Introduction

Global climate change and human activities are altering the ecological condition of estuarine and coastal ecosystems by intensifying problems such as eutrophication

Visual representation of eutrophication

Global climate change impacts

Changes in the climate system will cause detrimental effects on:

a) ecosystem structure and function

b) trophic interactions

c) habitat ranges

d) migration patterns

Global climate change impacts

Effects on temperature and salinity would increase water stratification

a) Higher surface water temperatures tend to strengthen pycnoclines – less vertical water circulation

b) Increase in freshwater runoff would help increase concentration of nutrients in the surface and decrease surface water salinity

Global climate change impacts

Regional wind patterns – will cause changes in circulation and mixing

Tropical storms and hurricanes – increased vulnerability of coastal habitats and potential effects on stratification

Enhanced hydrological cycle – more water, sediments and nutrients reaching the coastal zone which are likely to enhance eutrophication

Global climate change impacts

Sea level rise – Coastal wetlands are further affected by increasing erosion, flooding and saltwater intrusion and may reduce the services they provide as ecosystems.

Eutrophication and human activities

Related to excessive loading of nutrients – stimulates phytoplankton growth

Anthropogenic activities (industrialization and mechanized farming) produce huge quantities of reactive nitrogen and phosphorus which promote eutrophication processes.

Case history

Mississippi River watershed and Gulf of Mexico

a) Examples of continental – scale ecosystems that have suffered from landscape changes and are constantly exposed to increasing nutrient loads

Distribution of bottom – water hypoxia

Effects of tropical storms on dissolved oxygen

Summary

Coastal water quality is declining due to human activities (global climate, hydrological cycles, landscapes and the flux of nutrients such as nitrogen and phosphorus)

These excess nutrients are finding their way to coastal zones in increasing amounts and are predicted to increase the incidence and severity of eutrophication and hypoxic water formation.

There has to be a reduction of nutrient loads to prevent further degradation

Questions