The coastal salt marshes of California and Baja California

A comparative study of the North American salt marshes between Magdalena Plain (Baja California, 24° N)_and the north of San Francisco (California 38° N) is made in order to establish relationships between floristic and zonal gradients. The sigmatistic-phytosociological method along with Average Linkage Clustering are used to describe the zonation of these salt marshes and to define the optimum zone of several halophilous plants and communities.Abbreviations (As) Arthrocnemum subterminalis - (Ds) Distichlis spicata - (Fg) Frankenia salina - (Jc) Jaumea carnosa - (MI) Monanthochloe littoralis - (S1) Sarcocornia pacifica, prostrate biotype - (S2) Sarcocornia pacifica, erect biotype - (Sp) Spartina foliosa     

Ecological effects of seaweed harvesting in the Gulf of California and Pacific Ocean off Baja California and California

The ecological effects of harvesting were investigated for two species, the giant kelp Macrocystis pyrifera and Eucheuma uncinatum, by using harvest records and aerial surveys that show yield changes and by using studies of recruitment, survivorship and community interactions. There were no ecological effects found for M. pyrifera harvested with contemporary methods, and there are no recommendations for changing current management practices for this species. It is recommended that E. uncinatum, which on occasion produces commercially significant standing crops, not be harvested unless special precautions are taken to leave some plants for regeneration of the harvested populations.     

Mid-eocene climatic change,Southwestern California and Northwestern Baja California

A widespread paleosol of Paleocene and Early Eocene age occurs in southwestern California and northwestern Baja California. The dominant quartz-kaolinite mineralogy and cation-depleted chemistry of the buried soil indicate a humid, tropical paleoclimate similar to the modern equatorial belt. Although the Paleocene—Eocene paleomagnetic latitudes are similar to the modern latitudes (36–37°N to 32–33°N, respectively), rainfall was about 125–190 cm per year and average annual temperature was about 20–25°C in marked contrast to the present annual rainfall of 25 cm and average annual temperature of 16°C.A variety of indicators in the Late Eocene sedimentary succession suggests a change to a semi-arid paleoclimate. The nonmarine portions of the Late Eocene sedimentary record are dominated by a cobble conglomerate lithosome deposited in fluvial, alluvial fan and fan delta systems. Intertongued with the conglomerate is a sandstone lithosome deposited in flood-plain and nearshore marine environments. The conglomerate clasts were transported to the depositional site via a long-distance (200–300 km), moderate gradient, braided river system mostly by flash floods. Characteristic post-depositional, in situ fracturing of conglomerate clasts probably occurred due to salt crystallization.Within the flood plain sandstones, and to a lesser degree the conglomerates, are multiple well-developed caliche horizons of probable pedogenic origin. Clay minerals from the Late Eocene rocks are dominantly vermiculite and smectite with lesser chlorite and illite; this is in marked contrast to the kaolinite that comprises the underlying Early Paleogene lateritic paleosol.The character of the Late Eocene sedimentary succession indicates a semi-arid climate. Rainfall probably did not exceed 63 cm per year; it probably was seasonal and by occasional flash floods. This paleoclimate contrasts markedly with the earlier humid tropical paleoclimate and must indicate a widespread climatic change in late Middle Eocene time.     

Diagnosis and seroprevalence of leptospirosis in California sea lions from coastal California

The sensitivity and specificity of the microscopic agglutination test (MAT) as a method for detection of exposure to Leptospira spp. in California sea lions (Zalophus californianus) were determined. Sera came from individuals that demonstrated clinical signs of renal disease, had lesions suggestive of leptospirosis at necropsy, and had visible leptospires in silver stained kidney sections as positive controls. Sera from unexposed captive individuals were used as negative controls. The test was 100% sensitive at 1:3,200 for confirming renal infection and 100% specific at negative < 1:100 for detection of Leptospira interrogans scrovar pomona antibodies by MAT in California sea lions. Leptospira interrogans serovar pomona was used as a screening serovar because it has been isolated previously from the kidneys and placentas of California sea lions, and there appears to be cross-reactivity between serovar pomona and other serovars. Sera from 225 free-ranging California sea lions presented to one of three participating California (USA) coastal marine mammal rehabilitation centers in 1996 were then evaluated for antibodies to serovar pomona using the MAT. The overall seroprevalence was 38.2% (86/225), although the prevalence varied among locations from 100% (38/38) in animals at the Marine Mammal Care Center (Fort MacArthur, California, USA) to 0% (0/14) at SeaWorld California (San Diego, California). At The Marine Mammal Center (Sausalito, California) [prevalence 27.8% (48/173)], the majority of seropositive animals were subadults and adults, and males were 4.7 times more likely to be seropositive to serovar pomona than females. When combining results from all three centers, subadult and adult animals were more likely to be seropositive than pups and juvenile sea lions, and the highest proportion of seropositive animals presented during the autumn months. Serum elevations of blood urea nitrogen, creatinine, phosphorus, and/or calcium were associated with seropositivity to serovar pomona. We found no association between potassium or sodium levels and seropositivity.     

Habitat associations of California ground squirrels and Botta's pocket gophers on levees in California

Vegetation management on levees, especially removal of trees and shrubs, might affect burrowing mammals that are considered threats to levee integrity. We evaluated habitat associations of California ground squirrels (Otospermophilus beecheyi) and Botta's pocket gophers (Thomomys bottae) on levees in the Sacramento Valley to assess the effects of levee vegetation management on these species. Using burrows as an indirect measure of mammal presence, we found that the presence of trees had a negative effect on the occurrence and abundance of ground squirrels on levees, and on the location of their burrowing activities on the levee slope, potentially because visual occlusion caused by tall woody vegetation impedes detection of predators. Similarly, trees had a negative effect on the abundance of pocket gophers on levees and on the location of their burrowing activities on the levee slope, probably because of the effect of tree cover on food availability. The conversion of woodland habitats to grasslands on levees most likely will result in increased occurrence, abundance, or both of ground squirrels and pocket gophers, and thereby increase the potential threat that their burrowing activities pose to levee integrity. © 2012 The Wildlife Society.     

Helminthora and Helminthocladia from California

Summary The development of the male and female reproductive structures of Helminthora stricta and Helminthocladia california from California is described. Isotype material of the former shows that the development of the cystocarp, especially that of the sterile filaments, seems to be diagnostic when compared to what is known in other species. This is confirmed by a study of more recently collected material. The spermatangia of Helminthocladia californica, in contrast, furnish the diagnostic feature of this species. Both species are similar in some ways to other known species in both genera, but these diagnostic features distinguish them.