Life in a warming ocean

How will different marine species respond to climate change and which species are in greatest jeopardy due to their limited ability to escape warming waters? Two new studies provide insight from different angles.

Galeocerdo cuvier (Tiger shark)

In Eastern Australia, the ocean has been warming at a rate that's 4-times that of the global average. Many marine species have been appearing further south than they ever have before, while others have stayed put. The first study identifies which characteristics seem to be important for species to shift their ranges so quickly. 

As expected, swimming ability is important. Fish are stretching their ranges south faster than other organisms such as starfish and crustaceans. The researchers also found that animals that have large range sizes are also at equilibrium with their environment, and are therefore the most responsive to change and shift the fastest. The tiger shark, short-tail stingray and barren-forming urchin were some of the fish species with the largest range shifts in the region. Filter-feeding barnacles - omnivores that are notoriously invasive - also displayed some of the largest expansions of territory. Meanwhile the spotted handfish, a coastal species in the same region, hasn't extended its distributional range into cooler waters despite shifting temperatures.

We think that this is because species with large ranges are habitat generalists, so their ranges are currently limited more by temperature and not by habitat, allowing them to move freely when temperature changes.

Acanthochromis polyacanthus

Study no 2 examined how fish's genes responded after several generations living at higher temperatures predicted under climate change. Researchers  used a multi-generational rearing experiment to identify the molecular pathways associated with transgenerational thermal acclimation in the common reef fish, Acanthochromis polyacanthus. The project involved rearing fish at different temperatures for more than four years in purpose built facilities at James Cook University, and then testing their metabolic performance.

The research team sequenced and assembled transcriptomes of the different generations of fish and identified 53 key genes that are involved in long-term, multi-generational acclimation to higher temperatures. 

Metabolic genes were among the most upregulated transgenerationally, suggesting shifts in energy production for maintaining performance at elevated temperatures. Furthermore, immune- and stress-responsive genes were upregulated transgenerationally, indicating a new complement of genes allowing the second generation of fish to better cope with elevated temperatures. Other differentially expressed genes were involved with tissue development and transcriptional regulation. Overall, we found a similar suite of differentially expressed genes among developmental and transgenerational treatments. Heat-shock protein genes were surprisingly unresponsive, indicating that short-term heat-stress responses may not be a good indicator of long-term acclimation capacity.

The study is the first to reveal the molecular processes that may help coral reef fishes and other marine species adjust to warmer conditions in the future.

Understanding which genes are involved in transgenerational acclimation, and how their expression is regulated, will improve our understanding of adaptive responses to rapid environmental change and help identify which species are most at risk from climate change and which species are more tolerant.

Productivity and plant species richness

Before we can even begin to hope to reduce the dramatic loss of species the world is currently experiencing, we need to first have a clear understanding of where we should and should not expect biodiversity to be high or low.

Humans depend on high levels of ecosystem biodiversity, but due to climate change and changes in land use, biodiversity loss is now greater than at any time in human history. A leading global initiative is underway to determine whether there are widespread and consistent patterns in plant biodiversity. Sixty-two scientists from 19 countries spanning six continents studied the relationships between plant biomass production and species diversity. 

In a new study they show that a consistent biological rule governing the link between plant biomass and species richness in grassland ecosystems: plant species diversity is generally greatest at intermediate levels of plant biomass. The humped-back model suggests that plant diversity peaks at intermediate productivity. At low productivity only few species can tolerate environmental stress, and at high productivity only a few highly competitive species can dominate.

In this study, we were asking a very simple question: is there a consistent 'rule' governing how grassland plant diversity varies with local productivity? We are trying to determine how many regions of the world operate in the context of biodiversity patterns. Leaning under the hood [of a car] without any clear vision of what parts should be connected will cause all sorts of frustration. It is much easier to make the necessary adjustments once you learn how the system operates.

The results of these findings help unveil how natural systems operate and have global ramifications for the management and conservation of grassland biodiversity. 

As the underlying causes of biodiversity loss are highly contentious, this will be an active area of research for decades. We are hopeful that by understanding the core relationships between land productivity and biodiversity, we can then refine management recommendations for land users with the goal of enhancing both economic and environmental outcomes.

Horsetail identification

Horsetail (Equisetum arvense) is an herbal remedy that dates back to ancient Roman and Greek times. It was used traditionally to stop bleeding, heal ulcers and wounds, and treat tuberculosis and kidney problems. Horsetail contains silicon, which helps strengthen bone. For that reason, some practitioners recommend horsetail as a treatment for osteoporosis. It is also used as a diuretic, and as an ingredient in some cosmetics. However, few studies have actually investigated horsetail's effect in humans. It also contains traces of nicotine and is therefore not recommended for children.

The global herbal products market has grown in recent years, making regulation of these products paramount for public healthcare. For instance, the common horsetail (Equisetum arvense L.) is used in numerous herbal products, but it can be adulterated with closely related species, especially E. palustre L. that can produce toxic alkaloids. As morphology-based identification is often difficult or impossible, the identification of processed material can be aided by molecular techniques.

Researchers from Denmark have therefore explored two molecular identification techniques as methods of testing the purity of these products: a Thin Layer Chromatography approach (TLC-test) included in the European Pharmacopoeia and DNA Barcoding:

We found that each method has advantages and disadvantages, but the TLC-test is the most efficient way of confirming that material in herbal products is indeed E. arvense. On the other hand, the DNA barcoding can be used as a complementary test to determine the identity of adulterant species, particularly E. palustre.

Future work can focus on systematically studying which Equisetum species produce toxic alkaloids, which will assist the quality control of E. arvense herbal products. Further, a chemical method that directly tests for the presence of alkaloids in herbal products can circumvent problems in species identification, directly testing for the quality and appropriateness for human consumption of herbal products. Additionally, the steadily dropping price of next generation sequencing techniques – which massively amplify short DNA fragments – may considerably enhance the success rates of DNA barcoding in degraded or processed material. Finally, given the presence of several putative hybrids between E. arvense and other Equisetum species, further techniques can be applied to investigate the presence of hybrid material in herbal products.

Fake caviar

Caviar, which is harvested from sturgeons and paddlefishes (Acipenseriformes), is one of the most expensive animal products in world trade. Not surprisingly, poaching is a major threat to the survival of sturgeon species worldwide. According to the International Union for Conservation of Nature (IUCN) assessments in 2009, sturgeons are considered to be the most critically endangered group of animals worldwide. Since 1998, all 27 species of sturgeons and paddlefishes have been listed in the Appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which should support their protection from illegal trade. Consequently, any international trade of specimens (e.g., fingerlings or farmed fish), parts and products (e.g., caviar, meat, and fertilized eggs) is controlled and includes a mandatory universal caviar labeling system. With this labeling system, any primary sturgeon caviar containers, including tins, jars or boxes, regardless of the size, must bear a non-reusable label with a code providing all important information about the origin of the caviar. Although this caviar labeling system was developed to distinguish legal caviar from illegal caviar, market surveys using genetic tests for species identification have demonstrated that a considerable amount of mislabeled caviar is still in trade

Researchers from the German Leibniz Institute for Zoo and Wildlife Research (IZW) and the WWF Austria analysed 27 caviar samples from Bulgaria and Romania using a combination of mtDNA testing and microsats.

Only ten labeled tins or jars were in agreement with the species code on their label. Four samples were mislabeled, containing caviar from another sturgeon species or more than one species. In at least one case of mislabeling the caviar was "upgraded" from a lower-priced species to a more expensive one. Six samples were counterfeit and should not have been declared as caviar at all. Three of these counterfeits were free from animal DNA and probably made entirely of artificial substances. One sample was identified as lumpsucker (Cyclopterus lumpus) whose eggs are commonly offered as caviar substitute. The other two counterfeits were most likely made of sturgeon meat.

Four other samples were of great concern. These were sold in restaurants or by street vendors as originating from wild Danube sturgeon, which means they were illegally caught. All four samples were identified as the critically endangered beluga sturgeon (Huso huso) whose population in the Danube region is on the brink of extinction. 

Romania and Bulgaria are the only countries of the European Union where viable populations of sturgeons still occur in the wild, e.g. in the Black Sea and the Danube River. Although catch and trade bans were established in both countries, illegal fishing obviously continues. The results of our study demonstrate the weakness of sturgeon protection in Romania and Bulgaria. Therefore, we recommend enhancing conservation and enforcement efforts.

Comparing Methods for Prioritising Protected Areas

There are insufficient resources available to manage the world’s existing protected area portfolio effectively, so the most important sites should be prioritised in investment decision-making. Sophisticated conservation planning and assessment tools developed to identify locations for new protected areas can provide an evidence base for such prioritisations, yet decision-makers in many countries lack the institutional support and necessary capacity to use the associated software. As such, simple heuristic approaches such as species richness or number of threatened species are generally adopted to inform prioritisation decisions. However, their performance has never been tested. 

A group of colleagues from Madagascar and the UK now evaluated the performance of some site prioritisation protocols that used to rank the conservation value of 22 established and candidate protected areas of dry forest in Madagascar. The organisms of choice were reptiles for which there is comprehensive inventory data available from a range of sites in the contiguous dry regions of Madagascar. The country’s reptile fauna is very diverse, comprising almost 400 species, most of which are endemic (92%) and forest-dependent. Given the dramatic deforestation in Madagascar, such species may depend on the effective maintenance of protected areas for their long-term survival.

The authors tested if their rankings produced by four different protocols correlated with the results of a widely-used systematic conservation planning software called Zonation. The four indices scored sites on the basis of: 

• species richness 
• an index based on the species’ Red List status;
• irreplaceability (a key metric in systematic conservation planning, where each species is weighted by the inverse of the number of protected areas in which it was recorded); 
• a novel Conservation Value Index (CVI), which incorporates species-level information on endemism, representation in the protected area system, tolerance of habitat degradation and hunting/collection pressure.

All of the rankings correlated with the software results, but the CVI and Irreplaceability performed better than Species Richness and the Red List Index which lets the authors conclude:

Given that management is limited by insufficient financial resources, it is all the more critical that available funds are targeted towards the most important sites. While sophisticated analytical tools can and should be used to inform such investment decisions, decision-makers often lack the capacity to use them, or choose not to for other reasons. Instead, they frequently rely on non-transparent, subjective processes or simple measures such as species richness or the number of threatened species. It is therefore important to understand how such metrics can perform and in what circumstances they should be used. Our analysis suggests that some heuristic indices can provide a transparent framework to support evidence-based decision-making by practitioners, although their performance is variable and partially dependent on the amount of information required to use them. Our CVI, which incorporates measures of rarity and threat for individual species, appears to provide a useful alternative to more sophisticated systematic conservation planning tools, and emphasises the benefits of integrating species-specific data into conservation assessments.

Greetings from Pluto

Image credit: NASA/JHUAPL/SWRI

After a nine year long journey through our solar system, New Horizons made its closest approach to Pluto today, about 12 400 km above the surface, making it the first-ever space mission to explore a world so far from Earth. New Horizon traveled about 4.8 billion km and during the journey Pluto actually lost its status as planet and was downgraded to a dwarf planet. 

According to plan, the spacecraft is currently is data-gathering mode and not in contact with flight controllers. The Scientists are waiting to find out whether New Horizons is going to transmit a series of status updates that indicate the spacecraft survived the flyby and is in good health. This transmission is expected shortly after 9 p.m. EST tonight. First images of this flyby are expected for tomorrow. Judging from the ones send to Earth over the last couple of days they will be spectacular.

New Horizons' flyby of the dwarf planet is providing an up-close introduction to the solar system's Kuiper Belt, an outer region populated by icy objects ranging in size from boulders to dwarf planets. Kuiper Belt objects, such as Pluto, preserve evidence about the early formation of the solar system. Once the Pluto flyby mission is accomplished New Horizon will continue its journey into the Kuiper Belt and the team hopes to arrange for a couple of further flybys at larger objects.

Image credit: NASA/JHUAPL/SWRI

A new species a day

As announced previously, my weekly column "Discoveries of the week" ended with issue 45. However, I did not intend to get rid of it entirely but rather turn it into a daily blog under a different address: One species a day 

There are many reasons for this change. One was mere convenience as it much easier for me to have a daily short write up on one new discovery than a weekly assembly. A separate blog also addresses a less barcode enthusiastic crowd and it does justice to the amount of new discoveries the colleagues world-wide make every day. A new species every day might sound like a lot but it is not. There still will be discoveries I won't be able to cover even if I produce a post 365 times per year. And that number is dwarfed by the number of new species we have not yet encountered let alone described.

I thought it was about time to start an independent blog focusing on the amazing new species we find every day during our work as scientists. We are three species into this new series. Have a look and feel free to share the link with colleagues, friends, family: One species a day