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Biologists pull the large seine in the East Basin
Intertidal habitats are located between the low and high tide lines. Species living in these habitats are adapted to a fluctuating environment, and, except in the case of freshwater marsh, to saline conditions. Batiquitos Lagoon has several intertidal habitats:
MarshesMarshes are areas of low-lying land that are either permenantly or seasonally ponded or tidally influenced. Marshes often form a transition zone between open water and upland habitats. They are usually dominated by herbaceous vegetation, such as grasses or cattails. The water in a marsh may be either freshwater, brackish, or salt water. At Batiquitos Lagoon, most of the marshes are now salt water marshes. Algal BedsAlgal beds seasonally thrive on broad expanses of mudflats where tides do not scour surfaces too harshly. At Batiquitos Lagoon, algal beds flourish on the almost level terrain in the eastern basin. The dominant alga species are sea lettuce and green algae. Diatom films also blanket extensive portions of the intertidal mudflats and shallow lagoon bottom. (Diatoms are single-celled algae that have a glassy covering made of silica.) Unvegetated Mudflats
Birds in the mudflats
Unvegetated intertidal mudflats make up a substantial proportion of the eastern basin and smaller parts of the central and western basins. These mudflats comprise fine sediment between tidal elevations of approximately -2 feet to +3 feet Mean Lower Low Water (MLLW). To calculate the acreage of mudflats at Batiquitos Lagoon, 0 feet MLLW was used to define the interface between mudflats and open water. Mudflats at Batiquitos Lagoon have diverse microtopography and sediment consistency; the lagoon bottom has an irregular surface of ridges and valleys, with a vertical relief of about 1.6 feet. Dredging activity created furrows in the surface of the lagoon bottom, including the intertidal zone. As the site has weathered, this relief has been reduced-fine sediments have filled in the depressions, and the sharp ridges have eroded to more rounded forms. Through this weathering process, the bottom of the unvegetated mudflats is starting to look more uniform, but still has highly variable sediment density and grain size, especially at the far eastern end of the lagoon. Batiquitos Lagoon supports several planned and unplanned sand beaches and intertidal bars. Among these are the beaches with tern nesting sites, designed to be sandy locations, and high beaches of coarse sands, where finer sediments have eroded away. Exposure to high waves and vigorous currents has created such high beaches in parts of the northern shore of the eastern basin. Beaches and large midchannel sandbars also have formed in the western and central basins, next to the railroad bridge. These formations were created by sand migrating into the lagoon from the beach and accumulating in places where the tidal current has less energy. These sandy areas mostly are composed of unstable sediments with low organic content. The abundance of small shorebirds is directly linked to the availability of tidally influenced mudflat habitat. Salt PannesClosed-basin salt pannes, which trap marine waters during the highest spring tides, are located in the peripheral eastern basin. During summer months, the water in these basins rapidly evaporates, leaving hypersaline soils and a surface veneer of salt. These salt pannes are inhospitable to most of the flowering plants in the marsh, but can accommodate a few salt-tolerant species, such as alkali weed and blue green algae. When water is present in the salt pannes, blue-green algae can be seen as a bluish-green to brownish growth. The influx of marine water to the back basins of the lagoon is gradually replacing some brackish marsh depressions with salt pannes. This trend can be seen in the northeastern corner of the eastern basin, where brackish vegetation is retreating before a broad salt panne. In this area, pickleweed can't establish quickly enough to sustain the brackish plant community. Low-lying terrain near La Costa Avenue, in the southeastern corner of the eastern basin, supports isolated tracts of salt panne that were formed before the mouth of the lagoon was reopened. This microhabitat appears to be relatively stable and is persisting. Salt panne environments may decline if drainage channels cut into the salt pannes from the lagoon or if, during winter and spring, plants encroach and reduce the rate of evaporation by shading the soil, aerating it, and improving its drainage. In closed ponds with high freshwater infiltration, such as those near the mouth of Encinitas Creek (in the southeastern portion of the eastern basin), brackish marsh may grow over ponds and prevent the development of salt pannes. EelgrassEelgrass is a coastal plant with long, slender leaves that are bright green. Reestablishing eelgrass in Batiquitos Lagoon is an important component of its restoration because eelgrass provides many benefits to the coastal ecosystem. Eelgrass
View of the West Basin looking south
Eelgrass has been transplanted to five sites in the three basins: along the southeastern and northwestern shores of the western basin, along the northern and western shores of the central basin, and along the E-1 tern colony shoreline in the eastern basin. The transplants in the central basin and along the southern portion of the western basin are faring very well and may be expanding. The transplant in the northern portion of the western basin was buried in sand that naturally accumulated there. Although persistent, the eastern basin transplants have declined, apparently because of high turbidity and sediment levels. Only one other species, native cordgrass, has been planted as part the lagoon's restoration. 
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