User:LisaTruong3/Biodiversity loss draft

Marine species richness loss

Marine biodiversity encompasses any living organism which resides in the ocean, and describes various complex relationships within marine ecosystems. On a local and regional scale, marine communities are better understood compared to marine ecosystems on a global scale. In 2006, it was estimated that approximately 300,000 marine species have been documented. However, the number of described marine species remains low compared to terrestrial species due to various factors, which includes the assignment of different names for the same species, and insufficient taxa classification. It is likely that many undocumented species has already disappeared. Because not all marine species have been described, it is difficult to provide an accurate estimate of global extinction in marine ecosystems. As a result, abundances of marine species remain uncertain, with estimates ranging between 178,000 to 10 million oceanic species.

With anthropogenic pressure, this results in human activities having the strongest influences on marine biodiversity, with main drivers of global extinction being habitat loss, pollution, invasive species, and overexploitation. Other indirect factors that have resulted in marine species to decline include climate change and change to oceanic biochemistry.

Overexploitation has resulted in the extinction of over 20 described marine species, which includes seabirds, marine mammals, algae, and fishes. Examples of extinct marine species include the Steller’s sea cow (Hydrodamalis gigas) and the Caribbean monk seal (Monachus tropicalis). However, not all extinctions are because of humans. For example, in 1930, the eelgrass limpet (Lottia alveus) became extinct once the Zostera marina seagrass population declined upon exposure to a disease. The Lottia alveus were greatly impacted as the Zostera marina were their sole habitats.