Aquatic leeches (Hirudinea) as bioindicators of organic chemical contaminants in freshwater ecosystems

Freshwater leeches from an industrially polluted creek were found to contain very high residues of chlorophenols, when compared with fish, tadpoles and most other benthic invertebrates. Leeches are recommended as possible bioindicators of aquatic organic contamination.     

Seasonal migrations of plaice (Pleuronectes platessa) through the Dover Strait

Analysis of paired-haul mid-water trawling experiments conducted in the five months November to March during the years 1985 and 1988 revealed the seasonal pattern of migration of plaice (Pleuronectes platessa L.) moving through the Dover Strait between the Southern Bight of the North Sea and the English Channel. Mid-water catches of maturing fish were highest on south-going tidesprior to peak spawning (late January), while catches of spent fish, were highest on north-going tidesafter peak spawning. Detailed analysis of the catch data provided evidence that males complete their pre-spawning migration earlier, and their post-spawning migration later, than female fish and consequently spend more time on the spawning ground. Catches of immature female fish indicated a migration south following that of the mature fish. This dummy run may be a method by which immature plaice use the presence of high densities of mature and spawning fish to learn the location of the spawning ground. The analysis also indicated that differences in catch rates between day and night are unlikely to be the result of gear avoidance by day. The results confirm that selective tidal-stream transport is a key migratory mechanism for plaice in areas of fast tidal streams on the European continental shelf.     

Neonatal alloimmune thrombocytopenia due to anti-P1A1 (anti-hpa-1a): Importance of paternal and fetal platelet typing for assessment of fetal risk

Neonatal alloimmune thrombocytopenia (NAIT), which usually involves sensitization to P1^A1 (HPA-1a), may have devastating complications for the fetus. These may be prevented by antenatal treatment of severe cases with either maternally administered high-dose gamma-globulin and/or repeated intrauterine platelet transfusions. Determination of the paternal platelet phenotype is useful for counselling parents who have had one or more affected pregnancies. This report of an unaffected pregnancy in a woman with a history of previous pregnancies complicated by NAIT illustrates the role of paternal and fetal platelet phenotyping in managing existing pregnancies at risk of NAIT.     

Early nutritional conditions, growth trajectories and mate choice: does compensatory growth lead to a reduction in adult sexual attractiveness?

It is well documented that poor early nutrition can have profound negative effects on adult life-history traits. However, it has also been demonstrated that organisms can undergo compensatory resource allocation strategies (such as an accelerated growth rate) if food availability improves, so as to mitigate the effects of the poor early conditions. Previous research has indicated that elevated growth rates can incur costs in the longer term, such as an increased rate of senescence and shorter lifespan. We tested whether a phase of compensatory growth after a period of reduced food availability earlier in life affected the sexual attractiveness of adult male green swordtails Xiphophorus helleri, a species in which it has previously been documented that females prefer larger-bodied and longer-tailed males. The experiment compared the attractiveness of size-matched brothers that had experienced contrasting growth trajectories as juveniles; the experiments were initially conducted in the middle of a male’s sexually reproductive life and were then repeated towards the very end of life. At both ages, males that had undergone compensatory growth were equally as attractive as their brothers that had grown normally. These results suggest that the growth compensation benefits males through an increase in their attractiveness over that which they would have had if they had remained on their original growth trajectory. The lack of change in relative attractiveness with age indicates that the compensation does not cause greater deterioration in secondary sexual characters at older ages than in continuously well-fed males.     

Biological water quality assessment of running waters based on macroinvertebrate communities: history and present status in Europe

This paper reviews the history and development of biological water quality assessment using macroinvertebrates in Europe, and critically evaluates each of the principal approaches used. As the biotic approach incorporates the most highly regarded features of the saprobic and diversity approaches, it has received the most attention in recent years. Most modern biotic index and score systems have evolved from the Trent Biotic Index, through a series of refinements and adaptations (i.e. the Extended Biotic Index, Chandler's Score, Indice Biotique) into the two modern systems. These methods are the Biological Monitoring Working Party System, used mainly in Great Britain, and the Belgian Biotic Index Method. The results of these techniques are now influencing policy decisions concerning surface water management in Europe, where macroinvertebrate community assessment are being used as a planning tool for managing water uses, for ambient monitoring, and for evaluating the effectiveness of pollution control measures. New research directions aimed at improving the performance of bioassessment techniques are being explored. These include defining reference communities based on stream typology which can then be used to set water quality objectives, and applying these methods to the assessment of toxic pollution.     

An automated system to control and manipulate the flight activity of captive birds

Biologists have long been interested in the behavioural and physiological mechanisms that regulate flight. The manipulation of physical activity of birds under captive conditions, however, faces the experimenter with some technical problems. In this article, we describe a simple automated system that allows control and manipulation of the flight activity of captive birds and use it for the first time to induce blood oxidative stress in male zebra finches (Taeniopygia guttata). Finches subjected to a short-term flight effort regime had an increase of plasma oxidative damage and a decrease of thiol concentration in red blood cells and of body mass, respectively. However, no change in red blood cell glutathione peroxidase was observed. This simple experiment shows that our automated system may be successfully used to induce changes in the physiological state of small birds.     

Lake sediments record sensitivity of two hydrologically closed upland lakes in Mexico to human impact

We provide evidence of rapid, recent environmental change in two lakes in the highlands of central Mexico. Multiple sediment cores were obtained from Lago de Zirahuén (Michoacán) and Laguna de Juanacatlán (Jalisco). Analysis of diatom assemblages, magnetic susceptibility, and metal concentrations was carried out, with the chronology provided by 210Pb dating, 14C dating, and tephrochronology. There is evidence of catchment disturbance during the colonial period in both basins, but the most striking feature at both sites is the rapid change in diatom assemblages during the last 20 y, indicating the onset of eutrophication. Limnological data from Lago de Zirahuén support this interpretation, although none are available from Laguna de Juanacatlán. Paleolimnology is a powerful tool in tracking recent change, particularly in the absence of regular limnological monitoring programs. These lakes appear to be highly sensitive to changes in catchment exploitation, which must be considered in future drainage basin management.     

The toxicity of titanium dioxide nanopowder to early life stages of the Japanese medaka (Oryzias latipes)

In this study, fertilized Japanese medaka (Oryzias latipes) embryos were exposed from fertilization to 5 d post-hatch using static non-renewal assays to aqueous suspensions of titanium dioxide nanoparticles (nTiO₂) ranging in nominal concentrations between 0 and 14 μg mL⁻¹. The average size of the nTiO₂ in the stock solution before addition to the test treatments was 87 nm (±14 nm). TiO₂ materials accumulated in a concentration dependent manner on the chorionic filaments of developing medaka embryos with evidence of pericardial edema occurring during embryo development. However, no significant (p > 0.05) increases in mortality relative to control treatments were observed for the nTiO₂ exposed embryos. A concentration dependent increase in cumulative percent hatch was observed at 11 d, indicating that exposure to increasing concentrations of nTiO₂ resulted in the premature hatch of medaka embryos. Post-hatch, a significant proportion of sac fry from the nTiO₂ exposure groups exhibited moribund swimming behavior and these individuals also experienced greater mortality at 15 d post-hatch. Combined, these results demonstrate that exposure to nTiO₂ can impact the development of early life stages of fish.