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Drivers of Biodiversity Change

'Drivers of biodiversity change' refers to the direct and indirect causes of biodiversity loss and ecosystem degradation.

Owing to the geographical isolation and small size of the Maltese Islands, coupled with drivers of biodiversity change, a number of wild species have become threatened, while others have even become extinct, either on a local (for example from one particular wetland or sandy beach) or national scale. The loss of species is irreversible and leads to the deterioration of our natural heritage.

Man-mediated activities that are aimed at improving the quality of life eventually have a direct or indirect impact on biodiversity, such as increased exploitation of natural resources to cater for increased consumer demands. The heavy toll placed on biodiversity will inevitably be felt by humans, who rely on various biological components in their daily life, for their sustenance and for their overall comfort. 

The dependency of humans on biodiversity for human bell-being and the issue of drivers of biodiversity change have been covered in depth in reports compiled as part of the Millennium Ecosystem Assessment. This was initiated in 2001, with the objective to assess the consequences of ecosystem change for human well-being and the scientific basis for action needed to enhance the conservation and sustainable use of those systems and their contribution to human well-being. It involved the work of more than 1,360 experts worldwide.

Examples of direct drivers of change:
  • changes in land use (land conversion) and habitat fragmentation (when natural habitats are divided into smaller fragments);
  • desertification (development of desert-like conditions, as a result of inappropriate land-use practices that lead to soil erosion and loss of water-holding capacity in the soil; reference is made to the United Nations Convention to Combat Desertification); 
  • nutrient-loading (due to urban and agricultural run-off that lead to pollution in water bodies, including aquifers);
  • illegal dumping of household and construction waste in the countryside, leading to disturbance to natural habitats;
  • abandonment of farming practices in cultivated land, where human intervention would be necessary to prevent ensuing degrading activities and for maintaining the various species that are connected with agro-ecosystems (e.g. maintainance of rubble walls which serve as a shleter for various species);
  • displacement of native and endemic species by invasion of non-native species, leading to the disruption of natural communities;
  • illegal water abstraction, causing decline of water tables, which hence leads to impacts on water-reliant habitats and species;
  • overexploitation of species due to intensified collection;
  • incidental capture and killing of species falling prey to non-selective fishing practices and road kills;
  • outcome of uncontrolled recreation activities, such as littering;
  • intentional illegal fires;
  • climate change and associated environmental changes and changes in species distributions, population sizes, timing of reproduction and migration events (reference is made to the United Nations Framework Convention on Climate Change);
  • illegalities due to limited public awareness on nature protection legislation that is in place and on activities that are prohibited by law. 

Examples of indirect drivers of change:

  • demographic factors (rise in population growth coupled with increasing consumer demands);
  • economy-generating activities;
  • increased efficiency of exploitation of biological resources as a result of improvement in science and technology.

The above-mentioned drivers of change, or threats, generally also known from the Maltese Islands, contribute to the decline in population size of species, as well as to the degradation of natural habitats. Small fragmented populations face the danger of extinction from specific areas. Certain species are indeed more prone to extinction. These include:

  • long-lived species,
    • such as top predators (characterised by having low reproductive rates and late attainment of sexual maturity, 
    • e.g. the Great White Shark (Scientific: Carcharodon carcharias; Maltese: Kelb il-Baħar);
  • species with poor colonisation and dispersal ability, since they are less able of fleeing areas subjected to habitat degradation, fragmentation and loss;
  • species that are specialists,
    • such as those having particular breeding and feeding habits, for instance breeders affected by coastal development,
    • e.g. the Loggerhead Turtle (Scientific: Caretta caretta; Maltese: Fekruna Komuni);
  • endemics having restricted distributions, high habitat specificity and commonly low population abundance,
    • e.g. the Freshwater Crab (Scientific: Potamon fluviatile lanfrancoi; Maltese: Qabru);
  • isolated small populations comprised of low numbers of individuals, which have a greater chance of being extirpated as a result of a human activity or environmental event,
    • e.g. the Door Snail (Scientific: Lampedusa melitensis; Maltese: Dussies).
Potamon_fluviatile_lanfrancoi Caretta_caretta_1

The loss or removal of a species not only signifies the loss of species diversity, but also the disruption of ecosystem structure and functioning, hence interfering with food webs. This will in turn have a negative impact on other species that rely directly or indirectly on the presence of the species that would have been lost or removed. Furthermore, the disruption of individual ecosystems will inevitably have an effect on other ecosystems.

 

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