WHAT IS BEING MONITORED AND WHERE?

MONITORING PROGRAMMES 1974-1997

Using the baseline description of environmental features as provided by SVEAG during 1974-1977 as a basis against which to measure change, SOTEAG has adopted a flexible, but consistent, approach to monitoring. The main elements of the SOTEAG monitoring programme over twenty years are shown on Table 1. The table also shows statutory monitoring carried out by the Terminal Operator, work done by the Scottish Office Agriculture, Environment and Fisheries Department (SOAEFD) and other organisations. Map 1, 1974-1977 shows the location of the main baseline monitoring sites. Since the nature of activities at the terminal changes over its life-span, it is important to ensure that the programmes remain relevant and cost-effective. In the light of results and experience, and in response to changing statutory regulations, these programmes have increasingly focused on elements which provide maximum useful scientific information.

Map 2shows monitoring sites during the period 1977 to 1997. The earlier interrelated studies were carefully rationalised into a few core progammes. The number of sites which are surveyed at appropriate time intervals were also reduced. Having provided substantial scientific information to allow expert assessment and prediction of natural effects, some studies, having run for several years, have ceased. From time to time, specific one-off incidents or unexplained elevated results may require more intensive, short-term surveys to determine cause, and thus ensure recovery and return to normal levels.

SOTEAG has also been able to enhance its own scientific database by providing small-scale financial assistance to other scientific institutions, such as University-based environmental expeditions. The programmes can be considered under four main headings: (i) Statutory Monitoring; (ii) Baseline and early monitoring studies; (iii) Specific shorter-term studies; and (iv) The Core Monitoring Programme.

Many of the discharges from the terminal, including, for example, the ballast water effluent discharge into Yell Sound and the emissions to atmosphere from the gas flares and power station, are regulated by authorisations issued by Her Majesty's Industrial Pollution Inspectorate (HMIPI) in 1993 under the provisions of Part 1 of the Environmental Protection Act 1990. Other smaller discharges to water are regulated by the Control of Pollution Act 1974 via consents issued by the SIC as River Purification Authority (RPA). Monitoring of the seabed sediments for hydrocarbon and heavy metal contamination, and the health of plants and animals living there, is carried out around the effluent diffuser (see Map 2) by the Terminal Operator as a result of a condition contained within the site's petroleum process authorisation. The Environment Act 1995 established the Scottish Environmental Protection Agency (SEPA) with effect from 1 April 1996, and this organisation has become the new environmental regulator, taking over the duties of HMIPI, and the RPA duties of the SIC.

Although it has no direct responsibility to monitor impacts at Sullom Voe terminal, SOAEFD, through its Marine Laboratory in Aberdeen (MLA), directs a substantial effort towards assessing the general marine environmental quality of Scottish waters. In the context of oil-related work in the waters around Shetland, MLA was heavily involved in monitoring the effects of the Braer grounding and has a continuing marine environment monitoring programme covering the offshore oilfields area in the east Shetland basin. Much of its work is therefore complementary and compatible with that of SOTEAG, and SOAEFD co-operated with SOTEAG on two specific areas of work in the early 1980s. Dispersion studies of segregated "clean" ballast water which is discharged from tankers directly into Sullom Voe showed it did not "pond" around jetties, and monitoring of the potential tainting of natural scallop beds close to the effluent outfall diffuser showed no evidence of taint accumulation.

SOTEAG's Baseline and Early Monitoring Studies 1977-1988

Chemical Monitoring

This involved systematic studies of the water and the seabed at 29 sampling sites in Sullom Voe, Garths Voe and Yell Sound on an annual basis between 1978 and 1988. Temperature, salinity and dissolved oxygen have been measured in samples of seawater; samples of sediment from the seabed were monitored for oil contamination.

Between 1978 and 1985, heavy metals were also monitored in seabed sediments. Until 1982, samples of horse mussels and cockles collected by divers from natural populations were also measured for heavy metals in their tissues. These programmes demonstrated substantial spatial and temporal variations, and since Shetland has naturally occurring high levels of some heavy metals in the environment, these measurements indicated large natural fluctuations rather than contamination. Accordingly these programmes were terminated. The annual surveys of temperature, salinity and dissolved oxygen at all stations in Yell Sound and Sullom Voe were stopped in1987 on the basis that adequate records of natural changes in these parameters had been recorded to provide a baseline for subsequent comparisons. Similarly, a robust series of measurements for oil content in seabed sediments in Yell Sound had been recorded by 1988. These measurements remain on record for future use should the need arise. To maintain and compare the validity of this baseline information, further surveys were made in 1991 and 1996 and will be continued periodically into the future.

In order to emphasise that the practical benefits of monitoring can result in positive action, the example of Orka Voe contamination is provided. In 1983, a localised area of sediment contaminated with oil was detected in Orka Voe. Investigations revealed that this was not due to the normal operation of the terminal, but to the activities of former contractors in the works laydown area during the construction phase. Remedial action was taken by the Terminal Operator. Until 1987, SOTEAG surveyed the sediments at 5 stations in Orka Voe each year to ensure that levels of oil in the sediment were reducing. As a consequence, the health of the larger animals living on the seabed near the inner shore at Orka Voe was also surveyed by looking at the species populations to see if these were affected. Surveys have continued in alternate years since 1989 to ensure that the area remains stable and continues to recover.

Biological Monitoring

Seabed: The larger animals living on or in the seabed, called the macrobenthos, were surveyed at 12 stations in Sullom Voe and Garths Voe by grab sampling from a ship. Five biological samples are taken at each station in order to determine the species present and their abundance. A sixth sediment sample is used to characterise the nature of the sediments. In 1985, the chemical and macrobenthic programmes were amalgamated under one contractor for integration of sampling sites and to compare the health of these animals to the chemical conditions and type of sediment of their habitats.

From 1976, the study of plants and animals on rocky shores was based on an annual quantitative survey of the abundance of selected species in a large number of 3-metres wide transects from low to high water level, initially at 43 sites in Sullom Voe and Yell Sound, subsequently reduced to 27 in Sullom Voe. Extra monitoring has been done at additional sites which have had a history of pollution (e.g. the upper shore adjacent to the polluted stream at Mavis Grind and shores affected by the Esso Bernicia oil spill and subsequent clean-up operations). By 1984, sufficient data had been acquired and assessed to warrant reduction of this programme to annual expert surveillance for gross changes in the abundance of plant and animal communities, together with maintenance of annual photographic records for comparison. Only 23 of the primary sites previously monitored are now required for this purpose.

Seven beaches have been selected to provide a wide coverage of soft shore environments. Some of these are in Sullom Voe and its approaches (deemed to be most at risk from pollution), others are further afield but still potentially at risk, and there is a third category of beaches, again well away from the terminal and the effluent diffuser discharge point, which form reference sites. Samples of two commonly occurring species of shellfish, the cockle and the clam, were quanititavely surveyed for growth rate and population structure by measuring shell length and body weight. By 1984, sufficient data on soft shores had been obtained to warrant ending the annual studies. Nevertheless, the level of oil in the associated sediments at two soft shores in Sullom Voe continues to be measured as part of the ongoing chemical monitoring programme to provide an important link between animals and their habitats.

These are rare in Shetland, and in the Sullom Voe area are small and often fragmented. However, they are important because oil may be trapped in the vegetated, sheltered, upper part of the shore where it might be a threat to birds and sheep that feed there and to the sensitive vegetation of the marsh. Monitoring is difficult because they are unstable as a result of deposition and erosion of sediments, grazing by sheep and human disturbance. Between 1977 and 1987, monitoring has concentrated on a study of the common salt-marsh grass as a measure of salt marsh vitality. In 1986, chemical analysis of the salt marsh soils was introduced at four sites near to the terminal to try to relate any changes in the health of the salt marshes to possible low-level chronic oil contamination. In 1989, however, this approach was modified to a two-year programme of general surveillance by mapping changes in vegetation, whilst maintaining chemical studies and, where practicable, measurement of rates of natural erosion or deposition of the marsh area. The programme was terminated in 1990. Periodically, surveys will be undertaken to update information to enable the impact and recovery from any oil spills or oil-related activity in the vicinity of Sullom Voe to be assessed.

Atmospheric Monitoring

Knowledge of local weather and the amount and type of emissions to the air from the oil terminal meant that no problems were expected at ground level. This has been confirmed by five annual photographic surveys between 1978 and 1982 using lichens as an indicator species over a wide geographic range of 22 sites throughout Shetland. The annual programme was terminated in 1982. A single re-survey in 1986 showed no change.

The seabird populations of the whole of Shetland are included in the monitoring programme because of their national and international importance and vulnerability to oil spills. Seabirds are highly mobile, and because of tanker movements to and from Shetland and other shipping activities, monitoring is necessary on a wider geographical basis. The programme has concentrated on selected cliff-nesting species and inshore waterfowl, and sample study sites have been selected throughout Shetland. The following are the main elements of this programme:

(i) monitoring of breeding numbers of fulmar, gannet, shag, kittiwake, guillemot, razorbill and black guillemot (tystie);

(ii) monitoring of breeding success for fulmar, shag, kittiwake and guillemot;

(iii) surveys of diving seabirds and seaduck in inshore waters in winter;

(iv) surveys of eider moult flocks in late summer;

(v) surveys of beached seabirds;

(vi) studies of red-throated divers;

(vii) financial support for seabird ringing.

Ornithologists use internationally accepted standard methods of counting for each species. The data allow the estimatation of the percentage change in the number of breeding birds and the comparison of changes taking place in colonies in different parts of Shetland and in Britain as a whole. A full-time resident ornithologist is employed and works in close co-operation with the local officers and members of Scottish Natural Heritage, the Shetland Bird Club and the Royal Society for the Protection of Birds. The results of these investigations to date have produced one of the largest and best data sets of this kind in the UK.

During the Braer oil spill on the south-west coast of Shetland in January 1993, SOTEAG's beached bird survey programme was intensified in order to assess the mortality of the breeding seabird populations. In addition, one of SOTEAG's main study colonies at Sumburgh Head is near the site of the wreck, and additional monitoring was co-sponsored by the SVA Ltd. and Government's Ecological Steering Group on the Oil Spill in Shetland (ESGOSS) to provide a post-spill assessment of the effects on species breeding there, and on pre-breeding tysties at sites previously monitored by SOTEAG in south Shetland. The value of SOTEAG's up-to-date database in assessing the environmental impact of a major oiling incident was demonstrated to Government, the Shetland public and others.

In the early years, it was necessary to discover more about the ecology of certain species before they could be monitored effectively. In December 1978, the tanker Esso Bernicia spilled 1174 tonnes of fuel oil into Sullom Voe in a berthing accident. The incident highlighted the need to extend the monitoring work in three main areas.

Firstly red-throated divers breed in fresh-water pools, but feed in the sea, where they are vulnerable to oil pollution. Higher numbers of this species could be casualties of a significant oil spill occurring in the summer breeding season. Procedures were therefore initiated by SOTEAG for conducting a Shetland-wide survey of the breeding population and breeding success through collaborative research with the Royal Society for the Protection of Birds,

A second study covered an assessment of pre-breeding numbers of black guillemots (tysties) throughout Shetland. SOTEAG supported a three-year post-doctorate programme at Oxford University, solely to generate this essential information. These two seabird studies now form an integral part of SOTEAG's ongoing seabird monitoring programme.

Thirdly, and for the first time in Britain, otters were casualties of an oil spill, and at least thirteen were known to have died as a result of the Esso Bernicia spill. SOTEAG funded the Institute of Terrestrial Ecology to establish an estimate of otter numbers around the terminal so that any impact on the population from future spills could be assessed. The otter study was terminated in 1983, having achieved its main purpose.

Sheep, winter-grazing on seaweed on the foreshore, were also affected by the incident and SOTEAG responded by obtaining data on sheep breeding performance from the Scottish Agricultural College, and arranged for a study to be undertaken on the hydrocarbon levels of contaminated seaweeds.

Between 1982 and 1989, another innovative and advanced monitoring technique was applied for the first time in Shetland by the Plymouth Marine Laboratory. Common mussels at seven sites around Sullom Voe and a nearby "clean control" site were measured to assess the effects of environmental contaminants on the general health and condition of individuals. This involved studies of physiology, biochemistry, growth and reproduction. Growth provides one of the most sensitive measures of stress in an organism and represents the balance between feeding and digestion and energy expenditure. Together with the measurement of very low, sub-lethal levels (one part per billion was possible) of oil or other contaminants in the mussel tissues which subjects them to environmental stress, scientists can determine their 'scope for growth', that is any improvement or deterioration in their health and condition, and identify the main toxicants causing these effects. This improved understanding of the responses of marine organisms made it possible to assess the degree of pollution at a particular site before lethal and damaging effects occur to the animals as well as an evaluation of the wider ecological consequences. During this period in Shetland, it was demonstrated that mussels showed a significant reduction in scope for growth in Sullom Voe, but they were still able to grow, reproduce and maintain their populations. At the clean reference site in Shetland, organic contaminants were the lowest recorded anywhere in the UK, and other sites near the Sullom Voe oil terminal were less contaminated and impacted than many estuaries in industrial areas on the UK mainland.

One of the main effects associated with the oil terminal activities detected by SOAEFD monitoring programmes in 1988 and 1990 has been a significant deterioration of dogwhelk populations in Sullom Voe and its approaches in Yell Sound. Female common dogwhelks show a male characteristic response to the highly toxic, anti-fouling based paints used on the hulls of the world's tanker fleet, in aquaculture and, until 1986 when its use was banned, on the towing vessels, navigational buoys and harbour craft in Sullom Voe. New legislation now prohibits the use of these tributyltin (TBT) compounds in anti-fouling paints in the UK for these uses, including small boats.

Extensive reviews have been published showing TBT to be a serious probelm on a national and international scale. Since there are no fish farms in Sullom Voe and no significant small boat activity occurs in the area, TBT effects in Sullom Voe therefore arise from tankers. Thus, since 1991, SOTEAG has commissioned biennial surveys of dogwhelks as part of its rocky shore programme to determine the degree and geographical spread of these TBT effects on dogwhelks resulting from tankers approaching and leaving through Yell Sound, and docked at the Sullom Voe terminal jetties. Results of the SOAEFD and SOTEAG surveys confirm that TBT contamination has significantly affected populations in the vicinity of the terminal jetties, where in 1990 juvenile dogwhelks were totally absent and all females were sterile. By 1991, no dogwhelks were found in the terminal area, and at the Kames, the next closest site, juveniles were absent. Throughout Sullom Voe, a high percentage of female dogwhelks remain sterile and, to a lesser extent, throughout Yell Sound from TBT contamination effects. Monitoring will continue in order to assess signs and rates of recovery.

The Core Monitoring Programme - 1989 onwards

In 1986, using the Delphi 2000 technique, a major audit was undertaken on SOTEAG's long-term objectives, the entire monitoring strategy for Sullom Voe terminal, and relationships with the Sullom Voe Oil Spill Advisory Committee (SVOSAC - see page 16). SOTEAG and Monitoring Committee members participated with external scientific experts in order to assess an appropriate level and direction for future monitoring requirements through to the decommissioning and site rehabilitation phases of SOTEAG's remit, when it is predicted that monitoring requirements might increase. As a consequence, the Directors of the Sullom Voe Association Limited accepted the need for the following core monitoring programme, which includes a full-time programme of ornithology, during the entire life of the terminal, and during any future decommissioning stage:

(i) A biennial programme of seabed sediment chemistry for oil concentrations and macrobenthos continues throughout Sullom Voe and Garths Voe.

(ii) Included in the above programme are two soft shore sites in Sullom Voe for sediment chemistry.

(iii) For both the above sediment chemistry studies, grain size and organic matter content are measured as significant independent variables.

(iv) The annual rocky shore surveillance programme was critically reviewed in 1992/93 to improve the methodology, and continues. Dogwhelk monitoring will continue for as long as necessary.

(v) The full-time programme of seabird monitoring continues, as described on page 12.

(vi) Additional monitoring may be undertaken periodically, either to maintain surveillance or to up-date baselines.

SOME PRACTICAL BENEFITS OF MONITORING

Dogwhelk monitoring in Shetland and elsewhere has resulted in new UK legislation to prohibit the use of TBT compounds as an antifouling agent, and they became subject to controls under the Food and Environmental Protection Act 1985. The localised contamination in Orka Voe which resulted in remedial action by the Terminal Operator, also emphasises that monitoring can result in positive action. Other examples in SOTEAG's early history show that the chemical and biological-effects programmes had, as expected, detected changes in the structure and chemistry of the sediments and in the animals present in the general area of the jetties. This low-level contamination was caused by minor oil spillages that occur accidentally during loading operations at the jetties. More stringent operational procedures have now reduced the risk of such incidents to a minimum.

Early problems in the operation of the terminal's effluent treatment plant have been detected through the statutory monitoring of hydrocarbon levels at the effluent outfall discharge point. SOTEAG were involved with the Operator in finding solutions which included modifications to the effluent treatment plant, including the final holding pond stage. SOTEAG requested detailed information from offshore production platforms about the addition to the oil of chemicals which can affect effluent treatment.

PUBLICATIONS

All SOTEAG's scientific data have been published in two volumes of Proceedings of the Royal Society of Edinburgh (Biological Sciences: ISSN 0308-2113). The first, Vol. 80: 1981, contains all the implications of oil developments in Shetland, the early policies for environmental management, the monitoring strategy and results of the baseline monitoring programmes. Volume 103, published in 1995, for 1994, covers twenty years of Monitoring at an Oil Terminal - the Shetland Experience (Edited by G. M. Dunnet and A. D. McIntyre).