Change the pitch with a pinch of salt

The global balance of salinity of sea water is about stable. It is balanced by run-off from continents, evaporation, precipitation as well as inflow from hydrothermal vents and other interactions with the lithosphere. Salinity of different oceans and seas vary a bit reflecting mainly the regional balance of evaporation and run-off. Salinity of sea-water varies typically between 33 grams  and 37 grams per litre with a typical household average value of 35 grams per litre. However particular seas, like the Baltic Sea may deviate much from average salinity. Salinity of the open ocean is neither homogeneous nor fixed, and small variations are important for ocean dynamics and water flows. 

Surface salinity - see: Asian run-off, Arctic run-off etc.
[**]

Small variations of salinity are a markers for water-masses in the ocean, and tell us much about origin of these waters, their path and their fate. Early oceanographic research from the beginning of the 20th century discovered that already: The relative high salinity [1] of the North-Atlantic Ocean stems from waters of the Mediterranean Sea. 

Through the Straits of Gibraltar flows a mighty bottom current of very salty water [2] that is formed by the high evaporation in the eastern Mediterranean Sea. The  outflow at the bottom of the Gibraltar Strait is balanced by a surface flow of less saline waters of the North-Atlantic Ocean into the Mediterranean Sea. The relatively salty waters of the North-Atlantic move northward through the eastern North Atlantic touching on their westward flank relatively fresher waters flowing out of the Arctic Ocean. The mighty Siberian rivers discharge into the Arctic Ocean and cause a freshening of its surface waters. The high salinity of the North-Atlantic surface water is a key-parameter for the formation of  deep water in the Greenland Sea when sea-ice is formed in the fresher surface waters.

Deposits formed as Mediterranean was drying up
[***]

Throughout geological times salinity of the ocean varied reflecting geological or climatic change. A dramatic feature known for the Mediterranean Sea was its drying out a bit more than 5 Million years ago, in the so called “Messinian salinity crisis”, when the Strait of Gibraltar was closed - followed by the "Zanclean flood" once the straits opened again. Beyond such very dramatic events on a geological time scale, slight variations of sea-water salinity are a habitual play in the oceans. They are part of the “marine weather” below the surface. They are less well known to the general public than the known salinity changes in coastal zones in response to modified river run-off caused by human activity such as building the Assuan Dam on the Nile or water withdraw from the Colorado river or from China's big rivers. Human activity modifying the "marine weather" in the ocean would be of an impact of a higher magnitude than local changes of continental run-off. 

Inflow, evaporation and outflow
[#]

That anthropogenic climate change impacts on the physics and chemistry of the global ocean is established: rising sea-surface temperatures or climbing sea levels and ocean acidification by the absorption of excess carbon-dioxide  are known features.  “They are not, however, the only potentially important shifts observed over recent decades. Drawing on observations from 1955 to 2004, [researchers] found that oceans' salinity changed throughout the study period, that changes were independent of known natural variability, and that shifts were consistent with the expected effects of anthropogenic climate change.” [*] This conclusion was drawn recently from studying salinity in the top 700m of the global ocean between 60°N and 60°S. 

A suite of computer models of the general water circulation in the ocean and atmosphere was used to assess the salinity changes that were shown in the observations since 1955. It came evident that the known natural cycles could not explain the observations. However the observed changes were consistent with what anthropogenic climate change should cause by shifting the hydrological cycle of evaporation, precipitation and run-off from continents. Theoretically, that is little surprising because higher sea-surface temperatures leading to higher heat content should modify evaporation and thus influence the global water cycle, and so in turn the salinity of the sea-water. However, that this impact can be tracked in changing salinities is new. At least I would have guessed that any impact cannot be discerned from the natural variability. 

Various estimate of ocean heat content in surface layer
[****]

Thus we might now conclude: salinity of sea water is balanced by run-off from continents, evaporation, inflow from hydrothermal vents and other interactions with the lithosphere. But that recently human-induced climate change has  started to influence this balance. Human activity being a noticeable co-driver of hydrological cycles up to shifting salinity of the world ocean, a bit along the line of action: ...increase Greenhouse gases, increase sea-surface temperatures and heat-content, modify hydrological cycles and shift salinities of sea-water...

Martin.Mundusmaris@gmail.com
info@mundusmaris.org

[1] of about 36.5 grams per litre sea-water

[2] of about 38.5 grams per litre sea-water

[*] quote from: “Global ocean salinity changing due to anthropogenic climate change”, EOS, Transaction of the American Geophysical Union, Vol. 94(5) p.60 2013; reporting on research of Pierce et al. "The fingerprint of human-induced changes in the ocean's salinity and temperature fields" published in Geophysical Research Letters 39(21) 2012.

[**] http://www.sciencebuddies.org/science-fair-projects/project_ideas/OceanSci_p002.shtml

[***] http://records.viu.ca/~earles/messinian-crisis-apr03.htm

[#] from not identified source, picture found by Google  - the presentation is incomplete: (1) the out-flowing waters turn north flowing along continental margin, (2) the flow is structured by eddies that are spinning of to migrate south-westward 
[****] from: http://www.aip.org/history/climate/20ctrend.htm

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 et.al. 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."

Martin.Mundusmaris@gmail.com
info@mundusmaris.org

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 http://onlinelibrary.wiley.com/

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
http://www.flickr.com/photos/39425137@N04/5756290055

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.

Martin.Mundusmaris@gmail.com
info@mundusmaris.org

[*] 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)

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].

Martin.Mundusmaris@gmail.com

info@mundusmaris.org

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

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

[2] from Los Angeles Times

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]

Martin.Mundusmaris@gmail.com
info@mundusmaris.org

[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

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.

Martin.Mundusmaris@gmail.com
info@mundusmaris.org

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.

Considerations

• 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. 

Martin.Mundusmaris@gmail.com

info@mundusmaris.org

[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 et.al., 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)