Penguins cheated by ecosystem change

13 03 2018

Jorge Drexler sings “… I was committed not to see what I saw, but sometimes life is more complex than what it looks like …”*. This excerpt by the Oscar-winning Uruguayan singer seems to foretell the theme of this blog: how the ecological complexity of marine ecosystems can elicit false signals to their predators. Indeed, the fidelity of marine predators to certain feeding areas can turn demographically detrimental to themselves when the amount of available food shrinks. A study of jackass penguins illustrates the phenomenon in a context of overfishing and ocean warming.


Adult of jackass penguin (Spheniscus demersus) from Robben Island (South Africa) — in the inset, one of the first juveniles released with a satellite transmitter on its back. The species is ‘Endangered’ under IUCN’s criteria (28), following a recent halving of the total population currently estimated at ~ 80,000 adults. Jackass penguins are the only penguins living in Africa, and owe their common name to their vocalisations (you can hear their braying sounds here); adults are ~ 50 cm tall and weigh ~ 3 kg. Photos courtesy of Richard Sherley.

Surface temperature, dissolved oxygen, acidity and primary productivity are, by and large, the top four environmental factors driving the functionality of marine ecosystems (1). Growing scientific evidence supports the idea that anthropogenic warming of the atmosphere and the oceans correlates with this quartet (2). For instance, marine primary productivity is enhanced by increased temperatures (3), but a warmer sea surface intensifies stratification, i.e., stacked layers of seawater with contrasting physical and chemical properties.

In coastal areas experiencing ‘upwelling’ (where winds displace surface water, allowing deep water laden with nutrients to reach the euphotic zone where plankton communities feast), stratification weakens upwelling currents and, in turn, limits the growth of plankton (4) that fuels the entire trophic web, including our fisheries. The study of these complex trophic cascades is particularly cumbersome from the perspective of large marine predators because of their capacity to move long distances, from hundreds to thousands of kilometres (5), with strong implications for their conservation (6).

With those caveats in mind, Richard Sherley and colleagues satellite-tracked the movement of 54 post-fledged, juvenile jackass penguins (Spheniscus demersus) for 2-3 years (7). All individuals had been hatched in eight colonies (accounting for 80% of the global population), and were equipped with platform terminal transmitters. Jackass penguins currently nest in 28 island and mainland locations between South Africa and Namibia. Juveniles swim up to 2000 km in search of food and, when approaching adulthood, return to their native colonies where they reproduce and reside for the remainder of their lives (watch individuals swimming here).

The natural history of this species is linked to the Southern Hemisphere’s trade winds (‘alisios’ for Spanish speakers), which blow from the southeast to the tropics. In the South Atlantic, trade winds sustain the Benguela Current, the waters of which surface from some 300 m of depth and fertilise the marine ecosystems stretching from the Western coasts of South Africa to Angola (8). Read the rest of this entry »

Cartoon guide to biodiversity loss XLVII

7 03 2018

The next set of six biodiversity cartoons for 2018. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Our global system-of-systems

28 02 2018


I’ve just read an excellent paper that succinctly, eloquently, and wisely summarised the current predicament of our highly interconnected, global, complex adaptive system (i.e., our environment).

If you are new to the discussions around state shifts, hysteresis, tipping points, and system collapse, there might be a lot in the new paper by Philip Garnett of the University of York that you could find intimidating (and not just because of the complexity of the concepts he discusses). If you are more up-to-date on these discussions, I highly recommend reading this paper for distilling some of the more pertinent questions.

The essence of the paper is that our global environment (Earth) is one giant, complex system made up of interacting sub-systems. We can think of these as a giant, interconnected network of nodes and connections (often called ‘edges’) between them. If you do ecological network theory, then you know what I’m talking about.

What’s particularly fascinating to me is that Philip Garnett is not an environmental scientist; in fact, he’s a a lecturer in Operations Management and Business Analytics (although he does have a background in genetics and biology) who specialises in complex systems theory. In fact, much of his paper uses socio-economic examples of system complexity and collapse, yet the applications to environmentalism in general, and to ecological integrity in particular, are spot on.

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Offshore Energy & Marine Spatial Planning

22 02 2018


I have the pleasure (and relief) of announcing a new book that’s nearly ready to buy, and I think many readers of might be interested in what it describes. I know it might be a bit premature to announce it, but given that we’ve just finished the last few details (e.g., and index) and the book is ready to pre-order online, I don’t think it’s too precocious to advertise now.


A little history is in order. The brilliant and hard-working Katherine Yates (now at the University of Salford in Manchester, UK) approached me back in 2014 to assist her with co-editing the volume that she wanted to propose for the Routledge Earthscan Ocean series. I admit that I reluctantly agreed at the time, knowing full well what was in store (anyone who has already edited a book will know what I mean). Being an active researcher in energy and biodiversity (perhaps not so much on the ‘planning’ side per se) certainly helped in my decision.

And yes, there were ups and downs, and sometimes it was a helluva lot of work, but Katherine certainly made my life easier, and she has finally driven the whole thing to completion. She deserves most of the credit.

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Bring it back

13 02 2018

Protea compacta in fynbos, a form of shrubland at Soetanysberg, South Africa. Photo: Brian van Wilgen

Restoration of lost habitats and ecosystems hits all the right notes — conservation optimism, a can-do attitude, and the excitement of seeing biologically impoverished areas teem with life once more.

The Strategic Plan of the Convention on Biological Diversity includes a target to restore at least 15% of degraded ecosystems. This is being enthusiastically taken up in many places, including through initiatives such as the Bonn Challenge, a global aspiration to restore 350 million hectares of deforested and degraded land by 2030. This is in recognition of the importance of healthy ecosystems in not just conserving biodiversity, but also in combating climate change. Peatlands and forests lock away carbon, while grassland diversity stabilises ecosystem productivity during extreme weather events. So how can we make sure that these restoration efforts are as effective as possible? Read the rest of this entry »

Throwing the nuclear baby out with the fossil-fuel bathwater

6 02 2018

Lynas TwitterA really important paper was just published in Science Advances by Elizabeth Anderson & colleagues.

The team’s paper, Fragmentation of Andes-to-Amazon connectivity by hydropower dams, pretty much highlights what many pragmatic environmentalists have been stressing for years — so-called ‘renewable’ technology rolled out at massive scales (to the exclusion of other technologies like nuclear power) can really endanger biodiversity.

As environmental campaigner, Mark Lynas, rightly points out, renewables, with sufficient base-load back-up by technologies like nuclear, are so far ahead of other combinations (particular, regionally specific mix ratios notwithstanding) in terms of what they can potentially achieve for biodiversity, that our society’s blind push for 100% renewable (instead of 0% carbon), is doing far more environmental harm than good.

It is a case of throwing the nuclear baby out with the fossil-fuel bathwater. Read the rest of this entry »

Drivers of protected-area effectiveness in Africa

31 01 2018
Bowker_et_al-2017-Conservation_Biology. Fig. 1

Subtropical and
Tropical Moist Broadleaf Forest of
Africa with 224 parks surrounded
by a 10-km buffer area. ©
2016 Society for Conservation Biology.

I’ve just read an interesting paper published in late 2016 in Conservation Biology that had so far escaped my attention. But given my interest in African conservation recently (and some interesting research results on the determinants of environmental performance for that region should be coming soon out of our lab), the work caught my eye.

The paper by Bowker and colleagues asked a question that has been asked previously regarding the ‘effectiveness’ of protected areas — do they succeed in limiting forest loss? While forest loss itself is not necessarily indicative of biodiversity erosion in any given area (for that, you need measures of species trends, etc.), it is arguably one of the most important drivers of species loss today.

The first set out to differentiate ‘effective’ from ‘ineffective’ protected areas, which was a simple binary variable related to whether there was less deforestation inside the protected area relative to comparable points outside (effective), or greater than or equal to deforestation outside (ineffective). The authors then related this binary response to a series of biophysical and social indicators. Read the rest of this entry »