Inter-basin water transfer effects on the invertebrates of the Mvuzane River: A test of the SASS rapid biomonitoring protocol to assess the impact of flow modification

Effects of the transfer of water from the Thukela to the Mvuzane River were investigated using the SASS rapid bioassessment technique and more quantitative methods of guild composition and community analyses. Although the transfer was relatively small (< 1 m3/s) it completely dominated natural flows in the recipient system. SASS monitoring was found to be useful as a rapid, field-based assessment of water quality and can be used to act as a ‘red flag’ to problems in the future. However, it was not sensitive to changes in the community structure at different sites and was inefficient as a tool to investigate the wider ecological impacts of the transfer scheme, most notably those associated with flow modification. Changes in the invertebrate fauna were most easily explained in terms of the effect of increased flow velocities and volumes on taxa that were classified as ‘swimmers’ and ‘skaters’. Impacts via disruption to trophic pathways cannot be discounted and will most certainly occur with prolonged water transfer

Species identification, distribution and abundance of Gerreidae (Teleostei) Bleeker,1859 in the estuaries of Natal

Comparison of published meristic and taxonomic data with measurements taken from specimens collected from Natal estuaries have provided information for an identification key to the Gerres of southern Africa. Body markings were different on each species of fry (< 40 mm S.L.) as well as immatures and adults (> 40 mm S.L.). A comparison of otoliths from the different species showed that they can be used to Identify specimens from a standard length of 20 mm. Turbidity may be a factor limiting the distribution of the genus in estuaries. The known distribution of Gerres species in the estuaries of southern Africa is given. The species of Gerres which is dominant in a particular locality depends on the salinity

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Diet of Gerres fry in the Kosi system

No Abstrac

Article Mouthpart structure and function and the feeding mechanisms of Gerres (Teleostei)

Members of the genus Gerres feed almost exclusively on benthic invertebrates and have evolved efficient protrusible jaw mechanisms and modes of feeding. The methods employed in prey capture and feeding by five species that occur in the estuaries of Natal were studied using slow-motion cine photography and results were supplemented by field observations. All species use visual cues to detect and capture prey on or just below the surface of the substrate.The protrusible jaw mechanism is the most important feature in prey capture. Bones and muscles involved in jaw movement were studied by dissecting preserved specimens and cleaning jaws and skulls of muscle. The whole mechanism of protrusion of the mouthparts was found to be controlled by two sets of muscles acting on a modified maxilla which together with the cross-palatine ligament forms a groove along which the ascending process of the maxilla can slide when the mouthparts are protruded. The setting up of a suction pressure within the mouth further aids the uptake of items from the substrate. However, whether or not suction pressure is applied depends on the prey type

A preliminary investigation of the effects of an Inter Basin Transfer on the ichthyofauna of a small river in northern KwaZulu-Natal, South Africa

A study was carried out to provide baseline data so that future impacts of an Inter Basin Transfer on the fish fauna of the Mvuzana River could be assessed. Seven species of fish were recorded, and all were present under natural and regulated flow conditions. Although there were no significant differences in community structure between natural and regulated flow conditions, species distribution was more and the CPUE values lower under regulated conditions downstream from the transfer point.Key words: freshwater, Mvuzana River, impacts, fish

Salinity ranges of some southern African fish species occurring in estuaries

The recorded salinity ranges of 96 fish species occurring in southern African estuaries are documented. Factors influencing the tolerance of fishes to low and high salinity regimes are discussed, with most species tolerant of low rather than high salinity conditions. This is important since most systems are subject to periodic freshwater flooding, especially during summer. The penetration of freshwater teleosts and elasmobranchs into estuaries is examined and the occurrence of marine fishes in rivers documented. Mortalities arising from salinity extremes in southern African estuaries are discussed, with temperature a key factor initiating such fish kills. Only eight fish species have been recorded spawning in estuaries although the fry of many species are attracted to estuarine waters. It is concluded that a small percentage of southern African fishes have succeeded in utilizing estuaries and this may be attributed to the paucity of strong osmoregulators

The biology and taxonomic status of an estuarine population of Pranesus pinguis (Lacépède) (Teleostei: Atherinidae) in south east Africa

The biology and taxonomic status of Pranesus pinguis in the subtropical Kosi estuary in south east Africa were investigated. Data from Kosi specimens support the view that P. pinguis is a highly variable species in terms of fin, spines, rays and body ratios. Nearly all the variations reported for P. pinguis by Smith (1965) occurred within the Kosi population. Criteria used to distinguish P. capricornensis, P. ogilbyi and P. insuiarum fall within the range of variation of P. pinguis from Kosi and must therefore be considered synonyms. The diet of P. pinguis in Kosi consisted chiefly of Calanoida and feeding took place at night. The fish congregated in shoals around a reef during daylight. The structure and dimensions of the gill rakers related to the diet indicate that, although P. pinguis feeds mainly by capturing individual prey, it is also a facultative filter feeder. All stages of the reproductive cycle were recorded from P. pinguis in the Kosi estuary. The eggs have a covering of filaments which may allow for demersal attachment. Although no direct evidence was available, spawning within the estuary may occur

Horizontal trends in larval fish diversity and abundance along an ocean-estuarine gradient on the northern KwaZulu-Natal coast, South Africa

The structure of the larval fish assemblages along an ocean-estuarine gradient in the St Lucia region on the northern KwaZulu-Natal coast of South Africa was examined using a combination of univariate, distributional and multivariate techniques. The data was comprised of a full annual set of ichthyoplankton samples taken from three types of environment: nearshore coastal waters, surf zone and within the St Lucia Estuary itself. The mean monthly densities of each species in each environment were used in the species matrix, and the mean monthly values of salinity, temperature and turbidity were used in the physical variables matrix. The mean species diversity and eveness index was significantly higher in the nearshore waters than the surf zone and estuary. The patterns of relative species abundances in each environment (K-dominance curves) showed that the estuarine environment was dominated by a few species in large numbers, the surf zone was intermediate, and the nearshore coast was the most diverse. Classification and multidimensional scaling (MDS) ordination analyses of larval fish densities grouped together into three main clusters based on the three different environments. The species similarity matrix (inverse analysis) clustered into four groups at the 10% similarity level. The MDS analysis of the same matrix showed that the groups separated out more or less according to the type of environment they occur in, and hence the level of estuarine dependence of the various species. Species belonging to each assemblage showed similarities with regards to their reproduction modes and/or preference to a particular physical condition. Some species were restricted to one environment, whilst others were common to two or all three environments. The occurrence of partially estuarine-dependent species in all three environments suggests that ocean-estuarine coupling is an important process for the recruitment success of these species. The 'best fitting' physical variable which explained the larval fish community patterns was turbidity on its own, with the relationship of larval densities to the physical variables being species-specific. The present study indicates that a number of factors must play a role in determining the structure and composition of larval fish assemblages occurring in different types of environments along an ocean-estuarine gradient. It is suggested that these distinct assemblages might be considered indicators for the different environments which they inhabit