中国茶藨子属(虎耳草科)新植物

<正> 灌木,高约2米。小枝微弯曲,黑褐色,无毛。冬芽长卵圆形。叶片呈不等的五角形,长7—13匣米,宽8—16厘米,先端长渐尖,基部深心形,边缘有不等重锯齿,上面深绿色,散生硬毛,下面淡绿色,沿脉被短柔毛,主脉和侧脉均突起;叶柄长5—9.5厘米,近无毛。总状花序,下垂,花梗长3—4毫米,和总花梗均被短柔毛,常混生星状毛。果实长圆形,红色,直径约6毫米;萼片宿存,反折,近无毛。     

Annual growth rate of the calcareous red alga Lithothamnion corallioides (Corallinales,Rhodophyta) in the Bay of Brest,France

Lithothamnion corallioides Crouan et Crouan (Rhodophyta, Corallinales) is the main constituent of the maerl beds of the Bay of Brest (Atlantic coast of western Brittany). Its growth rate was measured monthly in situ during one year. Growth rates were obtained by an adaptation of the buoyant weight technique. The highest daily growth rate was observed in July and reached 0.26 % d^–1 (S.D. = 0.06), when expressed as the increase of calcium carbonate weight. The average daily growth rate was 0.12% d^–1 (S.D. = 0.04) for a period of 275 days (summer and autumn 1988, winter 1989). Using this preliminary data, the calcium carbonate accretion rate can be estimated provisionally: 876 g m^–2 year^–1, a rate much lower than that of tropical reef coralline algae, but higher than that of Lithophyllum incrustans, the well known temperate European reef-builder.     

Plankton populations of Lake Leake and Tooms Lake—Oligotrophic Tasmanian Lakes

The characteristic feature of Lake Leake and Tooms Lake is their great similarity in physical and chemical limnology. This similarity extends to the plankton populations in general terms, both lakes being dominated by Cyclotella stelligera Cleve et Grun. and having few other species. Floristic differences are minimal. Despite this floristic similarity distinct differences exist in plankton periodicity, principally in that of Cyclotella stelligera. The extreme oligotrophy of the lakes, already suspected from their low nutrient levels, is confirmed by the extremely meagre standing crops.     

Influences of salinity on the physiology and distribution of the Arctic coralline algae,Lithothamnion glaciale (Corallinales,Rhodophyta)

In Greenland, free‐living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthåbsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured in situ during summers of 2015 and 2016, and annual patterns of productivity in L. glaciale were monitored in laboratory‐based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold‐room measurements indicate that both L. glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 ± 0.17 or 0.002 ± 0.023 μmol CaCO ₃ · g^?1 · h^?1 and ?0.007 ±0.003 or ?0.004 ± 0.001 mg O₂ · L^?1 · h^?1 in each species respectively. Mesocosm experiments indicate L. glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L. glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 ± 1.73 mg · d^?1 of biomass through summer. These results indicate high freshwater input to the Godthåbsfjord region may drive the low abundance of L . glaciale , and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.     

Genetic diversity and dispersal of the moss Sarconeurum glaciale on Ross Island, East Antarctica

The extent of genetic variation and dispersal mechanisms were investigated over short distances of 1–100 m, and up to 3 km, by the random amplified polymorphic DNA (RAPD) technique, for the moss Sarconeurum glaciale , at three locations on Ross Island, Antarctica. At Arrival Heights, genetic variation occurred within single colonies, and the relationships between clumps indicated that they were dispersed down small, meltwater drainage channels by water. The genetic similarities between the colonies from Arrival Heights and others from Scott Base and Crater Hill, a few km away, together with the prevailing wind direction and absence of this moss in the intervening snow-covered area, suggested longer-distance dispersal by wind. Overall, the Ross Island samples appeared to form a single, polymorphic population that was distinct from another population at Canada Glacier, 110 km distant. Somatic mutation, rather than immigration of genetically different propagules from elsewhere, appeared to be the most probable cause of genetic variability in these haploid, vegetatively reproducing Antarctic moss populations. Initiation of recolonization of S. glaciale across a dirt track at Arrival Heights was also investigated by RAPDs, to investigate how regrowth of mosses in disturbed areas occurred in the extreme environment of Antarctica.     

Lipid content in the early life stages of three mesopelagic fishes

Changes in lipid concentration during early ontogenetic stages were determined in three mesopelagic fish species, Benthosema glaciale , Hygophum benoiti and Maurolicus muelleri . Total lipid content per larva was related to size and mass and increased over the course of development. In all three species, the dry mass : total lipid ratio displayed a better fit than the standard length : total lipid ratio. Larvae of B. glaciale had a higher amount of lipid content, at a given mass, than the other two species. The rate of lipid accumulation with increasing larval development was similar in B. glaciale and H. benoiti , and both were higher than in M. muelleri larvae. Furthermore, total lipid concentration values, as a proportion of dry mass, increased significantly from the larval to the juvenile stages in B. glaciale (from 16 to 55%) and M. muelleri (from 9 to 20%). The present study has allowed comparisons to be drawn of the ability on the early developmental stages of deep‐sea fishes to accumulate energy reserves, both within and among species.     

A Search for Trace Fossils of the Burrowing Cirratulid Polychaetes Dodecaceria fimbriata and D. concharum

This study used measurements and observations on the burrows of extant species of Dodecaceria fimbriata and D. concharum to identify their possible fossil burrows. The extant burrows were from marine littoral shale and the calcareous alga Lithothamnion. From published records unequivocal fossil burrows were not found for these two species. Trace fossils of D. fimbriata appear to have been present in the Miocene and Dodecaceria cretacea (probably not Dodecaceria) in the Cretaceous. The conclusion is that D. fimbriata and D. concharum separated from a common ancestor in the late Cretaceous.     

Biomineralization of calcium carbonate in the cell wall of Lithothamnion crispatum (Hapalidiales,Rhodophyta): correlation between the organic matrix and the mineral phase

Over the past few decades, progress has been made toward understanding the mechanisms of coralline algae mineralization. However, the relationship between the mineral phase and the organic matrix in coralline algae has not yet been thoroughly examined. The aim of this study was to describe the cell wall ultrastructure of Lithothamnion crispatum, a cosmopolitan rhodolith‐forming coralline algal species collected near Salvador (Brazil), and examine the relationship between the organic matrix and the nucleation and growth/shape modulation of calcium carbonate crystals. A nanostructured pattern was observed in L. crispatum along the cell walls. At the nanoscale, the crystals from L. crispatum consisted of several single crystallites assembled and associated with organic material. The crystallites in the bulk of the cell wall had a high level of spatial organization. However, the crystals displayed cleavages in the (104) faces after ultrathin sectioning with a microtome. This organism is an important model for biomineralization studies as the crystallographic data do not fit in any of the general biomineralization processes described for other organisms. Biomineralization in L. crispatum is dependent on both the soluble and the insoluble organic matrix, which are involved in the control of mineral formation and organizational patterns through an organic matrix‐mediated process. This knowledge concerning the mineral composition and organizational patterns of crystals within the cell walls should be taken into account in future studies of changing ocean conditions as they represent important factors influencing the physico‐chemical interactions between rhodoliths and the environment in coralline reefs.     

There is more to maerl than meets the eye: DNA barcoding reveals a new species in Britain,Lithothamnion erinaceum sp. nov. (Hapalidiales,Rhodophyta)

Due to the high plasticity of coralline algae, identification based on morphology alone can be extremely difficult, so studies increasingly use a combination of morphology and genetics in species delimitation. A DNA barcoding study was carried out on maerl-forming coralline algae using the mitochondrial cytochrome oxidase 1 gene, CO1, and the plastid gene, psbA, on field specimens from Falmouth and Oban together with herbarium specimens from the Natural History Museum, UK, and the Smithsonian Institution, Washington, USA. Results revealed the presence in the north of Britain of a new species, Lithothamnion erinaceum Melbourne & J. Brodie, sp. nov., which was previously misidentified as Lithothamnion glaciale. The results also indicated that Lithothamnion lemoineae, which had earlier been recorded from Britain, was not present. One of the biggest concerns at present is how organisms will respond to climate change and ocean acidification, and it is imperative that investigations are put on a firm taxonomic basis. Our study has highlighted the importance of using molecular techniques to aid in the elucidation of cryptic diversity.     

Variation in Photosynthetic Performance Relative to Thallus Microhabitat Heterogeneity in Lithothamnion australe (Rhodophyta,Corallinales) Rhodoliths

Rhodoliths are free‐living, coralline algae that create heterogeneous structure over sedimentary habitats. These fragile ecosystems are threatened by anthropogenic disturbances that reduce their size and three‐dimensional structural complexity. We investigated how physical disturbance from boat moorings affects photosynthetic performance in the rhodolith Lithothamnion australe. Photosynthetic parameters were measured for intact rhodoliths and crushed rhodolith fragments of two sizes (ca. 1 and 2 cm diameter), while chlorophyll fluorescence was measured at the surface of rhodoliths of these two sizes, between the interior branches of the larger rhodoliths, and at the surface of 52 various sized (0.4–3.5 cm diameter) rhodoliths. Gross productivity and net productivity were 15% and 36% higher, respectively, in the smaller L. australe, while respiration was 10% higher in the larger individuals. Thallus crushing reduced gross productivity by 20% and 41%, and net productivity by 9% and 14% in the smaller and larger rhodoliths, respectively. It also reduced respiration by 33% and 60% in the smaller and larger rhodoliths, respectively. Fluorescence parameters were all greater at the surface of the larger L. australe than the smaller individuals, and greater at the surface than in the interior parts of the larger individuals. Across a range of rhodolith sizes, surface fluorescence parameters were at their maxima in 1.54 to 2.32 cm diameter individuals. These results show that L. australe’s complex structure creates heterogeneity in photosynthesis and respiration between their surface and interior parts and among rhodolith sizes. This information can help predict how rhodoliths may respond to disturbance and environmental stressors.