Tidal Habitat Descriptions

Transcription

1 Tidal Habitat Descriptions Elkhorn Slough Tidal Wetland Plan DRAFT 4/4/05 KEY TO TIDAL HABITATS Channel (unrestricted tidal flow) Channel (restricted tidal flow) Salt Marsh/Tidal Creek (unrestricted tidal flow) Salt Marsh/Tidal Creek (restricted tidal flow) Brackish Marsh Mudflat (unrestricted tidal flow) Mudflat/Salt Panne (restricted tidal flow) Lagoon Levees (lines), Culverts/Tide gates (large dots) Failing Levees DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 1

2 INTRODUCTION Purpose The main purpose of this document is to provide a concise, science-based description of tidal habitats (channel, salt marsh/tidal creek, brackish marsh, mudflat/salt panne, lagoon) found in the Elkhorn Slough watershed to help guide management decisions. Some of the habitat types are further subdivided based on levels of tidal flow. Each section contains information about a different tidal habitat including a definition, examples of where each habitat can be found, representative plants and animals (note that this is not an exhaustive species list), and physical habitat changes and shifts in plant and animal assemblages. For those less familiar with Elkhorn Slough, a map showing the location of common place names is included in the appendix and selected definitions and acronyms are listed below. Contributing Authors This document was prepared by Barb Peichel, Kerstin Wasson, Andrea Woolfolk, and Eric Van Dyke of the Elkhorn Slough National Estuarine Research Reserve with enormous contributions from Science Panel (Elkhorn Slough Tidal Wetland Plan) members including Greg Cailliet and Mike Foster of the Moss Landing Marine Laboratories, Gary Page of the Point Reyes Bird Observatory, Isa Woo of the U.S. Geological Survey, and Fiorenza Micheli of the Hopkins Marine Station of Stanford University. Other Potential Reviewers: Josh Adams, Sean Anderson, Jason Brush, Andrew DeVogelaere, Kim Hayes, Jim Oakden, James Nybakken, Pete Raimondi, and Mike Vasey. Definitions Restricted tidal flow - areas that receive no or muted tidal flow from obstructions by the railroad and road levees or tide gates Unrestricted tidal flow - areas that receive unrestricted tidal flow (may include areas under bridges). Mean Lower Low Water (MLLW) - the average height of the lowest low tide from each day Mean Low Water (MLW) - the average of all the low water heights Endangered species status codes and acronyms SE = State listed as Endangered ST = State listed as Threatened FE = Federally listed as Endangered FT = Federally listed as Threatened LE = Locally extirpated NN = Non-native, invasive species (federal or state) *State listed as endangered as California Brown Pelican (Pelecanus occidentalis californicus), federally listed as Brown Pelican (Pelecanus occidentalis), federally listed as threatened as Southern Sea Otter (Enhydra lutris nereis) DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 2

3 TABLE OF CONTENTS Tidal Habitats Channel Unrestricted tidal flow Restricted tidal flow... 7 Salt Marsh/Tidal Creek Unrestricted tidal flow Restricted tidal flow Brackish Marsh Unrestricted tidal flow Restricted tidal flow Mudflat Unrestricted tidal flow..13 Mudflat/Salt Panne Restricted tidal flow.. 16 Lagoon Restricted tidal flow Wetland/Upland Ecotone Unrestricted tidal flow Restricted tidal flow Regional Habitat Trends Bibliography Appendix Map of Place Names DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 3

4 CHANNEL (UNRESTRICTED TIDAL FLOW) Definition Channel habitat (unrestricted tidal flow) occurs below the low tidemark (or MLLW) where the substrate is continuously submerged Location of habitat type Channel habitats (unrestricted tidal flow) comprise approximately 721 acres in Elkhorn Slough and can be found in the main Elkhorn Slough channel, the North and South Harbor areas, and large adjacent tidal creeks including areas in Parsons Slough. Representative plants Common Name Eel grass Scientific name Zostera marina Gracilariopsis sp. (Gracilaria pacifica?) Ulva spp. Representative animals Type Common Name Scientific Name Special Status or Notes Birds Brown Pelican Pelecanus occidentalis SE*, FE Bufflehead Common Goldeneye Common Loon Double-Crested Cormorant Eared Grebe Forster s Tern Red-breasted Merganser Snowy Egret Surf Scoter Bucephala albeola Bucephala clangula Gavia immer Phalacrocorax auritus Podiceps nigricollis Sterna forsteri Mergus serrator Egretta thula Melanitta perspicillata DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 4

5 Western Grebe Aechmophorus occidentalis Western Gull Larus occidentalis Mammals Harbor seal Phoca vitulina Sea otter Enhydra lutris FT Fishes Topsmelt Atherinops affinis Jacksmelt Shiner surfperch Black surfperch Pacific staghorn sculpin Leopard shark Bat ray Atherinopsis californiensis Cymatogaster aggregate Embiotoca jacksoni Leptocottus armatus Triakis semifasciata Myliobatis californica Invertebrates Gaper clam Tresus nuttalli Fat innkeeper worm Urechis caupo Physical habitat changes and shifts in plant and animal assemblages over the past 150 years The main channel of Elkhorn Slough has been getting deeper and wider since The mean cross-sectional area of Elkhorn Slough main channel has increased by approximately 16% in just 8 years ( ) with areas near the mouth of Parsons Slough increasing almost 3 m in depth during the same period (Dean 2003, Malzone 1999). A decrease in fine unconsolidated sediments along the main channel of Elkhorn Slough has been observed since the 1970s and fine sediments have been scoured away between Hummingbird Island and Kirby Park in the subtidal channel leaving hard polished clay with a patchy surface veneer of coarse rubble creating unsuitable conditions for a number of organisms (Kvitek et al. 1996). Bank erosion rates along the main channel of Elkhorn Slough are 0.4 to 0.6 m/yr in the upper slough and average 0.3 m/yr in lower slough-- with some areas approaching 2.0 m/yr (Wasson et al. unpublished). A compositional shift in the lower intertidal invertebrate and fish communities was detected. Lower abundances of many fish species in deep channel sites (>70% lower than 1970s levels) and an overall decline in fish species diversity from the 1970s to 1990s occurred in the main channel of Elkhorn Slough and has been attributed to changes in sediment size (Fenn 2003; Oxman 1995; Yoklavich et al. 1991; 2002). DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 5

6 A decline of eelgrass beds near the mouth of Elkhorn Slough since the 1930s (MacGinitie 1935). A likely decrease or loss of various invertebrates specialized for eelgrass beds and decrease in native oyster beds after 1947 (Wasson et al 2002) Invasion of the main channel by at least 58 non-native invertebrates from the 1930s- 1990s; many of these are now abundant (Wasson et al. 2001) A loss of fine sediments from various intertidal and subtidal mudflats causing a shift from gaper clams to boring clams in the Elkhorn main channel between 1970s and 1990s (Oliver et al. unpublished). An increase in sea otters and concurrent decrease in size of bivalve prey during 1990s (Jolly 1997). An increase in harbor seal numbers in the 1990s (Harvey & Connors 2002). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. Continued loss of fine sediments due to scour will lead to continued loss of those organisms (e.g. infaunal clams) associated with them (K. Wasson). Continued widening and deepening of the tidal creeks will result in their fauna continuing to become more similar to that of the lower main channel (K. Wasson). Continued deepening of the main channel will result in continued decline of organisms reliant on shallow water conditions, including eelgrass beds (K. Wasson). Will this be done by committee? I think the erosion will slow down and reach some kind of threshold. If geologists and hydrologists disagree, then I will back off. If a threshold is reached, there will be a shifting of fishes from one location to another, but most will still be accommodated (G. Cailliet). I question some of the predictions. Presumably we can now get down to talking about the relative ecological merits of the various habitats and the predictions about how these habitats may change. Then a discussion of what, if anything, should be done to change the current and predicted mix would be fruitful (M. Foster). Does this statement consolidate these predictions? Channels are likely to erode until some sort of threshold is reached (K. Wasson). DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 6

7 CHANNEL (RESTRICTED TIDAL FLOW) Definition Channel habitat (restricted tidal flow) occurs where former subtidal channels were removed from regular tidal exchange; usually managed as freshwater impoundments Location of habitat type Channel habitats (restricted tidal flow) comprise approximately 49 acres in Elkhorn Slough and can be found in lower Porter Marsh and in portions of upper Moro Cojo Slough. Representative plants Common Name Ditchgrass Scientific Name Ruppia sp. Ulva spp. Representative animals Type Common Name Scientific Name Special Status or Notes Birds American Coot Fulica americana Mallard Northern Pintail Anas platyrhyncho Anas acuta Fishes Longjaw mudsucker Gillichthys mirabilis Threespine stickleback Gasterosteus aculeatus Invertebrates Brackish water snail Tryonia imitator Batillaria attramentaria found in lower Moro Cojo Slough and east of Bennett Slough NN Physical habitat changes and shifts in plant and animal assemblages over the past 150 years An increase in this habitat type (formerly absent) resulting from the construction of levees and tide gates. DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 7

8 Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. If salinity continues to decrease due to freshwater impoundment diluting saline soils, in areas such as Porter Marsh and upper Moro Cojo, the biologically assemblages in channels in these areas is expected to shift from species associated with brackish water to species associated with freshwater (K. Wasson). Well, if there is restricted tidal flow, how will erosion change that? If it erodes connections to these habitats, then erosion will affect these habitats too (G. Cailliet)? Does this statement consolidate these predictions? If dikes or levees preventing tidal inputs fail, then brackish marshes currently impounding freshwater will convert to tidal marshes and be subject to erosion (K. Wasson). SALT MARSH/TIDAL CREEK (UNRESTRICTED TIDAL FLOW) Definition Salt marsh/tidal creek habitat (unrestricted tidal flow) occurs where plant-dominated intertidal habitat is punctuated by a network of tidal creeks; typically occurring between 4 to 6 feet above MLLW; salinity ranges from approximately 18.0 to 35.0 parts per thousand or higher Location of habitat type Salt marsh and tidal creek habitats (unrestricted tidal flow) comprise approximately 536 acres in Elkhorn Slough. Salt marsh habitats are mostly found flanking the main channel of Elkhorn Slough and forming narrow fringing margins in Parsons Slough. Representative plants Common Name Scientific Name Special Status or Notes Alkali heath Frankenia salina high marsh Atriplex spp. (Atriplex leucophylla?) Native species, high marsh Australian saltbush Atriplex semibaccata NN, high marsh Jaumea Jaumea carnosa high marsh Parasitic dodder Cuscuta salina high marsh Perennial Sand-spurrey Spergularia macrotheca var. macrotheca high marsh DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 8

9 Pickleweed Salicornia virginica dominates low and mid marsh Salt Grass Distichlis spicata var. stolonifera high marsh Representative animals Type Common Name Scientific Name Special Status or Notes Birds California Clapper Rail Rallus longirostris SE, FE, not seen since 1980 Great Blue Heron Great Egret Ardea herodias Casmerodius albus Long-billed Curlew Numenius americanus vegetated marsh plain Northern Harrier Circus cyaneus vegetated marsh plain Savannah Sparrow Passerculus sandwichensis vegetated marsh plain Snowy Egret Willet Egretta thula Catoptrophorus, semipalmatus Fishes Arrow goby Clevelandia ios Longjaw mudsucker Pacific staghorn sculpin Gillichthys mirabilis Leptocottus armatus Invertebrates Beetles Coleopteran vegetated marsh plain Flies Diptera vegetated marsh plain Spiders Arachnids vegetated marsh plain Striped shore crab Pachygrapsus crassipes Physical habitat changes and shifts in plant and animal assemblages over the past 150 years SALT MARSH An overall decrease in vegetated salt marsh along the Elkhorn Slough main channel has been attributed mainly to diking and tidal volume increases, but may also be due to other factors such as earthquake induced subsidence (Lowe 1999, Van Dyke and Wasson in press). Extensive tracts of salt marsh have also been lost over the past century in other portions of the estuarine system (along Moro Cojo, Tembladero Slough, and the old Salinas River DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 9

10 Channel, as well as in the current Moss Landing Harbor area), but these losses have not been quantified. The percent cover of pickleweed marsh in undiked marshes in the main channel of Elkhorn Slough decreased significantly while the area of bare mud increased significantly from 1931 to 1997, with the most significant decline between 1949 and 1956 (Lowe 1999). The mean percent cover of salt marsh vegetation in undiked marshlands in Elkhorn Slough decreased from approximately 90 % in 1931 to 46 % in 2003 (Van Dyke and Wasson in press). TIDAL CREEK Significant increases in the depth and width of tidal creeks in Elkhorn Slough (Kvitek unpublished, Van Dyke and Wasson in press). The mean width of 196 tidal creeks in undiked areas of Elkhorn Slough increased from 2.5 m in 1931 to 12.4 m in 2003 (Van Dyke and Wasson in press). Tidal creeks do not support the same, rich infauna they once did and therefore, the fish assemblages have changed and the role as nursery ground for fishes in the tidal creek has diminished (Lindquist 1998; cited in Yoklavich et al. 2002). Fish assemblages in tidal creeks have shifted from the 1970s to 1990s to now resemble those of the lower slough and have been attributed to changes in sediment size (Yoklavich et al. 2002). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. The trend of salt marsh degradation observed in undiked areas along the Elkhorn Slough main channel may continue (mechanisms are poorly understood, but there is no evidence that any of the possible forcing factors are likely to reverse soon) (K. Wasson). Species directly dependent on salt marshes (using them for refuge or food) or indirectly (feeding off organic matter from decaying pickleweed) are expected to decrease (K. Wasson). SALT MARSH/TIDAL CREEK (RESTRICTED TIDAL FLOW) Definition Salt marsh/tidal creek habitat (restricted tidal flow) occurs where vegetated habitat is currently restricted from tidal flow; dominated by pickleweed and other salt marsh plants (likely due to elevated soil salinity). Occasionally punctuated by tidal creeks, but it is not as common as in areas with unrestricted tidal flow. DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 10

11 Location of habitat type Salt marsh habitats (restricted tidal flow) comprise approximately 436 acres in Elkhorn Slough and can be found in the lower Porter Marsh, Estrada Marsh, North Marsh, the northern portion of the Salt Ponds, and upper portions of Moro Cojo Slough. Representative plants Common Name Scientific Name Special Status or Notes Alkali heath Frankenia salina high marsh Atriplex spp. (Atriplex leucophylla?) Native species, high marsh Australian saltbush Atriplex semibaccata NN, high marsh Jaumea Jaumea carnosa high marsh Parasitic dodder Cuscuta salina high marsh Perennial Sand-spurrey Spergularia macrotheca var. macrotheca high marsh Pickleweed Salicornia virginica dominates low and mid marsh Salt Grass Distichlis spicata var. stolonifera high marsh Representative animals Type Common Name Scientific Name Birds American Avocet Recurvirostra americana Black-necked Stilt Marsh Wren Savannah Sparrow Song Sparrow Western Meadowlark Himantopus mexicanus Cistothorus palustris Passerculus sandwichensis Melospiza melodia Sturnella neglecta Invertebrates Beetles Coleopteran Flies Diptera DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 11

12 Habitat changes over the past 150 years An increase in this habitat type (formerly absent) resulting from the construction of levees and tide gates. Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. The areas currently under this sort of management have been inundated by tidal flow fairly recently (within past decade). It is not yet clear how long salt marsh will persist in these areas if such tidal inundation is fully prevented in the future. Freshwater and upland vegetation is expected to replace salt marsh when soil salinity decreases (K. Wasson). BRACKISH MARSH (UNRESTRICTED TIDAL FLOW & RESTRICTED TIDAL FLOW) Definition Brackish marsh occurs where tidal saltwater is significantly diluted by freshwater during much of year; salinity ranges from approximately 0.5 to 18.0 parts per thousand; characterized by a mix of species typical of both fresh and saline areas Location of habitat type Brackish marsh habitats comprise approximately 219 acres in Elkhorn Slough and can be found in areas such as South Strawberry Pond, upper Moro Cojo Slough, and upper Porter marsh. Representative plants Common Name Bulrush Cattail Jaumea Pickleweed Scientific Name Scirpus sp. Typha sp. Jaumea carnosa Salicornia virginica Representative animals DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 12

13 Type Common Name Scientific Name Special Status or Notes Birds Common Yellowthroat Geothlypis trichas Marsh Wren Red-winged Blackbird Virginia Rail Cistothorus palustris Agelaius phoeniceus Rallus limicola Mammal Western harvest mouse Reithrodontomys megalotis Fishes Threespine stickleback Gasterosteus aculeatus Tidewater goby? Eucyclogobius newberryi FE Physical habitat changes and shifts in plant and animal assemblages over the past 150 years Decreases in these transitional areas resulting from decreased freshwater inputs and from the construction of tide gates and levees that separated the interchange of salt and freshwater. While freshwater would have formerly flowed through and out of these areas, it is now impounded (at Porter and upper Moro Cojo) with dikes, creating seasonal freshwater ponds. Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. Currently extensive brackish habitat is only found in areas being managed for no tidal flow; if such management is successful for a few decades, it is expected these areas would convert from brackish to freshwater marshes (K. Wasson). MUDFLAT (UNRESTRICTED TIDAL FLOW) Definition Mudflat habitat (unrestricted tidal flow) occurs in flat or gently sloping areas with no or sparse cover of vegetation; typically found below marsh habitats at approximately -1 to +3 feet above MLW; usually without channels or creeks DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 13

14 Location of habitat type Mudflat habitats (unrestricted tidal flow) comprise approximately 631 acres in Elkhorn Slough and can be found in the along the main channel and creeks of Elkhorn Slough, Parsons Slough, South Marsh, and the North Harbor. Representative plants Common Name Eel grass Scientific name Zostera marina Gracilariopsis sp. (Gracilaria pacifica?) Ulva spp. Representative animals Type Common Name Scientific Name Birds American Avocet Recurvirostra americana Black-bellied Plover Marbled Godwit Dunlin Ring-billed Gull Short-billed Dowitcher Western Sandpiper Willet Pluvialis squatarola Limosa fedoa Calidris alpina Larus delawarensis Limnodromus griseus Calidris mauri Catoptrophorus semipalmatus Fishes Arrow goby Clevelandia ios Jacksmelt Longjaw mudsucker Pacific staghorn sculpin Specked sanddab Topsmelt Atherinopsis californiensis Gillichthys mirabilis Leptocottus armatus Citharichthys stigmaeus Atherinops affinis Yellowfin goby Acanthogobius flavimanus NN DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 14

15 Invertebrates Amphipods Bentnose clam Gaper clam Macoma nasuta Tresus nuttalli Isopods Polydora socialis Physical habitat changes and shifts in plant and animal assemblages over the past 150 years Dramatic increase in mudflat habitat in areas with unrestricted tidal flow areas as salt marsh along the main channel has degraded and converted to mudflat (Van Dyke and Wasson in press). In areas diked for agricultural and grazing activities, subsidence from the drying of marsh sediments has lowered the marsh plain elevation so that when tidal flow was returned, these former salt marsh habitats mostly converted to mudflat or lagoon. Some intertidal mudflats have now also converted to subtidal habitats. A possible increase in abundance of Ulva sp. from the 1970s to 1990s (Zimmerman and Caffrey 2002). Invasion of mudflats by dozens of non-native invertebrates from the 1930s to 1990s and many now are highly abundant (Wasson et al. 2001). Dramatic changes in invertebrate community (increase in invasive species, decline in native species) composition from the 1970s to 1990s attributed to sediment grain size changes (Fenn 2003). Sharp declines in formerly abundant blue mud shrimp, ghost shrimp, green phoronid worms, and various native bivalves from the 1970s to 1990s (Wasson et al 2002). Local extinction of a native horn snail, likely by 1950s due to displacement by Asian mudsnail (Batillaria attramentaria) (Byers 1999). Increased density of large shorebird species (Willet, Marbled Godwit, and Long-billed Curlew) from the 1970s to 1990s in the lower section of Elkhorn Slough relative to the mid-slough probably due to the decreased extent of foraging habitat such as mudflat (Connors 2003). Beginning and increase of pupping by harbor seals (Harvey and Connors 2002). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. Continued decline of species reliant on ample soft-sediment for burrowing or feeding, due to tidal scour of the remaining truly muddy areas (K. Wasson). DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 15

16 Increase in species associated with high intertidal mud pans opening up in degrading salt marshes (a different and much less diverse assemblage than is found in low intertidal mudflats) (K. Wasson). MUDFLAT/SALT PANNE (RESTRICTED TIDAL FLOW) Definition Mudflat habitat (restricted tidal flow) occurs in flat or gently sloping areas with no or sparse cover of vegetation and are removed from regular tidal exchange. Salt panne habitat (restricted tidal flow) occurs in depressions, typically flooded in winter (with rain and extreme tides) but dry in the summer, leaving a salt crust on the soil surface. Location of habitat type Mudflat and salt panne habitats (restricted tidal flow) comprise approximately 243 acres in Elkhorn Slough and can be found in areas such as the Salt Ponds (designated management area near the mouth), Estrada Marsh, and North Marsh. Representative plants Common Name Pickleweed Scientific name Salicornia virginica Ulva spp. Representative animals Type Common Name Scientific Name Special Status or Notes Birds American Avocet Recurvirostra americana wet or flooded conditions American Wigeon Anas americana Bufflehead Bucephala albeola wet or flooded conditions California Gull Larus californicus dry conditions Gadwall Anas strepera Greater Yellowlegs Tringa melanoleuca wet or flooded conditions DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 16

17 Killdeer Charadrius vociferous dry conditions Mallard Anas platyrhyncho wet or flooded conditions Marbled Godwit Dowitchers Limosa fedoa Limnodromus spp. Least Sandpiper Calidris minutilla wet or flooded conditions Western Snowy Plover Charadrius alexandrinus nivosus FT, dry conditions Invertebrates Batillaria attramentaria NN, does not occur in salt pannes to our knowledge Physical habitat changes and shifts in plant and animal assemblages over the past 150 years An increase in mudflat habitat with restricted flow (formerly absent) resulting from the construction of levees and tide gates. Natural salt pannes in the lower portion of Elkhorn Slough have been modified (for salt harvesting) and increased in size (managed for snowy plovers) and salt pannes at Moro Cojo Slough have been destroyed for industrial development. With intensive management nesting Western snowy plovers have increased from 1995 to present in salt pannes (Harvey and Connors 2002, PRBO unpublished data). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. The salt ponds in the Salt Pond area will convert to mudflats unless dikes are maintained to prevent full tidal flow (K. Wasson). LAGOON (RESTRICTED TIDAL FLOW) Definition Lagoon habitat (restricted tidal flow) occurs where shallow perennial water is separated from full tidal action (typically created behind tide gates or culverts). DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 17

18 Location of habitat type Lagoon habitats (restricted tidal flow) comprise approximately 77 acres in Elkhorn Slough and can be found in North Marsh, Bennett Slough, Azevedo Ponds, and Whistlestop Lagoon. Representative plants Common Name Scientific name Ulva spp. Representative animals Type Common Name Scientific Name Special Status or Notes Birds American Avocet Recurvirostra americana American Coot Black-necked Stilt Bufflehead Great Egret Greater Yellowlegs Mallard Pied-billed Grebe Fulica americana Himantopus mexicanus Bucephala albeola Casmerodius albus Tringa melanoleuca Anas platyrhyncho Podilymbus podiceps Fishes Pacific staghorn sculpin Leptocottus armatus Topsmelt Atherinops affinis Tidewater goby Eucyclogobius newberryi FE Invertebrates Amphipods Gammarid spp. European green crabs Carcinus maenas NN Mud-flat crab Gem clam Polychaetes Hemigrapsus oregonensis Gemma gemma Spionid spp. DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 18

19 Physical habitat changes and shifts in plant and animal assemblages over the past 150 years An increase in this habitat type (formerly absent) resulting from the construction of levees and tide gates. In areas diked for agricultural and grazing activities, subsidence from the drying of marsh sediments has lowered the marsh plain elevation so that when tidal flow was returned, these former salt marsh habitats mostly converted to mudflat or lagoon. Dramatic increases in non-native invasive European green crab population from 2000 to 2004 in North Marsh (Wasson and Preisler in prep). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. If these lagoons continue to be managed as they are currently with tide gates and culverts, their biological assemblages should remain fairly stable (K. Wasson). WETLAND/UPLAND ECOTONE (UNRESTRICTED TIDAL FLOW & RESTRICTED TIDAL FLOW) Definition Wetland/Upland Ecotone habitats occur in transition zones where wetland and upland vegetation overlap; in tidal areas typically at elevations between +7 and +10 ft MLLW; only inundated on extreme high tide or flood events Location of habitat type Wetland/Upland Ecotone habitats are present everywhere except in highly disturbed areas. Representative plants Common Name Scientific Name Special Status or Notes Alkali heath Coyote bush Frankenia salina Baccharis pilularis Creeping wild rye Gum plant Italian thistle Grindelia camporum Carduus pycnocephalus DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 19

20 Jaumea Jaumea carnosa Mediterranean annual grasses NN Mustard Brassica rapa, Brassica campestris NN Poison hemlock Salt grass Conium maculatum Distichlis spicata var. stolonifera Sea lavender Representative animals Type Common Name Scientific Name Birds American Kestrel Falco sparverius Black Phoebe Western Meadowlark Red-tailed Hawk Song Sparrow Sayornis nigricans Sturnella neglecta Buteo jamaicensis Melospiza melodia Mammal California vole Microtus californicus Physical habitat changes and shifts in plant and animal assemblages over the past 150 years Decrease in transitional habitat areas resulting from levees, cattle grazing, and human disturbance. Extensive invasion of this habitat area by upland weeds, especially in diked areas. In heavily grazed and trampled areas, there are areas of bare ground instead of native vegetation (Martone and Wasson in prep; Wasson and Woolfolk in prep). Predicted future biological trends under a no action alternative The following trends could be discussed in a working group meeting. Continued invasion of this zone by upland weeds, especially in diked marshes such as Porter and Moro Cojo (K. Wasson). DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 20

21 REGIONAL HABITAT TRENDS Statewide figures are not well known for trends of estuarine habitat change in all regions of California. In areas that do have data, it appears that there have been more losses of all of the habitat types than gains. In Southern California, for example, salt marsh habitat has decreased by approximately 87 %, mudflat habitats have decreased by approximately 84 %, and the total extent of subtidal habitat areas has remained approximately the same from in the Tijuana Estuary, San Diego Bay, and Mission Bay (Zedler 1996). Bolinas Lagoon has had a decrease in subtidal habitat during approximately the same time period (Bill Carmen pers com.). The extent of historic habitat loss in San Francisco Bay has been about 80 % for tidal marsh habitats and 40 % for mudflat habitats (Habitat Goals Project). Statewide many natural salt panes were converted to salt ponds for industrial salt production. Some salt ponds in the south San Francisco Bay, are being restored to tidal influence. There has also been a loss of wetland/upland ecotone habitat in Southern California, resulting in the danger of local extinction to rare plant species that colonize only the marsh upland ecotone (James and Zedler 2000). BIBLIOGRAPHY Additional information on representative plants and animals for this document was gathered from Barry et al. 1996, Caffrey et al. 2002, and De Vogelaere et al Published works Barry, J.P., M.M. Yoklavich, G.M. Cailliet, D.A. Ambrose, and B.S. Antrim Trophic ecology of the dominant fishes in Elkhorn Slough, California, Estuaries, 19(1): Byers, J The distribution of an introduced mollusc and its role in the long-term demise of a native confamilial species. Biological Invasions, 1(4): Caffrey, J.M., M.T. Brown, W.B. Tyler, and M. Silberstein, eds Changes in a California Estuary: A Profile of Elkhorn Slough. Moss Landing, CA: Elkhorn Slough Foundation. Harvey, J.T. and S. Connors Birds and mammals. In J.M. Caffrey, M.T. Brown, W.B. Tyler, and M. Silberstein (Eds.), Changes in a California Estuary: A Profile of Elkhorn Slough (pp ). Moss Landing, CA: Elkhorn Slough Foundation. James, M. L. and J. B. Zedler (2000). Dynamics of Wetland and Upland Subshrubs at the Salt Marsh-Coastal Sage Scrub Ecotone. American Midland Naturalist, 143(2): MacGinitie, G.E Ecological aspects of a California marine estuary. American Midland Naturalist, 16(5): DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 21

22 Van Dyke, E. and K. Wasson. In Press. Historical Ecology of a Central California Estuary: 150 Years of Habitat Change. Estuaries. Wasson, K., E. Van Dyke, R. Kvitek, J. Brantner, and S. Bane Tidal erosion at Elkhorn Slough. In J. Carless (Ed.), Ecosystem Observations (pp ). Monterey, CA: Monterey Bay National Marine Sanctuary. Wasson, K., J. Nybakken, R. Kvitek, C. Braby, and M. Silberstein Invertebrates. In J.M. Caffrey, M.T. Brown, W.B. Tyler, and M. Silberstein (Eds.), Changes in a California Estuary: A Profile of Elkhorn Slough (pp ). Moss Landing, CA: Elkhorn Slough Foundation. Yoklavich, M.M., G.M. Cailliet, J. Barry, D. Ambrose, and B. Antrim Temporal and spatial patterns in abundance and diversity of fish assemblages in Elkhorn Slough, California. Estuaries, 14(4): Yoklavich, M.M., G.M. Cailliet, D.S. Oxman, J.P. Barry, and D.C. Lindquist Fishes. In J.M. Caffrey, M.T. Brown, W.B. Tyler, and M. Silberstein (Eds.), Changes in a California Estuary: A Profile of Elkhorn Slough (pp ). Moss Landing, CA: Elkhorn Slough Foundation. Zedler, J.B., Principal Author Tidal Wetland Restoration: A Scientific Perspective and Southern California Focus. Published by the California Sea Grant College System, University of California, La Jolla, California. Report No. T-038. Zimmerman, R.C. and J.M. Caffrey Primary Producers. In J.M. Caffrey, M.T. Brown, W.B. Tyler, and M. Silberstein (Eds.), Changes in a California Estuary: A Profile of Elkhorn Slough (pp ). Moss Landing, CA: Elkhorn Slough Foundation. Unpublished works Connors, S. Shorebird distribution in a changing environment: patterns at Elkhorn Slough. M.S. thesis, Department of Marine Sciences, San Jose State University and Moss Landing Marine Laboratories, San Jose, CA, De Vogelaere, A., J. Holte, M. Silberstein, and M. Jacobi A Species List for Elkhorn Slough and Adjacent Uplands. Report to the Monterey Bay National Marine Sanctuary. Dean, E.W. Tidal scour in Elkhorn Slough, California: a bathymetric analysis. B.S. capstone project, Department of Earth System Science and Policy, California State University, Monterey Bay, CA, Fenn, K.H. Spatial and temporal variability of benthic infaunal communities in the soft substrates of the Elkhorn Slough, Moss Landing, California. M.S. thesis, Department of Zoology, Miami University, Oxford, OH, DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 22

23 Jolly, J.M., Foraging ecology of the sea otter, Enhydra lutris, in a soft-sediment community. M.S. thesis, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, Kvitek, R.G., M.A. Silberstein, J.S. Oliver, P.N. Slattery, C. Jong, J. Nybakken, B.S. Anderson, and K. Finn. Persistence and change of infaunal invertebrate communities in the Elkhorn Slough. Unpublished manuscript, Elkhorn Slough National Estuarine Research Reserve, Lindquist, D.C. The effects of erosion on the trophic ecology of fishes in Elkhorn Slough, CA. M.S. thesis, Department of Marine Science, California State University and Moss Landing Marine Laboratories, Hayward, CA, Lowe, P.B. Marsh loss in Elkhorn Slough, CA: Patterns, mechanisms, and impact on shorebirds. M.S. thesis, San Jose State University and Moss Landing Marine Laboratories, San Jose, CA, Malzone, C.M. Tidal scour and its relation to erosion and sediment transport in Elkhorn Slough. M.S. thesis, Department of Geology, San Jose State University and Moss Landing Marine Laboratories, San Jose, CA, Martone, R. and K. Wasson. In prep. Trampling and tidal restriction facilitate invasion of upland plants into a California salt marsh. Oxman, D.S., Seasonal abundance, movements, and food habits of harbor seals (Phoca vitulina) in Elkhorn Slough, California. M.S. thesis, Department of Marine Sciences, California State University and Moss Landing Marine Laboratories, Stanislaus, CA, Wasson, K. and A. Woolfolk. In prep. Ecotone monitoring in Elkhorn Slough, CA. Unpublished data, Elkhorn Slough National Estuarine Research Reserve, CA, Wasson, K., A. De Vogelaere, E. Van Dyke, S. Lonhart, and S. Fork. Erosion monitoring results for Elkhorn Slough, CA. Unpublished data, Elkhorn Slough National Estuarine Research Reserve and Monterey Bay National Marine Sanctuary, DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 23

24 APPENDIX MAP OF PLACE NAMES DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 24

25 1 Zmudowski Pond fresh/brackish 2 McClusky Slough fresh/brackish 3 Struve Pond restricted flow 4 Bennett Slough restricted flow 5 Old Salinas River Mouth restricted flow 6 North Harbor fully tidal 7 West Salt Ponds restricted flow 8 East Salt Ponds restricted flow 9 Rubis Marsh fully tidal 10 South Packard Marsh fully tidal 11 North Packard Marsh fully tidal 12 TNC Marsh fully tidal 13 Hudson Landing Marsh fully tidal 14 Watsonville Ditch 15 Carneros Creek 16 Porter Marsh restricted flow 17 North Azevedo Pond restricted flow 18 Middle Azevedo Pond restricted flow 19 South Azevedo Pond restricted flow 20 Estrada Marsh restricted flow 21 Campanga Marsh restricted flow 22 North Marsh restricted flow 23 North Strawberry Pond restricted flow 24 South Strawberry Pond restricted flow 25 Coyote Marsh fully tidal 26 Whistlestop Lagoon restricted flow 27 Rookery Lagoon fully tidal 28 South Marsh fully tidal 29 Long Valley 30 Parsons Slough fully tidal 31 Five Fingers fully tidal 32 Yampah Marsh fully tidal 33 Pick-n-Pull Marsh fully tidal 34 Minhoto Marsh restricted flow 35 Moonglow Marsh restricted flow 36 Vierra Marsh fully tidal 37 South Harbor fully tidal 38 Old Salinas River 39 Moro Cojo Slough restricted flow DRAFT Tidal Habitat Descriptions - Elkhorn Slough Tidal Wetland Plan 4/4/05 25