A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary
<p class="p1">We used a combination of published literature and field survey data to synthesize the available information about habitat use by delta smelt <em>Hypomesus transpacificus</em>, a declining native species in the San Francisco Estuary. Delta smelt habitat range...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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eScholarship Publishing, University of California
2013-06-01
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| Series: | San Francisco Estuary and Watershed Science |
| Subjects: | |
| Online Access: | http://escholarship.org/uc/item/32c8t244 |
| _version_ | 1819075331831627776 |
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| author | Ted Sommer Francine Mejia |
| author_facet | Ted Sommer Francine Mejia |
| author_sort | Ted Sommer |
| collection | DOAJ |
| description | <p class="p1">We used a combination of published literature and field survey data to synthesize the available information about habitat use by delta smelt <em>Hypomesus transpacificus</em>, a declining native species in the San Francisco Estuary. Delta smelt habitat ranges from San Pablo and Suisun bays to their freshwater tributaries, including the Sacramento and San Joaquin rivers. In recent years, substantial numbers of delta smelt have colonized habitat in Liberty Island, a north Delta area that flooded in 1997. The species has a more upstream distribution during spawning as opposed to juvenile rearing periods. Post-larvae and juveniles tend to have a more downstream distribution during wetter years. Delta smelt are most common in low-salinity habitat (<span class="s1"><</span>6 psu) with high turbidities (<span class="s1">></span>12 NTU) and moderate temperatures (7 <span class="s1">°</span>C to 25 <span class="s1">°</span>C). They do not appear to have strong substrate preferences, but sandy shoals are important for spawning in other osmerids. The evidence to date suggests that they generally require at least some tidal flow in their habitats. Delta smelt also occur in a wide range of channel sizes, although they seem to be rarer in small channels (<span class="s1"><</span>15 m wide). Nonetheless, there is some evidence that open water adjacent to habitats with long water-residence times (e.g. tidal marsh, shoal, low-order channels) may be favorable. Other desirable features of delta smelt habitat include high calanoid copepod densities and low levels of submerged aquatic vegetation (SAV) and the toxic algae <em>Microcystis</em>. Although enough is known to plan for large-scale pilot habitat projects, these efforts are vulnerable to several factors, most notably climate change, which will change salinity regimes and increase the occurrence of lethal temperatures. We recommend restoration of multiple geographical regions and habitats coupled with extensive monitoring and adaptive management. An overall emphasis on ecosystem processes rather than specific habitat features is also likely to be most effective for recovery of the species.</p><p> </p> |
| first_indexed | 2024-12-21T18:23:43Z |
| format | Article |
| id | doaj.art-0984c04013ed431187b781ad2a4b2118 |
| institution | Directory Open Access Journal |
| issn | 1546-2366 |
| language | English |
| last_indexed | 2024-12-21T18:23:43Z |
| publishDate | 2013-06-01 |
| publisher | eScholarship Publishing, University of California |
| record_format | Article |
| series | San Francisco Estuary and Watershed Science |
| spelling | doaj.art-0984c04013ed431187b781ad2a4b21182022-12-21T18:54:28ZengeScholarship Publishing, University of CaliforniaSan Francisco Estuary and Watershed Science1546-23662013-06-01112ark:13030/qt32c8t244A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco EstuaryTed Sommer0Francine Mejia1California Department of Water ResourcesUniversity of Idaho<p class="p1">We used a combination of published literature and field survey data to synthesize the available information about habitat use by delta smelt <em>Hypomesus transpacificus</em>, a declining native species in the San Francisco Estuary. Delta smelt habitat ranges from San Pablo and Suisun bays to their freshwater tributaries, including the Sacramento and San Joaquin rivers. In recent years, substantial numbers of delta smelt have colonized habitat in Liberty Island, a north Delta area that flooded in 1997. The species has a more upstream distribution during spawning as opposed to juvenile rearing periods. Post-larvae and juveniles tend to have a more downstream distribution during wetter years. Delta smelt are most common in low-salinity habitat (<span class="s1"><</span>6 psu) with high turbidities (<span class="s1">></span>12 NTU) and moderate temperatures (7 <span class="s1">°</span>C to 25 <span class="s1">°</span>C). They do not appear to have strong substrate preferences, but sandy shoals are important for spawning in other osmerids. The evidence to date suggests that they generally require at least some tidal flow in their habitats. Delta smelt also occur in a wide range of channel sizes, although they seem to be rarer in small channels (<span class="s1"><</span>15 m wide). Nonetheless, there is some evidence that open water adjacent to habitats with long water-residence times (e.g. tidal marsh, shoal, low-order channels) may be favorable. Other desirable features of delta smelt habitat include high calanoid copepod densities and low levels of submerged aquatic vegetation (SAV) and the toxic algae <em>Microcystis</em>. Although enough is known to plan for large-scale pilot habitat projects, these efforts are vulnerable to several factors, most notably climate change, which will change salinity regimes and increase the occurrence of lethal temperatures. We recommend restoration of multiple geographical regions and habitats coupled with extensive monitoring and adaptive management. An overall emphasis on ecosystem processes rather than specific habitat features is also likely to be most effective for recovery of the species.</p><p> </p>http://escholarship.org/uc/item/32c8t244delta smelthabitatSan Francisco estuaryDeltaEcologyBiology |
| spellingShingle | Ted Sommer Francine Mejia A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary San Francisco Estuary and Watershed Science delta smelt habitat San Francisco estuary Delta Ecology Biology |
| title | A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary |
| title_full | A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary |
| title_fullStr | A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary |
| title_full_unstemmed | A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary |
| title_short | A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary |
| title_sort | place to call home a synthesis of delta smelt habitat in the upper san francisco estuary |
| topic | delta smelt habitat San Francisco estuary Delta Ecology Biology |
| url | http://escholarship.org/uc/item/32c8t244 |
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