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summaries - second marbena e-conference

Monitoring approaches strategies and indicators


The necessity to monitor marine biodiversity was recognised by all contributors to the discussion. There were however different opinions on how to monitor. The question whether a general methodology for biodiversity monitoring is possible for high and low diversity systems remained largely unanswered. It was emphasised by some people that marine biodiversity work to a greater extent than before should focus on functional aspects of diversity. Because knowledge of functional relationships enable us to assess effects on the ecosystem of species loss or invasion. It was also stressed that that the work to identify indicators of diversity should continue and be intensified. After a slow start a fair number of contributions were posted from people with experience from the Mediterranean to the eastern Baltic area. In the following I will attempt to summarise contributions to the key questions asked by the chair.

1. Should we monitor at all even if we only can register a fraction of the total diversity?

Biodiversity in a broad sense includes different measures at several different levels of biological organisation: Total communities, functional groups, keystone species, species, genes. At the same time, changes can be measured on widely different spatial scales depending on the problem: From regions to the scale of the sample. Given this complexity, is it practically possible to measure biodiversity in a broad sense? Should we monitor at all even if we only can register a fraction of the total diversity?

The answer to this question was a clear yes. The reasons given for this yes varied between different contributors. Although one contributor suggested that existing monitoring programmes could take care also of biodiversity (Anda Ikauniece) most contributors suggested different new approaches. It was stressed by Ferruccio Maltagliati that diversity on several ecosystem levels should be monitored, not only species level but also on individual/population level, and he called for methods (i.e. statistical ones) to compare different levels of biodiversity. Herman Hummel stressed the importance of study coupling between diversity and ecosystem function, and so did the chair. He (HH) further emphasised the use of indicators to meet the needs of managers and politicians, even if they did not reflect total biodiversity. For the case when they do not reflect total diversity, the consequences for the ecosystem and society of the discrepancy should be investigated.

2. What should we measure and where? Are there indicators of diversity?

If we agree that we should monitor, then what should we measure and where? In the marine domain a tradition is to register species of certain size fractions for example benthic macrofauna ( invertebrates >1mm mostly). But does diversity of this faunal compartment relate positively to overall diversity. This brings us to the question: Are there indicators of biodiversity, that is some property, easily measured, that reflects diversity of a greater part of the system, that will indicate environmental pressures on diversity? Do we have such examples in the Baltic or elsewhere?

It was thus agreed that we should monitor biodiversity, but clearly we cannot monitor every aspects of biodiversity. What parts of the ecosystems should be monitored? Johanna Wesnigk suggested to start with habitats where the threats were known, and to focus on key organisms. Anda Ikauniece suggested monitoring of key organisms like the bladder wrack (Fucus) as an indicator in shallow areas of the Baltic. The chair gave further examples of possible habitat forming organisms in the Baltic area and raised the question if monitoring should be restricted to such organisms. However, there was a general perception that determination of species was unavoidable when monitoring diversity. An example where species determination of species, both meio- and macrofauna, is necessary was given by Emil Olafsson,, the effect on meiofauna diversity of the macrofauna invader Marenzelleria. There was some discussion about whether or not the diversity of a single organism group could reflect the overall biodiversity. Emil Olafsson pointed to the fact that in some areas of the Baltic the macrofauna was extremely species poor, while meiofauna was rich in species, and suggested further studies of diversity in macro-, meio- and microbial communities, using T-RFLP genetic fingerprinting. In a message (not yet posted) by Jean-Pierre Feral described the work in WP2 of BIOMARE on bioindicators of diversity changes. A detailed account of the bioindicator concept was given and it was proposed to use pressure indicators and response indicators as they stand in the literature and to link with national and European policies. The efforts were focused on the sorting of state indicators, indices and set of species.

3. What determines the appropriate scale of a monitoring program?

The high dispersal ability of marine organisms and the paucity of rigid physical barriers require that marine diversity is monitored as well as managed on a large scale. Maybe, the appropriate scale for monitoring is the scale of major water masses rather than the scale of individual biotopes on the sea floor. If so, this means that monitoring and management actions should be internationally co-ordinated.

The chair used the fact that many marine organisms have good dispersal abilities, and that marine environments have relatively small physical barriers to argue for monitoring on a large spatial scale. However, Emil Olafsson pointed out that certain groups of organisms in fact have rather restricted dispersal ability, for instance free-living marine nematodes, and suggested that monitoring only on a large scale could be misleading. In a general message, Jean-Pierre Feral informed about the BIOMARE concerted action, where a large scale (and long term) approach have been taken to assess changes in biodiversity.

4. How do the target and the environmental pressures determine monitoring?

The monitoring approach is likely to depend on the target and the environmental pressure. The following two examples are encountered in the Baltic and elsewhere in coastal areas. 1) Hypoxia/anoxia in the bottom waters with negative effects on the biological system. Monitoring to document effects of hypoxia obviously requires high frequency measurements in space and time and the target is likely to be whole communities of organisms. 2) In addition to eutrophication derived threats, contaminants also threatens diversity in the Baltic area and elsewhere. In contrast to the effects of hypoxia which have a patchy distribution, the effects of contaminants is more diffuse and only affect some organisms in the communities. Is it possible to design feasible monitoring programmes that can answer all (or most) questions?

The chair raised the question whether different monitoring approaches should be adopted depending on biodiversity compartment and environmental problem. Johanna Wesnigk pointed out that anoxia in the deep Baltic Sea was not a problem for diversity of microbial communities, while it could be a problem for macrofaunal diversity. This illustrates that the same environmental problem may affect target diversity differentially between different organism compartments.

5. How does diversity determine the monitoring approach?

Should we have different approaches for monitoring in high and low diversity systems? While in low diversity systems like the Baltic, where it not may make much sense to use indici of diversity, maybe monitoring should be concentrated on key organisms, while in high diversity systems use of conventional indici used on whole communities may be more appropriate?

One example raised by the chair, should we have different approaches for monitoring in high and low diversity systems? There was not really any direct response to this question, however Christian Altaba, in a general reponse suggested different approaches in the Baltic than in systems with higher diversity.

Is there a coupling between diversity and ecosystem function in the Baltic Area?


Although high diversity may be a value in itself, the value would be even greater if there were a positive coupling to ecosystem function (for instance remineralisation of organic matter, fish yields etc). Are there evidence of such coupling in the Baltic Area? If so, what may be the consequences of species losses for ecosystem function?

The discussion was focussed on the following abbreviated questions raised by Ragnar Elmgren, For full questions see the introductory document:

  1. The call to preserve biodiversity is partly based on the hypothesis that species richness is important for the functioning of ecosystems, by making them more efficient, less sensitive to perturbations and species extinction, and better at delivering the commercial goods and ecological services humans expect from them. This hypothesis has proven difficult to demonstrate convincingly Only in the last decade has experimental and observational results in partial support of some of these assumptions started to accumulate, but as yet mostly from communities of primary producers, mainly grasslands Not all have found the hypothesised effects of increased species richness. Why have marine biologists largely missed this experimental opportunity?
  2. Facilitation between species is a mechanism whereby biodiversity might influence ecosystem function, and has been described both from deposit-feeding and filter-feeding freshwater ecosystems. Are likely candidates found also in the Baltic Sea?
  3. The naturally species-poor Baltic Sea is an ideal laboratory for comparative experiments on the coupling of biodiversity to system function In the macrobenthos, functional types do not disappear from the Baltic benthos as quickly as species, as we move towards lower salinity. Species may be redundant, that is replaceable by a functionally similar species without changes in ecosystem function, but functional groups or higher taxa may not. Whether a species is considered redundant will partly depend on how we measure ecosystem function. Which measures of ecosystem function are most appropriate for the different habitat types represented in the Baltic Sea?
  4. When we do comparative experiments with the Baltic Sea providing the low diversity treatments, we must also find medium and high diversity treatments that allow appropriate comparisons. Designing such comparative experiments would seem to provide excellent opportunities for joint EU research projects. Where can the best medium and high biodiversity habitats for comparison with the Baltic be found?
  5. If high biodiversity is good, then why should we worry about species invasions in low-diversity systems with “empty” niches, such as the Baltic Sea, which are thought to be particularly susceptible to invasions? Is high biodiversity positive for fisheries, by providing a larger number of target species, or negative, by making the fishery for each target species less efficient? Is maintenance of aquatic biodiversity important for tourism and recreational uses around the Baltic Sea? Should provision of ecosystem services, including catches for the fishery, be seen as an ecosystem function?

The activity under this topic was not overwhelming which may reflect the fact that very few studies have been performed relating to these questions. Still, several valid points were discussed, and several questions raised in the introduction were followed by more questions. The issue of most concern was whether or not invasive species constitutes a threat to low diversity systems in general, and the Baltic ecosystem in particular. The somewhat provocative question in the introduction of why worry about invasions in low diversity systems? was followed by several remarks. Most arguments for the view that invasions was a negative feature were of ethical nature, and no firm evidence was presented that ecosystem function had changed as a consequence of past invasions in the Baltic area. Nor were there firm examples where the native species had been excluded (by competition or otherwise) by the invader. One example of a threat was the comb jelly Mnemiopsis that recently invaded the Caspian Sea. Effects of this species, however, on the Caspian system seems still limited. One reason for the paucity of negative evidence from invasions in the Baltic may however be due to the fact that very few scientific investigations have been made of the relationship between diversity and ecosystem function.

In reply to the question of which type or types of function were the most desirable to preserve or enhance one example was given. The oxygenation of bottom sediments through bioturbation, which affects the biogeochemistry in the sediment and the exchange with the bottom water.

Questions still open and to be answered in the future is, if there is a relationship between diversity and ecosystem function, which types of function are affected, and what are the mechanisms. For instance, is facilitation in guilds of species such a mechanism?

Marine Biodiversity in the framework of GBIF and ENBI


What contribution can marine biodiversity researchers make to international ventures such as GBIF and ENBI? Is marine biodiversity adequately covered in these activities?

Neither this topic caused excessive activity, but several important points were discussed.

Both GBIF and ENBI rely on existing databases and the willingness/possibilities of the custodians to make their data accessible. ENBI will provide guidelines, data protocols, and the digital infrastructure to optimise this accessibility. The contribution of marine biodiversity researchers to GBIF and ENBI depends on:

  • willingness to share data (considering IPR issues and economic and political interests)
  • possibility to easily share data (digitised or not? budget available to digitise?)
  • issues such as the completeness of the data, taxonomic gaps, geographical gaps, etc.

In relation this point Hans du Buf informed about an Expression of Interest (IMAQUA - Introducing tomorrow's imaging technology for large-scale monitoring of microscopic, aquatic organisms) to the EC. After the small pilot projects DiCANN (dinoflagellates) and ADIAC (diatoms), which concerned automatic identification, and a similar project on coccoliths and foraminifera at ETHZ in Switzerland, already 50 biologists and specialists in pattern recognition teamed up to develop tools for automatic identification and for building databases that can be shared. These databases will contain images, validated taxonomy, as well as ecological information. The basic idea is that only a pan-European collaboration with many participants allows to cover enough taxa and habitats.

In co-operation with EuroCat (Species 2000 Europa) ENBI shall create the pan-European taxon list. This list will accommodate marine taxa from ERMS (European Register of Marine Species) higher plant taxa (Euro+Med Plantbase) and terrestrial macro-fauna (Fauna Europaea). Careful assessment of content will be needed here, both because of major gaps, because of a number of overlaps, and because of substantial differences in depth of treatment. Coverage of marine biodiversity by GBIF should/will be addressed by the GBIF representatives.

Ferdinando Boero acknowledged the importance of ENBI, GBIF, ERMS , but questioned the quality of the information in the databases. He essentially made two points; one about taxonomical confusion in some animal groups (Hydroids) and the other that the information was too scanty to be of great use to ecologists. The suggested remedy for the first point was more resources to good taxonomists.

Somewhat related to this issue were two points raised James Wilson 1) Any system is only as good as the information it contains. Although increasingly species lists are being held electronically, there is still a lot of data, including old data, in notebook or similar form, that is not yet electronically available 2) The second point was that the system should be easily accessible and encourage use. For instance, when met by messages like ”your browser does not support the pages” does not encourage deeper exploration. In response to point 1) Cees Hof informed that within ENBI there would be some trials on the digitisation of archived records. Methods, protocols, and standards will be developed for the (automatic) conversion of "paper" information into on-line information and to point 2). Indeed essential. ENBI has a work package devoted to the "user friendliness" of biodiversity services in Europe. This work package will also assess the special needs of specific groups of biodiversity information users.


Although the discussions in the two first sessions generated more questions than answers, there were several conclusions embraced by more than one person. There was a clear consensus on that biodiversity should be monitored, but there were different reasons given for monitoring and different views on what parts of biodiversity to monitor as well as which methods to use. It seemed clear that there were few, if any, monitoring programs running with the specific purpose to monitor changes in biodiversity in the Baltic marine area.

The question of the possibility of using indicators of biodiversity instead of monitoring the whole systems was discussed in several contributions. One issue raised was whether or not monitoring should be focussed on certain habitats formed by some key organisms, like the Fucus belt in the Baltic. Others argued forcefully for using indicators, even if their usefulness not were fully tested. It was suggested to adopt a common definition of biodiversity indicators, borrowed from the terrestrial domain, the so called Pressure-State-Response (PSR) model where measures of the systems should

  • identify the main causes of biodiversity changes,
  • detect the main effects, the rate and extent of biodiversity changes (loss) and
  • evaluate the benefit of the implementation of protective or remedial actions.
Implication for monitoring of this definition would be an ecosystem approach rather than species approach. It was stressed that the scientific work to identify useful indicators of biodiversity should be intensified and one way to go was through comparative work on high and low diversity environments coupled with experimental manipulations.

In relation to indicators, there was some discussion about whether or not the diversity of a single organism group could reflect the overall biodiversity. It was pointed out that in some areas of the Baltic the macrofauna was extremely species poor, while meiofauna was rich in species, and the traditionally used macrobenthos therefore not was the best general indicator of diversity. This issue certainly needs further studies of diversity in several faunal compartments. T-RFLP genetic fingerprinting was also suggested as a complimentary method to measure diversity in the species poor Baltic system.

Several contributors called upon more research to identify the eventual coupling between biodiversity and ecosystem function. The rationale for this efforts being the perception that part of the value of high diversity is due to positive effects on ecosystem functioning. It has been suggested that high diversity systems are more stable and uses resources more effectively than systems with lower diversity. There are however few scientific studies to support this suggestion. It was repeatedly suggested that the low diversity Baltic systems should be ideal for experiments in order to reveal such couplings. In relation to this point the question was raised of which type, or types, of function were the most desirable to preserve or enhance. One example given was the oxygenation of bottom sediments through bioturbation, which affects the biogeochemistry in the sediment and the exchange with the bottom water.

There was great concern about effects of invasive species, and there were calls for investigations specifically assessing effects of invasive species on the native systems. One example were given such as the comb jelly. Mnemiopsis. in the Caspian Sea, There were however no examples of negative effects, like species loss, on the “native” diversity in the Baltic, but rather the reverse, the diversity had increased as a consequence of these invasions. However, few if any, scientific investigations have assessed effects of invaders on the native fauna and such studies should have high priority in the future. One outstanding example in the Baltic is the large deep burrowing North American polychaete Marenzelleria viridis, which possibly affects sediment, layers not hitherto affected by the native fauna. The consequences of this invasion for macro- as well as meio-fauna diversity and for sediment biogeochemistry should be investigated. It was emphasised that by some that the functional effects of both invasions and losses of species deserve further and intensified studies.

First part of the question in the title of the conference “Is a general methodology for biodiversity monitoring possible and do ecosystems with high and low diversity function in a similar way? “ was answered with both yes and no. Yes because most people felt that species determinations were necessary, and no because different approaches in terms of organism compartments could be necessary in high and low diversity systems. Whether or not high diversity systems function differently from low diversity systems is still an open question.

The questions of what contributions marine biodiversity researchers could make to international ventures such as GBIF and ENBI, and if marine biodiversity adequately is covered in these activities, were discussed in the third and fourth session. It was pointed out that fundamental issues were the willingness of researchers to share data, user friendly access to the data bases linked to GBIF and ENBI, and good taxonomic/systematic quality of data in the databases.

One main conclusion of this conference and the message to managers and authorities is to increase funding for work with consequences of species loss and species invasions on the function of marine ecosystems. This because only when we know these relationships can we fully evaluate the loss of value due to a deteriorating biodiversity.

General coordination: Carlo Heip ,Herman Hummel and Pim van Avesaath
Web site and conference hosted by VLIZ