Wednesday, 28 November 2012

Your feet in the mud...

...and again there was this electric feeling.

Tidal Flat
Tidal flats, you walk through the mud. Feet well in the mud and there....

There is electrical power in the see bottom!

Bacteria do the trick. How and why?

First, close to the surface there is oxygen. Deeper in the mud there is little oxygen, or no oxygen at all. There, bacteria live on sulfur chemistry to survive. They do it so well that they need additional electrons, thus electrical current. The oxygen close to the mud's surface with water or air could deliver these electrons.

But how to get these electrons, the current down deep into the mud? Bacteria power lines is the answer. Electrical coupling by long, multicellular bacterial filaments do the job. Those who do the job are named "Desulfobulbaceae".

What's happening; what has been found out?

Mud Crap
The muddy sediments at bottom of sea or lakes are layered. Close to the sediment water interface the sediment is relatively rich in oxygen. That oxygen is used by oxygen-consuming organisms living in the mud.

Deeper in the sediment little oxygen, or no oxygen is found. The sediment is anoxic, and oxygen-consuming organisms cannot survive there. However other organisms are found, for example bacteria that are using sulphate to gain the energy they need. These bacteria exist since billion of years. They are steming from a time when Earth's atmosphere did not contain oxygen and photosynthese producing oxygen was not  - widely - used, or not used at all. Today these oxygen-hostile bacteria live in niches well hidden away.

However that particular oxygen-hostile bacterial life leads to accumulation of hydrogen sulphide, the wast of their specific life-style. Hydrogen sulphide is a gas. It is toxic for oxygen-consuming organisms living in the mud. Thus if, hydrogen sulphide accumulates in the mud and penetrates close to the surface or into the sea water it kills the organisms living there.

So how to get rid of it in a well balance ecosystem of mud? Hinder that the wast accumulates; or hinder that the wast is formed ! But how?

Oxygen is one possibility to transform hydrogen sulphide into inoffensive sulfur and water.  But oxygen is scare in mud, and there is better use for it than transforming a toxcit gas in close neighbourhood to oxygen-consuming organisms. Thus, best keep hydrogen sulphide away from oxygen rich mud. But how?

...a power line
Looking closer on what is needed to hinder forming hydrogen sulphide in first instances, it comes evident that the solution is simple.

The bacteria, when consuming sulfate for gaining their life have to get rid of electrons that are the initial waste of their metabolism. Once these electrons are gone no hydrogen sulfur can form. Thus to do the job, having some electrons "to share upward" would be sufficient. These electrons are captured by oxygen in the surface layer.

So, one needs a powerline to transmit electrons - an electrical current - up to the surface layer of the mud.  And that is happening - in scientist's wording (*):

"A major challenge for multicellular organisms is that of supplying every cell with food and oxygen. Nils Risgaard-Petersen and colleagues report a surprising solution to the problem, arrived at by multicelluar filamentous Desulfobulbaceae bacteria several centimetres long, living in the upper layers of marine sediments sampled in Aarhus Bay, Denmark. These organisms seem to function as living electric cables, transporting electrons from sulphides generated in organic matter in deeper anoxic sediments to the oxygen available in the surface layers. These living micro-cables raise a host of topics for future research, and could also find technological applications" as Nature's editor writes (Volume 491  8th November 2012).

(*) Bacterial power cords, Gemma Reguera, NATURE Vol. 491 8th November 2012; Filamentous bacteria transport electrons over centimetre distances, Christian Pfeffer NATURE Vol. "Oxygen consumption in marine sediments is often coupled to the oxidation of sulphide generated by degradation of organic matter in deeper, oxygen-free layers. Geochemical observations have shown that this coupling can be mediated by electric currents carried by unidentified electron transporters across centimetre-wide zones. Here we present evidence that the native conductors are long, filamentous bacteria. They abounded in sediment zones with electric currents and along their length they contained strings with distinct properties in accordance with a function as electron transporters. Living, electrical cables add a new dimension to the understanding of interactions in nature and may find use in technology development."

Monday, 8 October 2012

Warm the sea to shrink the fish?

Climate change will modulate physical and chemical properties of the ocean; changes of  temperature and acidity are the best understood. Evidently, temperature sensitive properties such a oxygen content of seawater will change too. Its change is going hand in hand with the change of seawater temperatures.  In turn changes of seawater temperature and oxygen content will directly affect marine animals, such as fish and other vertebrates. To recall the obvious, these animals are breathing water to gain the oxygen they need, they are water-breathers.  

Shark - from Animal Corner
The body size of aquatic water-breathers is strongly effected by temperature and oxygen content of the seawater. The maximum body weight of fish is limited by internal physiological balances. The energy demand for swimming, growing living has to be balanced by its supply through "breathing water". The ultimate key factor for energy supply is the amount of oxygen that the animal can breath from water passing through its gulls.  Some fish, sharks have to keep swimming with open mouth to drive a sufficient amount of water through their gulls to survive; their fate: swim or die.

For most fish their fate is a bit less dramatic. If the supply of oxygen is just sufficient to balance consumption for swimming and living, then the fish stops growing. In the sea oxygen limitation is one of the most fundamental limitation to growth of fish and other vertebrates.  Thus it is not for fun, that big marine animals as dolphins, whales or seals breath air.

Facing off their environmental conditions many big fish evolved to prefer cold waters and to exploit its marginally increased oxygen content.  As warmer the seawater is as lesser oxygen it can carry.  Cold bottom waters in which many fish find their preferred habitat have temperatures below 10 degree centigrade and relatively high oxygen content (some mmoles per cubic meter).

World Ocean Circulation Experiment data - oxygen distribution in North Atlantic -  from
Overall the ocean is projected to become a little warmer and less oxygenated under global warming conditions. The bottom water temperatures in the oceans are projected to increase by a tenth of a degree over half a century, and oxygen concentration is projected to decrease by some mmoles per cubic meter over the same period. This is little and fish can, happily, swim away - at least in many cases. Cold water fish move towards the poles and abundance of their populations shrinks if they cannot escape.

Thus the most prominent biological responses to higher temperatures or lower oxygen content are changes of geographical  distribution of fish and their productivity. Simple thermal tolerance being one of the known factors limiting the geographical distribution of species in sea. Take the example of Cod in the North Sea.

Adult Cod - Photo: August Linnman

Cod is preferring cold and thus oxygen rich waters. Increasing water temperatures of the North Sea during the last decades limited the area in which Cod is found, for many reasons: "Because global warming is making the sea warmer the fish are moving further north to look for colder waters, it has been revealed. Over the last 40 years the North Sea's temperature has increased by one degree centigrade, which has proved enough to prompt cod to seek alternative habitats. The warming has also changed the plankton distribution and that has hastened the departure of the cod." (The Telegraph 8th October 2012).

Beyond simple preference for colder water marine fish react also to astonishingly small changes of oxygen content. Both theory and observations support the assumption that warming and reduced oxygen will reduce also the body size of marine fishes.  That is well known, but surprisingly strong is the response.

The expected change of oxygen content of seawater because of global warming is small. The resulting changes in maximum body size of fish were found to be about 20%, what is a lot showing how effective the fish adapted to use that limited resource, oxygen.

Marine biologist [1] were examining the integrated biological responses of over 600 species of marine fishes [*] to build a general picture. They fund when looking at the global scale, that tropical and intermediate latitudinal areas will be more heavily impacted, than sub-polar areas. Average reduction of body size being more than 20%, than sub-polar areas.

From Greenpeace - Cod in Crisis
The marine biologist found changes of geographical distribution of fish, reduced abundance and shrunken body size. In a give habitat, about half of this shrinkage of maximum body size is to changes in physiology of the fish living there. The marine biologist found also that species composition changes. Species with the potential to grow big are replaced by different species of lesser maximum body size.

Evidently, all these changes are important for fishery and thus for (our) food. Their understanding provide an additional  insight to the aggregated impact of climate change on marine ecosystems, that our adaptation to global change has to consider beyond (stupid) overfishing.

[*] The researchers use a global model that has an explicit representation of ecophysiology, dispersal, distribution, and population dynamics of 600 species. They show that assemblage-averaged maximum body weight is expected to shrink by 14–24% globally from 2000 to 2050 under a high-emission scenario for global warming.

[1] Shrinking of fishes exacerbates impacts of global ocean changes on marine ecosystems; William W. L. Cheung, Jorge L. Sarmiento, John Dunne, Thomas L. Frölicher, Vicky W. Y. Lam, M. L. Deng Palomares, Reg Watson & Daniel Pauly; Nature Climate Change, 30 the September 2012 (online publication)

Tuesday, 11 September 2012

Levelling out, trawling the sea

Traces of bottom trawling
from the terramare projet
Bottom trawling is a commercial fishing technique much in vogue since engines powered fishing vessels, although it dates back to the 14th century (in English waters).

Bottom trawling (*)   is a non-selective fishing technique, taking anything into the net. Heavy nets and gear are pulled along the sea floor sweeping-up sediments and anything living there. Currently bottom trawling can be done down to more than 800m depth.

The impact of bottom trawling on fish populations and bottom-dwelling (benthic) animals and plants has received much attention.

However impact of bottom trawling goes beyond  direct effect on biology of the sea bottom. High-energy natural processes, such as tidal currents and bottom morphology interact. They drive sediment erosion, transport and deposition processes over wide parts of coastal shelf and continental margin. Bottom trawling links into these processes.

Satellite image of trawler mud trails
off the Louisiana coast (Wikipedia)
Bottom trawling puts fine sediments back in suspension. Then currents carry the re-suspended sediments further. Consequently, physical, morphological and chemical properties of seabed are altered. Sediment composition is modified, so that chemical exchanges and fluxes at the sediment water interface are altered too. The sea bottom of shelf seas is modified and benthic ecosystems are damaged deeply. Down to the continental slopes, the reworking of the sea floor by trawling gradually modifies the shape of the submarine landscape over large areas, finally altering its physics and chemistry.  

How trawl gear modifies the seabed in coastal seas over wide area has been presented recently [1]. Trawling-induced sediment displacement and sediment removal from fishing grounds thus causes the morphology of the deep sea floor to to change over time. The original complex bottom gets smoother. This is shown by high-resolution maps of the sea-floor relief.  "...marine geologist Pere Puig and colleagues examined a shrimp fishing region off Spain’s Mediterranean coast. Puig, of Barcelona’s Institute of Marine Sciences, used remote-controlled submarines to document gouged and flattened areas along trawling routes. While undersea erosion and other natural processes cut deep valleys into the continental slope, Puig and his team noted that silt had been dumped into one of these canyons by trawling gear" [2]

Testing a steam plough in the 1860s 
During recent decades of commercial fishing on global scale by industrialized fishing fleets, bottom trawling drives evolution of the "seascape", the bottom morphology of coastal and continental seas is influenced over wide areas.

Given the global dimension of bottom trawling, the morphology of the upper continental slope in many parts of the world’s oceans likely has  been altered by intensive bottom trawling. Effects on the deep sea floor are comparable to those generated by agricultural ploughing on land, as Pere Puig concludes [1].

(*) Bottom trawling is trawling (towing a trawl, which is a fishing net) along the sea floor.

[1] Ploughing the deep sea floor; Pere Puig Nature (2012) doi:10.1038/nature11410

[2] from Los Angeles Times

Tuesday, 4 September 2012

Poseidon's health check ?

The health of coastal seas and global ocean is critical for human well-being and sustainable economies. The sea provide food, livelihoods and recreational opportunities and regulates the regional and global climates of the globe. An aggregated  indicator of the "health of the ocean" that describes our interaction with the seas should integrate different sources of information. Then it could be a useful to shape policies, rise public awareness and guide further research catching the wider context of human uses of the sea. Such an indicator was proposed recently [1].

Halpern et al./Nature 2012 (from):
The ocean health score for an aggregate of all countries.
The outer ring is the maximum possible score for each goal.
The petal’s length represents the score for that goal,
and its width indicates how the goal was weighted.
Sustainable management of coastal seas generates a flow of benefits. To do this well requires comprehensive and quantitative methods to monitor the coupled human–coastal sea systems. May be inspired  by the use of the industrial composite indicators, such as Dow Jones tracking economic "health", marine researchers have created now an index that assesses health of coastal seas. From that extrapolation to health of the human-ocean system may be possible, such the claim.

The proposed index aggregates ten goals into a single score of how well a coastal seas are  doing. These goals include food provision, carbon storage, tourism value, etc. and biodiversity [2] and were chosen to reflect both the needs of human societies and ecosystem sustainability. Different from valuing pristine seas the index combine various public goals for a healthy coupled human–ocean system. A value of the composite index was calculated for the exclusive economic zone of every coastal country.

The index is a composite and its average is calculated in a region depending manner; avoiding that one size fits all. That has the consequence that the relative weight of the different goals determine very much the outcome; likewise the averaging method. This method is the strength and weakness of the method; it gives choice to settle on the regionally best mix of indicators but my rise too biases.

Each goal is assessed comparing the situation today with a value for where one would like to be or how likely it will be in the near future; a kind of "regional optimal value". Achieving each goal is expressed as a percentage of its optimal value. Each country's overall score is then the average of its 10 goal scores. The score rewards sustainable behaviour now and in the future. This approach is practical, but whether it makes sense depends on the policy choices for the "optimal value".

"Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Posting a global score of 60 out of 100, the index offers a seemingly gloomy outlook. Almost one-third of the world's countries scored below 50. But the study authors say that the range of scores for individual countries — from 36 to 86, with 5% of nations scoring higher than 70 — implies that there are successes amid the areas of concern. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50." [3]

The Ocean Health Index is a composite index and therefore relative weight of its different elements reflecting policy choices determine much the final score.  Germany's coastal area in the North Sea scores 73 (Belgium 64); Germany ranks fifth in global ranking shortly behind non-exploited waters in the Pacific because the index rewards “sustainable use” and “conservation.” compared to "sustainable fishing".

Ancient Greek God Poseidon and some of its children
"The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.... This should not be considered a failing grade for the oceans, The real value of the index will be the ability to track progress related to management policies over time,” (Co-author Karen McLeod; [ quote by 3])

The  Ocean Health Index gets exposure and debate is opened on the Web. "In October, it will probably be among the metrics considered by the Conference of the Parties to the Convention on Biological Diversity in Hyderabad, India. It may also prove useful in the UN General Assembly's first global integrated marine assessment this autumn", so Virginia Gewin [3]

[1] An index to assess the health and benefits of the global ocean, Nature 488, 615–620 (30 August 2012) by  Benjamin S. Halpern et al. and comment by [3] Virginia Gewin 15 August 2012

[2] for full list and further details see Table S.1 in "Supplementary Information" attached to the research paper or in related paper published by Scientific American

Sunday, 12 August 2012

Overfishing pupils...

Horse Mackerel catches 1950 to 2009 in the Atlantic
(from Wikipedia)
Overfishing is a serious threat for most marine ecosystems.  In its most general form, overfishing means that humans take out more fish and other organisms from the oceans (and freshwaters) than the affected ecosystems can regenerate. As a result, the more one fishes, the less can be harvested. Persistent overfishing may lead to the disappearance (entirely or at least commercially) of a formerly abundant resource (from Mundus Maris).

Industrial fishing in the North Atlantic and its adjacent seas, as authorized by the Member States of the European Union, is accused to hinder recovery of fish stocks. The allowed fishing quotas are too high. Thus, enforcing respect of these quotas is a must. At 1. August 2012 the European Commission took a step to do so. Quotas for 2012 were reduced for Member States having over-fished in 2011.  Maria Damanaki, European Commissioner for Maritime Affairs and Fisheries, said: "Nobody should harbour illusions that overfishing will be tolerated. The rules which exist should apply to all in a systematic and professional manner. Indeed I intend to use deductions to help achieve the main goal of the Common Fisheries Policy: long-term sustainability of Europe's fisheries." 

Horse Mackerel tracked where fished
Reduction of 71 quotas for 2012 were specified; up to 11,624 tons and that for Spain having over-fished Horse mackerel in the coastal sea north of Spain. Total quota reduction for Spain is more than 14,000 tons. However this is little compared to the total Spanish catches of marine fish that exceed 1 Million tons. Nevertheless, Denmark, with quota reduction of 82 tons and global fish catch of 1,2 Million tons seems to be the better pupil in the class  - the rules for the class aren't very demanding.

On consumers to-do-list: insist to get informed where the fish was caught, insist to get fish that had chance to reproduce,  insist on enforcing of existing regulation, and insist to set regulation in a precautionary manner so that fish stock can recover.

p.s. Horse Mackerel should have exceed 24 cm length so that it could have reproduced.

Saturday, 4 August 2012

Biodiversity Consensus ?

Apparent Marine Fossil Diversity
(from Wikipedia)
The variety of life, including variation among genes, species and functional traits - a variety simply called biodiversity -  is to value and biodiversity has a value. This seems to be a general consensus.

It is recognized that biodiversity is critical to maintain  ecosystem functions favourable for us and to benefit directly from ecosystem services. It took hundred of million years of evolution to build up modern levels of biodiversity. Thus evolution of species seems to foster their diversity. That in turn is a indicator, that biodiversity is important for ecosystems and the species forming it.  

Ecosystem functions are ecological processes that control the fluxes of energy, nutrients and organic matter through an environment. Ecosystem services are the suite of benefits that ecosystems provide for humanity, such as provisioning of renewable resources and regulating of climate or disease control.

Find out about threat to marine biodiversity.
Whether and how to express the value of biodiversity in monetary terms is being debated [1]. Considering the threat of biodiversity loss, at least by the pressure of the human population on global living resources, it is tempting  to put a monetary value on biodiversity loss. Having solid estimates of monetary value of biodiversity loss may strengthen conservation claims in face of demands of  economic players. But, before embarking on  a debate whether to apply "a monetary logic" to biodiversity loss, thus down grading somehow the relevance of precautionary or conservation considerations, it may helpful to gather what is state of the art understanding about biodiversity. 

Bradley J. Cardinale and co-workers [2] discuss impact of biodiversity loss on humanity in terms of ecosystem functions and ecosystem services. Their analysis may be framed in six statements and two considerations drawn from their article (**):

 Statements - Biodiversity Consensus

  • There is now unequivocal evidence that biodiversity loss reduces the efficiency by which ecological communities capture biologically essential resources, produces biomass, decompose and recycle biologically essential nutrients.
  • There is now sufficient evidence that biodiversity per se either directly influences or is strongly correlated with certain provisioning or regulating ecosystem services.
  • There is mounting evidence that biodiversity increases the intrinsic stability of ecosystem functions through time.
  • The impact of biodiversity loss on a single ecosystem process is non-linear and saturating, such that change accelerates as biodiversity loss increases.
  • Diverse communities are more productive because likely they contain more key species that have a large influence on productivity, and differences in functional traits among organisms increases total resource capture.
  • Loss of biodiversity across trophic level (*) level has the potential to influence ecosystem functions even more strongly than biodiversity loss within trophic level, and functional traits of organisms have large impacts on the magnitude of ecosystem functioning.


  • Today, for many ecosystem services there is mixed evidence and insufficient data to evaluate, beyond its contribution per se, the relationship between biodiversity, ecosystem services and their trade-offs.
  • Ecosystems deliver multiple services, and many involve trade-offs in that increasing the supply of one reduces the supply of another. The value of biodiversity change to society depends on the net marginal benefits of biodiversity – in terms of services gained – relative to marginal costs – terms of services lost.

The benefit of biodiversity for functioning of human societies seems beyond doubt. Also it seems established that the impact of biodiversity loss on ecological processes might be as large as the impact of  other global drivers of environmental change. Thus, in view of pressure of global human population and its (current) manner of production and reproduction on global ecosystems - e.g. plundering of marine resources [3] - the quantification of impacts of biodiversity loss is needed. 

The best available evidence solidly confirms firm qualitative relationships between biodiversity and ecosystem services. However, currently understanding is missing to establish the solid quantitative relationships that would be a prerequisite to assess biodiversity loss in monetary values. Particular difficulties arises when trade-offs between different ecosystem services is to be taken into account. 

Front page NOAA's National Marine Fishery Service
Thus precaution should prevail when biodiversity loss is to be handled, and conservation of biodiversity is appropriate, even if its monetary benefit can not be quantified and a more suitable use-based quantification may come at hand (***).

p.s. Curious about your feedback regarding how statements and considerations apply to marine biodiversity and marine biodiversity losses

[1] Paulo A.L.D Nunes, Jeroen C.J.M van den Bergh, Economic valuation of biodiversity: sense or nonsense? Ecological Economics Volume 39, Issue 2, November 2001, Pages 203–222

[2]  Bradley J. Cardinale, Biodiversity loss and its impact on humanity, Nature vol. 486, pp. 59-67 (doi: 10.1038/nature11148) 6th June 2012 and Corrigendum 25th July 2012 

[3] see Mundus Maris  for an overview

(*) trophic level: "The trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή (trophē) referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism is from the start of the chain is a measure of its trophic level. Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3 and typically finish with carnivores or apex predators at level 4 or 5. The path along the chain can form either a one-way flow, or a food "web." Ecological communities with higher biodiversity form more complex trophic paths." (from WIKIPEDIA)

(**)  The statements and considerations are largely written by paraphrasing wording used by the authors. The reader is referred to the original article for their exact wording. Any error or distortion is my mistake.   
(***) "Green economics is the economics of the real world—the world of work, human needs, the Earth’s materials, and how they mesh together most harmoniously. It is primarily about “use-value”, not “exchange-value” or money. It is about quality, not quantity for the sake of it. It is about regeneration---of individuals, communities and ecosystems---not about accumulation, of either money or material." (from GreenEconomicsNet)

Tuesday, 19 June 2012

We like “cod available”, Sir!

Hello dear Mr. No Cod 

your views about marine fisheries are acid, possibly even contributing the acidification of the sea. A joke. We have some questions for you. Ready for an interview, Sir? 

Yes, but let it keep straight, Mrs. Haddock and baby-cod are waiting!

So what drives you into these moods, Sir?
Fishery policy of European states; man they should no better! After well-sounding but non-binding declarations the 'compromise position' of the EU Council of Ministers on their Common Fishery Policy states some a very disappointing provisions.

Isn't overfishing not coming to an end, Sir?

The date is 2020. Known overfishing, which could be stopped today, may continue until 2020 for all stocks for which no reference estimate available; that is for 154 of 190 fish stocks. The precautionary principle to protect these stocks is only weakly implemented; and non-action in the case of lacking knowledge is not acceptable. 81% of European fish stocks are overfished despite international and EU-law require to maintaining and restoring its fish stocks. 

But by-catch will come to an end, Sir? 

Landings of by-catch shall be treated differently for every stock. This likely is the birth of a new market for by-catch and baby fish. 

I guess, Sir that neither multi-annual plans, nor subsidies nor interventions find grace under your eyes? 

Well, the multi-annual plans remain non-binding, have to be confirmed every year again. That is weak. Subsidies shall remain not only for 'coastal fisheries'; how far off-shore these go? And buying unsellable catch from tax money at fixed minimum price shall apparently continue. All together not a package to my taste.

Your hope, Sir?
Baby Cod

My hopes now lie with the European Parliament and with the public. Do they really want to allow legalize overfishing and discards to continue until 2020? Beyond that; other than merely developing policy tools, a genuine  fishery policy requires a legal framework to ensure that violations of the precautionary principle can be addressed in front of the court. A recent decision of the European Court of Justice gives me some hope. Direct and individual concern in cases instituted by environmental organizations in a precautionary context maybe listened to, in future.

Dear Mr. No Cod, thank you very much for the interview. 
Let's hope you survive.
And greetings to Mrs. Haddock and baby-cod. 
We like “cod available”, Sir.

Tuesday, 12 June 2012

Seagrass' doomsday, next?

"Seagrasses -- a unique group of flowering plants that have adapted to exist fully submersed in the sea -- profoundly influence the physical, chemical and biological environments of coastal waters. They provide critical habitat for aquatic life, alter water flow and can help mitigate the impact of nutrient and sediment pollution." [1]

Local Treasure 

Man is changing swiftly marine ecosystems around the world. Seagrass beds are declining not only in the Mediterranean: "Seagrass ecosystems rank with coral reefs and tropical rainforests in their many ecosystem services, yet are drastically declining worldwide as a consequence of both anthropogenic and natural pressures including habitat fragmentation, eutrophication, poor water clarity and climate change stressors." [2]  Only 0.2% of the planet's oceans floor is covered by seagrass ecosystems.  A precious marine resource is at risk, and untouched seagrass ecosystems are seldom, and thus are a precious resource and source of understanding: "Shark Bay, in remote Western Australia, is one of the last large seagrass ecosystems virtually untouched by mankind. Almost 800 km (500 miles) north of Perth, Shark Bay's remote location and small human population have protected it...  Here, where populations of tiger sharks, sea turtles, dolphins, and sea cows thrive, the Shark Bay Ecosystem Research Project is endeavouring to determine how this system works so we will be able to make recommendations about how to protect and restore other marine communities." Possibly to learn too about ecosystem services of inhabitants of seagrass beds that mitigate pollution: "Little clams living in the soil of seagrass beds consume toxic sulfides that accumulate in the silty sediments and turn what should be a toxic soup into a healthy aquatic environment where communities of fish, clams and shrimp thrive." [2]

Global Benefit

Seagras ecosystems link into global carbon cycle. The carbon cycle is a biogeochemical cycle of the earth in its own importance. It is interplaying with the biogeochemical cycles of other elements such as nitrogen or phospors. In Earth science, a biogeochemical cycle is a web of pathways by which a chemical element  moves through biosphere, lithosphere, atmosphere, and hydrosphere of the Earth. The cycle combines sources and sinks and matter is repeatedly exchanged between them. 

...and rock cycle.
The carbon cycle has a very visible role in how our planet function. It influences our climate. Strength of sources and sinks for carbon are key for the amount of carbon that is held in the atmosphere, as carbondioxyd, and so influence typical temperature of the globe.  A known major sink for carbon are the forests around the world, an other is the sea.  Now we start to understand that marine seagrass ecosystems likely are able to sequester about the same amount of carbon than forests.  Thus their ecosystem function goes beyond preserving local biodiversity. 

About 30,000 metric tons of Carbon per squarekilometer (C/sq. km)  is stored in your typical forest. Seagrass ecosystems can store up to 83,000 metric tons of C/sq. km.   Part of the carbon being stored since thousands of years  in the soils below them. Seagrass meadows store ninety per cent of their carbon in the soil and continue to build on this indefinitely. Despite their limited geographival range they account for more than 10% of carbon sequestered by the ocean per year.  The greatest concentration of carbon found was in the Mediterranean where seagrass meadows stored carbon many metres deep.

...end of seagrass?

Stingaree in seagrass
As the seagrass beds are disappearing rapidly, that may alter the balance of the global carbon cycle.  Seagrasses are among the world's most threatened ecosystems. A little thrid of all historic seagrass meadows have been destroyed. This is mainly due to dredging and degradation of water quality, what can be regulated by coastal zone management. A further 1.5 per cent of global seagrass meadows are lost each year. Emissions from destruction of seagrass meadows can potentially emit up to 25 per cent as much carbon as deforestation on land.  

However if seagrass meadows are restored they can effectively and rapidly reestablish storing carbon. They also are  providing then again a range of other ecosystem benefits, including water quality protection and  important biodiversity habitat. "In spite of this, the level of awareness is low and management ineffective. Seagrass research is fragmented and there is little integration between researchers and coastal zone managers." [3  This seems to be a doomsday's arrangement - low awarness, ineffective management, fragmented research and little interaction.

p.s. Seagrass is also a fiber that can be used.

[1] quote from Science Daily; [2] from PhysOrg 12th June, "Little clams play big part in keeping seagrass ecosystems healthy, new study finds" by D. Hesterman; [3] Project, Seagrass productivity: from genes to ecosystem management, quote; The text is based on: The study 'Seagrass Ecosystems as a Globally Significant Carbon Stock,' published in the journal Nature Geoscience (Nature Geoscience (2012)] which provides further evidence of the important role the world's declining seagrass meadows have to play in mitigating climate change.

Thursday, 7 June 2012

Share our pill with fish and frog, or not?

Fresh water fish get the pill. Ingredients of contraceptive pills passing through wast water treatment plants into rivers and lakes. For example one of them, ethinyl estradiol (EE2), causes  formation of eggs in tests of male fish. Thus their reproduction is reduced and populations may collapse. Likewise amphibian can be threatened. 

Frog aus dem Spiegel 
This problem is known since several decades. Now European regulation may be set up to limit it. Waste water treatment plants should be equipped to limit EE2 in water bodies to no more than 35 parts per thousand trillion. This is very little, but the substance is very active too. At that concentration a mouth full of water (20 cm³) would hold still 20 million molecules ethinyl estradiol among about three-hundred trillion more water molecules.

Opposition against this regulation is strong, also because of high cost to equip waste water treatment plants.  The wast water treatment process has to be augmented with a step using adsorption on to activated carbon. That treatment would clean the water of other harmful substance too.  Cost estimates are about ~ 30€ per person to install the equipment and ~ 3€ per year and person to run it.

It seems fair that this investment is proposed to the European legislator. It would allow to handle our reproduction in a responsible manner and to protect the environment.

But how to share that investment between public and private under the assumption that ethinyl estradiol (EE2) is suitable for mass production and mass consumption of contraceptive pills? Controlling potential harm to our environment by pollution or further population growth seems needed; also considering that worldwide only three in hundred woman are using contraceptive pills, leaving a wide margin for increase.

Nevertheless it should be asked too, why it was not replaced in due course of last decades since its harmful effects are known?  The substance was developed 1938 and is known too for having side effects on people. It is not the only substance released into fresh water systems that alter or hinder reproduction of fish and amphibian. The proposed enhanced wast water treatment process would clean water of these substances too. Thus it seems worth doing or o we have one control dilemma more, as NATURE [1] reports?

[1] The hidden cost of flexible fertility, R. Owen and S. Jobling, Nature, Vol 485 p. 441

Wednesday, 30 May 2012

Fish length A LITTLE up, so what...

Heavily fished oceans [1]
Integrity of marine ecosystems can be measured by average size of fish.

Therefore governments gather data on that feature all over the world knowing that a large portion of marine biomass is extracted by fishing. In may parts of the world ocean that share exceeds 30%. Many fish get caught before being mature. Thus the reproduction of fish populations gets brutally truncated!

One of the main indicator for the northern North Sea is average size of fish. It is based on the largest data set available and refers to an area heavily fished that still is trying to recover from lasting heavy over-exploitation. 

The "UK Biodiversity Indicators in Your Pocket 2011" [*] reports for large fish, thus equal to or larger than 40 cm: In in the northern North Sea the proportion of ) dropped 1982 to 2009 from about 15-20% in early 1980-ties to about 5% in 1995,  and since.  

 Large fluctuations in numbers between years are features of the size of North Sea fish populations, but changes in the size structure of fish populations and communities reflect changes in the health of the fish community. Thus not quite healthy change if the proportion of large fish in the Northern North Sea fell from around 15 per cent by weight of the fish community in 1982 to a low of two per cent in 2001 and was around seven per cent in 2009.  

What to do? Don't eat small fish!  Know the size, and say no to buy small  fish.

Haddock in the North Sea should have an average length of more than 30 cm length to have a population of mainly mature fish, ready to repoduce.

Now, in 2009 only some large Haddock are at that size - one out of ten. Sorry your food is gone!



Sunday, 20 May 2012

These Phototrophs, I love them so much...

Polished Stromatolite made
by cyanobacteria [**]
In the oceans, ubiquitous microscopic organisms,  the phytoplankton,  account for approximately half the production of organic matter on Earth. These organisms -  phototrophs [*], initially a kind of bacteria and later then algae -  are key for producing oxygen at earth. Since more than 3 Billion years they  are blubbering away -  causing around 2.4 billion years ago the Oxygen Catastrophe. The Oxygen Catastrophe, also called the  Great Oxygenation Event,  marks the transition to an atmosphere with abundant free oxygen to breath.

Phototrophs were producing oxygen already a little of 600 Million years before causing the  Oxygen Catastrophe. However, initially organic matter and dissolved iron captured any free oxygen then these became saturated [%]. The excess free oxygen started to accumulate in the atmosphere. This rising oxygen levels have wiped out a huge portion of the Earth's anaerobic inhabitants at the time. Thus Cyanobacteria, by producing oxygen that was toxic to anaerobic organisms, were essentially responsible for what was likely the largest extinction event in Earth's history, but opening the path to live as we know it. And still today we relying today on these ubiquitous microscopic organisms,  the phytoplankton. 

Analyses of satellite-derived phytoplankton concentration, which are available since 1979, have indicated that phytoplankton concentrations fluctuate over decades and may be linked to climate forcing. Historical records of ocean transparency measurements and direct chlorophyll observations show time dependence of phytoplankton biomass at local, regional and global scales since 1899 Phytoplankton biomass seems to decline in several ocean regions  [1].  Inter-annual phytoplankton biomass fluctuations are superimposed on long-term trends. These fluctuations being correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures.The global rate of decline seems to be ~1% of the global median  phytoplankton biomass per year. Such a decline of oxygen producers or food producers would need to be considered for geochemical cycling and fisheries. It is going well beyond local phenomena, such as  seasonal oxygen deficits that are observed to occur more frequently. 

Seasonal oxygen deficits in coastal ecosystems  already today represents  an acute perturbation to ecological dynamics and fishery sustainability  [2]. Its known that anthropogenic nutrient loading has increased the frequency and severity of  oxygen deficits  in  semi-enclosed seas such as the Baltic.  Also in some parts of the better mixed North Sea summer oxygen levels are declining  to critical values, probably because of ocean warming and the decay of photosynthetic blooms that form as a result of nutrient influx [3].  Historical data over the last century highlight an increase in seasonal oxygen depletion and a warming over the past 20 years.  In 2010, dissolved oxygen in central North Sea  came close to ecological critical values [#] that, if reached, would require management action under the European Union's Water Framework Directive.   

This image shows cold water up-welling near the coast of Peru
(purple) and joining the South Equatorial Current, which flows
westward across the Pacific Ocean. This MODIS SST image
from January 1-8, 2001 shows the ocean in normal conditions,
Credit: NASAaption
Oxygen deficits in open-coast up-welling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves. Up-welling systems support a large proportion of the world's fisheries. Therefore understanding how changes in ocean climate lead to  up-welling-driven oxygen deficits  is critical; even for getting the "blame" right in a sensitive region", such as Persian Gulf.

When large numbers of fish began dying off the northern coast of Oman in the Persian Gulf in late August 2000, the local media reported that the deaths were due to the release of contaminated ballast water from a U.S. tanker visiting the area. Red tide blooms are a common phenomenon in the coastal waters of Oman. Thus Omani authorities feared that a toxic algal bloom was killing the fish, raising concerns about health and food security for their nation's fishing industry. Neither seemed true, using data from two NASA Earth Observing System (EOS) satellites, a team of researchers demonstrated that the fish kill was due to environmental changes that severely reduced the oxygen content of the surface waters   [4, ##].

Thus, these ubiquitous microscopic bubbling organisms,  the phytoplankton, play their role. They are key for producing oxygen at earth, since more than 3 Billion years.  They are key for food. Their decline or absence, nothing to like for.

Modern stromatolites off the eastern coast of Australia.
[*] Phototrophs are organisms that gain the energy to run their metabolism from sunlight; most but are fixing carbon to build their tissues

[**, adapted from Wikipedia] Stromatolites are layered structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of micro-organisms, especially Cyanobacteria. Stromatolites provide some of the most ancient records of life on Earth.

[%; from 5]  Research published recently indicates that earth's output of "...reduction in volcanic gases brought about by a drop in mantle-melt intensity was an important precursor to oxygenation."

[#; adapted from [3]] A hydrographic survey in August 2010 mapped the spatial extent of summer oxygen depletion. Typical near-bed dissolved oxygen saturations in the stratified regions of the North Sea were 75–80 % while the well-mixed regions of the southern North Sea reached 90 %. Two regions of strong thermal stratification, the area between the Dooley and Central North Sea Currents and the area known as the Oyster Grounds, had oxygen saturations as low as 65 and 70 % (200 and 180 μmol dm−3) respectively. Low dissolved oxygen was apparent in regions characterised by low advection, high stratification, elevated organic matter production from the spring bloom and a deep chlorophyll maximum.

SeaWiFS captured this image of a dust storm over the
Arabian Peninsula on May 3, 1999
[##; adapted from [4]] Omani scientists know the Gulf of Oman and Arabian Sea contain oxygen-poor water at depths of about 100 meters  below the surface. This oxygen-poor layer is due to the fact that the whole northern Arabian Sea is so highly productive. Strong winds often sweep iron-rich desert dust out over the Gulf of Oman and Arabian Sea where much of it settles into the ocean. The iron contained in the dust effectively fertilizes biological productivity in the ocean's surface waters. Phytoplankton under the right conditions have the capacity to “bloom,” into exponentially large numbers in a matter of days. Over time, these biota die at the surface and begin to sink to the bottom as detritus. As this detritus sinks it decays, thereby using up oxygen in the water column. The Arabian Sea has one of the thickest oxygen-depleted layers of ocean water found anywhere in the world. Sometimes, due to shifts in the overlying wind field, these deep oxygen-poor waters upwell to the surface. So, ironically, the very reason that Oman’s fish reserves are the largest in the world also indirectly leads to periodic mass fish kills. Satellite imagery gave an indication that there was indeed an up-welling event along the coast of Oman. Remotely-sensed sea surface temperature data showed that cool up welled water appeared at the surface along the Batinah coast as early as August 21, 2000, reaching coolest temperatures by the time of the peak of the fish kill on September 4, 2000.

[1] Daniel G. Boyce, Marlon R. Lewis & Boris Worm;  Nature 466, 591–596 (29 July 2010) 
[2] Brian A. Grantham, Francis Chan, Karina J. Nielsen, David S. Fox, John A. Barth, Adriana Huyer, Jane Lubchenco & Bruce A. Menge; Nature 429, 749-754 (17 June 2004) |
[3] Bastien Y. Queste, Liam Fernand, Timothy D. Jickells und Karen J. Heywood, Biogeochemistry, 2012, DOI: 10.1007/s10533-012-9729-9

Monday, 14 May 2012

Just back again – and friends are there too

Gray whale
Some 800,000 years ago - about the time early human tribes were learning to make fire – a tiny species of plankton called Neodenticula seminae went extinct in the North Atlantic. Now, that microscopic plant has come back again. It drifted into North Atlantic from the Pacific through the Arctic Ocean.

The melting Arctic has opened a passage across the Pole for the tiny algae. And while it's a food source, it isn't being welcomed because it could change the marine food web.

The tiny marine plant's migration is paired with the arrival of a Pacific gray whale, spotted last year off the coasts of Spain and Israel. Gray whale vanished from the Atlantic three centuries ago, likely because of over-hunting.  

Neodenticula seminae off  Iceland
Other phytoplankton species, known as dinoflagellates, are moving steadily eastward across the Atlantic towards Scandinavia. That is looking less innocent then Neodenticula seminae because many dinoflagellates are harmful. Their bloom affects other marine creatures.

Jellyfish too are increasing in the northeast Atlantic, often forming massive blooms. Outbreaks of venomous warm-water jellyfish, Pelagia noctiluca a gluttonous predator of juvenile fish, have become an annual event, forcing the closing of beaches.

Rootmouth jellyfish
Simple changes in temperature mean some species are no longer available when their predators need them. Off Northwest Europe, the warming trend has led to earlier spawning of cod, while phytoplankton have kept their traditional biological schedule. The result is a mismatch between the cod's larval and its food. The impacts of such changes remain difficult to assess. The web of life in the oceans is complex. Some impacts will combine to magnify their effects on ocean life; others might neutralize each other; or marine life might alter abruptly. [*]

[*] after press release of project “Climate Change and European Marine Ecosystem Research”

Tuesday, 1 May 2012

Just a little time ago...

It's just a little time ago, when sea life was bursting. The long-lasting “Proterozoic” had came to its end, after about two billion ( years. Modern “Phanerozoic” times had started – just about five-hundred-forty million (540.000.000) years ago, and marine life made a giant leap. Previously, sea life already had left its traces on planet earth. Now more complex life forms, plants and animals, got ready to proliferate, first in the sea and then on land.

For the record, some dramatic events had happened: marine alga/bacteria-like life had oxygenated the atmosphere, several global glaciations have passed freezing the sea, and evolution of abundant soft-bodied multicellular organisms had taken place in the sea – but no fish, no shell-fish, no corals, no whales, just vigorously living jelly-stuff.

 Wayne Ranney  embraces the Great Unconformity
in Blacktail Canyon,
From blog: written-in-stone-seen-through-my-lens

Then, at the transition between the "Proterozoic" and "Phanerozoic", diversification of multicellular animals happens. Acquisition of mineralized skeletons, which get preserved more easily in the sediments, mark that step. The geological record shows a transition, the “Great Unconformity”. First trilobites and reef building animals such as corals appear; first appearance of a complex feeding burrows; first appearance of small, armored 'shelly fauna'. At their base crystalline rocks; the “Great Unconformity” represent a unique physical environmental transition.  

Global seawater chemistry changed during a time of profound expansion of shallow marine habitats. The marine sediments [1] record both an expansion of shallow continental shelf seas and a different pattern of chemical sedimentation.

Beast from Cambrian Sea
Oceanic alkalinity had increase and chemical weathering of continental crust had enhanced. These geochemical changes reflect a wast period of extensive continental erosion and physical reworking of soil and basement rock. A continental-scale marine transgression is observed. Increase input of silicates from the continents and lower solubility of calcareous minerals in the sea are favourable for the evolution of shells and skeletons. Massive marine sedimentary deposits form in shallow seas, bursting of new forms of life; the Cambrian explosion [2].

Pauline Lim - The Great Unconformity
(with her permission [4])
The stratigraphic surface, which separates (often) continental crystalline rock from much younger Cambrian shallow marine sedimentary deposits, is known as the Great Unconformity; its formation “may have been an environmental trigger for the evolution of bio-mineralization and the ‘Cambrian explosion’ of ecologic and biodiversity following the... emergence of animals" [3].

p.s. Seeing the article [3] by Peters and Gaines in NATURE caused the desire to share it in context of Maris Mundus, to illustate an other aspects of the enormous treasure the sea is. My text is built on their abstract. I hope that simplifying the matter did not distort their idea. For some related reading, also about bio-mineralisation see:
[1] deposited approximately 540–480 Million years ago

[2] from Wikipedia: The Cambrian explosion or Cambrian radiation was the relatively rapid appearance (over a period of many millions of years), around 530 million years ago, of most major animal phyla, as demonstrated in the fossil record, accompanied by major diversification of organisms including animals, phytoplankton, and calcimicrobes. Before about 580 million years ago, most organisms were simple, composed of individual cells occasionally organized into colonies. Over the following 70 or 80 million years the rate of evolution accelerated by an order of magnitude (as defined in terms of the extinction and origination rate of species) and the diversity of life began to resemble that of today.

[3] Formation of the ‘Great Unconformity’ as a trigger for the Cambrian explosion; Shanan E. Peters & Robert R. Gaines; for further reading: or