Range expansion by invasive marine algae: rates and patterns of spread at a regional scale

Aim  Introduced macroalgae are widespread in the world's oceans and, despite increasing awareness and attempts to limit the phenomenon, the number of species introductions in coastal waters has increased exponentially over time. Little is known about the rates and mechanisms of spread, even among species that have received the most attention. We compare patterns of range expansion for nine species of invasive algae across eight geographic regions.
Location  World-wide.
Methods  We compiled records of introduced algae from the scientific literature, herbaria, and by contacting experts to reconstruct chronologies for 22 algal invasions. These were used to map patterns of spread at a regional scale (thousands of km).
Results  Range size tended to increase linearly with time, often after an initial lag. Range expansion occurred at rates of tens to hundreds of kilometres per year, often with large infrequent increases. Rates of range expansion differed significantly between species within the same region, and between regions for the same species.
Main conclusions  Our results suggest that anthropogenic vectors likely play a key role in the spread of introduced macroalgae at a regional scale, although natural long-distance dispersal also may be important for some species. The lack of consistency in the rates within individual species and regions suggests that multiple interacting factors (e.g. algal traits, characteristics of invaded communities, environmental conditions and anthropogenic activities) determine where propagules of introduced algae are delivered and whether they become established.     

A hitchhiker’s guide to the Maritimes: anthropogenic transport facilitates long‐distance dispersal of an invasive marine crab to Newfoundland

Aim To determine timing, source and vector for the recent introduction of the European green crab, Carcinus maenas (Linnaeus, 1758), to Newfoundland using multiple lines of evidence. Location Founding populations in Placentia Bay, Newfoundland, Canada and potential source populations in the north‐west Atlantic (NWA) and Europe. Methods We analysed mitochondrial and microsatellite genetic data from European and NWA populations sampled during 1999–2002 to determine probable source locations and vectors for the Placentia Bay introduction discovered in 2007. We also analysed Placentia Bay demographic data and shipping records to look for congruent patterns with genetic analyses. Results Demographic data and surveys suggested that C. maenas populations are established and were in Placentia Bay for several years (c. 2002) prior to discovery. Genetic data corroboratively suggested central/western Scotian Shelf populations (e.g., Halifax) as the likely source area for the anthropogenic introduction. These Scotian Shelf populations were within an admixture zone made up of genotypes from both the earlier (early 1800s) and later (late 1900s) introductions of the crab to the NWA from Europe. Placentia Bay also exhibited this mixed ancestry. Probable introduction vectors included vessel traffic and shipping, especially vessels carrying ballast water. Main conclusions Carcinus maenas overcame considerable natural barriers (i.e., coastal and ocean currents) via anthropogenic transport to become established and abundant in Newfoundland. Our study thus demonstrates how non‐native populations can be important secondary sources of introduction especially when aided by human transport. Inference of source populations was possible owing to the existence of an admixture zone in central/western Nova Scotia made up of southern and northern genotypes corresponding with the crab’s two historical introductions. Coastal vessel traffic was found to be a likely vector for the crab’s spread to Newfoundland. Our study demonstrates that there is considerable risk for continued introduction or reintroduction of C. maenas throughout the NWA.     

20种含笑属植物在广东中山树木园的引种生长表现

以广东中山树木园20种含笑属植物为对象,研究其引种后的生长表现。结果表明：20种含笑属植物在中山树木园均生长良好,分析的13种含笑属植物在胸径、树高及冠幅的生长量上均存在显著差异。本地苗木黄兰、白兰、乐昌含笑及火力楠在树高、胸径及冠幅方面表现优异。2004年于湖南引种的5种含笑以灰绒含笑和多花含笑生长最好;2005至2009年引种的7种含笑属植物以亮叶含笑表现最佳。     

福建泉州垂直绿化植物引种筛选

从福建泉州周边地区引种栽培30种攀援植物,对其成活率、生长状况、物候期以及抗逆性等指标进行调查研究。结果表明,采用“百分法”综合评选出29种适用于泉州市垂直绿化的攀援植物,其中11种可作为骨干品种推广应用,以满足泉州市垂直绿化建设中对景观多样性、植物多样性的要求。     

珠海淇澳岛几种红树植物引种的初步研究

将红树植物正红树(Rhizophora apiculata)、海莲(Bruguiera sexangula)和木榄(B.gymnorhiza)从海南岛引种到珠海淇澳-担杆岛省级自然保护区,苗期生长正常。1a生的正红树、海莲和木榄平均苗高分别为45.3cm、28.7cm和56.7cm,平均地径分别为1.34 cm、0.64 cm和1.60 cm,保存率分别为40.9%、59.5%和70.5%。3种红树植物苗期抗寒性大小依次为木榄>海莲>正红树。正红树、海莲和木榄3种红树植物能基本适应引种地的自然条件,对其生长发育特性尚需进行跟踪调查。