ABSTRACT
Overfishing and pollution mining of coral reef resources tend to cause shifts from long-lived to short-lived organisms, from mature to immature individuals, and from higher to lower trophic levels. Conceptually, management goals might be to reverse these trends; i.e. simultaneously maximise species diversity, longevity and abundance, and raise the trophic level of populations in exploited and protected areas. Four potential indices incorporating these elements of community structure are proposed for monitoring trends in coral reefs and fisheries.
INTRODUCTION
The Maldives' National Workshop on Integrated Reef Resources Management reflects a widespread recognition of the need for integrated approaches to natural resource management. This workshop follows closely upon an international conference on 'Ecosystem Management for Sustainable Marine Fisheries' organised by the National Research Council (USA), and the material presented here is a modified version of a discussion paper submitted to that conference (Done and Reichelt 1996).
The ultimate measure of a country's success in management of renewable natural resources will be the realisation of the first four goals of ecologically sustainable development (ESD) as described by the Bruntland Commission: i.e.
1. improvement in material and non-material well-being;
2. equity between generations;
3. equity within generations;
4. maintenance of ecological systems and biodiversity.Principles arid tools for achieving these goals include,
5. global issues including international trade and co-operation; and
6. dealing cautiously with risk, uncertainty and irreversibility of impacts.
The principles provide a context for defining ecological, economic and social objectives for resource management, and are being reflected increasingly in the objectives of regulatory agencies around the world. However there are major difficulties in transforming the written objectives into effective action.
Some of the greatest difficulties have been in attempting management of coral reefs and marine fisheries in ways that ensures maintenance of ecosystem processes and biodiversity. Part of the difficulty stems from limits of understanding about ecosystem processes and biodiversity. Without serious scientific input, such concepts provide little if any guidance for management actions meant to sustain them.
Another, perhaps more important factor as seen from the fisher's perspective, is that words such as 'sustaining ecosystem processes and biodiversity are simply that...words. They have no meaning in the context of the realities of day to day life.
Dealing with the limits to scientific understanding calls for
i) improved assessment of ecosystem values and the threats which humans and nature pose to those values, andii) incorporation of these assessments into the decision making processes of resource managers.
Effectiveness in real life calls for 'ownership' of the ESD principles by the fisherfolk and, where they exist, the industry organisations and government agencies who coordinate and/or regulate there activities. 'Ownership' of the ESD principles, in particular principles 4 and 6, means understanding of, and commitment to ideas which are non-existent in the minds of most people, and vague even in the minds of most scientists and resource managers.
Many authors (see Pauly and Christensen 1995) note that over-fished tropical shelves and coral reefs are characterised by shifts from long-lived to short-lived organisms, from mature to immature individuals, and from higher to lower trophic levels. Conceptually, management goals for multi-species fishery managers might aim to reverse these trends; i.e. simultaneously maximise species diversity, longevity, and abundance, and the trophic level of populations in the protected area. These properties would need to be qualified as biological reference points for ecosystems in the same way that percentage of virgin biomass is used in fish population dynamics. Suggested indices are described later in this paper.
METHODS
Incorporating ecosystem concepts into fisheries management: a first attempt
In 1992 a regional committee of fisheries managers (Australia and New Zealand's Standing Committee on Fisheries and Aquaculture) outlined a framework for implementing the principles of ecologically sustainable development in fisheries. It led to development of the concept of Fisheries Ecosystem Management, which includes:
· public awareness and education programs,· long term monitoring of environmental factors, stock assessment, and adaptive management approaches,
· ensuring proper linkage between the usually separated activities of coastal zones management, total catchment management and fisheries management,
· developing strategic management plans, consistent with ESD principles, and focusing on rationalising fishing capacity in over-exploited fisheries.
An Assessment Proforma for implementing Fisheries Ecosystem Management is given in Table 1. It includes a description of the fishery in terms of its resources, description and assessment of current management (including jurisdictional) and research regimes, evaluation of stake-holders' interests and evaluation of integration of environmental and economic factors.
Application of Fisheries Ecosystem Management
The proforma in Table 1 was intended to be relatively all-encompassing and to encourage fisheries managers and the fishing industry to see their activities and responsibilities in the broadest possible context. Needless to say, this aroused serious suspicion among those who thought that their jurisdictional boundaries were being encroached upon or threatened by this notion of managing resources from the ecosystem perspective.
Table 1: Categories of information used to characterise fisheries with a view to implementation of Fisheries Ecosystem Management Protocols
1. Fishery description
2. Jurisdiction
3. Role and Management and Research Agencies
4. Enforcement agency.
5. Major stakeholders (extractive, non-extractive)
6. Detailed features of fishery (catch, value, employment, bait, by catch, discard, etc).
7. Biological information about the resource
8. Economic information (e.g. stakeholders, regional economy, economic efficiency)
9. Environmental information (climate, oceanography, pollution, habitat, status, impact of fishing)
10. Management arrangements
11. Current priorities (for industry, research and management)
12. Consistency with the fisheries ecosystem management framework (a: education, b: data collection and research, c: inclusion of cross sectoral issues and impacts, d: structured management mechanisms)
13. Review mechanism (to evaluate priorities regularly)
14. Any other significant issues not addressed in the above.
Source: Chesson et al, 1995.
The fisheries ecosystem management proforma was used for a tropical fisheries region that spanned most of the Northern Australia and include a set of diverse fisheries including fish, crustaceans, sharks and molluscs (pearl and trochus). The draft paper was prepared for the Bureau of Resource Sciences in Canberra and is not published. It highlighted the high diversity of the region and the complexity of the jurisdictional and regulatory arrangements in place for some of the resources.
A national workshop to review the idea of fisheries ecosystem management was convened and the proceedings published (Chesseon et al, 1995). This report highlighted a few of the difficulties confronting fisheries managers adopting this approach:
· difficulties in defining appropriate spatial scales;· lack of information in many areas;
· lack of resources to either complete the proforma or to provide the necessary information in the future;
· insufficient emphasis on the environment (i.e. non-fisheries elements);
· difficulties in interpreting the proforma in a consistent way.
Clearly the management agencies have had difficulty in fully embracing the idea. The principal obstacles are political but lack of knowledge of the ecosystems that sustain particular fisheries is also a critical problem.
Notwithstanding these difficulties, there has been considerable reform in Australian fisheries management over the past few years. There has been a steady increase in involvement of fishing industry representatives in the process of stock assessment and development of management plans. There has been an increase in the use of reference points in management, and also a move towards education rather than enforcement as the most effective method of resource management.
Performance indicators - comprehensible and ecologically meaningful
Education includes educating the educators. One challenge is for someone to come up with simple measures of ecosystem well-being for use across the diverse tiers of groups and individuals involved in resource science, use and management. In communications between scientist and manager, both parties need those values to be soundly based (i.e. on agreed properties of the ecosystem) and to be measurable in monitoring programs.
The precision of the measure and areas of uncertainty need to be identified 'up front'. In communications between manager and legislator, the scientific bases of the measures is less important than their relevance to international treaty goals and national production targets. In communications between manager or legislator and resource user, there needs to be acceptance that the measures are legitimate, even if their underlying basis is only vaguely comprehended. For example, through television, most Australians understand that a positive value for the 3 0 days mean of the Southern Oscillation Index is a' good thing' (rain likely), though few are aware of the basis or significance of its calculation (ratio between atmospheric pressure at Pappette and Darwin).
Communicating scientific advice to resource managers
Here, we present some indices, as yet untried, in which a high value is meant to reflect 'a good thing' in terms of ecosystem well-being. New protocols which may have broad applicability were recently put forward for assessing biodiversity and ecosystem processes on coral reefs (Done 1995a; Table 2; Fig 1). The goal was to develop a single index which reflected the most obvious manifestations of biodiversity and ecosystem processes. The index components are assigned subjectively, on five point scales, in rapid ecological assessments (REAs), but they have an underlying quantitative basis (Table 2, Eq. 1 and Eq. 2) which could allow assessments to be verified or modified using quantitative surveys when, for example, there are conflicting demands for the use of a particular place. The utility of the index and its components are currently being assessed by the Great Barrier Reef Marine Park Authority.
For biodiversity (Eq. 1, Table 2), the index describes representativeness (low scores) or uniqueness (high scores) of the species composition and species abundances at a site (areas from say 0.1 to 10 hectares) in the context of the region (e.g. the reef, archipelago, tract) of which it is a part. Sites are discriminated by assigning different weightings to species which are common, rare, and previously unreported in that region, and by incorporating an estimate of abundance of each species in the site.
For ecosystem processes, a 'bioconstruction' index (Eq. 2, Table 2) was developed, because it was seen as a measure of the quintessential outcome of 'successful' ecosystem processes - i.e. the extent of the contribution by living corals to the wave-resistant reef framework. This approach assumes that assessing an outcome of ecosystem processes is a legitimate surrogate for assessing the processes themselves. In coral reefs, longevity of individuals (say decades to centuries) at a site is manifest as the 'framework' mode of bioconstruction (i.e. incorporated into the reef matrix in, or close to, their position of growth). In other coral-dominated areas, more ephemeral coral species (years to decades) contribute to the 'sedimentary' mode of bioconstruction. i.e. they are broken and eroded into sedimentary particles from sand to block sizes, and are often transported into sedimentary 'sinks' by gravity, waves and currents. A 'framework' area is considered dysfunctional if it is dominated by more ephemeral, non-reef building biota such as algae and/or many soft coral species. The tricky part is determining when such states are symptomatic of anthropogenic degradation, and when they are a normal part of an ecological disturbance/succession cycle (Done 1992).
Given the importance of longevity, the index incorporates the age frequency distribution of all macroscopic benthos (not just corals) in the site, plus an estimate of the abundance of each age class in the area. Another way of viewing this index is as a measure of replacement time, in the event of complete destruction of the living community. This view brings it into line with successional thinking in the rest of the ecology, in particular, the conservation values associated with 'old growth' forest ecosystems. Whereas in coral reefs, 'old growth' equates most conspicuously with 'bioconstruction', it may also, as it does in terrestrial ecosystems, equate with enhanced ecosystem processes, diversity and symbiosis among less conspicuous components of the biota (Done et al. 1995).
Biodiversity and ecosystem process indices for coastal fisheries?
In a fishery context, a biodiversity type of index which reflects status of safe, vulnerable and endangered species (target and non-target) might be more useful than the 'representativeness/uniqueness' variant of biodiversity index described above (Eq. 1, Table 2). A 'conservation status' index (Eq. 3, Table 2), could be applied to catch records and to assessments of other benthic and pelagic habitats by using taxa whose taxonomy and conservation status are sufficiently well known. The three categories 'common', 'rare' and 'previously unreported' (Eq. 1, Table 2) could be replaced by the six Red List categories for conservation status (IUCN 1994): 'least concern', 'near threatened', 'conservation dependent', 'vulnerable', 'endangered' and 'critically endangered'. These would be given increased weightings from 0 to 3 in increments of 0.5 on a log10 scale (Eq.3, Table 2). These values give 'order of magnitude' increases in importance given to the presence of the more vulnerable and endangered species in assessments of ecosystems and multi-species stocks.
Age structure of populations has long been used in areas such as forestry and fisheries to provide an indicator of the population dynamics. A 'community age-trophic structure' (CATS' index, Eq.4, Table2) which is loosely analogous to the 'bioconstruction index' (Done 1995a), could be used to discriminate among potential protected areas and/or fisheries, and to monitor and report their progress under management. The x axis on Fig.2 shows how this index would be at a maximum at tomes and places where large predatory species, and by implication, their prey, were in abundance. It would be at a minimum where predators and omnivores were absent. Fig.2 shows how this index could be used in combination with the 'conservation status' index. The composite index could be useful in a manager/user context. A score of 1 is 'bad' by both criteria, and a score of 5 is 'good' by both criteria. The fact that scores o, 2, 3 or 4 can come about by different combinations of 'good' and 'bad' scores on the two axes is a positive feature in the sense that it specifies the areas in which stocks are deficient or improving.
Use of indices by resource managers: value versus risk
The Bruntland Commission's 6th principle, the 'precautionary principle' also has major practical implications. Regional risk analysis approaches (e.g. Suter 1993, - p 365) can be used, for example, to assess threats which onshore activities pose to various ecosystem values. Projected loadings of sediments, nutrients and contaminants at the point of discharge into the sea are linked with physical and biological transport and fate models to assess the likelihood that critical biological thresholds will be exceeded at places at varying distances and directions from that point. The critical biological thresholds may relate to human health (e.g. E. coli concentrations), or, as in this case, the human values ascribed to ecosystems measured by Conservation Status and CATS indices. The range of knowledge and technical skills needed to do these assessments is very broad, and provides a strong case for interdisciplinary teams o'f biologists, oceanographers, sedimentologists and engineers. Indeed, this section essentially describes the scope of work covered by an entire research program assessing status and threats to coral reefs in the Great Barrier Reef (CRC Reef Research Centre 1994).
Table 2: Indices which reflect Biodiversity, Bioconstruction, Conservation Status, and Community Age/Trophic Structure. 'Bioconstruction' is a key outcome of ecosystem processes on coral reefs
|
Index |
Explanation |
|
1) Biodiversity Index |
cj = the proportion of colonies, plants or bottom cover with j = 1 for common: j = 2 for rare |
|
Vb =S (cj · a j-1) |
and j = 3 for previously unreported, and |
|
|
a = a constant, here arbitrarily set at 10 so as to produce a minimum Vb of 1 when 100% of colonies, plants or bottom cover in the area common, and a maximum Vb of 100 when 100% of colonies, plants or bottom cover in the area are previously unreported. |
|
2) Bio-construction |
ai = age class i (in years) |
|
Index |
|
|
Vc = S (ai · mi) yrs |
mi = proportion of individuals or of defined area covered by individuals of age class i. |
|
3) Conservation |
cj = the proportion of biomass with j = 1.0 for 'least concern'; |
|
Status Index |
j = 1.5 for 'near threatened'; |
|
|
j = 2.0 for 'conservation dependant'; j = 2.5 for 'vulnerable'; |
|
|
j = 3.0 for 'endangered', and |
|
Vcs =S (cj · a j-1) |
j = 3.5 for 'critically endangered', and |
|
|
a = a constant, here arbitrarily set at 10 so as to produce a minimum Vb of 1 when 100% of biomass is 'least concern' and a maximum Vb of 100 when 100% of biomass is 'critically endangered'. |
|
4) Community age/Trophic Structure Index |
c. = the proportion of organisms withj =1.0 for juvenile primary consumers and 1.5 for mature primary consumers; j = 2.0 for juvenile omnivores and 2.5 for mature omnivores, andj =3.0 for juvenile predators and 3.5 for mature predators, and |
|
Vcats = S (cj · a j) |
a = a constant, here arbitrarily set at 10 so as to produce a minimum Vcats of 1 when 100% of sample are immature herbivores or planktotrophs, and a maximum Vcats of 100 when 100% of sample are mature predators. |
Source: Done 1995a for first two indices. The third and fourth are newly proposed here.
Remediation as an element of ICZM
Measures to control land runoff, including point and defuse sources of freshwater, sediment and pollution, may be an important component of coastal zone management in support of direct fisheries management (Done 1995b). Managers and policy makers need to assess the likely efficacy of remediation measures by addressing questions such as
a) over what spatial scales will the beneficial outcome be obtained, and
b) over what time frame can the outcome be expected?
Again the general approach of ecological risk assessment (ERA; Suter 1993) provides techniques and tools for such assessments. However in complex coastal environments, there may be major uncertainties in estimating dispersion of deleterious inputs into the sea, or the area benefiting from removal of a source of pollution (Wolanski 1994). In addition, there is a dearth of data on environmental boundary conditions necessary to support the desired benthic and/or pelagic communities.
For benthic communities, the success of remediation in the long term requires there is a long-term natural supply of larvae of appropriate invertebrates, plants, and fish from 'source' areas. This suggests that the most prudent strategy for policy makers and coastal zone managers is to implement networks of protected areas, taking ecosystem structure into account and crossing national boundaries if necessary. The success of remediation should be reflected in gradual increase in Biodiversity, Bioconstruction, Conversation Status and CATS indices, which would be computed from data derived from long term monitoring programmes.
DISCUSSION
The specific issues raised by this paper are:-
· Does the Australian Fisheries Ecosystem Management (FEM) approach have applications in the Maldivian IRRM programme?· Are indices such as those proposed here seen as potentially useful by managers?
· Do the particular indices facilitate accurate communication of meaningful ecosystem properties among different stakeholders?
· If they do not, are there others available, or can they be modified?
Recommendations on approaches to address the issues, and implications for researchers, managers and policy makers
These issues of the applicability of both FEM and the indices can both be addressed by field testing, in a broad sense. i.e the Proforma can be completed as far as possible for fisheries outside Australia, and the value of the information in development of action plans can be assessed. As for the indices, none of which has been used, it is up to researchers and stock assessors to assess their practically, and for managers and educators to assess their usefulness in communicating among parties.
We believe the concepts of FEM and performance indices have great potential both in providing the information base for resource managers and in education. If the specific examples we have provided do not stand up to rigorous scrutiny, that does not necessarily mean the concepts themselves should be discarded.
CONCLUSION
Recent recognition of the need to preserve biodiversity and ecosystem processes as well as production is now being reflected in fisheries and ICZM legislation and management plans. This paper suggests that, while stock assessment and management is an advanced scientific discipline with clear goals, ecosystem goals and paradigms for management are much less settled. Indices developed to reflect valued ecosystem attributes of coral reefs may have direct application to benthic marine protected areas. Derivations of these indices reflecting conservation status and community structure, i as yet untested, may be useful in describing valued attributes of the fishery itself. At an administrative and action level, any program of IRRM which embraces an ecosystem approach should be integrated with fisheries management initiatives focused in traditional catch/effort areas.
REFERENCES
CRC Reef Research Centre 1994. Annual Report, Co-operative Research Centre for the Ecologically Sustainable Development of the Great Barrier Reef. James Cook University of North Queensland, Townsville, Qld, Australia.
Done, T.J 1992 Phase shifts in coral reef communities and their ecological significance Hydrobiologia. 247:121-132
Done, T.J. 1995a. Ecological criteria for evaluating coral reefs and their implications for managers and researchers. Coral reefs 14: 183-192.
Done, T.J. 1995b. Remediation of degraded coral reefs: the need for broad focus. Marine Pollution Bulletin.
Done, T.J. Ogden, J.C., Wiebe, W.J., and Rosen, B.R.(in press) Biodiversity and ecosystem function of coral reefs. Chapter 15. In Mooney, H.A., Cushman, J.H., Medina, E., Sala, O.E., and Schultze, E-D. 1996. Functional Roles of Biodiversity: A Global Perspective. John Wiley, Chichester (in press).
Done, T.J., Reichelt, R.E 1996. The role of Integrated Coastal Zone Management in achieving sustainable marine fisheries through managing marine ecosystems. Discussion paper submitted to the meeting Ecosystem management for sustainable marine fisheries. Monteray, USA, February 19-23 1996. National Research Council Ocean Studies Board (USA).
Pauly, D., Christensen, V. 1995. Primary production required to sustain global fisheries. Nature London. 344: 255-257.
Suter. G.W., (Ed) 1993. Ecological Risk Assessment. Lewis Publishers, Michigan. 538 pp.
Wolanski, E., 1994 Physical Oceanographic Processes of the Great Barrier Reef. CRC Press, Boca Raton. 194 pp.
Figure 1. Suggested 5 point scales for coral communities. Value based on biodiversity as sole criterion for value (x axis), bioconstruction as sole criterion (x axis), and a composite of biodiversity and bioconstruction as joint criteria (matrix). The two indices of value are: Vb (based on the abundance, in the area of interest, of taxa which are endemic or rare either regionally or globally) and Vw, based on both the age structure and the percent cover of taxa in the area (Table 2). Value for composite criteria are the mean of Vb and Vw.
Figure 2: Conservation Status index Vcs combined with index for conventional herbivore/planktivore-omnivore-predator food chains Vcats which incorporates age structure in each trophic level. The text in each box of the matrix describes the biomass which most influences the value of the index. The terms 'least concern' and 'endangered' refer to Red List conservation status (IUCN 1994).
