Biodiversity Threats and Conservation Strategies Overview

Major Threats to Biodiversity\n* Habitat Loss and Degradation: This is a significant issue for over $90\%$ of endangered terrestrial species, involving permanent habitat destruction or quality reduction through fragmentation.\n* Invasive Species: Exotic (non-native) organisms that disrupt community structures; global travel has increased exchange rates (e.g., Zebra mussel).\n* Over-exploitation: The harvesting of wild organisms by humans faster than populations can reproduce; it is the dominant threat for marine species and includes bushmeat harvesting.\n* Climate Change: Global temperatures rose $0.74^{\circ}C$ ($1.3^{\circ}F$) in the $20^{th}$ century, with projected increases of $2.0-11.5^{\circ}F$ by $2100$, leading to ocean acidification and sea level rise.\n* Pollution: Threats include industrial pollutants (acid rain), pharmaceutical drugs in wastewater, persistent pesticides that biomagnify, and nutrient runoff causing eutrophication.\n\n# Effects of Habitat Fragmentation\n* Biomass Reduction: Fragmentation increases \"edge\" habitat relative to \"interior\" habitat, which leads to a sharp decline in average biomass.\n* Population Stability: Small fragments may be unable to support top predators and often lead to problems associated with small population sizes.\n\n# Impact of Climate Change on Organisms\n* Phenology Shifts: Changes in the timing of seasonal events, such as flowering, hatching, and migration, can cause mismatches between species.\n* Geographic Range Shifts: Species redistribute to more favorable \"climate envelopes,\" changing ecological interactions (e.g., Mountain pine beetles spreading north).\n* Evolutionary Adaptation: Changes in allele frequencies can occur, such as the adaptation of the red morph of ladybird beetles in warmer environments.\n\n# Species Vulnerability and Risk Factors\n* Small Populations: At high risk due to the \"extinction vortex,\" where inbreeding and genetic drift reduce genetic variability and individual fitness.\n* Body Size: There is a pattern of \"size-differential defaunation,\" where large-bodied species are at significantly higher risk of extinction.\n\n# Conservation Rationale and Strategies\n* Ecosystem Services: Biodiversity provides provisioning (raw materials), regulating (Earth life-support), cultural (quality of life), and supporting (pollination and nutrient cycling) services.\n* Targeted Focus: Conservation may focus on specific species types: Indicator, Umbrella, Flagship, or Keystone species (ecosystem engineers).\n* Biodiversity Hotspots: Efforts often target areas of mega-diversity with high numbers of endemic species.\n* Preserve Design: Considerations include movement corridors to promote dispersal and the SLOSS (Single Large Or Several Small) design trade-off.\n\n# Questions & Discussion\n* Terry Hughes (@ProfTerryHughes) reported aerial survey results for the Great Barrier Reef showing severe coral bleaching. In the Northern Sector, $81\%$ of the $522$ reefs surveyed were severely bleached, while less than $1\%$ were not bleached.