Estuarine fish communities respond to climate variability over both river and ocean basins

• Published in: Global change biology Vol. 21; no. 10; pp. 3608 - 3619
• Main Authors: Feyrer, Frederick, Cloern, James E, Brown, Larry R, Fish, Maxfield A, Hieb, Kathryn A, Baxter, Randall D
• Format: Journal Article
• Language: English
• Published: England Blackwell Science 01.10.2015; Blackwell Publishing Ltd
• Subjects: Animal Distribution; Animals; basins; Biodiversity; Brackish; California; climate; Climate Change; climate variability; community structure; data collection; demersal; demersal fish; Estuaries; estuarine fish; estuary salinity zones; Fish; fish assemblage; fish communities; Fishes - physiology; Fresh Water; freshwater; freshwater outflow; Habitats; North Pacific Gyre Oscillation; pelagic; pelagic fish; Population Dynamics; River basins; rivers; salinity; San Francisco Estuary; Seawater; watersheds; Pacific Ocean; California; INE, USA, California, San Francisco Estuary; IN, North Pacific, North Pacific Gyre; fish assemblage; pelagic; North Pacific Gyre Oscillation; estuary salinity zones; climate variability; demersal; San Francisco Estuary; freshwater outflow
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.12969

Estuaries are dynamic environments at the land–sea interface that are strongly affected by interannual climate variability. Ocean–atmosphere processes propagate into estuaries from the sea, and atmospheric processes over land propagate into estuaries from watersheds. We examined the effects of these two separate climate‐driven processes on pelagic and demersal fish community structure along the salinity gradient in the San Francisco Estuary, California, USA. A 33‐year data set (1980–2012) on pelagic and demersal fishes spanning the freshwater to marine regions of the estuary suggested the existence of five estuarine salinity fish guilds: limnetic (salinity = 0–1), oligohaline (salinity = 1–12), mesohaline (salinity = 6–19), polyhaline (salinity = 19–28), and euhaline (salinity = 29–32). Climatic effects propagating from the adjacent Pacific Ocean, indexed by the North Pacific Gyre Oscillation (NPGO), affected demersal and pelagic fish community structure in the euhaline and polyhaline guilds. Climatic effects propagating over land, indexed as freshwater outflow from the watershed (OUT), affected demersal and pelagic fish community structure in the oligohaline, mesohaline, polyhaline, and euhaline guilds. The effects of OUT propagated further down the estuary salinity gradient than the effects of NPGO that propagated up the estuary salinity gradient, exemplifying the role of variable freshwater outflow as an important driver of biotic communities in river‐dominated estuaries. These results illustrate how unique sources of climate variability interact to drive biotic communities and, therefore, that climate change is likely to be an important driver in shaping the future trajectory of biotic communities in estuaries and other transitional habitats.