Biodiversity is a hot topic these days. By any measure (species counts, genetic diversity, etc.) we appear to be losing it at rates that are uncharacteristic for our current climatic conditions. That is to say, there have been other major extinction events in Earth's history, but our current predicament is not the result of asteroid impact, and ice age or massive volcanic eruptions. Rather, evolution has produced an animal capable of exploiting planetary resources on an unprecedented scale.
But I'm not interested in getting into a climate change discussion today. I don't suffer the deniers of anthropogenic change on a global scale. What I would like to address stems from a conversation this morning that has long been an issue for me. It started simply:
— Dr Elizabeth Sargent (@esargent184) May 29, 2014
I remarked that lion fish are hardly unusual for classic invasive species that enters a new ecosystem and takes off as food items are plentiful and parasites and predators are not. There's hundreds of examples of this exact pattern playing out, even if most people will only be familiar with ones involving larger animals. But the discussion got a bit more complex and it is here that I have been thinking a lot recently:
— Dr. Wrasse (@labroides) May 29, 2014
Our planet is a complex and very dynamic place. It's a question of scale and most people focus on a scale that they can relate to. When we talk about the disappearance of species, 99% of time we're talking about things that were present within our lifetimes and are either highly restricted in their distribution now, or gone. It's a time frame we can wrap our heads around.
But the planet is more dynamic than that and sea level change, land mass movement and global temperature have fluctuated dramatically over time. We are so hyper-focused on preserving the current status quo or re-establishing the very recent past that it is easy to ignore the fact that biological invasions are the norm at a geological scale, not the exception. I'm not advocating for ignoring human-induced biologic invasions or the short-term havoc they cause on an ecosystem but it's important to keep them in context. We've made the situation worse, but "invasives" are not new. Not even close.
As an example that concerns me, we are rapidly approaching a time when there will be unobstructed ocean flow through the Arctic for much or all of the year. The lack of ice cover for longer periods significantly alters what can live in Arctic waters and current patterns are likely to move Pacific species east*. This is not a situation where we have a single species showing up and bullying a naive ecosystem, but the collision of two ecosystems that have been physically separated for a long time. It'll be the rough equivalent of submerging the isthmus of Panama (no, not the panama canal, which flows through fresh water).
Again, both of these dramatic events have happened before over geologic time. But in stark contrast to worrying about the fate of a single species or the preservation of a particular forest or reef, which is where much of our current conservation effort is focused, we will stand witness to forces far more dramatic. Unlike the lion fish eradication effort in the topical Atlantic, there will be no hope to put this genie back in the bottle**. But as noted here, we still think of conservation as stopping the changing of the tide:
— Madhusudan Katti (@leafwarbler) May 29, 2014
Now I realize this is a fairly rambly post written in multiple interrupted sittings, so I want to make clear I'm not against studying invasive species or using invasions as a model for projecting ecological impacts and niche shuffling. But I do think we need to view species mobility and biodiversity as a dynamic processes, albeit one that is being driven mightily both directly and indirectly by human activities. In fact, I think such research is going to be key to figure out how we mitigate some of the damage. But what we view as an "ideal state" for biodiversity may not be the stable state for the environment in the future, no matter how much we try and force it to be.
*Anecdotally, there are already some disturbing reports here.
**Okay, there's no hope to eradicate the lion fish from the Caribbean either, but this is a different level of crushed hope.