Biology 1B, Ecology Lecture 11, Page 1 Professor Resh • Spring 2010*Assigned readings, 8th Edition pp. 1260-12637th Edition pp. 1224-1229San Francisco BayOutline of Lecture 11A. San Francisco BayB. Biological Resources of BayC. Physical influences on habitatsD. Current problemsA. San Francisco Bay• Estuary: a point at which the rivermeets the sea, with a mixture ofsaline and freshwater conditions,tidal mud flats and salt marshes, anda characteristic and unique fauna.• Population change (pre- 1769:10-20,000 native Americans; after1848 San Francisco grew from 400to >25,000.• Legacy of gold mining activities stillaffects the Bay.Biology 1B, Ecology Lecture 11, Page 2 Professor Resh • Spring 2010*Assigned readings, 8th Edition pp. 1260-12637th Edition pp. 1224-1229San Francisco BayB. Biological Resources of Bay1. Commercial fisheries (decline ofsalmon, sturgeon, and striped bassbegan about 1900; only herring andanchovies fished commerciallytoday).2. Dungeness crab (in 1880 commercialfisheries left Bay; 1960 off-shorefishing collapsed ). Increased oceantemperature, predation by hatchery-reared salmon, and pollution causeddecline.3. Introduced species (oyster drill andshipworm; 20 out of 42 Suisunmarsh fish are introduced). Successof introduced species resulted fromlack of a diverse natural fauna, andopportunistic traits.Biology 1B, Ecology Lecture 11, Page 3 Professor Resh • Spring 2010*Assigned readings, 8th Edition pp. 1260-12637th Edition pp. 1224-1229San Francisco BayB. Physical influences on habitats1. hydraulic mining2. land reclamation – 1400 km2 offreshwater marsh, 800 km2 saltmarsh reclaimed, with 125 km2remaining today3. water diversion –pre-1850, 34 km3/year; now 40% removed for localconsumption, 24% for SouthernCaliforniaBiological response (lost of migratory fish, lossof ability to dilute contaminants.C. Current problems (agriculturalwastewater, domestic and industrialwastes).1. San Francisco Bay problems are notunique but problems are less obviousbecause urbanization is directly onestuary mouth, water quality hasimproved, and most changesoccurred long ago.2. What is the effect on furtherreductions on inflow?D. San Francisco Bay is a model ofgrassroots environmental activism.E. San Francisco Bay is an important casehistory of anthropogenic change. Discussother examples with your study
View Full Document
Unlocking...