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     

Osmoregulation in nestling California gulls at Mono Lake,California

• 1.1. Hematocrit (Hct), plasma sodium ([Na]_pl), chloride ([Cl]_pl) and osmotic concentration (Osm_pl); volume and concentration of 1.0MNaCl induced salt gland secretion (SGS); and weights of osmoregulatory organs: kidneys, adrenal glands, and salt glands and nonosmoregulatory organs (liver and heart) were determined in nestling California gulls, Larus californiens (CG), on Krakatoa Islet, Mono Lake, California.
• 2.2. The mean Hct was 40.0% + 1.0%, the mean [Na]_pl and [Cl]_pl were 153.9 ± 0.9 and 110.1 ± 0.5 mM (n = 22); and the mean Osm_pl was 323.6 ± 1.3 mOsm/kg (n = 18).
• 3.3. In CG nestlings with a mean age of 10 days (n = 7), the mean SGS [Na] was 719 ± 19 mM and the birds secreted 81 ± 18% of the injected fluid containing 59 ± 13% of the injected Na. By the mean age of 23 days (n = 7), mean SGS [Na] was slightly higher (790 ± 30 mM than in younger birds (P < 0.05), but the percentage of secreted fluid (54 ± 10%) and Na (42 ± 6%) tended to be less.
• 4.4. In 18 CG nestlings mean organ weights (% body weight) were: kidneys 1.52 ±0.06%; salt glands, 0.13 ±0.01%, and adrenal glands 0.07 ±0.01%.
• 5.5. Nestling CG had significantly greater Hct (P < 0.001), [Na]_pl and [ci]_pl (P < 0.001), Osm_pl, (P < 0.005), and adrenal gland weight (P < 0.01), compared to nestling glaucous-winged Gulls (GWG), L. glaucescens (Hughes, 1984), which nest under cooler, moister conditions. CG kidney weight was smaller (P < 0.001); salt gland weight and salt excretion were the same as GWG.