Anthropogenic causes of the western Steller sea lion Eumetopias jubatus population decline and their threat to recovery

• 1 The western Steller sea lion Eumetopias jubatus population has experienced a chronic decline since the 1960s. The causes are likely multifactorial and a combination of anthropogenic and natural factors. A draft revised recovery plan for the Steller sea lion has been published by the US National Marine Fisheries Service, listing both anthropogenic and natural factors that may have contributed to the observed decline or which may be a threat to the recovery of the western Steller sea lion population. The purpose of this review is to consider the anthropogenic threats to this stock.
• 2 Anthropogenic sources of mortality include fisheries competition resulting in nutritional stress, mortality incidental to commercial fisheries (i.e. fisheries by‐catch), subsistence hunts, legal and illegal shooting, commercial hunts, anthropogenic‐related contamination, and research‐induced mortalities.
• 3 We present evidence that the following anthropogenic factors likely contributed to the decline of the western Steller sea lion population over the last 40 years: (i) mortality incidental to commercial fisheries (i.e. by‐catch); (ii) commercial hunting of western Steller sea lions; and (iii) legal and illegal shooting; whereas the subsistence hunts for western Steller sea lions and mortality incidental to research were not likely to be contributors to the observed decline.
• 4 Further, we present evidence that the following can be excluded as significant anthropogenic threats to the recovery of the western Steller sea lion population: (i) mortality incidental to commercial fishing; (ii) legal and illegal shooting; (iii) commercial hunts of Steller sea lions; (iv) subsistence hunting; and (v) mortality incidental to research.
• 5 Competition with fisheries resulting in nutritional stress, and the potential impacts of contaminants, are two anthropogenic factors that should continue to be a priority for the various organizations currently doing research on this population.

     

1-M1-甲基环丙烯和氯化钙处理对鲜切西瓜果实脂质水解酶的作用(英文)

无籽西瓜(Citrullus　lanatus　Thunb.　Mansfeld,　cv.　Millionaire)果实在10　μL/L　1-甲基环丙烯(1-MCP)或正常空气中预贮18　h后,切取内果皮肉柱　(直径7　mm,长40　mm),再用2%　CaCl2或去离子水冲淋肉柱,然后将肉柱贮藏于10　℃。测定贮藏过程中的果肉硬度、电导率、磷脂酶D　(PLD)、磷脂酶C　(PLC)和脂氧合酶　(LOX)的活性变化。结果显示,2%　CaCl2刺激PLD、PLC和LOX的活性,维持果肉的硬度。单独用CaCl2处理并不足以维持切割西瓜的品质,还可能因刺激脂质水解酶而发生不良的作用。1-MCP能够抵抗CaCl2对PLD、PLC和LOX的刺激作用。与对照相比,1-MCP与CaCl2结合处理能延缓西瓜果肉的衰老过程,表现出较高的果肉硬度和较低的脂质水解酶活性。     

Spatial patterns of range contraction in British breeding birds

We use ornithological atlas data to assess evidence for the existence of a number of spatial patterns of range contraction in British breeding birds. For 18 of the 25 species which suffered the greatest range contractions between 1968 and 1991, there wais a greater likelihood of local extinction in areas where the species was initially less widespread, so ranges tended to contract towards their cores. However there was evidence for a number of other patterns, with some species having a greater likelihood of local extinction in the centres of their ranges and others suffering random local extinctions throughout their range. The different spatial patterns identified were largely independent of the overall range contraction suffered by each species nationally. We suggest that range contractions in British birds can generally be explained better by a general decline in habitat quality or other factors than by contagious anthropogenic effects, as might be expected in a country with a long history of human environmental modification.     

Phylogenetic revision of the Charis cleonus complex (Lepidoptera: Riodinidae)

Abstract.  A revision of the Charis cleonus group of Neotropical riodinid butterflies is presented, including discussions on the taxonomy, biogeography and biology of its species, and illustrations of the adults and male and female genitalia (where known) of all taxa. We recognize twenty-two species, including nineteen new species: C. ariquemes sp.n., C. brasilia sp.n., C. breves sp.n., C. cacaulandia sp.n., C. cuiaba sp.n., C. humaita sp.n., C. ipiranga sp.n., C. iquitos sp.n., C. ma sp.n., C. manicore sp.n., C. manu sp.n., C. matic sp.n., C. maues sp.n., C. negro sp.n., C. palcazu sp.n., C. rocana sp.n., C. santarem sp.n., C. tapajos sp.n and C. tefe sp.n. A cladistic analysis using thirty-six characters of male and female genitalia and external facies generated a single most parsimonious cladogram highlighting the existence of two clades, the major and cleonus subgroups. As each species largely occupies a parapatric range, this cladogram provides the opportunity to reassess historical relationships among areas of endemism in the Amazon basin.     

Amoeboflagellate Transformations and the Gibbs-Donnan Ratio*

SYNOPSIS. A number of protozoa may have amoeboid, flagellated, or intergrade forms. At the present time several mechanisms have been proposed for inducing the formation of each of the above forms, but a definite triggering mechanism has not been elucidated. However, some change in the environment precedes the transformation of the cell from one form to another. Jahn (1962) and Czarska (1964), respectively, correlated ciliary reversal and water expulsion vesicle activity with alterations in the ionic environment. In both cases the processes involved are correlated with changes in the Gibbs-Donnan (G-D) relationship rather than direct ratios or molarities. It seems reasonable to assume that additional environmentally induced phenomena may also be based on changes in the relationship. The assumption is here made that an amoeboid cell, possessing the necessary genetic and physiologic potentials, can respond to certain changes in its environment by enflagellation. The following hypothesis is being considered: a change in the environment that increases the relative concentration of associated divalent cations is perhaps one of the main triggers for amoeba-to-flagellate transformations. Thus, in accordance with the G-D theory, this transformation would be expected to occur when a given ionic environment is diluted. In addition, the transformation is discussed in relation to pH, population density, and other environmental parameters that alter the Gibbs-Donnan ratio.     

Archaeochlus Brundin: a midge out of time (Diptera: Chironomidae)

Abstract. Archaeochlus , a plesiomorphic genus of Podonominae (Chironomidae), is revised and two new species (biko from Namibia and brundini from southwestern Australia) described. The systematic status of the genus and the tribe Boreochlini is reassessed. Biogeographic evidence, sustained by a fossil record, dates the genus at least to the Upper Jurassic. The ecology of early Chironomidae is suggested to be eurythermic and hygropetric rather than cold stenothermic in lotic waters.     

Infection of Macrophages in Culture by Leptomonads of Leishmania donovani

SYNOPSIS. Peritoneal macrophages from hamsters were monolayered on coverslips in Leighton tubes. Twenty-four hours later these were transferred to a perfusion chamber. Leptomonads were added with fresh medium and the infection process observed with the aid of phase contrast. In the perfusion chamber free-swimming leptomonads attached to the macrophage by the tip of their flagella. Shortly after this initial attachment the macrophage extended a narrow pseudopodium around the flagellum which eventually reached and enveloped the body of the parasite. Upon complete envelopment the pseudopod containing the leptomonad was retracted into the central body of the macrophage. When first seen in the granular endoplasm of the macrophage, most of the leptomonads appeared to be surrounded by vacuoles. In most cases these vacuoles disappeared in a few minutes making it difficult to distinguish the parasite from the host cell cytoplasm.
Leptomonads also were added directly to Leighton tube cultures, and the coverslips with the adherent macrophages and parasites were removed, fixed and stained periodically during the infection process. In these preparations most of the parasites were in clumps in the vicinity of macrophages. Details of the ingestion of the clumps could not be seen, but occasionally a single organism was seen with its flagellum and part of its body enclosed by an extended pseudopod. Most of the intracellular leptomonads were in large vacuoles. Forms intermediate between elongate leptomonads and LD bodies were surrounded by smaller vacuole-like spaces. The halo-like vacuoles most frequently seen around LD bodies may have been fixation artifacts. Under favorable conditions the leptomonads transformed to LD bodies in 1–4 hours, but it was 48 hours before a population increase could be found.     

Effect of Acetaldehyde on Growth in Succinate Media and Labeling RNA with 14C Succinate in Polytomella caeca

SYNOPSIS. Acetaldehyde had been shown to prevent growth of Polytomella caeca in acetate media when present at 4 mM and to depress labeling of RNA with acetate-2-¹⁴C. In order to avoid inhibition by acetaldehyde of possible malate synthase activity believed necessary for incorporation of acetate, succinate was substituted for acetate. Acetaldehyde had the same effect on growth in succinate media and labeling of RNA with succinate-2-¹⁴C as it had on utilization of acetate.