Freshwater plastispheres as a vector for foodborne bacteria and viruses

There is growing evidence that plastic particles can accumulate microorganisms that are pathogenic to humans or animals. In the current study, the composition of the plastispheres that accumulated on polypropylene (PP), polyvinyl chloride (PVC), and high-density polyethylene (HDPE) pieces submerged in a river in the southeast Norway was characterized by 16S rRNA amplicon sequencing. Seasonal and geographical effects on the bacterial composition of the plastisphere were identified, in addition to the detection of potential foodborne pathogenic bacteria and viruses as part of the plastisphere. The diversity and taxonomic composition of the plastispheres were influenced by the number of weeks in the river, the season, and the location. The bacterial diversity differed significantly in the plastisphere from June and September, with a generally higher diversity in June. Also, the community composition of the plastisphere was significantly influenced by the geographical location, while the type of plastic had less impact. Plastics submerged in river water assembled a variety of microorganisms including potentially pathogenic bacteria and viruses (noro- and adenovirus) detected by qPCR. Cultivation methods detected viable bacteria such as Escherichia coli and Listeria monocytogenes. The results highlight the need for additional research on the risk of contaminating food with plastic particles colonized with human pathogens through irrigation water.     

Environmental exposure more than plastic composition shapes marine microplastic-associated bacterial communities in Pacific versus Caribbean field incubations

Microplastics have arisen as a global threat to marine ecosystems. In this study, we explored the role that plastic polymer type, incubation time and geographic location have on shaping the microbial community adhered to the microplastics, termed the plastisphere. We performed detailed bacterial plastisphere community analyses on microplastics of six different household plastic polymers, serving as proxies of secondary microplastics, incubated for 6 weeks in coastal Pacific waters. These bacterial communities were compared to the plastisphere communities grown on identical microplastic particles incubated in the coastal Caribbean Sea at Bocas del Toro, Panama. Ribosomal gene sequencing analyses revealed that bacterial community composition did not exhibit a significant preference for plastic type at either site but was instead driven by the incubation time and geographic location. We identified a ‘core plastisphere’ composed of 57 amplicon sequence variants common to all plastic types, incubation times and locations, with possible synergies between taxa. This study contributes to our understanding of the importance of geography in addition to exposure time, in the composition of the plastisphere.     

Soil plastispheres as hotspots of antibiotic resistance genes and potential pathogens

In the Anthropocene, increasing pervasive plastic pollution is creating a new environmental compartment, the plastisphere. How the plastisphere affects microbial communities and antibiotic resistance genes (ARGs) is an issue of global concern. Although this has been studied in aquatic ecosystems, our understanding of plastisphere microbiota in soil ecosystems remains poor. Here, we investigated plastisphere microbiota and ARGs of four types of microplastics (MPs) from diverse soil environments, and revealed effects of manure, temperature, and moisture on them. Our results showed that the MPs select for microbial communities in the plastisphere, and that these plastisphere communities are involved in diverse metabolic pathways, indicating that they could drive diverse ecological processes in the soil ecosystem. The relationship within plastisphere bacterial zero-radius operational taxonomic units (zOTUs) was predominantly positive, and neutral processes appeared to dominate community assembly. However, deterministic processes were more important in explaining the variance in ARGs in plastispheres. A range of potential pathogens and ARGs were detected in the plastisphere, which were enriched compared to the soil but varied across MPs and soil types. We further found that the addition of manure and elevation of soil temperature and moisture all enhance ARGs in plastispheres, and potential pathogens increase with soil moisture. These results suggested that plastispheres are habitats in which an increased potential pathogen abundance is spatially co-located with an increased abundance of ARGs under global change. Our findings provided new insights into the community ecology of the microbiome and antibiotic resistome of the soil plastisphere.Subject terms: Microbial ecology, Environmental sciences     

Contribution of stochastic processes to the microbial community assembly on field-collected microplastics

A growing body of evidence suggests that microplastics may be colonized with a unique microbiome, termed ‘plastisphere’, in aquatic environments. However, the deep mechanisms (deterministic and/or stochastic processes) underlying the community assembly on microplastics are still poorly understood. Here, we took the estuary of Hangzhou Bay (Zhejiang, China) as an example and examined the assembly mechanisms of bacterial communities in water and microplastic samples. Results from high-throughput sequencing showed that Proteobacteria, Firmicutes, and Actinobacteria were the dominant phyla across all samples. Additionally, microorganisms from plastisphere and planktonic communities exhibited contrasting taxonomic compositions, with greater within-group variation for microplastic samples. The null model analysis indicated the plastisphere bacterial communities were dominantly driven by the stochastic process of drift (58.34%) and dispersal limitation (23.41%). The normalized stochasticity ratio (NST) also showed that the community assembly on microplastics was more stochastic (NST > 50%). Based on the Sloan neutral community model, the migration rate for plastisphere communities (0.015) was significantly lower than that for planktonic communities (0.936), potentially suggesting that it is the stochastic balance between loss and gain of bacteria (e.g., stochastic births and deaths) critically shaping the community assembly on microplastics and generating the specific niches. This study greatly enhanced our understanding of the ecological patterns of microplastic-associated microbial communities in aquatic environments.     

Basin-scale distribution patterns of picocyanobacterial lineages in the Atlantic Ocean

Marine picocyanobacteria of the genera Prochlorococcus and Synechococcus are major contributors to oceanic primary production. The genera are genetically diverse, comprising several known ecotypes or lineages. However, little is known of the distribution of these lineages over large geographic areas. Here, we analysed the relative abundance of Prochlorococcus ecotypes and Synechococcus lineages at the ocean basin scale along an Atlantic Meridional Transect (AMT) using dot blot hybridization and fluorescence in situ hybridization (FISH) techniques. The transect covered several contrasting oceanic provinces (gyres, upwelling, temperate regions) as well as environmentally 'equivalent' regions in the northern and southern hemisphere (northern and southern gyres and temperate regions). Flow cytometric data revealed a discrete separation in abundance of major picocyanobacterial genera. Prochlorococcus reached highest abundance in oligotrophic regions, while more mesotrophic waters were dominated by Synechococcus. Individual genetic lineages of both Prochlorococcus and Synechococcus showed highly similar distributions in corresponding regions in the northern and southern hemisphere. In addition, Prochlorococcus showed a distinctive depth distribution, with HLI and HLII ecotypes near the surface and co-occurring LL ecotypes further down in the water column. Conversely, Synechococcus generally revealed no obvious depth preference, but did show highly specific distribution at the horizontal scale, with clades I and IV particularly dominating temperate, mesotrophic waters in both the northern and southern hemispheres. The data clearly reveal that specific picocyanobacterial lineages proliferate in similar oceanic provinces separated by large spatial scales. Furthermore, comparison with an earlier AMT dataset suggests that basin scale distribution patterns for Prochlorococcus ecotypes are remarkably reproducible from year to year.     

How do microbiota associated with an invasive seaweed vary across scales?

Communities are shaped by scale dependent processes. To study the diversity and variation of microbial communities across scales, the invasive and widespread seaweed Agarophyton vermiculophyllum presents a unique opportunity. We characterized pro‐ and eukaryotic communities associated with this holobiont across its known distribution range, which stretches over the northern hemisphere. Our data reveal that community composition and diversity in the holobiont vary at local but also larger geographic scales. While processes acting at the local scale (i.e., within population) are the main structuring drivers of associated microbial communities, changes in community composition also depend on processes acting at larger geographic scales. Interestingly, the largest analysed scale (i.e., native and non‐native ranges) explained variation in the prevalence of predicted functional groups, which could suggest a functional shift in microbiota occurred over the course of the invasion process. While high variability in microbiota at the local scale supports A. vermiculophyllum to be a generalist host, we also identified a number of core taxa. These geographically independent holobiont members imply that cointroduction of specific microbiota may have additionally promoted the invasion process.     

Distributions of Virus-Like Particles and Prokaryotes within Microenvironments

Microbial interactions are important for ecosystem function, but occur at the microscale and so are difficult to observe. Previous studies in marine systems have shown significant shifts in microbial community abundance and composition over scales of micrometres to centimetres. This study investigates the microscale abundance distributions of virus-like particles (VLPs) and prokaryotes in the lower reaches of a river to determine the extent to which microscale microbial patchiness exists in freshwater systems. Here we report local hotspots surrounded by gradients that reach a maximum 80 and 107 fold change in abundance over 0.9 cm for prokaryotic and VLP subpopulations. Changes in prokaryotic and VLP hotspots were tightly coupled. There were no gradients at tens of centimetres across the boundary layers, which is consistent with strong mixing and turbulence-driven aggregation found in river systems. Quantification of the patchiness shows a marked asymmetry with patches 10 times greater than background common, but depletions being rare or absent in most samples. This consistent asymmetry suggests that coldspots depleted by grazing and lysis are rapidly mixed to background concentrations, while the prevalence of hotspots indicates persistence against disruption. The hotspot to coldspot relative abundance may be useful for understanding microbial river dynamics. The patchiness indicates that the mean- field approach of bulk phase sampling misses the microbially relevant community variation and may underestimate the concentrations of these important microbial groups.     

Distinct spatiotemporal succession of bacterial generalists and specialists in the lacustrine plastisphere

The assembly processes of generalists and specialists and their driving mechanisms during spatiotemporal succession is a central issue in microbial ecology but a poorly researched subject in the plastisphere. We investigated the composition variation, spatiotemporal succession, and assembly processes of bacterial generalists and specialists in the plastisphere, including non-biodegradable (NBMPs) and biodegradable microplastics (BMPs). Although the composition of generalists and specialists on NBMPs differed from that of BMPs, colonization time mainly mediated the composition variation. The relative abundance of generalists and the relative contribution of species replacement were initially increased and then decreased with colonization time, while the specialists initially decreased and then increased. Besides, the richness differences also affected the composition variation of generalists and specialists in the plastisphere, and the generalists were more susceptible to richness differences than corresponding specialists. Furthermore, the assembly of generalists in the plastisphere was dominated by deterministic processes, while stochastic processes dominated the assembly of specialists. The network stability test showed that the community stability of generalists on NBMPs and BMPs was lower than corresponding specialists. Our results suggested that different ecological assembly processes shaped the spatiotemporal succession of bacterial generalists and specialists in the plastisphere, but were less influenced by polymer types.     

海南岛霸王岭热带云雾林木本植物功能性状的分异规律

研究植物功能性状的分异,有助于理解植物适应环境的方式和策略,也能为预测物种分布和环境变化提供依据。以海南霸王岭热带云雾林为对象,建立21个20 m×20 m固定样方,划分为336个5 m×5 m小样方;测定胸径在5cm以上所有乔灌木植物个体的功能性状(叶面积LA;叶干重LDW;比叶重LMA;叶绿素含量Chl;叶厚度LTh;木材密度WD)和土壤养分含量,通过方差分解分析植物功能性状在个体、种内、种间、群落水平的分异大小,探究土壤养分对功能性状分异的影响。结果表明,LA、LDW、LMA、CHl、LTh、WD在个体、种内、种间、群落水平的解释方差范围分别为0.06—0.47、0.09—0.35、0.35—0.72、0—0.07,在个体、种内、种间、群落层次上,种间水平的功能性状分异最大,而群落水平的分异最小。逐步回归分析表明,不同尺度的功能性状变化与土壤有机质、氮和磷含量都有密切关系。     

EVOLUTION OF MACROCYSTIS SPP. (PHAEOPHYCEAE) AS DETERMINED BY ITS1 AND ITS2 SEQUENCES1,

Macrocystis (Lessoniaceae) displays an antitropical distribution, occurring in temperate subtidal regions along western North America in the northern hemisphere and throughout the southern hemisphere. We used the noncoding rDNA internal transcribed spacer regions (ITS1 and ITS2) to examine relatedness among (1) Macrocystis and several genera of Laminariales, (2) four species of Macrocystis ( M. integrifolia Bory from the northern hemisphere, M. angustifolia Bory and M. laevis Hay from the southern hemisphere, and M. pyrifera [L.] C. Ag. from both hemispheres), and (3) multiple clones of several individuals. Of the taxa included in our phylogenetic analysis, the elk kelp, Pelagophycus porra (Lem.) Setch., was the sister taxon to Macrocystis spp. Macrocystis individuals from the southern hemisphere (representing three species) formed a strongly to moderately supported clade, respectively, when the ITS1 and ITS2 sequences were analyzed separately. No distinction was detected between the two species in the northern hemisphere. Thus, Macrocystis may be a monospecific genus ( M. pyrifera ). A northern-hemisphere-to-southern-hemisphere pattern of dispersal was inferred, because northern-hemisphere individuals were more diverse and displayed paraphyletic clades, whereas southern-hemisphere individuals were less diverse and formed a monophyletic clade. High intraindividual variation in ITS1 sequences was observed in one individual from Santa Catalina Island (CA), suggesting very recent and rapid mixing of genotypes from areas to the north and Baja California (Mexico) or introgressive hybridization with Pelagophycus.     

Microplastic polymer properties as deterministic factors driving terrestrial plastisphere microbiome assembly and succession in the field

Environmental microplastic (MP) is ubiquitous in aquatic and terrestrial ecosystems providing artificial habitats for microbes. Mechanisms of MP colonization, MP polymer impacts, and effects on soil microbiomes are largely unknown in terrestrial systems. Therefore, we experimentally tested the hypothesis that MP polymer type is an important deterministic factor affecting MP community assembly by incubating common MP polymer types in situ in landfill soil for 14 months. 16S rRNA gene amplicon sequencing indicated that MP polymers have specific impacts on plastisphere microbiomes, which are subsets of the soil microbiome. Chloroflexota, Gammaproteobacteria, certain Nitrososphaerota, and Nanoarchaeota explained differences among MP polymers and time points. Plastisphere microbial community composition derived from different MP diverged over time and was enriched in potential pathogens. PICRUSt predictions of pathway abundances and quantitative PCR of functional marker genes indicated that MP polymers exerted an ambivalent effect on genetic potentials of biogeochemical cycles. Overall, the data indicate that (i) polymer type as deterministic factor rather than stochastic factors drives plastisphere community assembly, (ii) MP impacts greenhouse gas metabolism, xenobiotic degradation and pathogen distribution, and (iii) MP serves as an ideal model system for studying fundamental questions in microbial ecology such as community assembly mechanisms in terrestrial environments.     

Frugivore gape size and the evolution of fruit size and shape in southern hemisphere floras

Abstract The present study uses differences among frugivore faunas of the southern hemisphere landmasses to test whether frugivore characteristics have influenced the evolution of fruit traits. Strong floristic similarities exist among southern landmasses; for example, 75% of New Zealand vascular plant genera also have species in Australia. However, plants in Australia and South America have evolved in the presence of a range of mammalian frugivores, whereas those in New Zealand, New Caledonia and the Pacific Islands have not. In addition, the avian frugivores in New Zealand and New Caledonia are generally smaller than those of Australia. If frugivore characteristics have influenced the evolution of fruit traits, predictable differences should exist between southern hemisphere fruits, particularly fruit size and shape. Fruit dimensions were measured for 77 New Zealand species and 31 Australian species in trans‐Tasman genera. New Zealand fruits became significantly more ellipsoid in shape with increasing size. This is consistent with frugivore gape size imposing a selective pressure on fruit ingestability. This result is not a product of phylogenetic correlates, as fruit length and width scaled isometrically for Australian species in genera shared with New Zealand. Within‐genus contrasts between New Zealand and Australian species in 20 trans‐Tasman genera showed that New Zealand species have significantly smaller fruits than their Australian counterparts. Within‐genus contrasts between New Zealand and South American species in nine genera gave the same result; New Zealand species had significantly smaller fruits than their South American counterparts. No difference was found in fruit size or shape between New Zealand and New Caledonia congeneric species from 12 genera. These results are consistent with the broad characteristics of the frugivore assemblage influencing the evolution of fruit size and shape in related species. The smaller‐sized New Zealand frugivore assemblage has apparently influenced the evolution of fruit size of colonizing taxa sometimes within a relatively short evolutionary timeframe.     

The persistent spatial patchiness of limpet grazing

The characteristic variability of grazing has potential consequences for intertidal productivity and community structure, particularly as many of the underlying functional relationships are thought to be non linear. As a first approximation, it can be hypothesised that grazing is patchy over short time periods before a more uniform coverage is established over longer time scales. This prediction is supported by relatively short term observations previously made of limpet foraging. We used eight arrays of wax disks on each of four shores to test the hypothesis that grazing is patchy in the short term, but that this pattern is lost as the pattern of grazing averages out over longer time scales. Wax disk arrays were exposed for two weeks at a time for a period of six weeks in 2001 and in 2002 using the same set of disk holes each time. Grazing at the same disk location could therefore be measured over two weeks and over longer periods by averaging successive deployments. We used all three successive deployments to estimate the average grazing at each disk location over a six week period in 2001 and 2002. All six deployments were used to characterise the pattern of grazing at longer time scales. The spatial pattern of grazing in arrays was summarized using semivariogram analyses. For two-week deployments, the average standardized semivariance of grazing for disks separated by 20 cm was less than one. This pattern implies spatial autocorrelation of grazing at this scale. There was no support for the hypothesis that small scale patchiness in grazing would disappear over time. The average strength of spatial autocorrelation increased when data were integrated over longer periods. A preliminary analysis indicated that the degree of autocorrelation within arrays increased with grazing intensity at short time scales. Surface roughness disrupted autocorrelation of grazing over both short and long time scales. The persistent patchiness of grazing is likely to have implications for biofilm productivity, particularly on smoother shores.     

Molecular phylogeny and dating reveals an Oligo-Miocene radiation of dry-adapted shrubs (former Tremandraceae) from rainforest tree progenitors (Elaeocarpaceae) in Australia

To better understand the historical biogeography of the southern hemisphere and evolutionary responses of plants to aridity, we undertook a detailed phylogenetic study of the predominantly southern family Elaeocarpaceae sensu lato (including Tremandraceae). Plastid trnL-trnF and nuclear ITS sequence data were analyzed using parsimony and Bayesian methods and molecular evolutionary rates calibrated using the Oligocene fossil record of Elaeocarpus mesocarps to estimate the minimum divergence dates. The results indicate the monophyly of all recognized genera and a placement for the former Tremandraceae (three genera and about 49 species of shrubby, dry-adapted Australian plants) within the widespread predominantly rainforest tree family Elaeocarpaceae (nine genera, over 500 species). The former Tremandraceae clade diverged from its sister (Aceratium + Elaeocarpus + Sericolea) during the Paleocene, after which it underwent a marked acceleration in evolutionary rate. Furthermore, this lineage diversified during the late Miocene, coincident with widespread aridification in Australian environments and extensive radiations of several sclerophyllous groups. The role of dispersal in explaining the current geographical distribution of Elaeocarpaceae is illustrated by Aristotelia. This genus, whose distribution was previously thought to reflect Gondwanan vicariance, is shown to have arrived in New Zealand from Australia at least 6-7 million yr ago.     

Microbiological testing of plastics: Ongoing activities of IBRG plastics project group to improve standard test procedures

The early development of standard test procedures for plastics was based primarily upon results of plasticised PVC. Ring tests carried out in the sixties used this material and provided the basis for national and international test specifications. In the meantime a large variety of plastics formulations has been developed which are chemically and structurally different from the formerly used PVC. This has prompted a re-examination of existing test specifications. For this reason the IBRG established a Plastics Working Group in 1984 to study the mechanism of the deterioration of plastics in relation to current standard test protocols.Fifteen laboratories from several European countries participated in a first international ring test (see Appendix). Two polyurethanes — a polyester and a polyether type — were chosen as test materials. A plasticized PVC was included for comparison with earlier interlaboratory experiments. Petri dish tests were carried out for four weeks and biodeterioration was assessed by visual examination and by weight loss. It was concluded that visual assessment as the sole criterion for the biodeterioration of polyurethanes was insufficient and that a test period of four weeks was too short for weight loss determination.In a second ring test with 12 participants, soil burial tests with the same test materials have been started. They will be conducted over a two-year period. Weight loss determinations and tensile tests will be carried out at six-month intervals. Provisional results are presented and are supplemented by joint experiments of some participants to examine the effects of special test parameters on the biodeterioration of plastics.     

Molecular phylogeny illuminates Amblyopinini (Coleoptera: Staphylinidae) rove beetles as a target for systematic and evolutionary research

The rove beetle tribe Amblyopinini (Coleoptera: Staphylinidae: Staphylininae) is a recently discovered monophyletic lineage comprising an estimated 1000 or more species of mainly leaf- and log litter-dwelling predatory insects found throughout the southern hemisphere. Of these, a single genus Heterothops Stephens somehow conquered all continents in the northern hemisphere as well. A few lineages of amblyopinines independently evolved into highly derived predators of mammal ectoparasites from free-living ancestors. In return, they are tolerated in the mammal fur and nests, which is a unique example of cleaning symbiosis between insects and vertebrates. For over a century the great majority of free-living southern amblyopinines were incorrectly placed in the northern hemisphere-restricted, and superficially similar, rove beetle genera from the subtribe Quediina. Only their mammal-associated derived forms were understood as amblyopinines, a nonmonophyletic taxon of volatile status and enigmatic sister-group relationships of its various members. Here we present the first comprehensive phylogeny of Amblyopinini inferred with Bayesian analysis of a six-gene molecular dataset (4672 bp) across a broad sample of taxa (90 species). This phylogeny provides a framework for the badly needed taxonomic inventory of this group and, in particular, reveals at least two independent origins of mammal association within the tribe. It frames the upcoming in-depth interdisciplinary exploration of a variety of phenomena such as evolution of the austral biota in response to continental drift and climate change, biotic exchange between southern and northern continents, origin and evolution of beetle–mammal symbiosis, and pathways and constraints of the evolutionary parallelisms.     

Unique microbiome in organic matter–polluted urban rivers

Approximately half of the global annual production of wastewater is released untreated into aquatic environments, which results in worldwide organic matter pollution in urban rivers, especially in highly populated developing countries. Nonetheless, information on microbial community assembly and assembly-driving processes in organic matter–polluted urban rivers remains elusive. In this study, a field study based on water and sediment samples collected from 200 organic matter–polluted urban rivers of 82 cities in China and Indonesia is combined with laboratory water-sediment column experiments. Our findings demonstrate a unique microbiome in these urban rivers. Among the community assembly-regulating factors, both organic matter and geographic conditions play major roles in determining prokaryotic and eukaryotic community assemblies, especially regarding the critical role of organic matter in regulating taxonomic composition. Using a dissimilarity-overlap approach, we found universality in the dynamics of water and sediment community assembly in organic matter–polluted urban rivers, which is distinctively different from patterns in eutrophic and oligotrophic waters. The prokaryotic and eukaryotic communities are dominated by deterministic and stochastic processes, respectively. Interestingly, water prokaryotic communities showed a three-phase cyclic succession of the community assembly process before, during, and after organic matter pollution. Our study provides the first large-scale and comprehensive insight into the prokaryotic and eukaryotic community assembly in organic matter–polluted urban rivers and supports their future sustainable management.     

Permineralized rhizomes of the Osmundaceae (Filicales): Diversity and tempo-spatial distribution pattern

The family Osmundaceae is among the most primitive ferns of the Filicales, with an extensive fossil record dating back to the Late Paleozoic. Numerous fossil osmundaceous rhizomes have been documented in the geological history. However, the diversity, variation and distribution pattern of permineralized rhizomes remain poorly known. Here we intend to analyze the fossil records with regard to the diversity and distribution pattern of the osmundaceous rhizomes based on available data. To date, about 83 species ascribed to 14 genera of fossil osmundaceous rhizomes have been described worldwide, assigned to two subfamilies, namely, Thamnopteroideae and Osmundoideae. Geologically, two groups (i.e., Thamnopteroideae and Palaeosmunda) have been reported in the Permian. All the Triassic taxa are from the southern hemisphere. Jurassic osmundaceous rhizomes are abundant and widespread throughout the world, most dominant in the southern hemisphere. During the transition of Jurassic to Cretaceous, the diversity of osmundaceous rhizomes declined rapidly. In the Cretaceous, however, the osmundaceous rhizomes from the northern hemisphere surpass those from the southern hemisphere in generic level for the first time. The Cenozoic taxa diversified in the northern hemisphere with the rise of angiosperms. Geographically, the osmundaceous fossil rhizomes have been found in both hemispheres; the major localities include Ural area of the former USSR, Tasmania of Australia, southern Argentina, Antarctica, northern India, central and western part of North America and northern China. We discuss the origin, radiation, and development of the Osmundaceae based on rhizomes, to help further understand the systematic relation and evolutionary history of the family Osmundaceae.     

Evolutionary significance of a flat-leaved Pinus in Vietnamese rainforest

Pines are generally absent from tropical rainforests. An important exception, Pinus krempfii, is a unique tree that bears flattened needles and competes with evergreen angiosperm trees in southern Vietnam. Here, the photosynthetic and hydraulic physiology of P. krempfii leaves were examined to determine whether this species departs from the widespread pattern of high-light-demanding photosynthetic physiology displayed in needle-leaved Pinus species. Maximum photosynthesis and light saturation of photosynthesis, as well as stem and leaf hydraulic efficiencies, were all very low in P. krempfii compared with other Pinus species. These characteristics were consistent with our observations of P. krempfii seedling regeneration under the forest canopy. By possessing shade tolerance coupled with the production of flattened leaves, P. krempfii has converged morphologically and physiologically with many genera of the southern hemisphere conifer family Podocarpaceae. This convergence extends to a key feature of leaf anatomy, the production of tubular sclereids in the leaf for radial transport of water from the vein to the margin. These observations suggest that few adaptive possibilities are open to conifers when moving into tropical rainforest, meaning that Pinus is forced into direct competition with southern hemisphere conifers for a narrow niche in the equatorial zone.     

Population dynamics of the wandering albatross (Diomedea exulans) on Macquarie Island and the effects of mortality from longline fishing

The estimated breeding population of wandering albatrosses on Macquarie Island increased from 17 in 1956 to a maximum of 97 in 1966, and then declined at an average rate of 8.1% per year. Mark-recapture analysis shows that the population is not closed (i.e., subject to immigration and emigration). The decline is correlated with the onset of large-scale fishing for tuna in the southern hemisphere using longlines. The effect of longline mortality on the population dynamics of the wandering albatross is estimated. An annual number of longline hooks in the southern hemisphere tuna fishery of 41.6 million is calculated as the ceiling below which the population would begin to recover.