ALBERT

Description: The annual winter sardine run along the South African east coast impacts the KwaZulu-Natal (KZN) coastal system in a variety of ways. These include ecological impacts, such as enrichment of a largely oligotrophic environment, competition between migrant sardine Sardinops sagax, other migrant and resident small pelagic fish species, and interactions with predators, as well as the socio-economic impacts of the sardine run on the local people. Enrichment of KZN coastal waters with organic nitrogen contained within the sardine is compared with alternative sources of nitrogen such as upwelling, river, sewage and stormwater runoff, and groundwater discharge. The sardine run appears to contribute most nitrogen to this system—96 000 t compared to 500–3 300 t for each of the other significant sources at trophic level 2, although upwelling estimates are extremely wide. Nonetheless, the majority of surviving sardine, their young and predators return southwards, suggesting that the nett export of nitrogen to KZN waters during the run is likely to be of a similar order of magnitude as that from other sources. Further, whereas the sardine supply of nitrogen is exclusively during winter, the bulk of the riverine input is in summer, thus ensuring that nitrogen supply in the region is maintained at fairly constant levels throughout the year. Competition for food between small pelagic fish is minimised by resource partitioning, but further dietary data are needed for resident species. Although interactions between sardine and top predators must exist, further studies are needed to confirm links between top predator life cycles and the sardine run. The estimated value of sardine as a tourist spectacle is compared to that from a seasonal beach-seine or boat-based purse-seine fishery for this species. Whereas the estimated value of the sardine as a tourist attraction appears substantially higher than could be derived from catching them, the small-scale beach-seine fishery itself draws tourists and also provides limited, seasonal employment opportunities.

Description: Subtle sexual dimorphism and its perception in apparently monomorphic bird species warrant assessment of how birds identify the sex of conspecifics, particularly of prospective mates. Visual sensitivity and its potential co-variation with cryptic sexual dichromatism are still uninvestigated in most avian taxa. Using molecular sexing, reflectance spectrometry and perceptual modelling based on the sequencing of short wavelength visual pigments, we assessed the sex-specificity of coloration and colour perception in the red-tailed tropicbird Phaethon rubricauda. We also measured morphological dimorphism at a previously unstudied breeding locality for this species. Our data are in line with both physical and avian-perceived monochromatism with a potential indication of achromatic sex differences in plumage reflectance. The moderate extent of size dimorphism is consistent with reports from other Pacific breeding populations, and morphological measurements from live specimens in this study are in line with reports on museum specimens from the same sample location. Potential differences between individuals of the same sex in size and coloration warrant the assessment of sexual dimorphism in larger sample sizes of this species.

Description: Our understanding of the fundamental regulatory roles that tyrosine phosphatases play within cells has advanced significantly in the last two decades. Out-dated ideas that tyrosine phosphatases acts solely as the “off” switch counterbalancing the action of tyrosine kinases has proved to be flawed. PTP1B is the most characterized of all the tyrosine phosphatases and it acts as a critical negative and positive regulator of numerous signaling cascades. PTP1B’s direct regulation of the insulin and the leptin receptors makes it an ideal therapeutic target for type II diabetes and obesity. Moreover, the last decade has also seen several reports establishing PTP1B as key player in cancer serving as both tumor suppressor and tumor promoter depending on the cellular context. Despite many key advances in these fields one largely ignored area is what role PTP1B may play in the modulation of immune signaling. The important recognition that PTP1B is a major negative regulator of Janus kinase – signal transducer and activator of transcription (JAK-STAT) signaling throughout evolution places it as a key link between metabolic diseases and inflammation, as well as a unique regulator between immune response and cancer. This review looks at the emergence of PTP1B through evolution, and then explore at the cell and systemic levels how it is controlled physiologically. The second half of the review will focus on the role(s) PTP1B can play in disease and in particular its involvement in metabolic syndromes and cancer. Finally we will briefly examine several novel directions in the development of PTP1B pharmacological inhibitors.

Description: A model is presented which tests the representation of the maturity process in terms of gonadosomatic indices (GSI) in chokka squid Loligo vulgaris reynaudii. It assumes that the true maturation process is reflected by the results of histological investigation, which cannot be used in large-scale ecological work in the field. However, the maturity scales used in ecological studies define some morphological categories which can be linked directly to microscopic development. Therefore, the overlap of GSI ranges for each morphological maturity category may be used to judge how well the GSIs represent the histological stages. Results have shown that the overlap is large and that GSI cannot be recommended as adequately reflecting the maturation process in squid. A morphological scale of maturity with possible broad applications in exploited families of squid is proposed as a better representation of the maturation process than GSI.

Description: There has been debate in the literature about whether jellyfish abundance has increased in the northern Benguela upwelling system, or not, over the past five decades and what impact they are having on pelagic fish. Here we review old expedition literature as well as more recent spatial and temporal patterns in distribution of jellyfish off Namibia at a number of different scales, using both published and previously unpublished data. Specifically, we have used data from fishery-dependent sources of both the demersal (359 638 trawls) and pelagic fisheries (11 324 purse-seine sets) that cover the period 1992–2006, supported by data from fishery-independent demersal (6 109 trawls) and pelagic trawls (1 817 trawls) from 1996 to 2006. Using frequency of capture as an index of abundance, it is clear that jellyfish are not randomly distributed within the northern Benguela ecosystem, but show specific areas of concentration that broadly reflect regional oceanography and the distribution of other zooplankton. Although jellyfish are present throughout the year, peaks in abundance are shown that often coincide with peaks in the spawning activity of fish of commercial importance. Interannual changes in jellyfish abundance observed from all sources do not agree, with some showing increases, others declines, and still others showing no change, which suggests caution should be exercised in their interpretation. Based on the multiple lines of evidence synthesised here, we conclude that jellyfish abundance has increased concomitant with a decline of pelagic fish stocks. We conclude that future recovery of the pelagic fishery off Namibia is likely to be considerably challenged because of significant overlaps in space and time between fish and jellyfish, and through the effects of competition and predation effects of jellyfish on fish.

Description: This paper provides an introduction to, and overview of, the natural phenomenon known as the KwaZulu-Natal sardine run. Previous literature on this topic and hypotheses about the reasons why, and the mechanisms how, the run occurs are briefly synthesised and described. Papers contributing to this suite that detail more recent work on a variety of aspects of the sardine run, ranging from physical oceanography through sardine biology and ecology to socio-economic and ecological consequences, are outlined. Such studies will lead to improved understanding of the factors that regulate the timing and intensity of the run, which may permit predictions of whether it will occur, when fish will arrive on the KZN beaches, and how long it will persist. Such predictions would have substantial benefits for this ecologically and economically important event.

Description: The capture of 52 specimens of the cirrate octopod Grimpoteuthis glacialis (Robson, 1930), of dorsal mantle length 20-165 mm during a 1996 trawling survey near the Antarctic Peninsula allowed the basic biology of the species to be examined. Their presence in bottom trawls at depths of 333-879 m, but their absence from benthopelagic and pelagic trawls, is consistent with a primarily benthic habitat. The largest single sample, 40 animals, came from a soft mud bottom and highlights the patchy nature of the distribution. Males tended to be bigger in total length and mass than females of similar mantle length. The males, however, were mature at a smaller size. Mature males have tiny sperm packets, rather than typical cephalopod spermatophores, in their distal reproductive tract. Mature females have large, smooth eggs in the proximal oviduct, in the huge oviducal gland and in the distal oviduct. Eggs in the distal oviduct have a thick, sticky coating that hardens in seawater into a secondary egg case. Ovarian eggs vary greatly in size, possibly indicating protracted egg laying. Observations on live animals indicate that the species swims primarily by fin action, rather than by jetting or medusoid pulses with the arm/web complex. It may be capable of limited changes in colour pattern, especially on the oral surface of the web. Three pairs of surface structures that appear superficially to be white spots anterior to the eyes and near the bases of the fins are actually transparent patches in the skin. When considered in association with the transparent subdermal layer and the anatomy of the eyes, optic nerves and optic lobes, these clear patches seem to function in detecting unfocused light on the horizontal plane of the benthic animal.

Description: This review provides an overview of the importance of beach accumulations of macrophytes and other organic beach-cast material on the ecology of sandy beach ecosystems. It describes the composition of these allochthonous subsidies, their abundance on beaches in relation to seasonal, lunar, tidal and spatial trends, their decomposition and utilisation by bacterial, meio- and macrofaunal communities. The paper then analyses the community structure and the species succession in both macrophyte wrack and carrion and reports the most important findings on individual wrack-inhabiting species (amphipods, isopods, dipterans). Other aspects, such as feeding and microclimatic preferences of certain species and their interactions in wracks, are also discussed. Links to vertebrate species and other secondary consumers that exploit beach-cast macrophytes and carrion as trophic resource are considered, and the importance of wrack in recycling nutrients to nearshore coastal ecosystems is stressed. The beneficial and detrimental effects of organic beach-cast material on both plants and animals of beach and nearshore communities and on the geomorphology of coastal beach-dune systems are pointed out. Another section is dedicated to human use of beach-cast macrophytes through harvesting of economically important species and of other stranded material through its exploitation for traditional reasons. The effects of harvesting on local faunal communities and on the stability of the dunes is discussed. A final section of the paper includes the positive and negative effects of man-made debris on sandy-beach ecosystems and briefly reviews the major findings.

Description: Current antifouling technologies rely on metal-based paints, but due to their toxicity, an expected worldwide ban of organotin-containing paints is now prompting the quest for safe and effective alternatives. One of these is antifouling coatings whose active components are naturally occurring compounds in marine organisms. A number of laboratory bioassays has been designed to search for antifouling compounds. However, there is no evidence to date that these assays provide results reproducible through ecologically realistic field experiments. Natural concentrations of the extracts from the Brazilian seaweeds Laurencia obtusa and Stypopodium zonale were tested in the laboratory through the 'mussel test' and in the field through the 'phytagel method' in order to compare the efficiency of these methods in assessing antifouling activity. L. obtusa extract significantly inhibited fouling in both the laboratory and field assays, while S. zonale stimulated fouling in both assays. Major compounds from the extracts were identified. The findings suggest that the 'mussel test' is a reliable time and cost-saving screening method for antifouling substances, although field assays are more sensitive for detection of their activity spectrum.