Monitoring and surveillance options



Monitoring considerations

Monitoring is defined by Hiscock (1998) as "a procedure by which a series of surveys is conducted in a sufficiently rigorous manner for changes in the attributes of a site (or species) to be detected over a period of time". Surveillance or surveillance monitoring is "an attempt to detect unanticipated impacts, particularly ones that may be wide ranging, subtle or that only slowly become large and obvious". Hiscock (1998) notes that in a marine protected area, there is likely to a background of surveillance of the features important for the designation of the site with monitoring being undertaken in relation to features which may be or are being affected by human activities. Initial survey will be followed by surveillance which gives a broad idea of the scale of the changes taking place, followed by monitoring which uses the results of surveillance to set limits outside which management action is likely to be taken. The process involves the identification of natural variability in order to determine the normal level of change in an inimpacted habitat. The purpose of site monitoring is essentially to:

  1. Determine whether the desired condition of the feature of interest for which thesite was deisgnated is being achieved, This can enable judgements to be made about whether the management of the site is appropriate, or whether changes are necessary.
  2. To enable managers and policy makers to determine whether the site series as a whole is achieving the required condition, and the degree to which current legal, administrative and incentive measures are proving effective.

Methods for monitoring and surveillance of marine conservation areas in the UK are at a relatively early stage of development; there are considerable gaps in our basic understanding of the ecology of coastal habitats and for maerl biotopes in particular (see Chapter VIII). However, although no European maerl beds could be described as either having been under surveillance or as having been monitored, there are nevertheless a number of maerl beds in Europe where research work has taken place at intervals over a number of years, perhaps sufficiently to begin to identify natural variation, for example.

In this introductory section we first highlight the challenges involved in monitoring maerl biotopes, then suggest some of the opportunities available, detail the methodology appropriate to different conservation objectives, and offer some guidance as to how progress may be made. The UK Marine SACs Project is conducting and publishing the proceedings of a series of workshops devoted to the development of monitoring and management programmes for marine SACs (Hiscock, 1998).


Maerl biotopes are underwater, often offshore in areas with dangerous currents and exposed to storm action, and can be found to depths in excess of 25 m.

Most of the species of plants and animals found in the maerl biotopes are small and difficult to identify.

There are no short cuts or high technology solutions available for the derivation of detailed, accurate, reliable biological data.

Sample collecting and sorting is extremely time-consuming, sorting alone requiring '... at least two full days per sample prior to the identification of maerl and the associated organisms ...' (Hall-Spencer, 1995c).


In any monitoring programme, these factors, among others, will need to be accepted and budgeted for. However, some conservation objectives, such as determining the extent and gross topography of the maerl beds, can be surveyed relatively cheaply. Remote sensing techniques are one of the most cost-effective methods of resource mapping: sonar is the optimal method of remote sensing the seabed in turbid, temperate marine waters. Inventory of biotopes, including amount of living maerl, can also benefit from remote techniques.

With regard to the determination of species richness and quantification of species present, studies in other biotopes are increasingly showing that identification of organisms to higher categories, rather than to the species level, can be ecologically informative (Warwick et al., 1990). This type of information is currently lacking for maerl, but it should be obtained to determine whether equally useful data could be obtained at lower cost.

Monitoring considerations

There are methods of studying the biology and ecology of maerl beds which have been used successfully in the past, and these are described below. However, given the present limited knowledge and understanding of the maerl biotopes, suitable methods of monitoring the status of these biotopes need ongoing evaluation and updating. In particular, methods for monitoring the chemical and physical parameters of maerl biotopes will need to be developed, probably by modifying present oceanographic techniques.

Five conservation objectives (Hiscock, 1998) appear to be relevant to maerl as a feature of SACs:

  • Ensure that major habitat types supporting maerl beds retain their area. This includes mapping the extent of major substratum features and the maerl biotope complex.
  • Ensure that the range and types of maerl biotopes or biotope complex present in an area is maintained. This involves the inventory of maerl biotopes present in a defined area.
  • Maintain or increase the species richness in the maerl biotope and/or abundance of key (rare, fragile, declining, representative) species in maerl biotopes. Survey objectives are to quantity the species present in maerl biotopes and their density or percentage cover, with statistical evaluation of the data.
  • Maintain or increase the quantity of particular species of conservation importance (those for which the site is 'special'), which involves the recording of numbers or cover of named species.
  • Establish degree of likely sensitivity of a population through gaining an understanding of longevity and growth rate of the species.

Relevant methodology for each of these conservation objectives is described in the following linked sections:

Determining the extent of the biotope complex

Inventory of Maerl biotopes present

Quantitative sampling of Maerl biotopes

Recording numbers or cover of named species

Determining longevity and growth rates

Chemical and physical properties of Maerl biotopes