Regional Estuary Monitoring Programme (REMP)

What is the Regional Estuary Monitoring Programme?

The Waikato Regional Council’s Regional Estuary Monitoring Programme (REMP) began in April 2001. REMP is a long-term monitoring programme, focused on using intertidal sediment-dwelling organisms (such as shellfish and marine worms) and the characteristics of the sediment in which they occur as indicators of the state of the monitored estuaries. Estuary monitoring sites have been established in the southern Firth of Thames, Whaingaroa (Raglan) Harbour, Tairua Harbour and Coromandel Harbour. Since 2001, quarterly, half-yearly and annual sampling has been undertaken to monitor the abundance and diversity of sediment-dwelling organisms and the physical and chemical characteristics of the sediment. Information provided by the programme allows early detection of negative environmental changes, and as such provide a trigger for assessing land management practices. Ultimately this information supports the development of policy and thus the sustainable management of estuaries in the Waikato region.

Estuaries are among the most productive, diverse and ecologically important environments in the Waikato region. They provide habitat for a diverse range of organisms including invertebrates, fish, birds and estuarine plants. Estuaries also function as a natural buffer between the land and sea, filtering sediment and contaminants from catchment water before it enters the coastal zone. In addition to these important ecological functions, estuaries are greatly valued by humans for cultural and recreational activities. Estuaries, their fringes and their catchments are also heavily utilised for forestry, agricultural, industrial and residential purposes. These uses can potentially result in degradation of estuarine habitat through mechanical disturbance, changes to water quality and the introduction of terrestrial sediment and contaminants. The degradation of habitat will in turn have implications for estuarine organisms and the important ecological functions they perform.
Intertidal sand and mud flats occupy large areas of the many harbours and estuaries that occur within the Waikato region. The sediment-dwelling organisms that occur on intertidal flats are essential to the overall functioning of estuarine ecosystems and provide a variety of ecosystem goods and services such as shoreline stabilisation, nutrient regeneration, carbon sequestration, filtration and detoxification of polluted waters and food resources to invertebrates, fish, birds and humans. Intertidal flats also have significant recreational and cultural value to humans as they facilitate activities such as gathering seafood and provide space for boating, fishing and waterskiing and sheltered beaches for swimming and relaxation. In many coastal communities, the goods and services provided by estuarine organisms and the habitats in which they occur underpin tourism and commercial activities (e.g. aquaculture) and are therefore drivers of the local and regional economy. Unfortunately, the estuarine sand and mud flat habitats and associated biological communities have been identified as being highly vulnerable to the pressures and disturbances associated with human activities. Accordingly, the maintenance and management of intertidal flats and particularly the ecosystem goods and services provided by the natural infrastructure of the estuary and catchment is a high priority.
Sediment-dwelling organisms undergo changes in abundance and community composition over time, even in a fairly stable environment. In estuarine environments these changes are amplified through natural environmental variability such as tidal range and seasonal temperature and light variation. Through evolution sediment-dwelling organisms have adjusted to cope with this natural variability and long-term monitoring data helps us to determine the changes in abundance and community composition related to natural environmental change.
If the environment changes as a consequence of human activities (e.g. changes in catchment use that increase sediment discharge into an estuary), habitats might become less favourable or unsuitable for sensitive species. As a result, abundance and community composition of sediment-dwelling organisms is likely to change beyond the changes caused by natural environmental variability. Because sediment-dwelling organisms respond predictably to many kinds of natural and human-made stresses or disturbances they have been widely used as indicators of estuary health in environmental monitoring programmes worldwide.
Consequently, the value of a long-term monitoring programme of sediment-dwelling organisms is that we can tease apart patterns in community structure associated with natural environmental changes and detect potential negative effects of localised disturbances (e.g. channel dredging), regional-scale pressures or activities (e.g. terrigenous sediment, nutrient enrichment) early and thus inform management responses.