Historical and contemporary perspectives concerning species composition, their distribution and general trends of their abundance over time. Phytoplankton, zooplankton and benthos

By Ferdinando Boero

Dear Participants, 

I will try to summarize the discussion, that took place yesterday in the first session of the MARBENA e-Conference. The discussion will continue until the end of this e-Conference and all of your ideas, comments and suggestions will be welcomed. Do not hesitate to respond/react to these first messages.
The discussion started from some points posed by the chairman to initiate the discussion: 
Patterns of events over ecological time are less distinguishable than the ones over geological time. 
Tendencies in the evolution of biota are not so easily detectable over ecological time, since the evolution of species assemblages, in spite of being faster than the evolution of species, is usually slower than our everyday perception.
The Mediterranean is undergoing a dramatic change in its species composition, with the entrance of many alien species (mostly of tropical affinity) and the change in the distribution of autochthonous species (mostly of southern species that move north), two phenomena labelled as tropicalisation and meridionalisation, respectively (although the former term has been used by fishery biologists to describe a different trend). This phenomenon has been recorded even in the Black Sea, the most distant area of the region:  the Mnemiopsis invasion led the Black Sea fisheries to near collapse. This point was also emphasized by Bella Galil who stated that that the littoral and infralittoral biota of the Mediterranean Sea are undergoing a rapid and profound change. She reported the case of Invasive Aquatic Species (IAS) in the Mediterranean and stressed that most of the data available stem from incidental collections, fisheries surveys, pollution monitoring surveys and the like. Francis Dove Por underlined the existence of thousands of samples kept in the Hebrew University and Tel Aviv University collections, waiting to be studied! So far, important collections of Nematoda, Isopoda, Cumacea, Amphipoda, Copepoda, Ostracoda, and many other taxa, including Ploychaeta, Mollusca, Decapoda, Fishes and Copepoda Harpacticoida have been studied. He argues that these are Indo-West Pacific species naturally expanding into the Eastern Mediterranean by way of the Suez Canal, the largest "experiment" in dynamical biogeography that is developing on Europe’s front door. He stressed that some of the recent migrants, certainly several species of fish are in fact returning, since they did live in the Pliocene Mediterranean but disappeared from it because of the consequent glaciations. Bella Galil states that a worse scenario is to come, deriving from the recently announced plans to widen and deepen the Suez Canal, a procedure which will allow an invasion of cohorts of new invaders. She concludes that unless stricter controls are brought to bear – more alien pathogens, parasites and pests, will follow. The role of the public, including the media, nongovernmental organizations, industry, and policymakers, in increasing awareness (e.g. www.ciesm.org/atlas) of the hazards of IAS is fundamental. Finally, a permanent concentrated research effort should be made in order to establish the overall qualitative composition of the Lessepsian migrant biota, the way in which they introduce themselves into the existing Eastern Mediterranean ecosystems and in defining the limits of their advance.
There is no scientifically sound evidence that long-term ecological predictions can be made, since Chaos theory has effectively demonstrated that long-term predictions of the behaviour of complex systems are inherently impossible (Huisman & Weissing, 2001).  Tim Wyatt states that power spectra and other indications of continuously changing systems should be given higher priority. It might be proved that none can be found; that is the common fate of theory! We need a much better understanding of what drives these trends, and how natural and human induced changes in ecosystems interact. Fisheries provide important examples of how far we are still from understanding population regulation, through predictions. He concludes by stating that climate change does not act like a change in the octane number of a fuel, but indirectly through its impact on the species’ life cycle strategies and their own mutual interactions.
What we should do is to identify patterns (the attractors of the chaotic systems), regularities and irregularities, trying then to understand the nature and the cause of change (mechanism), so as to describe and explain the history of the systems we are studying. 

The relevant questions, which would stimulate further discussion of the session, are: 

What are the biota that can change more quickly? (plankton, of course, but consider sudden mass mortalities of benthos, as well). 
This point has been further taken by Tim Wyatt, who stated that there is no reason to suppose that plankton “should respond more quickly than benthos to possible climatic changes”. He argues that his experience of many years of research on the nature of Alexandrium suggests that the distinctions between plankton, nekton, and benthos are to some extent, arbitrary.
What are the most sensitive systems to change? (plankton is preadapted to changeable conditions over a seasonal time frame, whereas benthos is possibly more stable in time and so more exposed to significant changes).
Do we have proofs of serious change in some ecological compartments? (It is important that case studies are not presented as anecdotes but as possible ways of detecting change and its bearing on ecosystem functioning).
Serena Umani tried to answer this question by giving some evidence from the Northern Adriatic Sea, and particularly from its northernmost western part, the Gulf of Trieste, which can be envisaged as one of this "topic" places where we can try to identify "real" community changes. She states that the general pattern is the existence of biological communities abundant in biomass value and poor in diversity ones, caused by the extreme environment conditions.
In this environment there are some interesting cases: a) the first dates back to 1914 when Leder (1915) reported for the first time the appearance in the Gulf of the cladoceran Penilia avirostris, coming from South. Today this cladoceran is the dominant species in the summer accounting at its maximum for even more than 80% of the total net-zooplankton individuals; b) the second is more recent and concerns a copepod (Diaixis pygmoea) absent in the Gulf until January 1990 and continuously present onwards.
Besides climatic change, can man alter the composition and the functioning of the biota in a significant way (besides the obvious destruction of habitats)? 
Is there any convincing evidence that history can be predicted by an algorithm and a mathematical model?  
Does natural history have some bearing on ecology? 
Are we ready to include into current ecological theory the changes that we perceive as separate events but that, instead, might be linked into an historical framework (see CIESM, 2001 pp. 55-58 for an attempt)?
These points have been made also by Serena Umani, who gave some examples:
Mucilage events, registered since 1729, evidenced scientifically since 1872 and thereafter almost each 10 years until 1930.
Red tides along the Emilia Romagna coasts and in some other confined Adriatic environments appearing since the end of '60s, reaching the largest diffusion in the early '80s. Red tides and mucilage events appear to exclude each other (http://www.vliz.be/marbena/summaries.htm).
Massive swarms of Jelly fish peaking at the beginning of '80s, and affected netzoo-plankton communities, reducing their biomass and diversity, thus leading to an increase of ungrazed phytoplankton, whose biomass reached extremely high values. 
Ungrazed red tides and ungrazed phytoplankton caused an increase of phytodetritus sedimentation with a consequent bottom oxygen consumption associated sometimes with massive benthic mortality.
The reduction in benthic communities could have increased the refractory Carbon storage at the bottom and via diffusion in the whole water column, thus contributing to the colloidal Carbon increase, which eventually leads to mucilage aggregation.

Wishing you a more “hot” discussion, 

Prof. Ferdinando Boero.

Summary of discussion about “Historical and contemporary perspectives concerning species composition and their distribution and general trends of their abundance ocer time: commercially and exploited fish and investebrates.” (topic 1 (ii)).

By Francisco Sardà

List of participants:

Introduction. F. Sardà
Biodiversity and fisheries. Dr. G. Tserpes
Some reflexions. D. Lloris
Slovene landings and effort data. B. Marceta
Response to F. Sardà. T. Wyatt
The true on fleets. F. Sardà
The importance of biodiversity conservation. S. Tudela
Comments. B. Mackenzie
Time to embark on Black Sea. W. Appeltans
The role of the EBMF. F. Andaloro
Ecosystem management. J. Gray

We have had a interesting interchange of ideas. and some discussions answered to the provocative aspects presented in the introduction. I will intend here put the more important opinions got during the e-conference, ordered by themes.

Summary 
i) Mediterranean fisheries are characterised by high diversity in terms of catch composition and the structure of the fisheries sector. Traditionally, most of fishing activities are concentrated along the narrow continental shelf and although commercial catches are composed of more than 100 species.  Generally, due to lack of systematic data collection from the fisheries sector, formal stock assessment studies are lacking or they have a high degree of uncertainty. However, it is generally accepted that most stocks are heavily and even over-exploited by any criterion. Fishing puts pressure in the marine community and as it intensifies it is observed a progressive disappearance of the larger individuals from the catches, which are finally consist of one or two year classes. This “fishing-down” phenomenon is common for several Mediterranean fisheries, mainly bottom trawl and static-net ones, targeting demersal species. Apart from the target species, fishing often reduces the abundance of non-target ones, either through the direct removal of individuals (by-catches or discards) or indirectly by altering food chains. Although it is clear that fishing activities have a serious impact on the biodiversity in the Mediterranean, particularly concerning coastal ecosystems, it is difficult to quantify such the impact, as these ecosystems are also affected by other non-fishing activities that cause habitat erosion and, consequently, affect biodiversity. Furthermore, the lack of reliable fishery statistics and the limited international co-operation, in terms of scientific surveys in the area, make much more difficult the extensive assessment of fishing effects on biodiversity.
ii) Critics comments about this pessimism support that most fisheries records, and not just in the Mediterranean, are not collected for scientific purposes, but usually for economic ends. Some records nevertheless can yield valuable information about the ecology of the target species. some of these time series are several centuries long. Their analysis reveals approx 100 year and 20 year signals which account for more than 50% of the variance and which are sychronous over the whole western Mediterranean. Higher frequency variation is sychronous at smaller spatial scales. There is almost no possibility that the low frequency signals are generated by economic or historical events, more likely the reverse could be true. This kind of analysis provides the evidence we need to describe the natural variability of populations as distinct from that induced by exploitation
iii) By other hand the invasive species are also important because invading species can move to which, then it is considered commercial, in individual, if the invading organism does not present/display the required characteristics (not to have economic value). All it to grief that the fishing activity contributes to drain of organisms a space that later will be occupied by others. With respect to other subjects that struggle it wanted to point out general considerations: The advances and backward movements of the organisms in the Mediterranean river basin come happening from always. The causes it is necessary to look for them in the geologic and climatic changes that have occurred from remote times to the present time. Their effects on the organisms, considered like native in a time interval, have followed one another time and time again, without we were there for documenting them.
iv) Under an Ecosystem-based Fisheries Management (EBFM) both of the concepts of conservation and management achieve a high level of integration. Increasing evidence and awareness of the shifting baseline effect and irreversible ecosystem changes point to deep structural and functional changes affecting ecosystems even over historical time-scales. The primacy of fishing and overfishing as the main factor for ecosystem change constitutes a key aspect. Fishing and overfishing so often being the most critical factor (through reducing ecosystem resistance) for further deterioration that is then often additionally mediated by other anthropogenic factors. It is clear that even form a conservationist perspective, the adequate goal could hardly be restoring previous pristine ecosystems, but the maintenance or rebuilding of exploited ecosystems reasonably healthy from the structural and functional point of view, compatible with the maximum conservation of biodiversity. These same goals would also be shared under a fisheries management perspective. Any real attempt to develop a precautionary ecosystem-based fisheries management regime would seek to maximise ecosystem resistance and resilience as well as optimise the return from the fishery or fisheries being managed. In this regard, it is suspected that resistance in degraded ecosystems is somewhat supported by varying levels of redundancy in the functionality of different species, pointing to the need to maintain and enhance biodiversity to increase resistance to ecosystem collapses. This latter principle is also valid for maintaining keystone species. Keystone species –crucial to keep the functional and structural integrity of ecosystems- can be extremely difficult to identify, and –what is more important- change with time since ecosystems are complex and evolving entities. With this premise in mind, it is evident that conserving biodiversity (including functional population levels of the different species) is not only a conservation objective but also a first order objective for fisheries management under an EBFM framework. The resolution of the declared crisis of the Mediterranean fisheries needs to pass through the maintenance of biodiversity and the conservation of resources. The only way to obtain this result is to apply as soon as possible the ecosystem based management principles to fisheries. Notwithstanding the importance of EBMF is highly emphasised by the Reykjavik Declaration, we can observe a strong resistance in adopting this approach by the Mediterranean fisheries policies and research. The ecosystem approach can produce impressive improvements in the understanding of ecosystem processes and conservation of biodiversity, although it has to take into account new types of information. Some of this information is available within the established biological fisheries research and regularly used in the management of several important fish stocks. Additional information, including information on changes in the marine ecosystem and an explanation of these changes are, however, important in order to ensure that decisions regarding management measures are consistent with the complex dynamics of the ecosystems in a long term perspective. Improved co-ordination and co-operation between national and international research institutes is imperative in this respect. Monitoring the ocean environment has important short-term implications for controlling the adverse effects of human activities. However, there is also a long-term purpose in registering changes taking place over decades or longer periods. Such long-term monitoring is essential in order to separate human influence from natural cyclical phenomena or distinct trends in the changes of the marine environment, that may run over many decades or even centuries. Without that sort of knowledge, managerial measures may be in vain, or have little positive effect on observed changes.
Finally
Biodiversity, however, is an important issue not only to protected resources and habitat, but also to sustainable fisheries. While many of the effects of fisheries on the biodiversity are obvious, evidence is lacking for drastic effects that can be produced on the time scale of decades. Those include changes in genetic and ecosystem diversity from levels that have been achieved over million of years through natural selection. Unfortunately, traditional centralized approaches to the management of fisheries are not always capable to control the fishing pressure. New approaches that would include establishment of closed seasons and reserves, and the ban of environment-damaging fishing methods, developed and enforced with the involvement and responsibility of fishing communities are needed.
Faunistic that, in general, increases progressively, adding to one and another species wanted to call the attention on the inventories, without considering if displaced person is a species, if or she has settled down or as it is its real origin. With them biodiversity indices are elaborated that do not lead to anything or, to only indicate, once again the faunistical wealth but not their diversity.
It is important that we look at long time periods because the short data sets we have make it very hard to resolve causes of changes in abundance and distribution since they have wide sources of error and because many factors are co-varying.  Longer data sets can help resolve this.  Also, many of the factors that affect fish abundance also vary at long time scales and we need long time series to have any hope of detecting them
The resolution of the declared crisis of the Mediterranean fisheries needs to pass through the maintenance of biodiversity and the conservation of resources. The only way to obtain this result is to apply as soon as possible the ecosystem based management principles to fisheries. Notwithstanding the importance of EBMF is highly emphasised by the Reykjavik Declaration, we can observe a strong resistance in adopting this approach by the Mediterranean fisheries policies and research. The ecosystem approach can produce impressive improvements in the understanding of ecosystem processes and conservation of biodiversity, although it has to take into account new types of information. Some of this information is available within the established biological fisheries research and regularly used in the management of several important fish stocks. Additional information, including information on changes in the marine ecosystem and an explanation of these changes are, however, important in order to ensure that decisions regarding management measures are consistent with the complex dynamics of the ecosystems in a long term perspective. Improved co-ordination and co-operation between national and international research institutes is imperative in this respect. Monitoring the ocean environment has important short-term implications for controlling the adverse effects of human activities. However, there is also a long-term purpose in registering changes taking place over decades or longer periods. Such long-term monitoring is essential in order to separate human influence from natural cyclical phenomena or distinct trends in the changes of the marine environment, that may run over many decades or even centuries. 

References

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Topic 1 The Known: Historical and contemporary perspectives concerning species composition, their distribution and general trends of their abundance over time.
Identification of "hot spots" of species/habitat diversity and productivity.

By John S. Gray

John Gray raised the point that the idea that one can identify “hot-spots” of high species richness and thereby better conserve diversity came from Myers et al. (2000 biodiversity and hotspots for conservation priorities (Nature 403:853-858) and concentrated exclusively on terrestrial systems.  In this paper Myers identified 25 hot spots based on two main criteria species endemism and the degree of threat. The data were on vascular plants, birds, mammals, amphibians and reptiles; the major visible taxa much loved by conservationist NGOs as a focus for advertising their agenda. The 25 terrestrial hot-spots cover mainly tropical areas such as the Indonesia-Philippines archipelago, Brazil, West Africa and Mesoamerica, but also Madagascar, parts of the Mediterranean, New Zealand Southwest Australia and the Cape Province of S. Africa amongst others. The main arguments used by Myers et al. is that 44% of all species of vascular plants and 35% of the vertebrate groups are confined to these 25 hot-spot areas.  Thus conservation priorities should be based in these areas. In a follow up paper Cincotta et al. (2000) examined the relationship between human populations and the biodiversity hot spots and showed convincingly that these hot spot areas were under threat from human-caused disturbances.

Taking this as a starting point the following points were raised for discussion:
Is the hot-spot idea a useful one to set priorities for marine biodiversity conservation?
Ferruccio Maltagliati (Dept. of Human and Enviromental Sciences, University of Pisa, Italy) suggested that it was very difficult to exactly define a “marine hot-spot”. Thus, a great amount of work should be still done in the marine environment in terms of basic biological, ecological and evolutionary studies. He argued that on one hand, we can obtain estimates of species richness in coastal habitats and those are often related to a number of ecological processes. On the other hand, it should be noted that more and more species, or species complexes, or sibling species are being discovered across most of the invertebrate taxa (e.g. see Hutchings & Ponder, Mar Pollut. Bull 46:153-154, 2003). So, are the estimates of species richness reliable?
John Richard Dolan (Oceanographic Observatory, Villefranche, France) agreed that the idea of  'hot spots' may be questionable with regard to very widely dispersed taxa.  For example, Finlay and Fenchel suggest that the species-richness of free-living marine protists is the same everywhere.  Clearly diversity in terms of species evenness is not.  John Gray added that recent data seems to suggest that marine bacteria and Archea are possibly also cosmopolitan so that there may not be as many species of these taxa as earlier thought. Tim Wyatt (Inst. Of Marine Science, Vigo, Spain) noted that Jim Carlton makes the point that the smaller a species is, the more likely it is that it will be considered cosmopolitan. Tim was recently informed that the morphospecies we call Skeletonema costatum may in fact hide several different species with different bloom periods. And the problem might not be confined to small species. Monteiro & Furness (1998) have shown there are cryptic species of storm petrels in the Azores. which occupy the breeding sites at different seasons. Finally, John Gray pointed out that Nancy Knowlton had reviewed sibling species in the marine environment some years ago and with the wider application of molecular techniques we are likely to find that many "species" are in fact complexes. He asked what does this mean in practical terms for biodiversity conservation? Should we be exploring more about cryptic species or trying to spend more effort conserving habitats in areas where they are under threat? John argued that it doesn't matter if we do not know whether there are 500,000 or 10 million new species to be found in the deep sea. They are not under threat but coastal species are so concentrate our conservation and research efforts in coastal zones.

2. Do we know enough about marine species richness to start to make an attempt to identify marine hot-spots
John Gray made the point that in considering species richness we often neglect the historical (evolutionary) aspects. The Black Sea (and Baltic Sea) are recent and most estuaries in northern Europe were covered by glaciers in the last ice-age so that recolonisation from the species pool outside these areas is slow and still occurring. 
Ferruccio Maltagliati pointed out that even during the last glaciation the Mediterranean was connected with the Atlantic, given that the sill across the Strait of Gibraltar was estimated to be around 280m depth (Bryden & Kinder, Deep Sea Res, 38:445+, 1991). Therefore, the occurrence of a Pleistocenic diversity pump at Mediterranean level must be excluded.  Estuaries in the Mediterranean have followed the recurrent hydrogeological dynamics of the coasts driven by the alternance “ice ages/interglacials”. A different and, at my knowledge, unknown situation is that dealing with coastal ponds and lagoons which aren subject to more drastic hydrogeological dynamics.
In a final comment Dov Por (Israel) commented with the Mediterranean fauna there would be a cycle from interglacial  Senegalian Strombus bubonius faunas, through present-day type faunas, to Boreal Arctica islandica faunas and back again.  These pulses (see also F.D.Por, Systematic Zoology 24:72-78, 1975) would have the short durations of the glacial fluctuations and therefore not produce species-level speciation. However, elements of the super-warm interglacial fauna continuously survive in the Eastern Mediterranean (and perhaps the Pelagian Sea!), whereas some boreal elements survive in the north of the Balearic Sea and the Adriatic.  In these "refugial areas" an infra-specific segregation from the parent populations might be already underway.  

3. Is there a negative relationship between species richness and productivity as on land where low productivity regions (e.g. Southwest Australia and Cape Province) have high species richness?
Although no-one addressed this issue specifically Bill Silvert (Inst. of Marine and Fisheries  Science, Lisbon, Portugal) pointed out that the presence of "hot spots" often reflects environmental conditions that serve as biodiversity factories, but it isn't clear that the number of species has any fundamental meaning. An archipelago with thousands of islands will quickly generate thousands of separate species, but if one of these species becomes extinct it will rapidly be replaced and the invading species is likely to evolve quickly in the same direction. Speciation often is the result of slow spatial diffusion in a heterogeneous environment, which is why there are so many more species of snails in the tropics than of bears in the arctic.
He suggested that we need first of all to consider the possibility that not all species have equal weight - to me the loss of a rare primate like the orangutan is probably a far greater matter than the loss of an equally rare beetle - and perhaps the best way to approach biodiversity is by asking about the marginal value of each species, how some measure of ecosystem quality would be changed if the species went extinct (and the marginal value of some species, like the Anopheles mosquito, may well be negative).
In reply Martin Attrill argued that loss of pandas would not have any great knock-on effect for the ecosystem in which they live, but may have their own value (see below). Therefore, key species to target are those who do have an important role to play in their ecosystem yet are still appealing - a kind of sentinel species that all is not well with the ecosystem. Martin suggested that Posidonia was such a species that was important in the Mediterranean.
Continuing on this theme Bill Silvert replied that some species are vital to the functioning of ecosystems, and we should conserve them for that reason. Other species are attractive to us and their presence enhances our quality of life - these are commonly referred to as charismatic species. And we have the political goal of gaining public support for ecological goals. One way of doing this is to fight for the concept of biodiversity and argue that all species need to be conserved, but this is a pretty crude tool. He then argued against the thesis that the determination of the "value" of different species can be determined solely by ecological experiments. There are a lot of factors to be considered, and at some point I think that these need to be identified and discussed in detail. A quick list he suggested was:
* What does it (the species of interest) do?
* How important is this role?
* Can some other species do the same thing?
* Does it have intrinsic value to man?
* Is it aesthetically desirable? 

Finally Bill raised the issue of making proper risk assessments for the loss of marine species, a view that was supported by John Gray who felt that risk assessment was a severely neglected aspect of marine biodiversity studies.

5. Do we agree that if we conserve the habitat we conserve the species therein so habitat conservation should be a priority in the marine environment?
Miquel Alcaraz (Inst. of Marine Sciences, Barcelona) agreed that conservation of habitats was the way to conserve species and pointed out that in terrestrial systems fragmentation of habitats was the main cause of species loss. This view was echoed by Ferruccio Maltagliati, who added that conservation of biodiversity must also take account of the ecological and evolutionary processes that have generated it.  So that habitat conservation alone was not enough. In other words, some species have requirements that cannot be satisfied by the conservation of only one or a few habitats or biotopes. But, Martin Attrill (University of Plymouth, UK) questioned that the same phenomenon was as important in marine habitats. He argued that in an open system with most species dispersing as young in the plankton, islands of habitat are still completely interconnected and so it could be argued that fragmentation in the marine environment does not create 'islands' in the sense that we know them on land. Whilst conceding that fragmentation of, for example, sea-grass beds will reduce available area and increase edge effects, he questioned that it would really isolate species or populations from others in similar sea-grass islands and cautioned against extrapolating conservation methods and priorities from the land into the sea.
However, Alcaraz and Gray counter-argued that there was strong recent evidence that even species that appeared to be adapted for widespread dispersal did not in fact do so.  Data on barnacle and fish larvae showed much more limited dispersion patterns than one might predict.

Raising a new topic Dov Por argued that we should first of all deal with the "Blank spots", areas that are insufficiently known such as The Pelagian Sea, or the Syrte Sea in south-central Mediterranean.  In reply Martin Attrill suggested that the danger is the gaps will never be truly filled in, or by the time they are it is too late to protect vulnerable known systems. Can we ever know much about the deep ocean, including areas of the Mediterranean? He concluded that due to the way pressures on marine systems are increasing procrastination is not an option!

There was also an interesting side-debate on the ecological impacts of aquaculture, but this had little relevance to the main topic biodiversity of the Mediterranean and Black Seas!

John Gray
24/04/2003

Problems and gaps in the knowledge of Mediterranean biodiversity

By Roberto Danovaro

Why studying gaps in Mediterranean biodiversity?

The Mediterranean Basin is the largest of the world's five Mediterranean-climate regions, stretching east to west from Portugal to Jordan and north to south from northern Italy to the Canary Islands. Surrounding the Mediterranean Sea, the hotspot's 2,362,000 square kilometres, including countries (e.g., Italy, Spain, France, Greece, Israel), is rich of scientific history on the relationships between humans and the sea.
 
The Mediterranean Sea is a potential example for an excellent study system. There are several attributes of the Mediterranean Sea, not the least of which is its attraction to all mankind, that make it the perfect site for conducting both large scale and small scale research projects in the field of biodiversity.  In this regard Rachel Noble pointed out that the Mediterranean Sea should be considered as an optimal model study site for marine biodiversity due to its concentration of the overall characteristics (human population, non point source inputs, response to climate-related warming and trends, and importance to a wealth of societies).

The Mediterranean is the “cultural basin” where the first experts of biodiversity were born (e.g., the Zoological station of Naples, Banyuls-sur-mer, Villefranche sur mer, the Museum-laboratory-of the Aquarium of Monaco, Barcelona). For such historical reasons and for the scientific effort provided into the study of the marine species, the Mediterranean could be the best-studied basin of the world. It is therefore not surprising the large number of species encountered (leading to a high species richness for the Mediterranean region) and the high percentage of endemism.

Because of its long history and strong anthropogenic impacts, the Mediterranean often anticipated environmental problems (e.g., eutrophication, mucilage, impact of fish farming known since Romans’ Empire), which appeared in other world’ seas decades if not centuries later. For example, the Mediterranean is well known for the presence of a strong nutrient gradients. Such gradient of trophic conditions is optimal for testing the hypothesis of a trophodynamic control of biodiversity. 

The Mediterranean Sea is also a good example system for addressing a variety of issues, including the role of temperature in controlling biodiversity and life strategies of marine organisms (as the Mediterranean is a warm sea at temperate latitudes, where deep-sea temperature is always above 12.8°C). The much faster response of the Mediterranean to climate change, make this system as a model for investigating biodiversity response to direct and indirect effects of temperature changes.

1. Overall gaps of knowledge on Mediterranean biodiversity. We still do not have sufficient information for defining the “big picture” of the problems and implications of biodiversity conservation in the Mediterranean. This makes evident that our knowledge of Mediterranean marine biodiversity has a very "limited value", because we are not able to translate our scientific information into precise indications and guidelines to support adequate political decisions. Is this because we did not investigate marine biodiversity in the right way? Simonetta Fraschetti suggested that such “limited value” of our knowledge of Mediterranean biodiversity can be interpreted in two ways. The first aspect is certainly linked to a problem of translation from science to opinion and policy makers (more than 60 Marine Protected Areas have been established in the Mediterranean without any detailed knowledge of the distribution of population, assemblages and habitats to be protected). Secondly there is a matter of approach: the effectiveness of existing MPAs  has been often evaluated without the use of sound experimental designs with the consequence that for most of them we still do not know if they work or not. Simonetta Fraschetti also pointed out that the North Sea has been studied as extensively as the Mediterranean Sea (and maybe since longer adopting quantitative methods and sound experimental designs) but is far from having the same richness of the Mediterranean area. However, John Gray  suggested to take account of the age of the Mediterranean and North Sea in an evolutionary context. The North Sea was land just 10,000 years ago and is shallow with fairly uniform sediment types. So it is not surprising that it has low richness. On the Norwegian continental shelf we have 2,500 species in soft sediments and probably 5,000 in total. There is no reduction in number of species to the Barents Sea, which is species rich. The Mediterranean should be more species rich due to it having been relatively undisturbed by ice ages. It would be nice to have comparative studies to compare richness and molecular clocks of key organisms. Ferruccio Maltagliati suggested that aspects of the evolutionary/historical context invoked by J. Gray can be found in the Northern Adriatic Sea, whose age is comparable to that of the North Sea. Northern Adriatic, in fact, was emerged during last ice age due to the sea-level low stands (about -120m). Thus, the present day marine communities of that area originated from re-colonisation from the south. It would be interesting, as suggested by JS Gray, to compare richness and molecular clocks of key organisms from the Mediterranean and North Sea, also including North Mediterranean samples. 

The Mediterranean sea suffers of a major lack of information especially on global deep-sea biodiversity. There are just few studies that reflect specific programmes and cover only few taxa on small spatial scales. This also reflects the lack of adequate financial support for deep-sea investigations. 
Nelly Sergeeva summarised the knowledge on biodiversity in the bottom sediments bathyal and bathypelagial of the Black Sea. From the moment of founding the hydrogen sulphide zone in the Black Sea and up to the present time they considered, that its depths are lifeless: there is no life in the hydrogen sulphide region except microbial. During entire century lifelessness of deep hydrogen sulphide zone in Black sea is being accepted by the world science as an axiom. This played a decisive role in the planning of hydrobiological studies in the Black Sea only to the depths. Inasmuch as bathyal bottom sediments as benthic life biotopes were neglected by hydrobiologists, three zones were recognised in the Black Sea depending on the occurrence of different dimensional and ecological groupings of zoobenthos. The first, from tide mark to 120–150-m depth, is inhabited by macro- (> 1–2 mm), meio- (1–0,1 mm) and microbenthic (< 0,1 mm) organisms. The second, from the 120–150-m to 250–300-m depth, is occupied by meio- and microbenthos. The third, from the 250–300-m depth to the greatest depth, is where only bacteria dwell. Investigations of the deepwater bottom sediments (40 stations) of the Black Sea at a range of 470-2250 m depths revealed that benthos of the anaerobic zone was partially represented by usual Black sea species, characteristic for the shelf zone, and by hydrobionts, earlier unknown for the Black Sea and for science. About 40 species of benthic organisms from Ciliata, Nematoda, Foraminifera, Kinorhyncha, Harpacticoida, Amphipoda, Acarina and 20 unknown forms of conditional up to the present time taxonomic belonging have been found. These organisms have so peculiar structure that it impedes their attribution to known types and classes of invertebrates, therefore, they have been only tentatively identified.
The occurrence of the same taxa over the wide depth range and in different locations of the sea indicates to the factual existence of life-forms with the status higher than microbial. Therefore, it is logical to presume that “marine snow” sunken to the deep-sea anoxic zone is utilized not only by microflora but also by benthic organisms of different trophic groupings. The deep-water benthic fauna is highly diverse and specialised. The hydrobionts inhabiting sea bottom of the Black Sea bathyal were subdivided according to the origin into 1) species common on the shelf which are brought down into the depth one way or another, and 2) endemics of deep-sea anoxic zone which markedly differ from fauna of surface and subsurface waters of the Black Sea.
In conclusion, it should be stressed that the term “azoic” is not valid when applied to anoxic zone of the Black Sea: the life is diverse and plentiful there. Investigations must be conducted on to fill the gaps in the current knowledge about principles underlying functioning of the deep-sea anoxic ecosystem.
Studying the composition of fauna confined to the anaerobic abyssal, its morphological and physiological features, vertical and spatial distribution would answer many questions about the origin and formation of the endemic fauna, the role it has been performing in organic matter transformation and cycling in ecosystem of the Black Sea. 
We need to better investigate fauna common on the shelf and able to survive in the hydrogen sulphide-contaminated environment; about the ways by which these organisms penetrate the deep sea, the related adaptations and energy sources sustaining their life. The revision of marine life occurrence in the Black Sea will stir up interest of many marine biologists and geologists. Today, our study may be regarded as search, and the obtained results as tentative, both asking for further development.

2. Lack of information on biodiversity distribution at different scales. The field of biodiversity is multi-scalar, there is an evident need for future advancement on approaches covering a wider perspective (from global - ecosystem - community - population down to genotype biodiversity), but also we need more information on variability of biodiversity at different spatial scales (from local to meso-, regional and macro scale). Simonetta Fraschetti, in this regard, rightly observed that the difficulty in comparing the biodiversity of different areas recall the urgent need for using proper monitoring protocols and the develop of efficient and rapid sampling techniques. This would represent the basis for a wide-scale monitoring network of Mediterranean coastal system. The prospect of carrying out large-scale studies to tell apart the sources of natural variability (if still exist) from those induced by human activities is still the requirement to understand effects of pollutants and efficacy of protection. The generalisation of unreplicated small-scale studies is basically unreliable. John Gray and Simonetta Frashetti raised the point of sampling scale for biodiversity analysis. Most studies have no idea what the patterns are at larger scales, i.e., at the regional and biogeographical province levels. Recent research suggests that local species pools are largely determined from regional pools. This holds for coral species but we do not know much for other groups. In the terrestrial literature it is argued that since there is a linear relationship between local and regional richness then local richness is not greatly influenced by proximal factors such as predation and competition. Yet there are few marine studies that have been done on this topic. It is a large gap in our knowledge, but needs large comparative data sets and the Mediterranean would be hugely interesting area in which to tackle this topic.

3. Limited knowledge on the role of  physical processes in the development and maintenance of biodiversity. Rachel Noble pointed out the role played by physical mixing and watermass movement characteristics provide a potential link between studies of “open ocean biodiversity” and other aquatic systems like lakes, streams, and rivers, but also stressed that our understanding of the role that physical processes play in the development and maintenance of biodiversity across aquatic systems is nominal, at best. Alessandro Bergamasco suggested that a possible approach to overcome this difficulty is the study of (small) regions where the two classes of processes interact at comparable scales. A particularly important role could be assigned to the Straits of Messina, where several oceanographic processes are detectable, e.g. strong tidal currents and turbulence, upwelling, thermal fronts, internal waves. Furthermore, the system exhibits strong and very steep gradients of physical features and biodiversity, including deep-sea as well as sheltered areas (coastal ponds). Several questions remain unanswered: Can abiotic features of the environment play a control on the processes which influence spatial and temporal patterns of biodiversity?  Can global-scale climatic changes determine indirect local changes to biodiversity?  Could the above happen through the modulation of the role of a “deep-coastal system” as a generator, carrier and amplifier of biodiversity? To support the discussion on these items Salvatore Giacobbe and Franco Decembrini proposed the example of benthic alien animals and plants, which through the Straits of Messina began their spreading in the two sub-basins (Tyrrhenian Sea and Ionian Sea; e.g., the crustacean decapod Percnon gibbesi coming from the Atlantic Ocean, and the lessepsian migrant seagrass Halophila stipulacea), but other examples and case studies are needed.

4. Lack of information on long-term biodiversity trends. Rachel Noble stated that, in order to begin to properly assess biodiversity in the Mediterranean, there must be a concerted, cross-nation effort to establish baseline information for assessing historical trends in biodiversity. Of course, this is not possible for many taxa, but it may be possible to utilize several "sentinel" species over the past 1,000s of years, to begin to understand this concept of species loss, and how natural stressors and anthropogenic stressors affect loss. Nickolai Shadrin pointed out that climate is a main driver of biota changes. But detecting climate impact over marine biota means gathering long-term data set. There are studies on periodical changes in the Black Sea plankton and benthos (in Russian). But this aspect of biota changes is very poor studied in both the Mediterraenan and the Black Sea. Therefore, we cannot quantitatively assess the role of variability of different climatic parameters (temperature, precipitation regimes, wind regimes, etc.). We only try to start to do it. A possibility would be using the archaeology: e.g., for studying mollusc shells compositions in antique and middle age village litter. Investigation of climatic variability impact on biota on different spatial and temporal scales is possible only with strong international coordination.

5. Predict the impact of pollutants on biodiversity and species loss. The effects of anthropogenic impacts (eutrophication, environmental stressors and micro pollutants) on both structural and functional aspects of biodiversity are of special interest for the Mediterranean Sea with its high degree of human activities and ever increasing coastal development. For a better understanding of the quantitative importance of pollution on biodiversity there is strong need for methods able to specifically detect structural and functional biodiversity parameters. The development of accurate methods for measuring biodiversity with time may allow us to also estimate the magnitude of species richness, and possibly monitoring the species list.  In this regard Simone Mirto suggested that changes in biodiversity, can be very useful for environment impact assessment, but we need overall rapid diagnostic tools, allowing a "real time" environmental monitoring, which is requested for an appropriate and effective management. Macrofauna is commonly utilised for E.I.A. for assessing anthropogenic impacts. However, the use of macrofauna, due to long life span of most species and to the larval supply from other areas, can be not suitable for studies aiming at identifying early indicators of ecosystem change. Probably, microbial-molecular parameters and short life-span species are more suitable to detect different typologies of impacts on the environment. There is a need for identifying generals biodiversity descriptors of overall biodiversity. Moreover, another major scientific task is investigating the resilience of an ecosystem in terms of structural and functional biodiversity. There seems to be a strong sense that we need to find something to measure, anything, so that we can talk about biodiversity in numerical terms. The problem is that quantities we can measure are often only poor proxies for the things that really matter. William Silvert proposed to investigate trophic breadth as it is possible that the loss of some top predators might actually increase the total number of species in a system, but surely that is not what we would consider an improvement in the biodiversity index (unless the vanishing top predator were man). It is possible that finding something that we can measure accurately will not help us with biodiversity issues. We should work in conjunction with all interested parties and find indices that reflect both ecological and social values. And we should test these indices against sample scenarios to see whether they agree with common sense. Simone Mirto also proposed the use biodiversity in an applied framework, but only after we are able to select adequate tools (i.e., taxa), and monitoring changes in biodiversity for these "elected". William Silvert. however, did not agree that all species are equally important, neither that selecting a single indicator taxon to measure biodiversity is a good strategy. The debate on the importance of different species involved Ferruccio Maltagliati, William Silvert and Simone Mirto. A possible solution proposed by William Silvert is: we cannot realistically hope to conserve all species, we have to gamble, and inevitably we will make some mistakes. The argument that we so often hear from scientists, that since we don't know everything we can't do anything, just doesn't work. We can't protect biodiversity without public support, and that means following a strategy that is politically acceptable. In other to achieve the conservation objectives, Paolo Magni proposed to increase the value of existing data by combining them into a common data set to determine large-scale relationships. In this context, the UNESCO/IOC Ad hoc Study Group on Benthic Indicators has merged data sets containing synoptic information on environmental variables and benthic macrofaunal communities from several coastal regions around the world. As such, it is critical identifying variables that could serve as indicators, or “warning signals,” of related adverse environmental conditions leading to stress in the benthos and strong changes in biodiversity. Important attributes of such an indicator are: 1) reliability in their ability to detect stress or change in biodiversity and 2) ease of use and broad applicability in different parts of the world. In the Mediterranean Sea, relevant initiatives have been recently started within the first MedGOOS (Mediterranean Global Ocean Observing System) project MAMA “The Mediterranean network to Assess and upgrade Monitoring and forecasting Activity in the region.” In particular there is a clear need of scientific assessment of existing ocean observing (and monitoring) systems in the Mediterranean at regional, coastal and national scales to design scientifically proven and cost effective coastal data acquisition systems, fully integrated to the basis scale systems. 
Nikolai Shadrin illustrated the case of the Black Sea, which is experiencing drastic changes. There are about 60 alien species, which are spreading in the Black Sea now. Results from invasions of few of them are well known: Mnemiopsis, Rapana, Balanus, etc., but for most part of invasions results are not evaluated yet. We are far from integrated value of total alien species role in the Black Sea biota changes. Now we can make several conclusions: invasion is never neutral. Even if an incomer does not replace a native species but occupies the niche, which is or has became vacant owing to some other factors, it may excludes the possibility for the native species to colonise this niche. Additionally newcomer can create new niches in some biotopes or water bodies. The impact of alien species is complex and unpredictable in principle. The Black Sea is not only recipient of aliens but it plays important role as a donor and transit water body for alien species. Initially in the Caspian Sea (more than 30 species) and then in the Marmara and Mediterranean Sea. Nelly Sergeeva concluded illustrating other aspects of the impact of anthropogenic pollution on the Black Sea, which is steadily increasing. The negative effect is revealed in extinction of species, community perturbations, serious physiological changes arising in organisms, resulting in different pathological phenomena. In the course of the long-term investigation of the Black Sea meiobenthos nematodes subjected to revealed distinct morphological deviations. In some nematodes amphids were anomalous in number, arrangement and localization. The occurrence of anomalous specimens in certain nematodes species, from natural gas seep areas in the western part of the Black Sea, is also of special interest and poses several questions, among which: What is the specific cause of these anomalies? Is that related with highly polluted habitats? Have these anomalies been identified from other polluted or extreme habitats? How spread is the phenomenon that’s been noted in the Black Sea? 

6. Insufficient coupling of classical and molecular techniques for studying biodiversity. There is a limited confidence of “classical” taxonomists in the opportunities offered by molecular biology. For instance, the number of species defined on the basis of the morphological features certainly does not give an appropriate idea of the actual species number, considering the discovery of an increasing number of cryptic species. Moreover, Antonio Dell'Anno opened another window on microbial species richness, which is estimated to range from 105 to 106, but yet almost completely unknown. Molecular tools have provided new insights on prokaryotic diversity, revealing a surprisingly high number of new taxonomic prokaryotic groups in all marine environments investigated so far. Noteworthy the case of the deep anoxic basins of the Mediterranean investigated in the frame of the  EU projects (such as the BIODEEP). The limited information available on microbial diversity, particularly  in deep-water masses and marine sediments is a major gap in our knowledge of Mediterranean biodiversity. However, possible biases of the actual microbial diversity induced by the presence of 16S rRNA gene associated to extracellular DNA have been never addressed. This appears of paramount importance since marine sediments among all aquatic systems investigated so far contain high amounts of extracellular DNA exceeding up to ten times DNA content associated to living cells. Therefore, extracellular DNA may potentially represent a reservoir of genes contributing to misleading the actual diversity of prokaryotes. This could be another gap in the investigation of prokaryote diversity.

7. Lack of studies addressing the coupling of biodiversity with ecosystems functioning, productivity and economical profitability. Investigating marine biodiversity does not mean making a simple species list (although essential as first step). Wulf Greve suggested that functional biodiversity could be the key to successful prognoses and we need to focus our research on a fast development of operative prognostic tools. Roberto Danovaro pointed out that we need to better understand the way biodiversity contributed to the preservation of the natural capital and related economical value. Rachel Noble suggested the linkage between biodiversity, ecosystem function, and economic profitability could not be stressed highly enough. If we do not create tools for assessing biodiversity as a scientific community, and create them in a language and manner useful to managers and public policy makers, then we will have two alternatives. One, the managers will make the tools themselves, to please themselves. Two, the issue will be largely ignored because the impression will be that biodiversity does not matter. Given our choices, we, as a community have to make an effort to demonstrate the "real world" intrinsic value of biodiversity, and the cross-discipline importance of work to preserve biodiversity across all systems. In a sense, as aquatic scientists, we have an even more difficult job to do, because the undersea world is not visible, giving us the added hurdle of 'out of sight, out of mind'. In studies of biodiversity, we are responsible for creating the imagery necessary to interest and engage the policy makers in the "real world". In response to this John Gray raised the question: does species richness matter? The reason for such question started from studies on the Norwegian continental shelf were the John’s lab found that of 809 species over 200 occurred at one single site and 180 others at just two sites (of 101 studied). If this were a general rule, most species would just hanging in and would not provide "goods and services" for mankind. Sure they contain genetic diversity but the only "product" come out of deep-sea diversity that I know is Craig Smith's bacteria that degrade sterols and fats at below 4oC and are likely to appear in detergents of the future. So, claimed John Gray, there is huge species redundancy that makes most species functionally unimportant. This position provoked several reactions and different positions and perspectives. Ferdinando Boero  made the point of the value of biodiversity which is not important just because it is of some use for us (e.g., providing goods and services). Ferdinando Boero also posed strong arguments for defending apparently unimportant species as they are the core of biodiversity. Functionally important species are often a ridiculous minority, but an unimportant species now might be very important tomorrow. Mammalians were irrelevant when the dinosaurs ruled the planet, but were expendable. Function cannot be studied in an ahistorical framework, and evolution is the other medal of ecology. Unfortunately experiments cannot take evolution into account, and also history. The message by Ferdinando Boero is clear: take into the highest consideration also species that, apparently, have no major functional role because in the future they could rule the world. John Gray reported that functional roles of marine species is an increasingly investigated issue that could open interesting research fields for young scientists, indeed Roberto Danovaro stressed that species redundancy can be just apparent. We need more tools for understanding exactly which is the functional role of each species. It is increasingly evident that higher biodiversity increased (in a non linear relationship) ecosystem functioning and efficiency. This give a warn about the importance of apparently "redundant" species. Until we do not know enough about the functional role of most species and even less about the functional relevance of their interactions we should apply a precautionary principle to all species, independently from our present anthropocentric view. John Richard Dolan recognized the that the experimental evidence demonstrating links between diversity and function is quite weak - and for the marine environment simply non-existent. We can hide behind Petri dish experiments or elegant mathematics but at our risk and peril. We need to be open to the possibility that we are examining the wrong scales of time or space - no matter what kinds of experiments we concoct. At the same time we know more about functional aspects of prokaryotic diversity than not on metazoans. This is a great temptation for trying to solve major ecological questions (such as the one dealing with the relationship between structural and functional biodiversity) using bacteria. Understanding ecosystem functioning at the bacterial level is extremely important, but as, Ferdinando Boero says, from one side there are people who say that biodiversity is important only if it is useful to us, from another side there are people who say that we are irrelevant and that bacteria make the world turn. We need a compromise. But there are priorities. According to Ferdinando Boero the final extinction of a species is hard to document and we cannot find a single example of final extinction. Maybe there is something going on for a limpet at Malta. The rest is just a  short list of threatened species (the usual monk seal, turtles, Pinna nobilis, red coral, dolphins). The real threat to biodiversity is that, possibly, lots of inconspicuous species became extinct and we do not even know that they ever existed. Extinction, for species, is like death for individuals. And speciation is their reproduction, leading to perpetuation. But if the habitats disappear, some body plans might disappear. I agree that we can give not much care to one or two species of nematodes that are possibly in danger, but if they die because their habitat is disappearing, then they are the sentinels of something that might worry us. Ferdinando Boero thinks that we have to make the list of all the species and the inventory of habitat types and to map them, doing habitat geography. Monitoring the boundaries and seeing what is shrinking and what is widening would be another approach to biodiversity, complementary to the taxonomic one.  This position was sustained by Gaby Gorsky, who proposed to think about a Mediterranean census of marine life (see www.coml.org) in EU or Mediterranean framework with a minimum of constraints and a maximum of information exchange. William Silvert pointed out the difficulty in defining species importance, as we have to make decisions about marine management, the best decisions, but we cannot hope to protect all habitat. If we could save every species it would certainly conserve biodiversity, but the whole reason we are discussing this topic is that we can't do so. The point of making a list of functionally important species is a matter uncertainty and risk, as declared by  William Silvert. For this we need to use common sense as well as looking for experiments which can give precise answers to unanswerable questions. There are several possible  criteria for evaluating the "value" of a species, including social as well as ecological factors. There are of course others - perhaps a species may prove a source of a valuable pharmaceutical product. But a rigorous scientific analysis can be insufficient to produce adequate answers to issues of conservation of biodiversity. We have to take into account other factors, some of them subjective, to arrive at realistic solutions to the problems of possible species loss. 

Roberto Danovaro, Department of Marine Sciences, Polytechnic University of Marche, Italy

The unknowable - Identification of the drivers of change - Potential drivers of change to marine resources in the Mediterranean and Black Sea; prediction and mitigation schemes
By Prof. Carlos Duarte
Carlos M. Duarte opened the topic with an introduction discussing the major changes in marine biodiversity in the Mediterranean following large changes in sea level over geological time scales, as well as chatastrophic perturbations - as pointed out by Tim Wyatt - to then identify human pressure as a new, growing driver of biodiversity change in the Mediterranean and Black Seas in the past two millenia. John Gray elaborated on the importance of the deep-sea as a posible repository for fauna to recolonise folowing major climatic changes, along with inmigrants from adjacent seas, although perturbations, due to changes in the oxygen level of deep waters, have also impacted deep marine biodiversity in geological times (Dr. Por). Miquel Alcaraz argued that because of the small size of the Mediterranean and Black Sea basins relative to other seas, these amplify the impacts of climate change, marine biodiversity may show an earlier response in the Mediterranean and Black Sea than elsewhere. 
The combination of human impacts overimposed on climate change may render drivers of large-scale changes in marine diversity uncertain, as human impacts also result in climate change. Yet, the Mediterranean Sea ranks amongst the best studied in terms of marine biodiversity, so that Dr. Dolan submitted that if drivers are to be found anywhere, this may be certainly most likely in the Mediterranean and Black Seas, although some communities, such as microphytobnethos are not yet adequately described,a s indicated by Dr. Nevrova. The good basis of knowledge on marine biodiversity in these Seas is allowing the detection of tropicalisation of the Mediterranean and Black Sea through the finger prints left by on going invasions by warm-water species, with examples provided by Drs. Shurova, Duarte, and Gili. Many of these invasions are, however, facilitated by human activity, and do not add to local biodiversity but lead to loss of marine biodiversity, at least locally, and an increased vulnerability to change,a s indicated by Dr. Gili 
Ian David drew on these discussion to indicate that, provided climatic changes may lead to changes in baselines of marine biodiversity over time scales as short as a few decades, there is a need to identify and integrate these change in management and conservation frameworks. 
Prominent among the drivers of change, participants identified human growth in the Mediterranean basin as the major driver of biodiversity loss (e.g. Drs. Ignatiades,Gili, Duarte, Boero). The important role of humans as drivers of change must be conveied, within the existing uncertainties, to society, and Dr. Sardá urged scientists to comunícate with society more often than we do, although Dr. Boero indicated that media filtres the knowledge we are able to convey to society highlighting those ideas than are impacting and can be conveied quicly (seconds). 
The notion that external drivers of change may be identified was, however, challenged by Drs. Silvert and Gili, as intrinsic changes may occur due to desease, natural periodicity of systems, chaotic population dynamics, which may lead to extinctions, and the ability of systems to respond to noise at frequencies close to a resonant frequency of the system.