| A. Prime indicators to gauge coastal water health (Environment Impact Assessment) |
| A.1. Water quality |
| Chlorophyll a:
elevated concentrations of chlorophyll a can reflect an increase in nutrient loads and increasing trends can indicate eutrophication of aquatic ecosystems. |
| CO2 partial pressure:
is the gas phase pressure of carbon dioxide which would be in equilibrium with the dissolved carbon dioxide. An increase in the CO2 concentration of the atmosphere (due to global warming) directly leads to an increase in the amount of CO2 absorbed by the oceans. This is called ocean acidification and it is a very serious issue. |
| Dissolved oxygen:
the amount of oxygen contained in water, and define the living conditions for oxygen-requiring (aerobic) aquatic organisms. Coastal discharges of wastes rich in organic carbon (e.g. from sewage treatment plants, paper manufacturing, food processing and other industries) can substantially reduce dissolved oxygen concentrations. |
| Marine pathogens:
faecal streptococci/enterococci are the recommended indicator for human pathogens in marine waters. |
| Metal contaminants:
Anthropogenic sources of metals in the marine environment include industrial and municipal waste products, urban and agricultural runoff, fine sediments eroded from catchments, antifouling paints from ships (mainly tin and copper), metals from pipes in sewage treatment plants and drainage from acid sulfate soils and mine sites. |
| pH:
a measure of acidity or alkalinity of water on a log scale from 0 (extremely acidic) through 7 (neutral) to 14 (extremely alkaline). pH is driven more frequently to greater extremes under eutrophic conditions, allowing algal species with tolerance to extreme pH levels to grow and dominate communities, and to potentially form algal blooms. Changes in pH have indirect impacts on aquatic organisms. pH is important in calcium carbonate solubility (calcite or aragonite), which is important for shell-forming organisms. Shell growth (i.e. calcification) is inhibited if water becomes too acidic. |
| Salinity:
a dynamic indicator of the nature of the ecosystem. Most aquatic organisms function optimally within a narrow range of salinity. When salinity changes to above or below this range, an organism may lose the ability to regulate its internal ion concentration. |
| Turbidity:
results from coloured dissolved organic matter and suspended particulate matter in the water column. The most obvious effect of increased turbidity is reduction in light available for photosynthesis. |
| Water column nutrients:
the nutrients nitrogen (N) and phosphorus (P) are essential building blocks for plant and animal growth. Nutrient loads are enhanced by human activity. Major anthropogenic sources of nutrients include runoff from agricultural areas (e.g. fertilisers), urban stormwater and wastewater (including sewage), eroded soils and aquaculture. |
| Water temperature: unnatural change in water temperature is an indicator of water quality. |
| A.2. Sediment quality |
| Benthic CO2 flux:
refers to the amount of carbon dioxide (CO2) released from a unit area of sediment over a specific time interval, during the decomposition of organic matter. Organic matter loadings to sediment are usually the main control on the magnitudes of the benthic CO2 fluxes. |
| Denitrification efficiency:
is the percentage of inorganic nitrogen released from the sediment as nitrogen gas during the decomposition of organic matter. Denitrification efficiency is a good indicator of sustainable carbon loading rates in bays, shallow coastal lagoons. |
| Organic matter & nutrients:
are assessed as Total Nitrogen (TN) and Total Phosphorus (TP) concentrations, and have inorganic as well as organic sources. The amount of organic matter found in sediment is a function of the amount of various sources reaching the sediment surface and the rates at which different types of organic matter are degraded by microbial processes. |
| Sedimentation rates:
refer to the amount of material (organic and mineral) deposited by the action of water over a given interval of time. Sedimentation is measured in terms of vertical accumulation over time or sediment density per unit area over time. |
| Toxicants:
in coastal waters are derived from a range of agricultural, industrial and domestic sources. Common toxicants from industrial and domestic sources include paints & primers, petrol & oil, garden pesticides & fertilisers and anti-freeze. |
| c. Biotic indicators |
| Plankton:
Plankton are small plants or animals that float, drift, or swim in the water column of any body of water. Populations of this marine plant or animals will grow or diminish rapidly in response to changes in its environment. Changes in the trends for a given plankton population—such as its density, spatial distribution, and rate of population growth or diminishment—will alert Earth scientists, that environmental conditions are changing there. |
| Benthic organisms:
the biomass of benthic organisms in coastal embayments is often high. It declines if communities are affected by prolonged periods of poor water quality. Hence benthic faunal density serves as a yardstick to asssess the water quality. |
| Fish assemblages:
Fishes have long been used as indicators of environmental change because of their generally large size and relative ease of identification. Different types of fish assemblage indicators include changes in population abundance , the presence/absence of key species and modifications of local assemblages including changes in biomass, species composition, ratios of species or feeding groups; species diversity and recruitment success (i.e. number of young fish entering a population); and measures of health (frequency of deformities, diseases and other anomalies). Monitoring of fish communities is advocated as an alternative to water quality monitoring for assessing ecosystem integrity. |
| Indicators to monitor the effectiveness of ICZM:
ICZM requires robust indicators of sustainability that gauge the ‘health’ of the coast in relation to environmental, social and economic activity. These indicators need to be based on rigorous scientific, social and economic research. To prove that ICZM is actually integrating management, policy, and effort, ICZM specific indicators are used. These indicators are vital to monitor the status and trends of biological diversity, to improve the effectiveness of biodiversity management and to signal key issues to be addressed through policy interventions and other actions (including early warning systems). |