LL2-20 digest — Ch20 Invasive alien species: a growing but neglected threat?#

EEA 2013, Part C “Emerging issues”, report pp. 486–508 (text pp. 486–502; Table 20.1 p. 502). The six authors are insiders to IAS governance (Annex 1, pp. 687–697): - Brunel (scientific officer, EPPO); - Fernández-Galiano (“in charge of” the Bern Convention since 1985; head of the Council of Europe Biodiversity Unit); - Genovesi (chair of the IUCN Invasive Species Specialist Group); - Heywood (Reading; co-author of the horticulture code); - Kueffer (ETH Zürich); - Richardson (Stellenbosch).

About 30% of the references are their own work, and the chapter doesn’t mention their roles in the institutions it describes. No panels.

Core argument#

This is a review of a whole class of hazard, not a single case. Invasive alien species (IAS) are “one of the five major causes of biodiversity loss”. The hazard is a by-product of trade and travel, “more a human-driven environmental problem than a strictly biological one” (p. 487). Despite more than 42 treaties, invasions “continue to grow at a rapid rate, with no indication yet of any saturation effect” (p. 493).

• Scale. Invasive species were among the causes in 91 (54%) of the roughly 170 animal extinctions whose causes were compiled, and the only known cause in 34 (p. 487). Europe has about 11,000 alien species, about 10% with ecological and 12% with economic impacts (p. 492).
• Cost. Economic costs in Europe are put at over EUR 12.5bn a year (p. 491; “EUR 12 billion” on p. 494), against EUR 40–190m a year for policy action (p. 494), both from Kettunen et al. (2009), co-authored by Genovesi. The chapter hedges the resulting “very cost-effective” claim as “according to this perspective”.
• Speed pays. Weed eradication costs rise at least 40-fold with delay (p. 487). Caulerpa was found early in France in 1984 but tackled only after it had spread to “a large portion of the Mediterranean”. California began eradication 17 days after detection in 2000 and succeeded (p. 498).
• Neglect in Europe. EU law is vague and fragmented (Box 20.1, p. 492). Water hyacinth is still freely traded after costing 18 million euros to control in Spain. Grey squirrels are still sold in Italy 12 years after the Bern Convention asked for a trade ban (p. 492).
• The central late lesson. About 20 years passed from scientists alerting governments (around 1993) to a dedicated EU instrument, which was still only expected “before 2013” (Box 20.4, p. 501).

Key mechanisms#

• Prediction is limited. No common list of traits separates invasive from non-invasive species, though traits remain “highly relevant” alongside propagule pressure, habitat, land use and economics (pp. 490, 500). Invasiveness elsewhere is the best predictor, to be used “with great caution” as the climate and other conditions change (pp. 490, 501). Complexity “still limits the precision” of risk tools (p. 501).
• The lag phase. Species can go unnoticed for decades, so traceability of who introduced them “may be lost” and liability becomes “very difficult”. Decisions must be made at introduction, far ahead of evidence (p. 497).
• Definitions shape evidence. Academics mostly define “invasive” by spread, decision-makers by impact; lists built on different criteria are hard to aggregate, which “contributed to” an incoherent political response (pp. 488, 494).
• Misclassification both ways. Harmless species mistaken for invaders waste resources; “invaders in disguise” escape action (pp. 486, 488).
• Turf disputes. A health-versus-agriculture dispute delayed ragweed control (pp. 496–497).
• Deferral upward. Governments cited EU free movement as a reason not to act nationally (Box 20.4).
• Regulatory asymmetry. EU rules on releasing biological control agents are strict; rules on known invasive species are “non-existent” (p. 496).
• Voluntary codes. Industries prefer them, and they have “limited effectiveness and buy-in” (Drew et al., 2010). Horticulture has been “collaborative” where “some alternative can be found”; some firms favour legislation so non-compliers cannot undercut them. The industry claims are the authors’ unsourced judgements (pp. 498–499).
• Fixes that became hazards. Signal crayfish, brought in after a disease hit native crayfish, carried that disease and became invasive (p. 497). Cane toad is another example (p. 496).
• Values and emotion. An animal-cruelty prosecution of two officers ended Italy’s grey squirrel eradication (told only from the eradicators’ side; Genovesi co-authored the cited account). RSPB backing, at a cost of “probably a few thousand members”, unlocked UK ruddy duck control (Box 20.2, p. 495).

Authors’ lessons (pp. 499–502)#

1. Align concepts for public understanding: make expert disagreement transparent rather than speaking “with one voice”.
2. Harmonise definitions and data, and link science to management.
3. Take account of wider social interests and values (“a late lesson not yet learnt”, taken from Volume 1).
4. Avoid paralysis by analysis (the text under this heading describes better but still imprecise risk analysis; the “don’t wait” point is implied, not argued).
5. Don’t use the need for EU coordination as an excuse for inaction.
6. Anticipate blind spots such as biofuel crops and managed relocation.
7. Don’t let philosophical debates block action.

The chapter also says precaution means acting before full assessment (p. 487) and that where to draw the risk line is a value judgement needing societal debate (p. 497). It concedes that “rigid” precaution is problematic under free trade (p. 497).

Transferable insights (technology-neutral)#

• Delayed harm defeats liability and forces decisions up front (p. 497). Moderate.
• Windows for intervention close fast, so precaution can mean acting quickly, not only restricting in advance (pp. 487, 498). Moderate.
• How a harm category is defined decides what data exist and whether policy can cohere (pp. 488, 500). Moderate.
• Hazards that cross institutional mandates can stall in turf disputes (pp. 491, 496–497). Suggestive.
• Waiting for higher-level coordination can become a reason to do nothing; resource-pressed institutions put legally mandated work first (Box 20.4, p. 501). Moderate.
• Countermeasures can face stricter rules than the harm they address (p. 496). Suggestive.
• Harmful items stay on sale while public money pays to contain them (p. 492). Moderate.
• Voluntary codes without sanctions underperform (pp. 493, 498). Moderate.
• Fixes can become the next hazard, and their beneficiaries resist reversal (pp. 496–497). Moderate.
• Harm scales with the volume of human activity carrying the agent, which favours regulating pathways over inspecting items (pp. 490, 498–500). Moderate to strong.
• Intrinsic properties alone predict poorly in complex systems; track record elsewhere is the best guide and degrades as conditions change (pp. 490, 500–501). Strong within the domain; transfer by analogy.
• Stakeholders judge hazards on different criteria from experts (human role, aesthetics, personal experience) (p. 500). Moderate.
• Misclassification cuts both ways: wasted effort on benign items, missed hazards that look benign (p. 488). Suggestive.
• Political attention follows monetised costs (pp. 491, 501). Suggestive; the chapter hedges it (“may also have been helped”).

Main caveats#

• Participant advocacy. The authors’ roles are undisclosed in the chapter. There is no panel or commentary; critics (Sagoff; Davis et al.; Larson and Warren) are summarised in a few sentences and answered at greater length by the ISSG and “Simberloff and 141 scientists” (pp. 493–495).
• Cost figures used unevenly. Pimentel’s species count is called “misleading” (p. 488), yet a Pimentel-attributed global cost of USD 1.4 trillion a year is used without caveat, alongside uncited US and China figures (p. 494). The cost comparison sets total existing damage against the cost of new policy.
• Self-criticism is about the field, not the institutions. The chapter admits early conceptual blind spots, poor communication and biocontrol mis-assessments (pp. 490, 496, 499–500), but the governance failures it shows are all other actors’.
• No false positives on the hazard side. Volume 2 promises attention to false positives (p. 9); here the only false alarm is about a remedy (Réunion biocontrol, p. 496), though misidentification waste (p. 488) and context-dependent impacts (p. 494) are acknowledged.
• Hindsight in the “missed opportunity” cases (Caulerpa, signal crayfish).
• Unresolved tension between transparency (p. 499) and not letting debate “create blockages” (p. 502).
• Balance. The chapter is candid about its own field’s blind spots (p. 500).
• Uptake in the synthesis. The report’s synthesis uses the chapter mainly as its example of ambiguity calling for participatory precaution (p. 656).

Checkable forecasts: an EU instrument by end 2012 (pp. 492, 501); European ruddy duck eradication by 2015 (p. 495); grey squirrel spread across Europe (p. 495); continued unsaturated growth of invasions (p. 493); biofuel and biomass crops “present a risk of favouring new invasions” (p. 495, framed as a risk rather than a forecast).