Factors Affecting Aquatic Ecosystems (Part 1) PDF

FACTORS AFFECTING THE AQUATIC ECOSYSTEMS (PART 1) 1. Habitat change Change in the local environmental conditions in which a particular organism lives. Habitat change can occur naturally through droughts, disease, fire, hurricanes, mudslides, volcanoes, earthquakes, slight...

FACTORS AFFECTING THE AQUATIC ECOSYSTEMS (PART 1) 1. Habitat change Change in the local environmental conditions in which a particular organism lives. Habitat change can occur naturally through droughts, disease, fire, hurricanes, mudslides, volcanoes, earthquakes, slight increases or decreases in seasonal temperature or precipitation, etc. However, it is generally induced by human activities such as land use change and physical modification of rivers or water withdrawal from rivers.  Habitat loss and fragmentation saltwater intrusion into freshwater Wetland. Saltwater intrusion into freshwater wetlands and causesO shifts in the plant and - animal community - changes in species composition: - Aquatic species are replaced by upland species; - loss of large, wide-ranging species (diversity loss); - loss of genetic integrity when isolated habitats are too small to support viable populations; - increased numbers of competitor, predator, and parasite species tolerant of disturbed environments  ① Habitat change. 2. Climate change Climate change is the significant variation of average weather conditions becoming, for example, warmer, wetter, or drier—over several decades or longer. It is the longer-term trend that differentiates climate change from natural weather variability. United Nations Convention on Climate Change: ‘change of climate which is attributed directly & indirectly to human activity that alters the composition of the global atmosphere & which is in addition to natural climate variability observed over comparable time periods’ Observed changes over the 20th century include increases in global air and ocean temperature, rising global sea levels, long-term sustained widespread reduction of snow and ice cover, and changes in atmospheric and ocean circulation as well as regional weather patterns, which influence seasonal rainfall conditions. These changes are caused by extra heat in the climate system due to the addition of greenhouse gases to the atmosphere. These additional greenhouse gases are primarily input by human activities such as the burning of fossil fuels (coal, oil, and natural gas), deforestation, agriculture, and land-use changes. These activities increase the amount of ‘heat-trapping’ greenhouse gases in the atmosphere. The pattern of observed changes in the climate system is consistent with an increased greenhouse effect. 3. INVASIVE SPECIES Definition by Convention on Biological Diversity as: ‘an alien species is a species, sub-species or lower taxon, introduced outside its natural past or present distribution, which include any parts, gametes, seeds, eggs or propagules of such species that might survive & subsequently reproduce (CBD, 2002)  New habitat lacks natural predators to Outcompete native control their species for resources population. such as space, light, and food Consume native species, compete with them for food or space, There may be no natural or introduce disease enemies present to help keep exotic populations in check - easier for They are opportunists. them to multiply and Once they get expand their range established in their new environment, they spread and multiply Invasive species: native or non-native species that produce negative consequences in the environment; or produce effects that humans don’t like & deem harmful  Cause economic or environmental harm or harm to Direct economic human health losses and management/ control costs Disrupts native ecological processes thus causing Decreased native environmental and populations, economic harm modified water tables, changes in run-off dynamics Cause species extinction and loss of biodiversity Other invasive species may be native, but may also rapidly reproduce and become nuisances.  4. Overfishing Malaysia is a nation with more sea than land and there are more than 120,000 licensed fishermen. Fisheries resources have depleted since 1970 in Malaysia due to over fishing, by-catch and destructive fishing practice. Government implemented Fisheries Act 1985 for sustainable management of fisheries.  vi. Industry Adverse effects: - reduction of wetland acreage, - alteration of wetland hydrology due to industrial water intake and discharge, - water temperature increases, - point and nonpoint source pollutant inputs, - pH changes as a result of discharges, and - atmospheric deposition. Saline water discharges, hydrocarbon contamination, and radionuclide accumulation from oil and gas production Polynuclear aromatic hydrocarbons (PAHs) are extremely toxic compounds that can enter estuarine wetlands through industrial effluent and atmospheric deposition. Fish contaminated with PAHs exhibit external abnormalities, such as fin loss and dermal lesions vii. Agriculture