Overview of integrative tools and methods in assessing ecological integrity in estuarine and coastal systems worldwide




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Title: Overview of integrative tools and methods in assessing ecological integrity in estuarine and coastal systems worldwide


Authors: Angel Borja1*, Suzanne B. Bricker2, Daniel M. Dauer3, Nicolette T. Demetriades4, João G. Ferreira5, Anthony T. Forbes4, Pat Hutchings6, Richard Kenchington7, João Carlos Marques8, Changbo Zhu9


Affiliations:

1 AZTI-Tecnalia; Marine Research Division; Herrera Kaia, Portualdea s/n; 20110 Pasaia; Spain, aborja@pas.azti.es

* Corresponding author

2 NOAA—National Ocean Service, National Centers for Coastal Ocean Science, 1305 East West Highway, Silver Spring, MD 20910, USA; suzanne.bricker@noaa.gov

3 Department of Biological Sciences; Old Dominion University; Norfolk, VA 23529; USA, ddauer@odu.edu

4 Marine & Estuarine Research; P.O. Box 417, Hyper by the Sea, 4053, South Africa; ticky@mer.co.za

5 IMAR - Institute of Marine Research, Centre for Ocean and Environment, FCT-UNL, Portugal; joao@hoomi.com

6 Marine Invertebrates, Australian Museum, Sydney NSW 2010 Australia, Pat.Hutchings@austmus.gov.au

7 Australian National Centre for Ocean Resources and Security, University of Wollongong, NSW 2522, Australia, richard .kenchington@netspeed.com.au

8 IMAR - Institute of Marine Research, University of Coimbra, Portugal, jcmimar@ci.uc.pt

9 South China Sea Fisheries Research Institute, CAFS, P. R. China. changbo@ecowin.org


Abstract


In recent years, several legislations worldwide (Oceans Act in USA, Australia or Canada; Water Framework Directive or Marine Strategy in Europe, National Water Act in South Africa, etc.) are intending to assess the ecological quality or integrity, within estuarine and coastal systems. Most of these legislations try to define quality in an integrative way, by using several biological elements, together with physico-chemical and pollution elements. This approach will allow assessing the ecological status at the ecosystem level (‘ecosystem approach’ or ‘holistic approach’ methodologies), better than at species level (i.e. the mussel biomonitoring or Mussel Watch) or just at chemical level (i.e. quality objectives) alone.


Increasing attention has been paid to the development of tools for different physico-chemical or biological (phytoplankton, zooplankton, benthos, algae, phanerogams, fishes) elements of the ecosystems. However, there are very few methodologies integrating all the elements into a unique evaluation of a water body. The need of these integrative tools to assess the ecosystem quality is very important, both in terms of scientific and stakeholder point of view. Politicians and managers need to get simple, pragmatic, but scientifically sound methodologies, suitable to show to the society the evolution of a zone (estuary, coastal area, etc.), taking into account human pressures or recovery processes.


These approaches include: (i) multidisciplinarity, in the teams involved in their implementation; (ii) integration of biotic and abiotic factors; (iii) accurate and validated methods in determining ecological integrity; and (iv) adequate indicators to follow the evolution of the monitored ecosystems.


While countries are increasingly using the establishment of marine parks as ways in which to conserve marine biodiversity, there is awareness at least in Australia based on terrestrial systems that conservation and management of biodiversity cannot be restricted to MPA’s but must include areas outside such reserves. An alternative approach which has been adopted in some areas of Australia is the declaration of multi-use parks which allow activities such as commercial shipping and fisheries although regulated.


This contribution reviews the current situation of the integrative ecological assessment worldwide, by presenting several examples from each of the continents: Africa, Asia, Australia, Europe and North America.


Key Words:


Ecological integrity, integrative assessment, ecological status, environmental quality, marine parks


Introduction

The marine environment presents high levels of complexity, diverse habitats and supports a high level of biodiversity, providing goods and services together with different uses which should be undertaken in a sustainable way. However, the marine, and particularly estuarine, environment is facing increasing and significant impacts, which include physical and chemical transformation and changes in biodiversity. Causes include land reclamation, dredging and sediment discharges, pollution (hazardous substances, litter, oil-spills, eutrophication, etc.), unsustainable exploitation of marine resources (sand extraction, oil and gas exploitation, fishing, etc.), unmanaged tourism, introduction of alien species, and climate change. These are driven by economic and social pressures for development and access to marine resources and activities through commercial fishing, aquaculture, tourism, recreation, maritime transport, etc.

To face these problems, policy-makers world-wide tend to develop strategies to protect, conserve and manage the marine environment. Hence, the United Nations Convention on Law of the Sea (UNCLOS, 1982) is the international basic legal framework that governs the uses of the oceans and seas. UNCLOS establishes an obligation to protect and use the resources of the marine environment sustainably as does the 1992 Convention on Biological Diversity (CBD, 2000), as highlighted by Parsons (2005).

At a national or regional level, several initiatives have been developed recently: (i) in December 1998, Australia released an Oceans Policy (Commonwealth of Australia, 1999); (ii) the Canadian Parliament passed the Oceans Act, which came into force in January 1997, being the Canada's Oceans Strategy released in 2002 (Parsons, 2005); (iii) in the USA, the Pew Oceans Commission, created in 2000, and the US Commission on Ocean Policy, created by the Oceans Act of 2000, reported in 2004 (Granek et al., 2005); (iv) in Europe, the Water Framework Directive (WFD), which promotes the protection of continental, estuarine and marine waters, was released in 2000 (Borja, 2005), and the European Marine Strategy (EMS) Directive, was presented in 2005 (COM, 2005a, 2005b, and 2005c; Borja, 2006); (v) in South Africa the National Water Act of 1998 (www.dwaf.gov.za/documents/publications) and the developing Coastal Management Act are presently in the form of the Integrated Coastal Management Bill (www.deat.gov.za); and (vi) in the People’s Republic of China (PRC) a substantial body of legislation exists to address environmental protection (laws on Water (1988/01/21) and Environmental Protection (1989/12/26): Sea Water Quality GB 3097-1997, Environmental Quality for Surface Water GB 3838-2002, and Provisions for Monitoring of Marine Culture and Propagation Areas (2002/04/01)).

The objectives of these initiatives are to protect and/or restore the corresponding seas, ensuring that human activities are carried out in a sustainable manner, providing safe, clean, healthy and productive marine waters. In summary, they try to promote the sustainable use of the seas and conserve marine ecosystems. Hence, the main objective of these legislations is to achieve marine waters in a good environmental or ecological status. Actually, the concept of environmental status takes into account the structure, function and processes of the marine ecosystems together with natural physiographic, geographic and climatic factors, as well as physical and chemical conditions including those resulting from human activities in the area concerned.

Hence, this concept defines quality in an integrative way, by using several biological elements, together with physico-chemical and pollution elements. This approach will allow assessing the ecological status at the ecosystem level (‘ecosystem-based approach’ (EBA) or ‘holistic approach’ methodologies (Browman et al., 2004; Nicholson and Jennings, 2004; and Rudd, 2004)), better than at species level (i.e. the mussel biomonitoring or Mussel Watch) or just at chemical level (i.e. quality objectives) alone. The EBA is defined as: "a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way. The application of the EBA will help to reach a balance of the conservation, sustainable use, and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources” (CBD, 2000).

Following this approach, increasing attention has been paid to the development of tools for different physico-chemical or biological (phytoplankton, zooplankton, benthos, algae, phanerogams, and fishes) elements of the ecosystems. However, there are very few methodologies integrating all the elements into a unique evaluation of status and performance of an aquatic system. The need of these integrative tools to assess the ecosystem quality is very important, both in terms of scientific and stakeholder point of view. The scientific challenge is to develop robust simple, pragmatic, but scientifically sound methodologies, which can provide communities and decision-makers with tools to define and monitor the evolution, current condition and biological performance of marine ecosystems and bioregions.

These approaches include: (i) multidisciplinarity, in the teams involved in their implementation; (ii) integration of biotic and abiotic factors; (iii) accurate and validated methods in determining ecological integrity; (iv) accurate and validated methods for determining the extent and effect of human uses and impacts; (v) adequate indicators to follow the evolution of the monitored ecosystems; and (vi) use of protected areas as means of conserving and managing marine environments especially coastal areas where the greatest anthropogenic inputs occur.

The aim of this contribution is to review the current situation of the integrative ecological assessment worldwide, by presenting several examples from each of the continents: Africa, Asia, Australia, Europe, and North America.


Current situation in Africa

Legislative framework

South Africa is a dry country with an annual national average rainfall of less than 500 mm, well below the global average, with expectations of declines associated with climate change over the next century. Reviews of environmental legislation in South Africa, particularly relating to aquatic resources and the coastal zone, are associated with reviews by the Council for the Environment (1989, 1991) which began proposing policies for coastal zone management. The status of coastal management was subsequently reviewed by Sowman (1993) and this preceded the development of a green paper (Department of Environmental Affairs and Tourism, 1998) focussed on sustainable coastal development, followed by a white paper (Department of Environmental Affairs and Tourism, 2000) on the same topic. The appearance of these policy documents was paralleled by publications by Glazewski (1997) and Glavovic (2000a, 2000b) aimed at converting the policies and concerns articulated in the white paper into an integrated coastal management bill and ultimately a national Coastal Management Act (www.deat.gov.za) which is presently in the process of ratification.

On the aquatic resources side, which includes the freshwater, estuarine and marine environments, the National Environmental Management Act of 199 was superceded/complemented by the National Water Act of 1998 (www.dwaf.gov.za/ documents/publications). This new act represented a radical digression from the philosophy inherent in the historical approach to the management of aquatic resources in that aquatic environments, particularly fresh water and estuarine systems, were granted a legal persona in that the dependence of the functionality of these systems on a minimal level of freshwater flow was given a legal status which had to be taken into account when any water abstraction was contemplated. The arguable premise that aquatic systems, such as wetlands, rivers and estuaries are ultimately dependent on minimal levels of freshwater availability, beyond which their functionality will be impaired, clearly generates the question as to what this level is and how it might be established. This aspect will be dealt with in the next section.


Tools and methodologies used in assessing ecological integrity

In the present context the emphasis will be on the determination of the freshwater requirements of estuaries (DWAF, 1999): Resource Directed Measures for Protection of Water, henceforth referred to as the “reserve” although the procedure is described as part of a package dealing also with reserve requirements of rivers and wetlands (www.dwaf.gov.za/documents/policies/wrpp).


Some examples of integrative assessment

An example of the above where an assessment of the current status was followed by remedial action and the institution of a monitoring system to check on the effectiveness of the measures instituted is provided by the Mhlanga estuary (290 42’S; 310 6’E) on the northern outskirts of the city of Durban on the east coast of South Africa. This small system with an estuarine area of barely 12 ha (Begg, 1978) is nevertheless typical of many of the 73 systems which occur along the 570 km of the KwaZulu-Natal coastline and further south into the Eastern Cape Province. The major physical and chemical features of these systems are determined by the seasonal rainfall, and consequently variable river flow, coupled with strong wave action and longshore sand transport which typically result in the closure of these systems during winter low flow periods. Under these conditions tidal action is lost and with it any organisms dependent on an intertidal habitat. Salinities typically fall due to sustained low levels of fresh water input and outward seepage through the bar, but layering may develop if the bar is low enough for overwash to occur during high wave conditions. Water levels behind the bar will rise, depending on the height of the bar, and can result in substantial backflooding such that the overall extent of the aquatic environment, in terms of water column and benthic habitat, increases well beyond that associated with high tides during open mouth periods. Under natural conditions this bar would be naturally breached during summer high flow periods but historically (Begg, 1984) this pattern has been disrupted by artificial breaching to prevent flooding of cultivated land or infrastructure in the backflooded areas.

The Mhlanga estuary has over the last 25 years become one of the better known of the smaller KwaZulu-Natal systems by virtue of i.a., general surveys of the system carried out in 1980-1981 (Begg, 1984) and a coincident more intensive focus on the fish fauna which produced information on trophic relationships within the fish community (Whitfield, 1980a), distribution in relation to food resources (Whitfield, 1980b) and factors affecting the recruitment of juveniles into the estuary (Whitfield, 1980b). Harrison et al. (2000) produced a nationwide assessment of the state of South African estuaries based on the geomorphology, ichthyofauna, water quality and aesthetics. The latter three parameters were rated on a scale of poor, moderate or good. The fish fauna was assessed on the basis of species richness and community composition, the water quality on suitability for aquatic life in terms of dissolved oxygen, ammonia, faecal coliforms, nitrate nitrogen and ortho-phosphate and the aesthetics on a “visual appraisal of the state of development in and around the estuary” incorporating i.a. any type of anthropogenic influence, algal blooms, odours, noise or invasive plants. The fish fauna and aesthetics of the Mhlanga estuary were rated as good but the water quality as poor. The poor water quality reflects the vulnerability of these small systems during the closed mouth periods when water exchange is minimal and tidal effects non-existent. In 2002-2003 a multi-disciplinary study incorporating mouth dynamics, physico-chemical conditions, nutrient conditions, phytoplankton and microphytobenthos, zooplankton, benthos, fish and birds, sponsored by the South African Water research Commission was undertaken (Perissinotto et al., 2004) aimed at contributing to the implementation of measures for reserve determinations for estuaries. In the local context the project focussed on the “responses of the biological communities to flow variation and mouth state in temporarily open/closed estuaries” one of which was the Mhlanga.

In summary, the study supported perceptions and interpretations developed some 20 years earlier (Begg, 1984), viz. that the broad natural cycle of summer breaching and winter closure due to the seasonal rainfall pattern was a major driving force in the functioning of these temporarily open/closed systems. Although these estuaries became non-tidal and salinities dropped to virtual freshwater levels during closed periods, with a consequent limiting effect on benthic invertebrate diversity, the fish fauna, which tended to consist largely of juveniles recruited to these nursery grounds during open mouth periods or through overwash, appeared able to handle these low salinities. Retention and accumulation of water behind the bar also resulted in an expanded aquatic and benthic environment relative to that existing under high tide conditions. The increased and stable water column permitted the development of a phytoplankton and in turn the development of a zooplankton and a planktivorous fish fauna while the benthos was able to expand in abundance although not in diversity. Optimisation of these processes was dependent on regular seasonal cycles of breaching or overtopping, allowing fish or invertebrate migration, followed by periods of closure which allowed the accumulation of biomass, both plant and animal, before the next exchange. Disruption of this cycle by artificial breaching and draining of the estuary during winter when water levels normally peak would disrupt this cycle. Additional impacts would be imposed by nutrient inputs resulting from agricultural runoff or urban pollution causing algal blooms, eutrophication and oxygen depletion.

In the Mhlanga situation records of mouth behaviour coupled with historical observations (Begg, 1978, 1984), calculations of the pristine mean annual and monthly runoff and the present situation indicated that outflow of treated water from a sewage works situated upstream of the estuary significantly increased the total flow into the estuary and the frequency of mouth breaching, resulting in the type of impacts described above. At low input levels the variable quality of the treated effluent was such as to generate periodic localised low or anoxic conditions resulting in fish kills. The increase in water inflow into the river from the sewage works resulted from the fact that the water used in the catchment was derived from other catchments and resulted in an overall increase in the Mhlanga flow. In this situation then the impacts on the estuary arose from the rather unusual situation of excess flow rather than the more common problems arising from water abstraction.

The provisions of the reserve determinations allow for either the maintenance of an existing acceptable ecological status or the implementation of measures to improve the ecological status of an estuary. In this case the measures that have been implemented by the local municipality involve the installation of a pipeline to transport the excess water to an adjacent catchment which has been subject to significant abstraction as well as improved treatment of the waste water from the sewage works. A monitoring operation has been implemented to assess the success or otherwise of the reduction in water input as well as a closed circuit camera to monitor mouth dynamics including the possibility of anthropogenic interference.

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