factors, and longer-term geological processes, these include: seaborne exploration, colonisation, communication and trade; the impacts of agriculture, forestry and pastoralism; and the convergent evolution of the flora in response to human disturbances, notably land clearing and burning.

Histories of bioinvasions undermine notions of timeless continuities or geographical or environmental determinism. They feature an array of introduced species from across the globe’s oceans and shores, following diverse invasion pathways facilitated by unexpected vectors, imported for numerous purposes (or accidentally). Just possibly, in aggregate, bioinvasions herald a terminal disruption of the ecological coherence used to define a ‘Mediterranean basin’ region. So, this book offers both an argument for thinking in terms of a Mediterranean region, and offers a warning of its fragility, conceptually and physically.

Our book features nine case studies of bioinvasions from the plant and animal kingdoms, encompassing marine, freshwater and terrestrial environments. These include an overview of all marine bioinvasions, a chapter focussing on invasive marine and freshwater decapods (crayfish, crabs and prawns), terrestrial invasions by Argentine ants and waxbills, invasions of islands by reptiles, amphibians and Australian plants, invasions of coastal salt marshes by cord grasses, and of freshwater waterways by African clawed frogs. These invasive species have been transported from around the globe or internally within the Mediterranean region. My own chapter includes a section on the important role of fire coupled with invasive introduced plants in Mediterranean ecosystems. It also adds a comparative look at South Africa’s Mediterranean climate region, and the history of invasions of its unique fynbos biome, examining the reasons for introductions, and cultural, political and scientific responses to their social and environmental impacts. The chronological range of this collection extends from the Neolithic and the Bronze Ages through Classical times, the ages of European maritime discovery, to the present.

Ana Isabel Queiroz (NOVA-FCSH, Lisbon) and I (the editors) are grateful for the enthusiasm and patience of the scientists among our contributors in working through many exchanges and versions to steer their work towards more historical writing. The material reads unevenly as history, in parts, but we feel the gains are substantial. In the course of editing this book, we have noted some interesting gaps in historical knowledge. For example, our knowledge of the chronology of introductions and spread of species prior to the twentieth century is surprisingly imprecise. Awareness of most of these invasions has come surprisingly late, with most discoveries and interventions described here occurring in the late twentieth or early twenty-first centuries.

In our Introduction to the book, Ana and I highlight promising avenues for further research by environmental historians. For instance, too little is known about some major pathways of invasion (notably maritime) into Mediterranean Europe, and historians have paid scant attention to invasions from species moved around within the region. There is interesting work to be done on the role of empires and their collapses, and resulting movements of humans and biota, in the introduction of invasive species. Comparative histories of management interventions and their outcomes could provide important contextual information for attempts to control bioinvasions in the region. It seems that shrubs of the region survive or recover from anthropogenic disturbances, and on the whole resist invasions by plants introduced from the other Mediterranean climate regions, possibly (as ecologist Jon Keeley has argued) because of the long history of coevolution of humans with the local biota. An exception is the western Iberian region, and it would be useful to have environmental histories of the introduction and spread of Australian trees and shrubs in this region. Finally, there are fascinating opportunities to synthesise histories of the colonisation of the region by the terrestrial fauna after humans arrived on the scene.

Histories of Bioinvasions in the Mediterranean ed. Ana Isabel Queiroz and Simon Pooley, is available now from Springer.

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An archaeologist’s life (or how I learnt to love the pickaxe)

Dr Melissa Butcher from the Department of Geography discusses a recent trip to the Greek Island of Despotiko for her first experience of an archaeological excavation, ahead of Birkbeck’s new BA Archaeology & Geography, which launches this year.

Archaeologists at work

As a human geographer studying the complexities of contemporary urban cultures, I have the distinct advantage over my archaeological colleagues in that if I need to understand ‘why’ I can ask someone. I am immersed in a world of material objects that can be traced and described in real time. Yet the contemporary never escapes the markers of the past. Our present is a palimpsest: the uppermost layer of thousands of years of human history reflecting that which we think we are at this moment in time.

Working out how we got to be where we are today requires excavation, figurative and literal, and if you think the latter is all about fancy trowel work and air-brushes think again. If you want to be an archaeologist, learn to love your pick-axe and your wheelbarrow. This was my first lesson after accepting an invitation (or perhaps more accurately, pleading to be allowed to go) to spend a week at the Paros Ephorate of Antiquities’ excavation on the Greek Island of Despotiko, run by Yannos Kourayos and his assistant Ilia Daifa, with collaboration from Birkbeck.

The site itself constitutes the only activity on Despotiko apart from the resident shepherd and his goats (the team stays on the neighbouring islands of Antiparos and Paros). But its position in the centre of the Cyclades archipelago suggests some past importance in maritime trade in the Mediterranean, and ritual significance in the Archaic (6th century BCE) sanctuary, possibly dedicated to the Ancient Greek deities Apollo and Artemis, that has already been uncovered and reconstructed in parts.

The excavation site

The excavation is only open for six weeks each year to allow the team to work on the site, and they are joined by international undergraduate and postgraduate volunteer students from Argentina, Brazil, Italy, Spain, the USA, and the UK, including students from Birkbeck. Starting at 7.30am (ish) with a ferry ride to the site, it’s then pickaxes and shovels, with the occasional sweeping up of dirt, until lunch at 11.30am (ish). We finished by 3pm (ish) so there was always time for a swim in crystal clear blue water before the ferry ride back to Antiparos.

On paper, this may not sound like a particularly difficult schedule but any romantic visions I had of spending days delicately dusting off ancient finds were soon dispelled by a relentless sun and the head-to-toe film of dirt disseminated by a prevailing westerly, giving me my second important lesson: always stay up-wind of anyone with a shovel. The first layer of an archaeological dig is all spade work and shifting large rocks out of the way by hand. It is rare in an academic life that our labour makes us so tired we are in bed and asleep by 7pm, but then it’s also not often that you can have a solid piece of work done at the end of the day: to look at your trench and say ‘I did that’ is highly satisfying.

However, my third lesson in archaeology was understanding the difference between digging a trench and digging holes, the latter being very bad. Each layer of an excavation has to go down as evenly as possible and if that means leaving exposed ancient pottery on the surface then so be it until the next layer is removed. Each layer is photographed, and finds from that depth carefully bagged, cleaned, re-bagged and labelled so that the research team knows exactly which part of the excavation they came from. It is painstaking work most definitely not for the disorganised, and randomly digging out individual artefacts just disturbs the layers and creates confusion. But leaving pieces of pottery exposed for any length of time was for me like putting a chocolate bar within arm’s reach and saying ‘don’t touch’. It is an incredible feeling to hold something in your hands that is over 2500 years old and such did my obsession with digging up bits of amphorae become that I almost had my trowel confiscated and had to banish myself to the cleaning area for a day for my own good.

A sunset over St Georgios Antiparos

My love for pottery remains undiminished, perhaps because these battered shards of the everyday (cooking pots, water jugs, lamps) remind me of the continued importance of the quotidian in contemporary geographical research. They are part of the material record that tell us about our present, yet, given that we are ‘reading’ them thousands of years outside the context of their use, they also generate intrigue and controversy. In material artefacts, it is possible to see traces of trade, migration, war and civilizational collapse, but the pieces can’t always say why it happened.  The order in which artefacts are found and analysed can change how a site is understood. For example, if household pottery is found first and only later a major ritual shrine is unearthed, or vice versa, does that change how we view what happened? And along with the mundane are the mysteries: at my trench, we discovered an alignment of rocks that could have been a wall, or maybe not. Like detectives, the archaeologists tried to determine where it might begin and end, if it had collapsed, what may have been built on top of it. We needed to determine this before we started moving rocks around in case we accidentally removed a 2500-year-old structure. It is the archaeologist’s expertise, gained through years of digging trenches, reading the archives and debating the alternatives with colleagues, that brings back to life a pile of rubble that can give us some explanation of the ‘who’, ‘what’ and ‘why’ of ancient history.

If you are interested in excavating such questions, as well as contributing to the material history of human existence, explore our new BA Archaeology & Geography. Students will get the opportunity to work on Despotiko as well as our other excavation, the Buried Humanities Field School at Must Farm.

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