1 live reef shark in Palau = 179,000 USD in the ecotourism industry. Or killed and sold once for 108 USD. Just economically, not even considering the ecosystem services involved, sharks are worth much more alive. This has been in the news for a bit but worth pointing out especially in the wake of Shark Week.
There is an interesting editorial in the Guardian regarding the recent news of the beginnings of a fishery recovery off the Canadian coast. (For those outside the paywalls of Nature, Hannah over at Culturing Science has nicely reviewed the paper here).
The gist is that despite this bit of sunlight within global overfishing, the situation is still alarming. For example, the editors point out that:
In the North Sea, 93% of cod are fished before they can breed.
The article’s worth a read.
Dr Jason Hall-Spencer has written an excellent essay on the urgency of oceanic action, fueled by the recent findings of the International Programme on the State of the Ocean (IPSO). Make sure to check it out.
The crux of the problem is that the rate of changes in ocean systems is accelerating and outstripping what was expected just a few years ago. Destructive fishing practices, pollution, biodiversity loss, spreading low-oxygen “dead zones” and ocean acidification are having synergistic effects across the board – from coastal areas to the open ocean, from the tropics to the poles.
Ideally, your expenses are offset by your paycheck, so as you spend money for say, rent and food, you have cash coming in. On the surface at least, this is similar to the dovetailing of extinction and speciation. The vast majority (~99%) of all the species ever to have existed on Earth are extinct, never to be seen alive again. However, this process is balanced by new species evolving, a process known as speciation. So what happens when species extinctions far outpace species creation? Mass extinctions, timeframes during which 75% of species are lost in a relatively short period (usually less than two million years and sometimes significantly less), have occurred five times (the Big Five) in the past 540 million years. They are unique, singular events that stand out above the background level of extinction that is constantly ongoing. However, more and more modern extinctions are being observed, amidst the myriad of human-derived disturbances, such as rapid climate change, invasive species introductions, habitat fragmentation, directly killing species, among others.
It is not a straightforward task to ascertain whether or not we are on track to another mass extinction—data from the fossil record must be comparable to historic and modern species assessments. In a paper recently published in Nature, Dr Anthony Barnosky and colleagues point out why data comparisons of this type are difficult and proceed to broadly get around them by looking at the global picture.
The fossil record is not evenly distributed across taxa or geographies. Fossils are particularly meager in some broad swathes of Earth, such as the tropics. On the other hand, distributions are known for many modern species. In terms of taxa, or groups of species, usually only animals with hard bits fossilize well. Studying modern species is easier, because they’re still around, but less than 2.7% of known species have been assessed for risks (e.g. endangered, extinct in the wild, etc.) by the International Union for the Conservation of Nature (IUCN). There’s also trouble with the species concept. Fossils are usually identified at the genus, rather than species, level; modern work frequently uses genetic approaches to identify individuals to species. Fossils are also not distributed evenly through time. Fossil extinctions are recorded when a certain group of animals vanishes from the fossil record, the extinctions known are likely underestimates since most species have no fossil record.
In spite of these caveats, the researchers evaluated the existing data and show that it is possible to circumvent these various data comparison issues by taking a ‘big-picture’ global approach. Conservatively, mass extinctions occur when the extinction to speciation ratio becomes so unbalanced that three quarters of species disappear, usually within less than two million years. If two million years sounds like a leisurely long time, bear in mind that the Earth is ~4.54 billion years old. Most living things forever blinking of out existence in roughly 0.04% of that time is a colossally unique situation indeed.
Using a rate-based method, the researchers compared extinctions per million species-years (E/MSY)1 from throughout the fossil record and modern time. By using various paleontology databases and accounting for data biases, they were able to establish a background rate of extinction. Through this approach, it is clear that the maximum extinction rates since about 1,000 years ago are much higher than the average fossil rate and the recent average extinction rates are also significantly higher when compared to pre-anthropogenic (that’s pre-us, mind you) averages.
Another way to consider this is by splitting up the fossil record into 500-year intervals and calculating the likelihood that extinction rates were as high in many of these 500-year intervals as they were in the most recent 500 years. In the case of mammals, which have an average of 1.8 extinctions per million species-years, only 6.3% of these 500-year segments could have extinction rates comparable to the current 500-year interval in order to preserve the background E/MSY. So no, it is supremely unlikely that many of these past 500-year bins had extinction rates that were as high as they are today.
But would these current rates produce a large magnitude extinction event? By using modern species assessments of very well-surveyed groups coupled with fossil data, Dr Barnoksy and his team calculate that extinction rates for mammals, birds, amphibians, and reptiles are as quick or quicker than all rates that would have been responsible for the previous five mass extinctions. If all threatened species (defined by IUCN criteria) are lost within a century, and the current extinction rate continue, land-based amphibians, birds, and mammals would reach mass extinction thresholds in ~240 -540 years. This slows down a bit if ‘only’ critically endangered species disappear within the next 100 years to ~890 – 2,265 years for those same groups of animals. Current extinction rates are higher or as high as those that preceded and caused the previous mass extinctions. The researchers point out that while a pressing need for new research exists, the 75% species loss threshold could occur within the next three centuries.
Modern species losses are serious but does not pass the threshold for a mass extinction event yet. Relatively small numbers of species surveyed historically have been lost, although scores of species have yet to be discovered and/or evaluated. However, the researchers point out that losing critically endangered species would put us on the fast track to mass extinction, and losing endangered and vulnerable species would achieve the sixth extinction even faster, within a few hundred years. Sobering commonalities between the present-day and the past mass extinctions exist:
It may be of particular concern that this extinction trajectory would play out under conditions that resemble the ‘perfect storm’ that coincided with past mass extinctions: multiple, atypical high-intensity ecological stressors, including rapid, unusual climate change and highly elevated atmospheric CO2. [Barnosky et al.]
The diversity of life should be preserved while it’s still here.
1 Think of this as man-hours (or really person-hours). On a purely mathematical basis, if you had one million species and an extinction rate of 1 per million species-years, one species would go extinct a year.
Barnosky AD, Matzke N, Tomiya S, Wogan GO, Swartz B, Quental TB, Marshall C, McGuire JL, Lindsey EL, Maguire KC, Mersey B, & Ferrer EA (2011). Has the Earth’s sixth mass extinction already arrived? Nature, 471 (7336), 51-7 PMID: 21368823
This article is also posted at The Urban Times.
On December 8th, Belize signed legislation into place that bans bottom trawling in the nation’s entire Exclusive Economic Zone (out to 200 nautical miles). Oceana (press release), an international organization focused on ocean conservation, assisted the government by negotiating the buyout of existing trawlers; this action also received the full support of the Belize Fishermen Association.
Bottom-trawling has long been compared to its terrestrial analog of forest clear-cutting1. Imagine your local forest bulldozed in order to collect a single target species; not only is the suite of animals and their diversity enormously changed, but their habitat is largely destroyed. However, this happens on an enormous scale in the global ocean, and in the vast majority of cases, is totally legal due to the lack of an international moratorium on trawling and far too few marine protected areas. Fishing gear dragged along the benthos can crush and bury marine animals, utterly decimating structure-forming organisms, such as sponges or corals, which provide habitat. The size, diversity, and turnover time of dominant species are reduced, leading to highly-altered community structure, which can persist for decades. Trawling is not a series of isolated incidents but affects immense areas. For example, off New England and in the Gulf of Mexico in the U.S., the total area fished by trawling is 138,000 km2 and 270,000 km2, respectively, with many areas being swept more than once per year2.
Trawling is a devastating, non-selective fishing method that adds to the global issue of overfishing and obliterates biologically-produced habitat. Trawling impacts are visible from space. In a recent study assessing the impact of human activities on the deep ocean in the North East Atlantic, researchers found that the spatial extent of bottom trawling is, conservatively, at least an order of magnitude larger than all other quantified activities combined, including dumping, communication cables, the hydrocarbon industry, and research activities 3.
This action by Belize should set an example to all coastal nations, and hopefully represents a small step towards comprehensive legislation in both national and international waters. Belize’s ban goes into effect December 31, 2010.
1. Watling L, Norse EA (1998) Distrubance of the seabed by mobile fishing gear: a comparison to forest clearcutting. Conservation Biology 12: 1180-1197
2. For review see: Jackson JBC (2008) Ecological extinction and evolution in the brave new ocean. PNAS 105: 11458-11465
3. Benn AR, Weaver PP, Billet DSM, van den Hove S, Murdock AP, et al. (2010) Human Activities on the Deep Seafloor in the North East Atlantic: An Assessment of Spatial Extent. PLoS ONE 5(9): e12730. doi:10.1371/journal.pone.0012730
In 1883, the world shuddered as the loudest known sound in human history echoed from its epicenter in Indonesia. The noise generated by Krakatoa, a volcanic island in the Sunda Strait, was heard over 3,000 kilometers aways both to the east and west; the resulting tsuanamis produced waves over 30 meters in height and killed 36 thousand people. The eruption altered weather globally. The volcanic dust suspended in the atmosphere halted a proportion of the solar radiation able to reach the Earth–in the year that followed global temperatures were reduced by as much as 1.2 degrees Celsius, not reverting back to normal until 1888.
From this volcanic destruction (two thirds of Krakatoa sank into the sea due to the blast), the island of Anak Krakatau-‘child of Krakatau’-was born, rising from Krakatoa’s crater less then 80 years ago. This newly emerged island presents a unique opportunity to witness to the early stages of ecosystem development.
Eruptions on Anak Krakatau have been active recently, leading some to speculate whether or not another epic volcanic event is on the horizon. Interestingly, fringing coral reefs have since formed on Anak Krakatau and nearby areas. The recovery of the island’s terrestrial ecosystems has been subject to much attention and research. However, the marine communities have largely been unstudied until the last decade. In a work published this year in Coral Reefs, Dr. Starger and colleagues examined the genetic diversity in two reef-building corals, organisms within a marine ecosystem that was totally obliterated by the eruption in 1883. Using microsatellites–short, repeating sequences of DNA–the researchers found that the genetic diversity in Pocillopora damicornis and Seriatopora hystrix, has largely recovered due to initial larval migration from other upstream sources. Further analyses indicate that the coral populations within the Krakatau region may be self-recruiting at this point, and may even be providing larvae to other regions.
So these species of corals have recovered after an sudden, violent eruption. What can we glean from this? Coral reefs worldwide are in trouble, experiencing rapid decline, with mass mortality events projected. In the face of such degradation, more data are needed for conservation, particularly in order to design effective marine protected areas (MPAs). Connectivity is paramount in placing reserves. Coral reefs can serve as larval sources, able to provide offspring to other areas, or sinks, which cannot. The researchers show the repopulation of a destroyed marine ecosystem in the Java Sea from other sources, eventually becoming self-seeding. This larval transport, especially in corals, may not permanently sustain reef populations over time, but can help to initally repopulate areas, for example, after a giant volcano pops its top. Understanding the source-sink dynamics of these hugely-diverse ecosystems will likely be imperative in conservation planning. Recovery of reef environments after disasters is dependent on healthy, nearby larval sources, giving importance to identifying and protecting these areas in networks of MPAs.
C. J. Starger, P. H. Barber, Ambariyanto, & A. C. Baker (2010). The recovery of coral genetic diversity in the Sunda Strait following the 1883 eruption of Krakatau Coral Reefs, 29, 547-565 : 10.1007/s00338-010-0609-2
How should we go about managing the conservation of biodiversity in the face of a changing climate? Species by species? Seems tedious. And expensive to carry to completion. Wouldn’t it be easier if we could determine what factors contribute to high species richness in a non-abstract way, find areas with those parameters, and start there, in terms of protection measures? A new study in PLoS ONE by Drs Mark Anderson and Charles Ferree, both of The Nature Conservancy, is a step towards this. The majority of conservation plans do not account for shifts in species distributions resulting from climate change; the authors posited that if some combination of large scale, geophysical variables, such as elevation or local geology, predicted species richness independently of climatic variables, then ecological reserves could be created that function to protect a large number of species in current and future climate scenarios.
Using geology, elevation, species, and climate datasets for a section of the northeast US, combined with the Maritime Provinces of Canada, the researchers ran linear regressions in search of a model in which non-climatic factors predicted species richness, and did not show dependence on climate. They found that the number of geology classes (like acidic shale or fine sediment), latitude, elevation range, and the amount of calcareous bedrock produced a non-climate dependent model with an R (sq) of 0.94—meaning that the model accounts for 94% of the variance in the species diversity among these states/provinces.
That’s a stunningly significant statistical value, especially considering that this study concerns itself with an area that’s roughly twice the size of California. When the 13,500 + species were split into their respect taxa, the model performed well. During geographic analysis, 40% of rare species within this area were shown to be constrained within 1 geology class; 61% of rare species were constrained in two classes, further making the case of a species and geology class relationship. In a further test, rare species were distributed non-randomly among geological classes—so some classes were associated with higher densities of rare species than others. These results also show that habitat—in this case geophysical—heterogeneity may be more important than the size of the area surveyed (when no relationship exists between area and heterogeneity) in determining the number of species.
This study sets the stage for conservation approaches associated with geophysical settings, but also stresses scale is an issue—entire functioning ecosystems would need to be protected, not just bits of heterogeneous geology here and there. However, this is a long-term strategy that may be successful in biodiversity conservation in a changing climate, and will not necessarily prevent specific species extinctions. Species specific and geophysical conservation approaches could of course be combined, but the authors realistically expect that “inevitable tradeoffs” between these efforts in a period of rapid climate change should be expected. Scale and connectivity between species’ geophysical environments are more important than before realized.
Images: PLoS ONE makes figures and articles available under a Creative Commons attribution license.
Anderson, M., & Ferree, C. (2010). Conserving the Stage: Climate Change and the Geophysical Underpinnings of Species Diversity PLoS ONE, 5 (7) DOI: 10.1371/journal.pone.0011554
A recent article (Sutherland et al. 2010) from Trends in Ecology and Evolution provides insight on several emerging research areas through a practice called ‘horizon scanning’—really, a sciency way to say that the authors shortlisted environmental issues that they collectively felt were important, merited further discussion, and could effect biodiversity. The point is made that science needs to occur before critical policy decisions are made. Admittedly, this is a fairly obvious statement; but it’s important that we be reminded of it. For example, if a fisheries council realizes that their country’s commercial fishers are rapidly depleting a certain fish stock, it would really be nice to know facets of that organism’s life history (e.g. time to reproductive maturity, lifespan, etc.) so that intelligent management decisions could be made before the fishery potentially collapses. The authors discuss 15 issues on the horizon, so to speak. All are quite interesting and have mostly been understudied, so let’s have a look…
Microplastic pollution: Plastic resins comprise the majority of general litter and over time it degrades to small particles. The effects on wildlife are largely unexplored, but hormonal effects are known and a disproportionate impact on filter-feeding sessile organisms is likely. Alan Weismann gives an eye-opening perspective on the history and implications of this, especially in the North Pacific Gyre, in his book The World Without Us.
Nanosilver in wastewater: Nanosilver refers to tiny particles of silver that are used mainly as an antimicrobial and could be potentially used in utensils, air conditioners, and medical devices.
Synthetic meat: Pretty much what it sounds like…meat grown from muscle stem cells in a lab. Costs are prohibitive at this point (this study cites figures between 10,000 and 100,000 USD per kilogram). This has implications for reducing livestock produced greenhouse gases and relieving pressure on exploited fish stocks, as well as land-use changes. The authors warn of possible adverse effects on plant life dependent upon grazing, however. Plus, they don’t know if anyone would actually want to eat the stuff.
Artificial life: Essentially, designing genomes…a topic of enormous ethical and environmental consequence.
Stratographic aerosols: Geoengineering is increasingly being thrown around in academic circles and in the news. This particular idea has to do with injecting particles into the upper atmosphere to reflect sunlight, sort of a planetary sun block. This study concedes that such an approach could lower temperatures, but also warns that it would be ineffectual for reducing the atmospheric carbon load or mitigating ocean acidification. Some aerosols could even reduce the pH of precipitation and increase ozone destruction, while virtually all could modify regional climates. Pretty gloomy possible outcomes for something that’s supposed to help, if you ask me. We can all agree that something needs to be done, but I personally doubt that large-scale geoengineering within earth systems that are not even totally understood should be considered without further research.
Biochar: Burning organic material without oxygen produces biochar. The idea is that such a mechanism would sequester carbon (decomposing plants release carbon) and mitigate climate change. However, to have any real effect It would have to be used globally. Questions remain regarding the effect on biodiversity.
Deoxygenation of the ocean: Dissolved oxygen in certain regions of the world ocean has declined since mid-1900s. This spread of anoxia/hypoxia is predicted to get worse with our current carbon emissions. This water condition is having and will continue to have detrimental effects on marine life and may restructure marine food webs.
Changes in denitrifying bacteria: These bacteria convert anthropogenic nitrogen (via fertilizer runoff into rivers, etc., etc.) to molecular nitrogen which then is reincorporated into the atmosphere. However in some cases, these communities, especially it seems in estuaries, have become nitrogen fixing, rather than denitrifying, effectively becoming a source of nitrogen, rather than a sink, with possible ramifications in ocean acidification or the production of nitrous oxide, a greenhouse gas.
High-latitude volcanism: Step 1: Glacial melting. Step 2: There’s a volcano! Okay, maybe not that dramatic, but there is volcanic activity under glaciers that’s being uncovered. Volcanic activity could speed up glacial melting, leading to potential sea level rise.
Invasive Indo-Pacific lionfish: Lionfish are an invasive species now found from Rhode Island to Columbia, occurring in far greater densities here than in their natural range. They are protected by a barrage of poisonous spines and have the potential to reduce the recruitment of coral reef fish (through consuming larvae). Their effects on the reef ecosystem dynamics are largely unknown.
Trans-Arctic dispersal and colonization: The Arctic in past climatological regimes (e.g. mid-Pliocene) has acted as a dispersal barrier and a controlling force in terms of marine species biogeography. As the waters warm and the ice melts, species may be able to move between the Atlantic and Pacific oceans via the Arctic, with the capacity to alter long established ecosystems. Increased shipping activity through the Northwest Passage is likely to worsen this issue.
Assisted colonization: A significant portion of terrestrial species is predicted to be at risk of extinction by 2050 due to climate change. Assisted colonization refers to the controversial practice of moving organisms to locations that may be more climatologically suitable than where they naturally occur, due to warming in their original locales.
Possible impact of REDD on non-forested ecoystems: REDD (the UN’s Reducing Emissions from Deforestation and Forest Degradation program) focuses on increased forest protection, which may in turn cause more pressure to be put on less-protected systems, which may also have high carbon sequestration potential.
Large-scale international land acquisitions: This refers to countries buying up large amounts of farmable land in order to ensure food supply. Despite having potential positive impacts on developing countries in terms of supplying capital, technology and markets, this study warns of the impact of land-use conversion and intensive agriculture on biodiversity. Locals losing access to their own natural resources is also a possible concern.
Mobile-sensing technology: Using the cellphones of the masses to provide real-term data regarding the environment.
All in all, these topics have largely been overlooked, yet seem destined to become conversation issues in the not-so-far-off future (well, some already are) and therefore research should lead policy decisions, rather than the other way around.
Image: Common lionfish (Pterois volitans) from Jens Peterson on Wikimedia Commons.
Sutherland, W., Clout, M., Côté, I., Daszak, P., Depledge, M., Fellman, L., Fleishman, E., Garthwaite, R., Gibbons, D., & De Lurio, J. (2010). A horizon scan of global conservation issues for 2010 Trends in Ecology & Evolution, 25 (1), 1-7 DOI: 10.1016/j.tree.2009.10.003