Monitoring Program Design - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 314

affected by changes in the relative number of species, through removal
of commercial species, mortality of nontarget species, physical distur-
bance of the bottom, fish discards, and use of antifouling paints. It is
important to restrict fisheries to “safe biological limits” and to take
measures to eliminate and/or restrict potential negative effects of over-
harvest on the ecological community, which is what occurred in Dalyan
Lagoon, Turkey. Estimation of total allowable catches (TACs) and esti-
mation of “safe biological limits” for fisheries are based on monitoring
of fish resources and environmental conditions for fish reproduction and
growth. Commercial fish species are well monitored to secure commer-
cial catches for the future; however, monitoring of impacts on noncom-
mercial fish species and on the environment is usually neglected and even
poorly understood.
• Mariculture—Lagoons are often utilized for mariculture, partly due to
their shallow nature and shelter from the open sea. Mariculture can have
a great effect on the ecosystem, due to excess of nutrient supply and
introduction of contaminants such as pesticides and antibiotics. For exam-
ple, the Ria Formosa Lagoon, Portugal, is experiencing these effects.
Mariculture should be kept under control through management and regular
monitoring of its environmental effects.
• Transport/Shipping—Commercial shipping, including ferry boat traffic,
causes input of hazardous substances by cleaning tanks, illegal discharges
of fuel and bilge oil, burning of fossil fuels, discharges of waste water,
introduction and transfer of marine species (mostly by the discharge of
ballast water), use of antifouling paints, and loss of cargo and refuse
dumping. Thus, monitoring is required not only for organic chemicals but
also for organisms. Violation of the environment in coastal areas and
lagoons (e.g., illegal discharges) seems to be less frequent in lagoons than
in the open sea and off-shore areas. Such cases are most often detected
and punished. In some areas the use of antifouling paints, particularly
those containing organo-tin compounds, has caused serious biological
effects, including mortality of commercial and natural oyster beds and
some other mollusk species.
• Introduction of alien species—Although occasionally the result of natural
migration, introduction of new species into lagoons is mostly of anthro-
pogenic origin, often the result of discharge of ballast water. The effects
in lagoons are often greatly magnified compared with similar events in
the open sea. For example, the effects of the spread of the zebra mussel
( Dreissena polymorpha) has been devastating in coastal and semienclosed
water bodies throughout the northern hemisphere. There are ecosystem
models for invasive species illustrating the ecosystem impact and trophic
cumulative effects of some introduced species in the Great Lakes and the
Mediterranean Sea. 10 The models aim at emphasizing effects other than
just prediction and competition for food, effects that are often less obvious
in the ecosystem, by incorporating quantitative data on abundances,
growth and uptake rates, etc.