Translocation and Spread of Piscivorous Fishes in the Burdekin River, North-eastern Australia

The distribution of the biogeographically distinctive fish fauna of the Burdekin River, north-eastern Australia, is largely determined by the presence of a large waterfall located at the lower quarter of the river’s length. Downstream of the falls, assemblages are characterised by the presence of piscivorous fishes whereas such species are largely absent from upstream reaches. Sleepy cod (Oxyeleotris lineolatus), a large piscivorous gudgeon, was first introduced into the upper reaches of the Burdekin River in 1980 and other releases, both official and unofficial, have occurred subsequently. The population remained small and restricted to the site of introduction for a decade, but expanded in size and distribution after the occurrence of a large flood and entry into a prolonged period of drought. This gudgeon is now present in every tributary system of the Burdekin Basin. Despite the occurrence of substantial temporal variation in fish abundance due to a highly variable flow regime, negative impacts on one species, a small gudgeon (Mogurnda adspersa), are evident. Both deliberate and accidental releases of other species into the upper Burdekin River have also occurred, often to satisfy recreational fishing demand. Such species are typified by large size and piscivorous habit, characteristics alien and inimical to the native fish fauna. It is hypothesised that these piscivorous species may have even greater impact than O. lineolatus in some tributary systems of the upper Burdekin River.     

Isolation and characterization of polymorphic microsatellites in a Yangtze River fish,brass gudgeon (Coreius heterodon Bleeker)

The brass gudgeon (Coreius heterodon) is a fish of economic importance in the Yangtze River. From a (GATA)_n‐enriched genomic library, 25 microsatellites were developed by employing the fast isolation by AFLP of sequences containing repeats (FIASCO) protocol. Nine loci exhibited polymorphism with two to 12 alleles (mean 3.9 alleles/locus) in a test population, and observed heterozygosity ranged from 0.1111 to 0.9630 (mean 0.4426). Three of the nine loci showed polymorphism in a congeneric species, the largemouth bronze gudgeon Coreius guichenoti. These loci should provide sufficient level of genetic diversity to evaluate the fine‐scale population structure of C. heterodon.     

Morphology and habitat use by fishes of the Rio das Velhas basin in southeastern Brazil

We analyzed the morphology and habitat use of 16 small-sized fish species that are abundant in the Rio das Velhas basin using 17 morphological attributes. Habitat use was characterized in terms of the species mean density considering three hydraulic factors: substrate, water depth and mean water velocity. The distribution of species within the morphological space demonstrated congruence between the morphological attributes of a species, and their occupation of vertical microhabitats. Based on this data, the species could be classified as benthic A, benthic B or nektonic zone-dwelling species. Benthic A and B species differed mainly in relation to their body shapes, which were fusiform or depressed, respectively. Generally, habitat selection by each species was related to certain hydraulic factors, water velocity in particular. Siluriformes generally had morphological or behavioral adaptations to live in fast flowing habitats, and they were found more frequently than Characiformes in microhabitats with greater water velocities. Benthic species were the most selective with respect to substrate type. Between congener species, the habitat use of Serrapinnus heterodon and Serrapinnus piaba greatly overlapped, but these species were separated in morphological space. In contrast, Characidium species were closely related in morphological space but had great habitat segregation. Fish requirements and habitat use are poorly understood but are important to species management and habitat restoration.     

Seasonal variations in food resource partitioning among four sympatric gudgeon species in the upper Yangtze River

Knowledge of food resource partitioning among sympatric fish species is crucial for understanding the potential mechanisms of species coexistence. Gudgeons (Teleostei: Cyprinidae: Gobioninae) often dominate fish assemblages in the upper Yangtze River. However, little research has been conducted on their trophic interactions. In this paper, seasonal diet and feeding strategy variations of four sympatric gudgeon species, Coreius guichenoti, Coreius heterodon, Rhinogobio ventralis, and Rhinogobio cylindricus, were investigated by analysis of intestinal tract contents, aiming to explore whether food resource partitioning occurred among them. Fish specimens were collected during spring (April–May) and autumn (August–October) in 2010 in Hejiang, a free‐flowing stretch of the upper Yangtze River. Coreius guichenoti, C. heterodon, and R. cylindricus showed omnivorous feeding habits, while R. ventralis exhibited an obligate carnivore feeding habit. Diet overlap among the four studied species was high, especially in spring. However, changes in feeding strategies were observed in autumn. Specifically, C. guichenoti and R. cylindricus expanded their dietary niche breadth and consumed detritus, Sinopotamidae or Hydropsychidae as important complementary food resources. In contrast, C. heterodon and R. ventralis reduced their dietary niche breadth and became more specialized on mussels (Limnoperna lacustris). These results confirmed that sympatric fish species can coexist with high diet overlap, and food resource partitioning among these species may also fluctuate with the seasons.     

Terpenes from Cantinoa (Lamiaceae) native to Rio Grande do Sul,South Brazil

Cantinoa althaeifolia, C. heterodon, C. mutabilis, C. stricta and C. sylvularum were investigated for the essential oil and exudate composition. The essential oils of these species, previously placed in the genus Hyptis, demonstrated the presence of at least 46 compounds, being β-pinene, δ-3-carene, β-caryophyllene, bicyclogermacrene, caryophyllene oxide and globulol the compounds present in higher amounts. Besides monoterpenes and sesquiterpenes, three species presented diterpenes. Kaurenoic acid was isolated from C. heterodon exudate and detected by gas chromatography in C. stricta and C. mutabilis. Although kaurane diterpenes are widely found in nature, their occurrence in Lamiaceae seems to be restricted to few genera.     

Larval and juvenile fishes occurring with flood tides on an intertidal mudflat in the Tama River estuary, central Japan

Intertidal movements of fish larvae and juveniles on a mudflat in the Tama River estuary, central Japan, were investigated by comparing the abundance and sizes of fishes caught in the intertidal zone during flood tides with those in the subtidal zone during low tides. A total of 28465 individuals, belonging to 9 families and 20 species, were collected by small purse seine. Among the abundant species, planktonic larvae and juveniles of gobiids and Konosirus punctatus were more abundant in the intertidal zone at flood tide than the subtidal zone at low tide. Similar occurrence patterns were found in juvenile Plecoglossus altivelis altivelis and Lateolabrax japonicus, having fully developed swimming abilities. In contrast to these species, much higher abundances of epibenthic juveniles of 2 gobiids (Acanthogobius flavimanus and Gymnogobius macrognathos) were found in the subtidal zone at low tide, although they also utilized the intertidal zone at flood tide.     

Size and diel differences in activity patterns of Metapenaeus ensis,penaeus latisulcatus and P. merguiensis

The nursery function of mangroves as shelter has been postulated to explain the positive correlation between shrimp catches and mangrove area. This study was undertaken to document shelter use and other activities in mangrove‐associated penaeids and to determine diel and size differences relating to these activities. Juvenile Metapenaeus ensis, Penaeus latisulcatus and P. merguiensis collected from mangrove areas in Guimaras, central Philippines and stocked individually in glass tanks (= replicates) provided with artificial shelters and sand substrate were observed every hour for 25 h. Size classes tested were very small (1–5.9 mm carapace length); small (6–10.9mm CL); medium (11–15.9mm CL); large (16–20.9mm CL); and very large (21–25.9 mm CL). Due to limited juvenile supply, only 3 sizes were tested for each species: P. merguiensis (very small to medium), M. ensis (small to large) and P. latisulcatus (medium to very large) with 5 replicate animals (one per tank) per size. Juvenile M. ensis and P. latisulcatus showed a strong diel periodicity of daytime burial and nocturnal activity. In contrast, P. merguiensis showed active swimming and feeding throughout the day and night. Very small to small P. merguiensis were observed on the shelters, but burying was exhibited only by a few medium‐sized juveniles. This shelter use is consistent with observations of small P. merguiensis entering the mangrove forest (where roots, twigs, etc. contribute to structural complexity) on the flood tide and concentrating in the shallow, turbid waters of adjoining creeks during ebb tide and slack water.     

Biology of the rainbowfish,Glossolepis multisquamatus (Melanotaeniidae), from the Sepik River floodplains,Papua New Guinea

Synopsis G. multisquamatus is abundant in the Sepik River, preferring floodplain lakes and marginal areas of floodplain with moderate turbidity. It is the only rainbowfish documented to inhabit river floodplains. Migrations onto and off the floodplain occur in response to changes in flood conditions. Seasonality is evident in reproduction, condition factor and fat deposit and stomach fullness indices; all increasing in the flood season. Fecundity is high compared with stream dwelling rainbowfish species mainly due to decreased egg size. The reproductive strategy ofG. multisquamatus is interpreted as a response to increased adult mortalities encountered on floodplains in comparison to more stable stream habitats occupied by related species.G. multisquamatus is carnivorous, its diet being similar to other rainbowfishes, consisting of a variety of small invertebrates taken from mid-water or the water surface. The ecology and behaviour ofG. multisquamatus is explained as a partial colonisation of newly developed floodplains in this river.     

Phylogenetic relationships of the Chinese cyprinid genus <Emphasis Type="Italic">Rhinogobio </Emphasis>Bleeker (Teleostei: Cyprinidae) based on sequences of the mitochondrial DNA control region,with comments on character adaptations

Rhinogobio is a cyprinid genus restricted to the river drainages of China. Sequences of the mitochondrial DNA control region were determined for four Rhinogobio species and one outgroup species, Coreius heterodon, to investigate the phylogenetic relationships within the genus. The control region of the Rhinogobiospecies ranges from 922 to 930 base pairs and comprises 930 base pairs in Coreius. Our phylogenetic analysis indicates two distinct lineages in the genus Rhinogobio. The first includes only R R. ventralis. In the second lineage there are three species, two closely related species R.cylindricus andR.hunanensis, and their sister speciesR. typus. An analysis of character adaptations suggests an evolutionary trend in this genus towards a relatively lower body and caudal peduncle depth, a shorter dorsal fin, and a more anterior anus. In addition, there is a trend towards shorter barbels and relatively larger eyes. Some or all of these traits may be associated with a habitat shift from fast-flowing turbid rivers to slower-flowing clear river habitats.     

Ethylene metabolism in Pisum sativum L.: Kinetic parameters,the effects of propylene,silver and carbon dioxide and comparison with other systems

The kinetic parameters of in vivo ethylene metabolism by seedlings of Pisum sativum L. cv. Alaska have been determined. The oxidation of ethylene to CO₂, (Ox) and the incorporation of ethylene into the tissue (TI) were both shown to display Michaelis-Menten kinetics (K_m Ox = 0.9 × 10^–6 M liquid phase, V_max Ox = 2.4 × 10^–10 moles g^– dry mass h^–1 K_m TI = 1.6 × 10^–6 M liquid phase, V_max TI = 4.5 × 10^–10 moles g^–1 dry mass h^–1). Propylene competitively inhibited both Ox (K_i = 7.0 × 10^–6 M) and TI (K_i = 3.7 × 10^–7 M). A system comparable to Ox was absent from imbibed cotyledons of Vicia faba L. cv. Aquadulce even at saturating concentrations of ethylene similar to those used in kinetic analysis on Pisum. Silver ions were shown to inhibit TI but promoted Ox, while carbon dioxide inhibited Ox but promoted TI. Kinetic data on both these effects are presented. Data on the effect of a range of concentrations of CO₂ on TI and Ox are also presented.To whom editorial correspondence should be sent     

Common mechanism controlling phase and antigenic variation in pathogenic Neisseriae

The expression of the Neisseria gonorrhoeae opacity protein (Op, protein II), a major antigenic determinant of the outer membrane, is subject to frequent phase transitions. At least nine expression loci (opaE) are involved in the production of a large number of serologically distinct Op types. Using opa-specific oligonucleotides as probes in genomic blots, we detect Op-related gene sequences (opr) in N. meninglitidis as well as in N. lactamica. DNA sequence analysis of such opr genes derived from N. meninglitidis reveals distinct regions of homology with gonococcal opa E genes. As shown in the immunoblot, the proteins encoded by ops and opr are serologically related. Like the opa E genes, the 5′-coding sequences of the opr genes include a repetitive sequence composed of pentameric CTCTT units. The number of these coding repeat (CR) units is variable. This finding, together with the observation that all opr genes are constitutively transcribed, regardless of the status of protein production, suggests a translational control mechanism identical to that of the opa genes in gonococci. The related structures and control mechanisms of opa and opr genes imply a general significance of their gene products for the pathogenic character of the investigated Neisseria species.     

ASPECTS OF THE FISHERIES OF LAKE LIAMBEZI,CAPRIVI

SUMMARY

Lake Liambezi, situated in the Linyanti Swamp, Caprivi, is inhabited by 43 fish species. Population estimates with seine nets, rotenone and explosives gave values of 74 to 157 kg ha^?1. The composition of seine net catches differed markedly from gill net catches where non-Cichlids form a majority. Results of a fleet of gill nets show that best catches of 25 kg 50 m^?1 net night^?1 can be made with 60 mm mesh nets, catching predominantly non-Cichlids (Marcusenius macrolepidotus, Schilbe mystus, Synodontis spp.). A small commercial fishery is established on the lake, with 60 active fishermen using large mesh (100–150 mm) gill nets. Their catch consists mainly of cichlids (Sarotherodon andersoni and S. macrochir) and Clarias spp. Production figures dropped from 637 ton in 1973–74 to 115 ton in 1975–76. This drop is ascribed to reduced effort as well as a reduction in catch per unit effort. Recommendations are made to utilise the fishery potential of Lake Liambezi in a more balanced way by introducing small mesh gill nets to harvest non-Cichlid populations.     

Comparison of the ovaries and oogenesis of some Australian and South African viviparid clinid fishes (Clinidae,Blennioidei, Perciformes)

The ovaries of the studied 16 viviparous blenny species of the fish family Clinidae (Teleostei, Perciformes) from Australia and South Africa, are of the cystovarian type and bilobed, ending in a common short oviduct at the gonopore; they are elongated in juvenile fish, becoming bottle-shaped or oval with maturation and onset of embryogenesis, when they comprise 18–20% of the total body weight. The ovarian lumen is covered by the germinal epithelium, resting on a basal membrane. The primordial germ cells are situated along the inner side of each lobe, juxtaposed internally to the lumenal epithelium. Single primary oocytes or nests of such, each in a follicular envelope and covered externally by the lumenal epithelium forming clusters protruding into the lumen, along which the inoculated sperm settle. Two different types of reproductive strategies are demonstrated by the Australian species of Heteroclinus and Cristiceps and the South African species of Clinus and related forms. The Australian species produce high numbers of small (350 ± 50 μm in diameter) eggs that develop synchronously, while the South African species produce much fewer and larger (1.0 ± 0.1 mm) eggs, asynchronous in development. An exception in the latter group is Blennophis striatus, with eggs of ca.1.4 mm that develop synchronously. The Australian species are thus mass releasers that bear and release up to 1000 small (11 ± 1.5 mm in length) embryos/spawn, while the South African Clinus species are discrete releasers that bear eggs of various sizes and small numbers of mature for release embryos that reach up to 22 mm in length, and are released throughout the year. The cytogenesis of the oocytes and surrounding envelopes is discussed.     

Early development of the northern logperch,Percina caprodes semifasciata,according to the theory of saltatory ontogeny

Synopsis The early development of northern logperch, Percina caprodes semifasciata, was examined from an ecological perspective and in relation to the theory of saltatory ontogeny. Steps, the intervals of relative homeostasis, separated by thresholds, rapid switches to new form and function resulting from canalization of changes in the preceeding step, are described and related to environmental factors. Adaptive shifts in growth allometries provided further evidence of the saltatory nature of ontogeny. Logperch eggs are small (1.2 mm diameter), demersal, and adhesive. The simple embryonic respiratory system reflects high oxygen availability on the lotic spawning grounds. Hatching occurs early, relative to other darters, and free embryos are pelagic. The small free embryos presumably drift downstream to lentic areas, where small planktonic food is more abundant. Logperch are therefore nonguarding, open substrate spawning lithopelagophils and, along with other Percina species, have not advanced from ancestral percid reproductive styles. Percina species have generally remained in ancestral habitats-rivers and lakes. The close correlation between developmental patterns of logperch and environmental factors is therefore interpreted as a restriction based on retention of ancestral characteristics, not as evidence of novel adaptations to new habitats.     

Transformation of riparian forest to woodland in Mapungubwe National Park,South Africa,between 1990 and 2007

Canopy tree survival and compositional change of the Greefswald forest on the Limpopo River, South Africa, were monitored between 1990 and 2007 in response to a severe drought (cessation of flow in 1991/2), water abstraction commencing in 1991, a mega‐flood in 2000 and increasing impact of elephants since 2000. Aerial photographs confirmed that forest area had not decreased during the 35 years prior to the study. In total, 25% of 428 canopy trees tagged in 1990 had died by 2005. Tree density was reduced from 22.8 to 16.3 trees per hectare. Forest was thus transformed to woodland. Mortality was attributed mainly to drought stress (47%), drought in combination with creeper infestation (30%) and the flood (21%). Of the nine main canopy species, mortality was highest for Acacia xanthophloea (56%) and Faidherbia albida (37%) mainly because of drought‐related stress, and Ficus sycamorus (25%) mainly because of the flood. Water extraction increased drought‐related mortality in the area of extraction by 45%. Creepers rendered microphyllous but not broad‐leafed species more vulnerable to drought‐induced mortality. Elephants were responsible for a further 3% mortality between 2005 and 2007. Composition has shifted towards ‘drought‐tolerant’ species not selected by elephants, namely Philenoptera violacea, Xanthocercis zambesiaca and Schotia brachypetala. Initial concern about water abstraction was eclipsed by a rapid, unpredictable concatenation of a series of rare events that transformed forest to woodland in less than 15 years.     

Polymorphic microsatellites in largemouth bronze gudgeon (Coreius guichenoti) developed from repeat‐enriched libraries and cross‐species amplifications

Largemouth bronze gudgeon (Coreius guichenoti) is a medium‐sized fish endemic from the upper Yangtze River of China and its survival is threatened by the construction of the Three Gorges Dam. This study reports 20 new polymorphic microsatellites from a repeat‐enriched genomic library with a mean number allele of 5.2, and observed and expected heterozygosities ranging from 0.035 to 1, and from 0.13 to 0.917, respectively. In a cross‐species amplification test, nine of the 37 tested loci were found to be also polymorphic in a congeneric species, brass gudgeon (C. heterodon). In addition, other four loci from common carp (Cyprinus carpio) were also polymorphic in C. guichenoti. Out of these 24 polymorphic microsatellites, only three loci significantly deviated from Hardy–Weinberg equilibrium in the sampled population (P < 0.0025), and all pairwise tests for linkage disequilibrium among loci were nonsignificant after applying sequential Bonferroni correction (P > 0.0026). These novel microsatellites provide sufficient levels of polymorphism for studies on population genetics and conservation in C. guichenoti and its related species.     

Fishery of the Deep-water Rose Shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea: Decapoda) in the Northern Tyrrhenian Sea (Western Mediterranean)

The aim of this study is to provide information on the fishing pattern of Parapenaeus longirostris in the northern Tyrrhenian Sea (western Mediterranean), in order to improve the management of the resource in the area. Data were obtained from commercial fishery, covering the period 1991–2002. Catch rates revealed notable inter-annual fluctuation of the P. longirostris landing, probably due to the life cycle of the species. The highest yields (kg per hour of trawl) of the commercial fishery were obtained at depths ranging between 180 and 300 m, the lower ones at depths between 100 and 180 m, where small specimens are more abundant. Commercial catches were characterised by a very low presence of specimens smaller than 20 mm carapace length (CL), mainly due to the deeper localisation of the fishing grounds when compared to the recruitment areas of the species. The size at which 50% of the specimens were discarded by the fishermen was 15 mm CL, while the estimated size at first capture of the individuals caught by the commercial net was 12.4 mm CL.     

Species interactions and habitat associations of birds inhabiting urban areas of Sydney,Australia

Abstract The absence of small birds from many suburban areas may be due to adverse garden characteristics, interspecific aggression or human behaviour such as supplementary food provisioning that encourages predators. We investigated the relationship between these factors and the presence of seven small bird species in Sydney through a community‐based survey. The survey was conducted by participants over a 7‐day period between 7 am and 10 am in November and early December 2000. Three dominant species, the noisy miner (Manorina melanocephala), pied currawong (Strepera graculina) and common myna (Acridotheres tristis) were each present in over 59% of gardens. Each small bird species was present in less than 40% of gardens. All small birds were negatively associated with noisy miners, but only the silvereye (Zosterops lateralis) was negatively associated with pied currawongs. None of the species of small birds was negatively associated with common mynas. Four species of small birds were associated with at least one habitat variable, notably the proportion of native vegetation. Although more birds were recorded in gardens in which meat was provided, there were significantly fewer small birds in these gardens. There were also more birds recorded in gardens where seed was provided, with red‐browed finches (Neochmia temporalis) positively associated with seed provisioning in most regions of Sydney. The presence of dogs and cats was not related to the total abundance of birds overall or small birds in gardens. While garden characteristics may influence the presence of small birds to some degree, the presence of noisy miners, a species that are thought to aggressively exclude other species from their territories, is likely to be an important influence on these species in suburban areas. Furthermore, supplementary feeding by people is likely to negatively influence some small birds. The presence of carnivorous pets does not seem to influence the presence of small birds at the scale of the individual garden.     

The influence of spring floods on small mammal communities in the Nemunas River Delta, Lithuania

The influence of the annual spring floods on small mammal communities was studied in the Nemunas River Delta, SW Lithuania. The aim of the investigation was to compare the diversity of small mammals inhabiting spring-flooded meadows, meadows not subjected to flooding and spring-flooded forest in years characterized by differing heights and durations of spring flood. In the years of the high flood, the number of species and diversity index were higher, while index of dominance was less than in the years of low flood. Significantly, the highest proportions of Apodemus agrarius were recorded in spring-flooded meadows in years of high flood (41.7%), while Microtus oeconomus occurred in the highest proportions in spring-flooded meadows in years of low flood (66.8%) and in meadows not subjected to flooding (47.1%). In non-flooded areas, M. Oeconomus is not expelled by the floods and outcompetes other species. After high levels of flooding, during the process of re-population, the voles may be outcompeted by A. agrarius. In the absence of dominant species, greater opportunities existed for the establishment of more species (13 species in flooded meadows). Micromys minutus accounted for up to 19.5–30.1% in the years of high flood. We concluded that the annual spring floods in the Nemunas Delta had no long-term negative effects, the number of small mammal species and their abundance had been restored in just a few months. The worst consequences of the high flood were recorded in forest habitat. Spring floods, and especially the higher floods, are natural environmental agents, maintaining the high diversity of small mammals in meadows and reed-beds.