Habitat Destruction and Fragmentation - Coastal Wiki (2023)

Information for this article is derived primarily from Airoldi, L., Balata, D., Beck, M.W. 2008. The Gray Zone: Relationships between habitation loss and marine diversity and their applications in conservation. Journal of Experimental Marine Biology and Ecology 366, 8-15

habitatDestruction and fragmentation is a process that describes the emergence of discontinuities (fragmentation) or the loss (destruction) of the environment inhabited by an organism. marineecosystemsare experiencing high rates of habitat loss and degradation, and these processes are considered to be the most critical threat to marine biodiversity^[1]. It is estimated that between 1960 and 1995 one kilometer of coastline was built on every day, resulting in permanent loss of valuable habitats such as coastal wetlands,Seegraswiesenandrocky shore ^[2]. About 20% of the world's coral reefs were lost and another 20% were degraded in the last decades of the 20th century, and about 35% of the mangrove area was lost during that time^[3].

Habitat can be defined as dominant features that create structural complexity in the environment, such as B. Plants (e.g.Seegraswiesen,Seetangwälder) or animals (eg.sabellariareefs, burrowing fauna in sand flats).

habitat loss and biodiversity

Researchers have identified three main components of habitat loss that relate to biodiversity^[4]:

1)The loss of resident species.

There is a unique diversity of plants and animals living in close association with specific habitats or habitat-forming species. For example, invertebrate assemblages associated with mussel beds, epiphytic and epibenthic assemblages, communities living in kelp forests, or fish communities associated with coral reefs. It was predicted that the consequences of habitat loss would likely be much more severe than the loss of individual species, as the ecological interactions between species result in a chain of impacts^[4].

2)The loss of food resources.

Most biogenic habitats are highly productive compared to simpler habitats. They produce large amounts of nutrients and organic matter that can be used directly as a food source by other organisms. Habitat loss also implies the loss of these food resources, negatively impacting the survival of other species and the productivity of individual species or communities, with more profound effects likely to spread along food chains^[4].

3)The loss of ecosystem functions provided by the habitat.

Structurally complex habitats provide a variety of ecosystem functions to the environment, including providing food and shelter for other species, trapping sediment, altering light and hydrodynamic conditions, and providing resilience to the system. When habitats are lost, these functions are lost with them^[5][4]. For example, replacing macroalgal canopies with turf affects sediment dynamics on rocky coasts, where fronds prevent sediment accumulation, while turfs tend to trap sediment even on exposed coasts

Impact of habitat loss on biodiversity

Habitat loss has generally been associated with drastic declines in the overall abundance and diversity of marine organisms. In the Wadden Sea, for example, the destruction of biogenic habitats over the past 2000 years has led to the regional extinction of at least 26 species^[6]. Similarly, the loss of seagrass beds leads to a reduction in species number and fish abundance. In general, the environmental changes associated with the destruction of natural habitats encourage the arrival and colonization of opportunistic species that can benefit from disturbed-state conditions. An example is the proliferation of opportunistic short-lived green or turf-forming algae following the destruction or removal of canopy species such as seaweed. Other species that may benefit from disturbed habitats are alien species. Once alien species become established, they can further contribute to reducing local diversity through interaction with native species.

Human activities as drivers of habitat loss

Some anthropogenic activities responsible for habitat destruction include the construction of coastal defenses, land reclamation, aggregate (sand and gravel) extraction, recreation, and developments including ports, ports, and industries. In addition, the growing number of tourists poses a significant threat to many coastal habitats in Europe, which can be disturbed by trampling or direct harvesting. In offshore waters, exploration and development of oil and gas activities threaten marine habitats, mainly through discharges of oil and other pollutants. Physical damage to marine habitats can be caused by fishing activities such asbottom trawling. Deep-sea trawlers use heavy rock-hoppers that are reported to be causing long-term damage to seabed habitats such as cold-water coral reefs in Norwegian, Scottish and Irish waters.

Implications for conservation and management

Habitat loss often leads to species becoming endangered or threatened and eventually to extinction, leading to significant loss of overall diversity and changes in ecosystem functioning. Coastal and marine habitat conservation efforts have been driven in part by the impact of habitat loss on biodiversity decline. However, it is not enough to look at the impact of habitat loss on species richness. Conservation efforts must consider the impact of habitat loss and fragmentation on all components of biodiversity and ecosystem functioning and the services provided by habitats:

• Regulatory services such as coastal buffering from storms
• supply services such as fish production
• cultural services such as tourism
• supporting services such as primary production^[7].

There is an urgent need to implement long-term and large-scale monitoring programs for changes in marine habitats and species distributions. This monitoring should be coupled with studies designed to treat management measures that result in habitat loss as large-scale experiments. For example the use ofmarine protected areas(MPA) andmarine protected areasas tools to underpin the relationships between habitat functionality and the distribution and abundance of target taxa. According to the Global Biodiversity Assessment^[8]Almost everyone agrees that the most effective way to conserve biodiversity is to prevent habitat conversion or degradation.

There is an ongoing debate among conservation biologists about whether it is preferable to protect multiple already fragmented habitats or a single large area, often referred to as the Single Large or Multiple Small (SLOSS) debate.

An important aspect to consider as well is habitatRestoration. On land there is a long tradition of habitat restoration, such as B. Mining dumps. There are some examples of habitat restoration in the marine environment, such as B. the well-publicized Cleanup of the River Thames in Britain, where salmon can now be found in London. The evolving science of restoration ecology should be part of a strategy to conserve coastal biodiversity.

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