When to pay the cost of reproduction? A brood size manipulation experiment in great tits (<Emphasis Type="Italic">Parus major</Emphasis>)

Parental investment (PI) theory assumes that optimal parental investment is a function of expected cost/benefit ratio of current versus future reproduction. This study tests the prediction of PI theory that in a species with high adult mortality, paying of reproductive costs can be induced or prevented by manipulation of brood reproductive value (RV). Analysis of recruitment rates in a 10-year study of great tits (Parus major) showed that brood RV was affected by both fledgling number and quality (body mass and tarsus length). A 4-year brood size manipulation experiment (±2 hatchlings) resulted in reduction of fledgling quality in enlarged versus control and reduced broods, while the fledgling number did not differ between manipulation categories due to increase of nestling mortality with brood size manipulation score. Hence, the experiment resulted in reduction of brood RVs in enlarged broods. Females rearing enlarged broods survived better than those with control and reduced broods, while male survival was not affected by the experiment. This indicates that paying the survival costs for reproduction was a part of normal life history for studied female great tits, and that decisions whether to pay this cost were based on the estimation of brood RV. Recruitment rate was lowest (but extremely male-biased) in reduced broods, while control and increased broods did not differ in the number of locally recaptured offspring.     

To what extent does upright sessile epifauna affect benthic biodiversity and community composition?

Small-scale habitat complexity, including that caused by biological structures, is an important factor in structuring benthic communities and also sometimes in increasing biodiversity. The aim of this study was to determine if hydroid colonies have an effect on the composition of benthic communities in the Irish Sea, and if so, which components of the fauna are affected. Forty-six seabed core samples were taken by divers from two sites off Port Erin, Isle of Man, Irish Sea. Half of these were centred on hydroid colonies, half were not. All taxa retained by a 63-m sieve from the cores were identified and counted. Community composition and diversity were compared between hydroid and non-hydroid cores using multivariate and univariate methods. Benthic communities were significantly different between the two sample groups. This was almost entirely due to the presence of sessile and mobile epifaunal taxa in the hydroid cores. The tube-building amphipod, Ericthonius punctatus, was particularly abundant attached to the hydroid stems. Infauna was not significantly different between the two groups. Upright sessile epifauna may play a particularly important role in the Irish Sea as a settlement substrate for juvenile scallops (Pecten maximus and Aequipecten opercularis), which are an important fishery resource in this area. The 11-year closure of an area to dredging has not only enhanced scallop stocks but has had the added benefit of enhancing habitat complexity and biodiversity.Communicated by J.P. Thorpe, Port Erin     

Nutritional phagostimulants function as male courtship pheromone in the German cockroach, <Emphasis Type="Italic">Blattella germanica</Emphasis>

Summary. Males of the German cockroach, Blattella germanica, secrete a pheromonal substance from the abdominal tergal glands, which elicits a feeding response in females during the sequential courtship behavior. The nuptial secretion consists predominantly of a synergistic mixture of sugars and phospholipids. Cholesterol and a series of amino acids, which are also components of the males glandular secretion, significantly enhanced the phagostimulant activity of the sugar components. The nuptial feeding behavior of the female cockroach is therefore elicited by a complex assortment of nutritive components in the male tergal secretion, including sugars, phospholipids, cholesterol, and amino acids. These results indicate that a mixture of primary metabolites, and not of specific secondary metabolites, serves as a pheromonal cue that appeals to the females gustatory sense and effectively brings her to the precopulatory position. Although the male secretion consists of nutrients, we suggest that these compounds probably do not represent a significant nutrient investment in females and their progeny but rather function as a signal in the mating sequence of B. germanica.     

Geographical patterns in reproductive biology of the Pan-American sandy beach isopod<Emphasis Type="Italic"> Excirolana braziliensis</Emphasis>

Eleven populations of the Pan-American sandy beach isopod Excirolana braziliensis, distributed from tropical (9°N) to temperate (39°S) sandy beaches in Atlantic and Pacific Oceans, were analyzed to determine latitudinal variations in: breeding and recruitment patterns, sex ratios, size of ovigerous females and of juveniles and length–fecundity relationships. E. braziliensis exhibited strong latitudinal patterns in all reproductive traits throughout its distribution range. Breeding and recruitment shifted from continuous to seasonal from tropical to temperate beaches, having a predominance of females at higher latitudes. In agreement with the latitudinal gradient hypothesis, ovigerous females inhabiting tropical sandy beaches (low latitudes) were smaller, became sexually mature at smaller sizes and had lower individual fecundity than on temperate beaches. Juveniles were also smallest at low latitudes. Between-ocean comparisons showed very similar reproductive characteristics for roughly the same latitude. These linked reproductive parameters suggest that the intensity of breeding effort is associated with the duration of the breeding season and geographically size-related characteristics of the species. Geographic variations in the breeding and recruitment seasons, as well as in individual fecundity, size structure of mature females and sex ratios, are proposed to have major consequences in explaining local variations in population demography. Our paper also reinforces the notion that sandy beach animals are highly plastic.Communicated by O. Kinne, Oldendorf/Luhe     

Habitat selection in a coastal dolphin species (<Emphasis Type="Italic">Cephalorhynchus hectori</Emphasis>)

Hector's dolphin ( Cephalorhynchus hectori) is a small New Zealand delphinid with a coastal distribution. Within a strip of 1 km from shore, the present study quantified the habitat used by the dolphins ( n=461 groups) over a 19-month period (216 field days with 966 survey hours) by recording the abiotic factors sea surface temperature (SST), water depth and water clarity. Resource selection functions were used to distinguish the properties of 461 "used" sites (dolphins present) from 425 "unused" sites (no dolphins present) in six different study areas. Most dolphins were encountered in waters <39 m depth, with <4 m Secchi disk visibility and >14°C temperature. The preference of Hector's dolphins for warm and turbid waters was tested using eight models. Water depth, water clarity, SST and the study area explained dolphin presence to a very significant degree ( p<0.001), and the model allowed the creation of probability plots for a variety of combinations of the variables. Habitat selection by dolphins differed between study areas, particularly between east and west coasts, in summer (December–February) and winter (June–August). Dolphin abundance appeared to change seasonally in some study areas, possibly due to a more offshore distribution of their prey in the winter, with its lower SSTs. This was so especially in summer (the main reproductive season), when dolphins (frequently with calves) occupied shallow and turbid waters, whereas in winter less use was made of this habitat.     

Disinfection efficacy on cyst viability of<Emphasis Type="Italic"> Artemia franciscana</Emphasis> (Crustacea),<Emphasis Type="Italic"> Hexarthra fennica</Emphasis> (Rotifera) and<Emphasis Type="Italic"> Fabrea salina</Emphasis> (Ciliophora)

Resting stages (cysts) of Artemia franciscana, Hexarthra fennica and Fabrea salina were exposed for two periods (acute and chronic exposures) to different concentrations of five aquaculture disinfectants (formalin, sodium hypochlorite, potassium permanganate, organic iodine, copper sulphate). The effects of chemical treatments were ranked according to their action on cyst hatching: total inhibition (no cyst hatching), heavy inhibition (significant decrease of cyst hatching), alteration of hatching synchrony, and occurrence of anomalous hatching (death of emerging individuals or birth of malformed organisms). Resting-stage viability was not completely impaired by disinfectant exposures at the ordinary doses used in aquaculture, so that usual treatments are possibly ineffective against the protist and metazoan cysts potentially present in breeding systems. On the other hand, the high resistance shown by cysts suggests the possibility of using these chemicals in live-feed disinfection.     

官厅流域农田地表径流磷流失初探

农田径流和侵蚀泥沙是磷进入官厅水库的主要非点污染源。针对该流域夏季农田暴雨径流发生的典型情景进行模拟降雨径流试验，对该流域农田地表径流泥沙和磷流失进行了初步的研究，结果表明，本降雨过程径流累积泥沙产量为30．5l～2493．34g／m^2，受雨强、坡度和作物覆盖的影响明显；径流溶解态磷(DP)中绝大部分是生物可利用性磷(DRP)，径流平均DP、DRP浓度都远大于水体允许临界值0．02mg／L，对官厅水体存在直接污染危害。径流累积全磷(TP)流失达O．0439～2．0798g/m^2；估算的流域农田径流全磷(TP)流失水平达2．67kg／(hm^2．a)以上，其颗粒态占969，0以上，可能成为官厅水库浮游生物长期丰富的潜在可利用磷源。降低农田土壤速效磷水平、减少水土侵蚀，是控制库区水华季节性发生和复原库区水体富营养化状态的关键。     

Morphology of<Emphasis Type="Italic"> Ecklonia radiata</Emphasis> (Phaeophyta: Laminarales) along its geographic distribution in south-western Australia and Australasia

Ecklonia radiata (C. Ag.) J. Agardh is a common macroalga on reefs in the warm-temperate parts of the southern hemisphere. It is a dominant habitat-former and as such has a strong structuring effect on associated algal assemblages. Morphological variation in E. radiata potentially affects its interactions with the surroundings and contributes to confusion about its taxonomy. We quantified the magnitude of morphological variation in fully developed E. radiata sporophytes across Australasia and tested the hypotheses that E. radiata has different morphology at different locations and that the degree of morphological difference depends on spatial distances among locations. A total of 11 morphological characters were sampled from 11 locations along the Australian coastline from Kalbarri in Western Australia to Sydney in New South Wales as well as from Doubtful Sound, New Zealand. Most morphological characters varied considerably from one location to another. For example, the average (±SE) thallus length was 135.2±12.5 cm in Kalbarri and only 69.7±5.5 cm in Sydney. There were no consistent spatial patterns of variation among individual morphological characters, and, generally, variations among individual characters were poorly correlated (-0.5< R<0.5). This suggests that individual morphological characters develop independently of each other in response to processes operating at different spatial scales. Multivariate measures of morphology were found to be different among some locations and similar among others (-0.37=Clarke's  R=1), but there was no correlation (Spearman's R=0.08) between morphological similarity and distance between locations. Consequently, our results do not support clinal variation in E. radiata morphology. Rather, they suggest the presence of discrete morphologically different populations, in which the morphology at any one location reflects multiple forcing factors operating on different morphological characters at different spatial scales.     

Effects of fertilization and elevated CO<Subscript>2</Subscript> on larval food and butterfly nectar amino acid preference in<Emphasis Type="Italic"> Coenonympha pamphilus</Emphasis> L.

The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO ₂environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO ₂conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO ₂, but adult emergence weight was not affected by CO ₂treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO ₂. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding.     

Enzymatische Umsetzung von Arsenkampfstoffen durch das Pilzenzym Mangan-Peroxidase

Degradation of organo-arsenical chemical warfare agents by fungal enzyme manganese peroxidase. The fungal enzyme manganese peroxidase was used to degrade different organo-arsenical chemical warfare agents in cell-free reaction mixtures (in vitro). The decrease in the concentration of arsenical chemical warfare agents was determined by gas chromatography after derivatization with thiols. All organo-arsenical compounds tested were converted by room temperature for more than 90%. Aliphatic arsenical compounds were attacked more rapidly than aromatic derivatives.