Mountain Caribou are a rare ecotype of Woodland Caribou (Rangifer tarandus caribou) inhabiting the high-snowfall region of southeastern British Columbia, and are defined by their late-winter reliance on arboreal hair lichen of the genus Bryoria. During early winter, there is considerable variation in habitat use among populations. We snow-trailed Caribou in the southern Purcell Mountains during early winter to determine foraging patterns for the Purcell population. When snow was ≤51 cm deep, Caribou fed on Grouseberry (Vaccinium scoparium), the terrestrial lichen Cladonia, and arboreal lichens of the genus Bryoria. When snow was ≥62 cm deep, they ate exclusively arboreal lichens. In both periods, Caribou ate arboreal lichen from essentially every downed tree or branch encountered and fed with a higher intensity at downed trees than standing trees. During the low-snow period, Caribou fed at fewer trees but used those with greater lichen abundance, and fed more intensively at each, compared to the deep-snow period. In comparison to trees occurring on the foraging path but at which Caribou did not feed, those from which arboreal lichen was foraged intensively were of larger diameter, had greater lichen abundance, and were more likely to be Subalpine Fir (Abies lasiocarpa) or Engelmann Spruce (Picea engelmannii) and less likely to be Whitebark Pine (Pinus albicaulis), Lodgepole Pine (P. contorta) or Alpine Larch (Larix lyalli). The shift in diet between the low-snow and deep-snow periods reflected two modes of foraging within the early winter period, distinct from one another and apparently also distinct from the late-winter season. Management for early-winter habitat will require retention of some commercially significant forest across extensive areas, both near the subalpine forest – subalpine parkland ecotone and lower in the subalpine forest.

Sea anemones and associated crustaceans are important components of coral reefs, but their population structure and microhabitat use remain poorly understood. We quantified both types of patterns for two sea anemone and 10 crustacean species at Akumal Bay, Mexico. Rosetip anemones, Condylactis gigantea (Weinland, 1860), occurred as solitary individuals on patch reefs throughout the midbay, while sun anemones, Stichodactyla helianthus (Ellis, 1768), formed dense aggregations on reef patches in the inner bay. Both populations were abundant with exponential size distributions that indicated potentially high recruitment and stable population structure. Individuals of corkscrew anemones, Bartholomea annulata (Le Sueur, 1817), were too rare to analyze their population structure. Crustaceans significantly segregated their microhabitat use among zones on the anemone bodies. Most exhibited exponential size structure, but the chaotic size patterns of some crustaceans suggested recently-sporadic recruitment. We report a previously undocumented association of blue-legged hermit crabs, Clibanarius tricolor (Gibbes, 1850), and anemones; crabs clustered along the anemone columns, and possessed an external, removable coating that protected them from host toxins. We conclude that some anemones and crustacean associates exhibit strong partitioning of habitat and stable population structure on these coral reefs.

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The Q o of excised Cardisoma guanhumi gill tissue is higher in hypo-osmotic than in hyperosmotic sea water.2. Gill tissue Q ._, is maximally stimulated by Na + ; K + does not stimulate Q 02 ; addition of Na + and K + simultaneously causes no greater stimulation of oxygen uptake than that following Na + alone.3. Ouabain, a Na + transport inhibitor, reduces Na + -, and Na + + K + -stimulated gill tissue respiration. In addition, Qo 2 of gill tissue measured in 75% sea water is reduced by ouabain. LITERATURE CITED

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