Because the dry season is longer than the 

 winter inundation period, barren conditions 

 prevail; hence, the habitat is called a salt 

 panne, rather than a temporary tidal pond. 

 The ephemeral nature of the aquatic phase 

 makes it difficult to appreciate the productiv- 

 ity and complexity of these communities. It is 

 often recommended in mitigation proposals 

 that salt pannes be converted to some other 

 use, because their wetland values are assumed 

 to be low. Very little research has been done 

 in salt pannes, so their habitat values have not 

 been quantified. 



Species that are characteristic of salt 

 pannes have developed adaptations to the 

 extremes of prolonged inundation and high salt 

 accumulation. Many soil-dwelling insects 

 utilize "plastrons," or air traps, that allow 

 them to respire when the water or soil is 

 anaerobic (Foster and Treherne 1976). In 

 addition, many have developed waterproof 

 integuments and mechanisms for secreting 

 hypertonic rectal fluids to regulate osmotic 

 and ionic balance. 



Rove beetles (Staphylinidae, Genus 

 Bledius; Figure 3.14) were studied at Tijuana 

 Estuary by Nordby (1984). Several species 



of these small beetles inhabit complex 

 underground labyrinths that are evidenced at 

 the surface by excavated "middens." The 

 density of middens reaches 500/m 2 ; the 

 tunnels beneath them are about 20 cm in 

 depth. Densities of beetles were highest in 

 March 1984, when 8 adults and 22 juveniles 

 were recorded per 1,650 cm 2 core. 

 Reproduction occurred in the spring with eggs 

 attached to the sides of burrows by means of a 

 clear, threadlike material. 



Intertidal elevation is the most important 

 physical variable that characterizes rove 

 beetle distribution patterns. They are densest 

 in a narrow belt at about the high tide line. 

 The beetles prefer soil dampened by tidal 

 inundation but not covered by standing water. 

 A typical biweekly fluctuation of midden 

 densities occurs with the high summer tides: 

 as a high tide recedes, midden mounds appear 

 as the beetles begin to burrow, more densely 

 at the region where the soils have begun to dry 

 and less densely at the water's edge; as the soil 

 dries, the middens accumulate as excavation 

 activities continue; then, an ensuing high tide 

 erases the surface middens, and the pattern is 

 repeated. It is not known where the beetles 



Figure 3.14. The salt panne insects include species of rove beetle (Bledius; Coleoptera: 

 Staphylinidae, on left) and tiger beetle (at center: adult Cicindela gabbi and larva of C. oregona; 

 Coleoptera: Cicindelidae). The saldid bug (Pentacora signoreti; Hemiptera: Saldidae, 8 mm long) is 

 an important and widespread marsh predator. Mclntire collection, © 1986 by Zedler. 



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