Gene flow of the canker pathogen Botryosphaeria australis between Eucalyptus globulus plantations and native eucalypt forests in Western Australia

Abstract The eucalypt plantation industry in Western Australia provides a unique opportunity to study the movement of pathogens between closely related host taxa. Eucalyptus globulus, a native to Tasmania and south‐eastern Australia, is the predominant species in Western Australian plantations, often being planted adjacent to native forest containing Eucalyptus marginata and Eucalyptus diversicolor. Since the commencement of the plantation industry 20 years ago, several fungal species, previously known only to eastern Australia or overseas, have been reported on E. globulus in Western Australia. Botryosphaeria australis is a newly described species, recently found causing cankers on Acacia spp. in eastern Australia. However, during a routine survey, B. australis was found to be the predominant species associated with E. globulus plantations and native Eucalyptus spp. in Western Australia. In this study, six short simple repeat markers were used to evaluate genetic diversity and gene flow between collections of B. australis from native eucalypt forest and E. globulus plantations at two locations in south‐western Australia. In both cases, there was no restriction to gene flow between the plantations and the adjacent native forest. Botryosphaeria australis has now been isolated from a wide range of hosts across south‐western Australia and was not isolated from E. globulus in Tasmania or South Australia. This extensive distribution and host range suggests B. australis is native to Western Australia. This study demonstrates the ability of a pathogen to move between plantation and forests.     

Electrophoretic analysis of populations of the southern hemisphere lampreys Geotria australis and Mordacia mordax

Electrophoretic data for 15 enzymes encoded by 18 loci were analysed in samples of larval lampreys from two southern hemisphere species (Geotria australis and Mordacia mordax). Low values for Nei genetic distance coefficients for all loci in populations of G. australis from Western Australia, Tasmania and New Zealand (0.0013 to 0.0058) suggest that adults may intermix over distances greater than 4000 km. The average heterozygosity for four populations of G. australis (0.086) was much greater than for two populations of the far less widely distributed M. mordax (0.021).     

Occurrence and Structure of Iron Inclusions in Adipocytes of Larval Lampreys

The occurrence and structure of adipocytes in the larvae of two lamprey species, Geotria australis and Petromyzon marinus, were examined by electron microscopy. Adipocytes from both species possessed large electron-dense inclusions which histochemical and energy dispersal X-ray analyses show as containing iron. The greatest concentration of inclusions in adipocytes was found in the nephric fold of G. australis. While some iron is present in the cytoplasmic matrix as ferritin, the majority is seen in large ammocoetes in membrane-bound dense aggregations of haemosiderin. The wide variety of inclusion types seen in smaller larvae may reflect on the method of formation of these inclusions within the cell. Because of the high level of iron loading in the larval lamprey nephric fold, this readily accessible tissue may provide a valuable model for studies of iron metabolism in vertebrates.     

The cardiovascular chromaffin cell system of the southern hemisphere lamprey,Geotria australis gray

This study demonstrates that the silver technique of Grimelius (Acta Soc. Med. Ups. 73:243–270, 68) is ideally suited for the study of cardiovascular chromaffin cells in lampreys. This method showed that in the Southern Hemisphere lamprey, Geotria australis, the distribution of chromaffin cells differs from that described for holarctic species. In G. australis, the chromaffin cells are found mainly in the sinus venosus, atrium, and nearby regions of the cardinal and jugular veins, and they are absent from the ventricle and conus arteriosus. The location and discreteness of the large accumulation of chromaffin cells in the lateral wall of the right posterior cardinal vein of adults resemble those of the precardiac axillary bodies of elasmobranchs. Chromaffin cells become more abundant during metamorphosis. The possible phylogenetic and functional significance of lamprey chromaffin cells is briefly discussed.     

New genera,species and records of rhinebothriidean cestodes (Platyhelminthes) parasitic in Australian stingrays (Elasmobranchii: Batoidea)

Collections of rhinebothriidean cestodes (Platyhelminthes) from Australian batoid elasmobranchs revealed the presence of a number of new genera and species. Ruptobothrium louiseuzeti n. g., n sp. is described from the reticulate whipray, Himantura australis Last, Naylor & Manjaji-Matsumoto, from off the Northern Territory and Mixobothrium queenslandense n. g., n sp. is described from the green sawfish, Pristis zijsron Bleeker, from off north-eastern Queensland. Two new species of Rhabdotobothrium Euzet, 1953 are described: Rhabdotobothrium meridionale n. sp. from the southern eagle ray Myliobatis tenuicaudatus Hector from off South Australia and Rhabdotobothrium anoxypristidis n. sp. from the narrow sawfish, Anoxypristis cuspidatus (Latham) from off north Western Australia. A new species of Scalithrium Healy & Reyda, 2016, Scalithrium australiense n. sp., is described from the reticulate whipray, Himantura australis Last, Naylor & Manjaji-Matsumoto, from off northern Western Australia. Scalithrium smitii (Shinde, Deshmukh & Jadhav, 1981) n. comb. is reported from Australian waters for the first time in the black spotted stingray Maculabatis toshi (Whitley) from off northern Western Australia. New host and geographical records are provided for Stillabothrium jeanfortiae Forti, Aprill & Reyda, 2016 from the brown whipray Maculobatis toshi (Whitley) and the black-spotted whipray, Maculabatis cf. astra (Last, Manjaji-Matsumoto & Pogonoski) from Moreton Bay in southern Queensland.

     

Communicating (gap) junctions between chloride cells in the gill epithelium of the lamprey,Geotria australis

Summary Freeze-fracture replicas show that communicating (gap) junctions are present between chloride cells in the gill epithelium of young adults of the Southern Hemisphere lamprey, Geotria australis, acclimated to full-strength sea water. The junctions, which were already present when these lampreys were migrating downstream, may help coordinate the secretory activities of the chloride cells during the marine phase of the lamprey life cycle.     

Development and analysis of a germline BAC resource for the sea lamprey, a vertebrate that undergoes substantial chromatin diminution

Over the last several years, the sea lamprey (Petromyzon marinus) has grown substantially as a model for understanding the evolutionary fundaments and capacity of vertebrate developmental and genome biology. Recent work on the lamprey genome has resulted in a preliminary assembly of the lamprey genome and led to the realization that nearly all somatic cell lineages undergo extensive programmed rearrangements. Here we describe the development of a bacterial artificial chromosome (BAC) resource for lamprey germline DNA and use sequence information from this resource to probe the subchromosomal structure of the lamprey genome. The arrayed germline BAC library represents ∼10× coverage of the lamprey genome. Analyses of BAC-end sequences reveal that the lamprey genome possesses a high content of repetitive sequences (relative to human), which show strong clustering at the subchromosomal level. This pattern is not unexpected given that the sea lamprey genome is dispersed across a large number of chromosomes (n ∼ 99) and suggests a low-copy DNA targeting strategy for efficiently generating informative paired-BAC-end linkages from highly repetitive genomes. This library therefore represents a new and biologically informed resource for understanding the structure of the lamprey genome and the biology of programmed genome rearrangement.     

Host specificity testing ofRhodometra sacraria [Lep.: Geometridae], a possible biological control candidate forEmex australis in Australia

The foliage feeding geometridRhodometra sacraria L. was collected onEmex australis Steinheil in South Africa, cultured, then tested as a possible biological control agent forE. australis, in Australia. Tests on its host specificity were carried out in South Africa and Australia.R. sacraria was specific to plants of the familyPolygonaceae rather than toE. australis. Request for the reintroduction and release ofR. sacraria into Australia has not been made.      

Metamorphic changes in the intestine of three species of lampreys

Measurements have been made of those changes which lead to increases in the surface area of the intestine during the metamorphosis of three species of lampreys. Although the intestine of the Southern Hemisphere lamprey, Geotria australis, increases in length by 1.13 times and in diameter by 1.12 times, the main factor influencing the 5.71 times increase in surface area is the development of longitudinal folds. The contribution of the typhlosole to the internal perimeter of the intestine is less in most life cycle stages of G. australis than in Lampetra spp. The changes in the various intestinal measurements of the nonparasitic species L. planeri parallel those of the presumed ancestral parasitic species, L. fluviatilis, during the first six stages of metamorphosis. However, the longitudinal folds, but not the typhlosole, subsequently start regressing in L. planeri just after the time when the rate of gonadal development increases markedly. An account is also given of the pattern of fold formation and the development of the typhlosolar vein in G. australis.     

Axial rod growth and age estimation of the sea pen,Halipteris willemoesi Kölliker

Halipteris willemoesi is a large octocoral commonly found in the Bering Sea. It is a member of a ubiquitous group of benthic cnidarians called sea pens (Octocorallia: Pennatulacea). Sea pens have a skeletal structure, the axial rod, that in cross section exhibits growth rings. Pairs of adjacent rings, or ring couplets, were assumed to be annuli and were used to estimate the age and growth of H. willemoesi. Twelve axial rods, extracted from H. willemoesi collected in the Bering Sea, were selected to represent small (25–29 cm total length), medium (97–130 cm TL) and large (152–167 cm TL) colonies. Each rod resembled a tapered dowel; the thickest part (0.90–6.75 mm in diameter) was at about 5–10% of total length from the base tip, the distal part was more gradually tapered than was the base. The number of ring couplets increased with rod size indicating their utility in estimating age and growth. Estimated age among rods was based on couplet counts at the thickest part of each rod; the average estimated age (±SE) was 7.1 ±0.7, 19.3 ±0.5, and 44.3 ±2.0 yr for small, medium and large-size rods, respectively. Based on these estimated ages, average growth rate in total length was 3.9 ± 0.2, 6.1 ± 0.3, and 3.6 ± 0.1 cm yr^–1 for small, medium, and large-size colonies. The average annual increase in maximum rod diameter among all colonies was 0.145 ± 0.003 SE mm yr^–1; therefore, age prediction from maximum rod diameter was calculated (estimated age (yr) = 7.0 * (maximum rod diameter, mm) –0.2; R ² = 0.99). At maximum diameter, the average couplet width was relatively constant among the three colony sizes (0.072 ± 0.05 mm). X-ray diffraction and electron microprobe analyses revealed that the inorganic portion of the rod is composed of a high-magnesium calcite. Radiometric validation of these age and growth rate estimates was attempted, but high amounts of exogenous ²¹⁰Pb precluded using the disequilibria of ²¹⁰Pb:²²⁶Ra. Instead, ²¹⁰Pb activities were measured in a series of cores extracted along the axial rod. These activities ranged from 0.691 ± 0.036 (SE) to 2.76 ± 0.13 dpm g^–1, but there was no pattern of decay along the length of the rod; therefore, the growth rates and corresponding ages could not be validated. Based on estimated age from ring couplet counts, growth in total rod length is slow at first, fastest at medium size, and slows toward maximum size, with an estimated longevity approaching 50 yr.     

Spawning dynamics and biomass estimates of an anchovy Engraulis australis population in contrasting gulf and shelf environments

The spawning biomass of Australian anchovy Engraulis australis in gulf and shelf waters of South Australia was compared using the daily egg production method (DEPM). The total survey area was 128 700 km² with recorded spawning areas in gulf and shelf waters of 4898 and 44 618 km², respectively. High egg densities in the warm, shallow gulf waters were produced by small, young (<1 year old) E. australis that spawned relatively small batches of eggs (c. 855) approximately every 3 days. In cooler, deeper shelf waters, where larger, older E. australis are found, lower egg densities occurred despite individuals producing much larger batches of eggs (c. 15 572) approximately every 7 days. In shelf waters, the highest densities were recorded at inshore sampling stations. Spawning appeared to peak between 0000 and 0100 hours. Females were more abundant than males in samples from both gulf and shelf waters with sex ratios of 0·61 and 0·56, respectively. The spawning biomass of E. australis in shelf waters was 101 522 t, whereas the estimate for gulf waters was 25 374 t. Due to the differences in mean size of the spawning females, however, c. 6 × 10⁹E. australis were present in each region. The results support the hypothesis that variability in habitat conditions may directly influence E. australis reproduction. A large reserve of young fish in the relatively stable gulf environment may increase the resilience of the E. australis population in South Australia to unfavourable interannual changes in offshore environmental conditions.     

Species identification and likely catch time period of whale bones from South Georgia

Skeletal remains of baleen whales killed during the onset of 20th century commercial whaling lie scattered across the shores and abandoned whaling stations of the subantarctic island of South Georgia. Here we report on genetic species identification of whale bones collected from South Georgia using standard historical DNA protocols. We amplified and sequenced short fragments of the mitochondrial DNA (mtDNA) control region from 281 available bone samples. Of these, 231 provided mtDNA sequences of sufficient quality and length (174–194 bp) for species identification: 158 bones were identified as humpback whale (Megaptera novaeangliae), 51 bones were identified as fin whale (Balaenoptera physalus), 18 bones were identified as blue whale (B. musculus), two bones were identified as sei whale (B. borealis), one bone was identified as a southern right whale (Eubalaena australis), and one bone was identified as a southern elephant seal (Mirounga leonina). The prominence of humpback, fin, and blue whale bones in the sample collection corresponds to the catch record of the early years of whaling on the island of South Georgia (pre‐1915), prior to the depletion of these populations.     

Dietary composition of juvenile Dissostichus eleginoides (Pisces, Nototheniidae) around Shag Rocks and South Georgia, Antarctica

A diet analysis of the Patagonian toothfish Dissostichus eleginoides, trawled in the South Georgia Islands area in March–April 1996, was carried out by frequency of occurrence (F%) and coefficient Q (%) methods. The samples consisted chiefly of immature specimens, with predominant length ranges of 30–70 cm (TL). Fish was by far the main food on the shelves of Shag Rocks and South Georgia, accounting for about 70% of prey. Krill appeared as secondary food, although its importance was overestimated by the frequency of occurrence method. Cephalopods and mysids were infrequent in the stomachs, and only at Shag Rocks and South Georgia, respectively. Lepidonotothen kempi, Champsocephalus gunnari and Chaenocephalus aceratus constituted the main fish prey and their variability between Shag Rocks and South Georgia depended on their local abundance. The large proportion of fish exhibiting stomachs full or close to fullness (together 62%) suggests that feeding intensity of the species was high.     

A panel of new microsatellite loci for genetic studies of antarctic fur seals and other otariids

Nine dinucelotide microsatellite loci were developed in the Antarctic fur seal Arctocephalus gazella. Each locus possessed between 4 and 9 alleles in a sample of twenty individuals sampled from Bird Island, South Georgia, and expected heterozygosity ranged from 0.52 to 0.84. All but one of the loci conformed to Hardy–Weinberg equilibrium and no evidence was found for genotypic disequilibrium. Additionally, all of the loci successfully cross-amplified in the South American fur seal Arctocephalus australis, the New Zealand fur seal Arctocephalus forsteri and the Steller’s sea lion Eumetopias jubatus, and six also yielded products in the more distantly related harbour seal Phoca vitulina and walrus Odobenus rosmarus. These loci should prove useful for studies of the population genetics of Antarctic fur seals and other important otariid species.     

Proximate body composition of the larval,metamorphosing and downstream migrant stages in the life cycle of the Southern Hemisphere lamprey,Geotria australis

Synopsis The water, total lipid, protein and ash content have been measured in larval, metamorphosing (stages 1–7) and downstream migrantGeotria australis caught in Western Australia between October 1977 and August 1979. The total lipid content of ammocoetes changed markedly with season and increased with body size. Although, unlike other species, the ammocoetes ofG. australis continue to increase in length during the latter part of larval life, the relative amount of total lipid still rose during this period, eventually reaching levels equivalent to approximately 14% of the wet body weight at the commencement of metamorphosis. During the six months between the onset of metamorphosis and the downstream migration, total lipid declined to approximately 8%. Assays for phospholipid of larval and metamorphosingG. australis indicated that changes in total lipid were almost entirely due to variations in neutral lipid. Changes in the percentage amount of total lipid were accompanied by an inverse but slightly greater amount of change in percentage water. During metamorphosis, the absolute amount of total lipid in a standard animal declined from 122 mg at stage 1 to 53 mg at stage 7, whereas water rose initially from 597 mg at stage 1 to 638 mg at stage 3, before declining to 442 mg by stage 7. Although the percentage amount of protein and ash tended to increase slightly during larval life, neither showed conspicuous seasonal changes. In both relative and absolute terms, protein declined during metamorphosis. A comparison of the data on the proximate body composition inG. australis and holarctic lampreys shows that different strategies have been employed to accumulate large amounts of fat by the end of larval life and to utilize protein during metamorphosis.     

Timing of Recruitment Events, Residence Periods and Post-Settlement Growth of Juvenile Fish in a Seagrass Nursery Area, South-Eastern Australia

We sampled juvenile fish approximately fortnightly using a fine mesh beach seine net to determine the recruitment patterns of Sillago ciliata, Centropogon australis and Girella tricuspidata to seagrass, Zostera capricorni, habitats in Botany Bay, south-eastern Australia. We used trends in the length frequency distributions of juveniles to estimate the timing of recruitment events, rates of post-settlement growth and the residence time of each species in seagrass. We detected discrete pulses of recruitment by each species. The timing of recruitment events by S. ciliata reflected the timing of spawning events. Recruitment by G. tricuspidata reflected lunar or tidal cycles. The factors influencing the timing of recruitment by C. australis were unclear. The growth rate of S. ciliata length cohorts varied and was positively related to estuarine water temperature. The timing of emigration from seagrass of C. australis and G. tricuspidata juveniles appeared to be length-dependant.     

Development of the Testis During Post-metamorphic Life in the Southern Hemisphere Lamprey Geotria australis Gray

Spermatogenesis during post-metamorphic life in the anadromous parasitic lamprey Geotria australis was examined in histological sections of testes of animals collected in the field or maintained in the laboratory. The fully metamorphosed downstream migrants of G. australis possessed a very small testis in which the germ cells consisted of irregularly arranged prospermatogonia. By the end of the subsequent protracted marine trophic phase, the testis had increased in cross-sectional area by about 20 times and become organised into well-defined cysts. Since approximately 40% of these cysts possessed spermatocytes and 12% contained spermatids or early sperm, meiosis is initiated prior to the non-feeding upstream migration, which in G. australis lasts for the unusually long period of 15–16 months. The incidence of cysts with meiotic and post-meiotic stages decreased during the first 3 months of the spawning run before starting to rise during subsequent months. Spermiogenesis was never completed in any animals caught in the field during the first 9 months of the upstream migration or in those subsequently held in the laboratory up to and beyond November, the month when spawning naturally takes place. The phasing and asynchrony of spermatogenesis during post-metamorphic life in G. australis differs markedly from the situation in Northern Hemisphere lampreys.     

Genetic examination of the type specimen of Ulva australis suggests that it was introduced to Australia

‘Ana‐aosa’, one of the most common marine green algae in Japan, was described as Ulva pertusa Kjellman in 1897 from Hakodate in northern Japan. Ulva pertusa was considered to be a temperate species, with its native distributional range restricted to northeastern Asia. Although this species has been reported from various regions outside northeastern Asia, these records have been explained as non‐indigenous populations. Recently, on the basis of genetic data and nomenclatural priority, U. pertusa was synonymized with U. australis Areschoug, a species described in 1851 from specimens collected in South Australia. Based on genetic studies, Australian populations identified as U. pertusa had been considered to have originated from Japan. However, the published genetic data on U. australis in Australia have been based only on recent collections and no historical specimens have been examined. We tested the hypothesis that native (true) U. australis is an independent species of very similar morphology to U. pertusa, but that its natural domination of shoreline habitats has been suppressed by introduced populations of U. pertusa from Asia. In the present study, we extracted DNA from the type specimen of U. australis housed in the Swedish Museum of Natural History (S) and obtained DNA sequences of the chloroplast rbcL gene and the nuclear rDNA ITS2 region. Our results show that U. australis and U. pertusa are genetically virtually identical, confirming that U. pertusa is a synonym of U. australis. This suggests that the introduction of U. australis to Australia occurred by the middle of the 19th century, when the type was collected and before there was a direct shipping route between Japan and Australia. We speculate that the introduction of U. australis to Australia occurred as a secondary introduction from non‐indigenous populations in northeastern Asia, but not directly from Japan.     

Role of Life History Strategy in the Colonisation of Western Australian Aquatic Systems by the Introduced Crayfish <Emphasis Type="Italic">Cherax destructor</Emphasis> Clark, 1936

The presence of the yabbie Cherax destructor in a number of wild aquatic systems in the Pilbara and Southwest Coast Drainage Divisions of Western Australia is documented. This is of great concern as all native freshwater crayfishes in Western Australia are endemic and restricted to the southwest, while the Pilbara Division has no native species. An introduced population of C. destructor was sampled monthly from the Hutt River (Pilbara Drainage Division) for determination of life-history and reproductive biology in a wild aquatic system in Western Australia for the first time. Proliferation in that system was attributed to specific traits including: attaining first maturity at the end of its first year of life; a protracted spawning period (July–January); relatively high mean ovarian fecundity of 210.2 (±9.24 S.E.); and a rapid growth rate (curvature parameter K = 0.78 and asymptotic orbital carapace length OCL_∞ = 51.25 mm ascertained from a seasonal von Bertalanffy growth curve) that was comparable to the larger sympatric marron Cherax cainii in this system. The life-history characteristics of C. destructor in the Hutt River were typical of many other invasive crayfish species and it has the potential to impact the unique aquatic ecosystems and the endemic freshwater crayfish species of the region.     

Behavioral thermoregulation by Ammocoete larvae of the sea lamprey (Petromyzon marinus) in an electronic shuttlebox

Ammocoete larvae of the sea lamprey Petromyzon marinus, a member of the primitive vertebrate class Agnatha, were tested for thermoregulatory behavior in an electronic shuttlebox (ichthyotron). The final preferendum derived from pooled data for 24 individually tested ammocoetes was characterized by a mean of 13.6 ± 0.17 (s.e.m.)°C, a mode and median of 140°C, and a range of voluntarily occupied temperatures from 10–19°C over a 3-day period.