The costs of secondary sexual characters in the lekking great snipe (Gallinago media)

Summary Recent studies of the lekking great snipe (Gallinago media) have shown that male mating success increases with display rate and the amount of white on the tail. An obvious question then arises: what is setting the limits to male display rate and to the evolution of even whiter tails? In this study the costs of these two traits are considered. In the case of the white on the tail, almost no predation was observed during the display period. However, predation on the winter grounds and/or during migration cannot be ruled out. Males differed in the amount of white on the tail between years. It is suggested that increasing the amount of white is costly, though the reason for this is still unknown. In the case of display rate, it is shown that predation cannot be a considerable cost, again because of the near absence of predation on the leks. Instead, it is shown that male displays are energetically costly. The daily energy expenditure of displaying males was estimated to be on average 4 times the basal metabolic rate, which is close to the supposed maximum sustainable work load for birds. Furthermore, males lost on average 1.8 g per h (1.7% of the body mass) which is about 7.2 g (6.8%) during a night of display activity. Males do gain some weight during the day when no displays are performed but loose on average 9 g during an 11-day period in the early part of the breeding season. These results indicate that high energetic demands set the limits to male display performance and that males do not have to trade off the benefit of attracting females by their displays against a cost of attracting predators. Offprint requests to: J. Höglund     

Effect on fishes of two toxic polypeptides isolated from Anemonia sulcata

The effects of two toxic polypeptides isolated from Anemonia sulcata Pennant (Anthozoa) were tested on Gadus morhua, Pleuronectes platess and Platichthys flesus. In tramuscular injections caused paralysis and death, with symptoms similar to those of death caused by lack of oxygen. In cod, the LD₅₀ dose of Toxin II was 50 times higher chan that of Toxin I (Toxin I=6.9 mg/kg, Toxin II=0.14 mg/kg). Flatfish were less sensitive. The LD₅₀ of Toxin II was 0.37 mg/kg for Platichthys flesus and 0.38 mg/kg for Pleuronectes platessa. Both toxins are less lethal to fishes than to crustaceans.     

Influence of dead coral substrate morphology on patterns of juvenile coral distribution

This study examines the abundances of three morphological categories of juvenile corals (massive, branching and encrusting) on two different types of natural substratum, dead massive and dead branching corals. The overall results show that the morphological characteristics of dead coral substratum have a significant influence on the coral recruitment patterns with respect to the morphology of the recruits: juvenile corals of massive and branching types were more abundant on substrates of corresponding morphology. The results obtained from this study suggest that dead coral might attract coral larvae that are morphologically similar. On the other hand, it may be the result of post-settlement mortality. Whatever the mechanism shaping the patterns is, it seems that the physical morphology of the dead coral substrate has a significant influence on the coral recruit assemblage. Hence, we suggest that substrate morphology can be an important qualitative factor for coral settlement and a possible determinant of community structure.     

Low aggression levels and unbiased sex ratios in a prey-rich environment: no evidence of siblicide in Ngorongoro spotted hyenas (<Emphasis Type="Italic">Crocuta crocuta</Emphasis>)

Avian models of facultative siblicide predict that rates of sibling aggression and the incidence of siblicide should be lower in prey-rich than prey-poor environments, and that siblicide should only occur when fitness benefits outweigh costs. We tested these predictions by comparing data from spotted hyena (Crocuta crocuta) twin litters in the Ngorongoro Crater, Tanzania, a habitat with a high density of resident prey (176 animals/km²) with similar data from the adjacent Serengeti National Park where density of resident prey is low (3.3 animals/km²). As predicted, rates of sibling aggression in Crater twin litters were substantially lower than those among twin siblings in the Serengeti. There was no evidence of siblicide in the Crater, in contrast to the Serengeti, where facultative siblicide occurs frequently. The growth rate of Crater cubs in singleton litters was similar to that of cubs in twin litters, whereas the growth rate of Serengeti singletons was higher than that of cubs in twin litters. Thus despotic behavior by dominant Crater cubs was unlikely to provide fitness benefits, while dominant Serengeti cubs that eliminated their sibling benefited from increased growth and enhanced survival. Previous studies have demonstrated biases in the sex-composition of hyena litters due to facultative siblicide. No such biases were apparent in Crater litters. Our results provide strong evidence that levels of sibling aggression in spotted hyenas are adjusted in an adaptive manner, and that siblicide is facultative and resource dependent. Our results do not support the idea of pre-natal manipulation of offspring sex by female spotted hyenas in response to changes in resource abundance.     

Genetic population structure and sociogenetic organisation in Formica truncorum (Hymenoptera; Formicidae)

Summary The genetic population structure and the sociogenetic organization of the red wood ant Formica truncorum were compared in two populations with monogynous colonies and two populations with polygynous colonies. The genetic population structure was analysed by measuring allele frequency differences among local subsets of the main study populations. The analysis of sociogenetic organisation included estimates of nestmate queen and nestmate worker relatedness, effective number of queens, effective number of matings per queen, relatedness among male mates of nestmate queens and relatedness between queens and their male mates. The monogynous populations showed no differentiation between subpopulations, whereas there were significant allele frequency differences among the subpopulations in the polygynous population. Workers, queens and males showed the same genetical population structure. The relatedness among nestmate workers and among nestmate queens was identical in the polygynous societies. In three of the four populations there was a significant heterozygote excess among queens. The queens were related to their male mates in the polygynous population analysed, but not in the monogynous ones. The data suggest limited dispersal and partial intranidal mating in the populations with polygynous colonies and outbreeding in the populations having monogynous colonies. Polyandry was common in both population types; about 50% of the females had mated at least twice. The males contributed unequally to the progeny, one male fathering on average 75% of the offspring with double mating and 45–80% with three or more matings. Correspondence to: L. Sundström     

Measurement of movement patterns of Caenorhabditis elegans (Nematoda) with the Multispecies Freshwater Biomonitor (MFB)--a potential new method to study a behavioral toxicity parameter of nematodes in sediments

The nematode Caenorhabditis elegans receives increasing attention in sediment ecotoxicology and new toxicity tests with sensitive test parameters are under development. In this study, the motility of C. elegans could be measured for the first time online in sediment, using the Multispecies Freshwater Biomonitor. Whereas single nematodes could not be recorded, groups of 10 nematodes gave typical locomotive signals in different media (water, agar, sediment) with comparable precision and accuracy. The results of this study encourage to develop a new rapid online whole-sediment toxicity test with behaviour as sensitive test parameter.     

Enhanced growth and reproduction of Caenorhabditis elegans (Nematoda) in the presence of 4-nonylphenol

The nematode Caenorhabditis elegans was exposed over a whole fife-cycle (72 h) to several concentrations of 4-nonylphenol (NP; nominal concentrations: 0-350 microg/l). Growth and reproduction of C. elegans were enhanced at NP concentrations of 66 and 40 microg/l, respectively, with effects showing dose-response relationships. These stimulatory effects might be of ecological relevance in benthic habitats, where organisms can be exposed to high concentrations of NP.     

Natural pollution caused by the extremely acidic crater lake Kawah Ijen, East Java, Indonesia

Background. Aims and Scope Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH 〈 0.3. It is the source of the extremely acid and metal-polluted river Banyupahit (45 km). The lake has a significant impact on the river ecosystem as well as on a densely populated area downstream, where agricultural fields are irrigated with water with a pH between 2.5 and 3.5. The chemistry of the river water seemed to have changed over the past decade and the negative effect in the irrigation area increased. A multidisciplinary approach was used to investigate the altered situation and to get insight in the water chemistry and the hydrological processes influencing these alterations. Moreover, a first investigation of the effects of the low pH on ecosystem health and human health was performed. Methods Water samples were taken at different sites along the river and in the irrigation area. Sampling for macroinvertebrates was performed at the same sites. Samples of soil and crop were taken in the irrigation area. All samples were analysed for metals (using ICP-AES) and other elements, and concentrations were compared to local and international standards. Results and Discussion The river carries a very high load of SO4, NH4, PO4, Cl, F, Fe, Cu, Pb, Zn, Al and other potentially toxic elements. Precipitation and discharge data over the period of 1980 – 2000 clearly show that the precipitation on the Ijen plateau influences water chemistry of the downstream river. Metal concentrations in the river water exceed the concentrations mentioned in Indonesian and international quality guidelines, even in the downstream river and the irrigation area. Some metal concentrations are extremely high, especially iron (up to 1600 mg/l) and aluminium (up to 3000 mg/l). The food-webs in the acidic parts of the river are highly underdeveloped. No invertebrates were present in the extremely acid water and, at pH 2.3, only chironomids were found. This also holds true for the river water with pH 3.3 in the downstream area. Agricultural soils in the irrigation area have a pH of 3.9 compared to a pH of 7.0 for soils irrigated with neutral water. Decreased yields of cultivated crops are probably caused by the use of Al containing acid irrigation water. Increased levels of metals (especially Cd, Co, Ni and Mn) are found in different foodstuffs, but still remain within acceptable ranges. Considering local residents” diets, Cd levels may lead to an increased risk for the human health. Fluoride exposure is of highest concern, with levels in drinking water exceeding guideline values and a lot of local residents suffering from dental fluorosis. Conclusions, Recommendations and Outlook In short, our data indicate that the Ijen crater lake presents a serious threat to the environment as well as human health and agricultural production.     

The environmental occurrence of hexabromocyclododecane in Sweden

The brominated flame retardant hexabromocyclododecane (HBCD) is extensively used in Europe, but data on the environmental concentrations of this chemical are scarce. A first screening has been performed concerning the environmental occurrence of HBCD in Sweden, a country where the chemical is not produced and the current industrial use is very limited. Possible emission sources were identified through a systematic analysis of the use in a life cycle perspective. In addition to a few point sources, diffuse emissions from polymeric products are possible. Measurements have been performed close to certain possible point sources, in the urban environment and in remote regions, and included air, deposition, water, soil, sediments, sludge, biota and foodstuffs. HBCD was detected in all media analysed and in all environments. The relatively high concentrations detected in herring and foodstuffs provide evidence for bioaccumulation of HBCD. The presence of HBCD in remote background air implies that HBCD has potential for long-range atmospheric transport. There are also some indications that diffuse emissions of HBCD occur in the urban environment.