Gross solids from combined sewers in dry weather and storms, elucidating production, storage and social factors

Variation in rates of sanitary hygiene products, toilet tissue and faeces occurring in sewers are presented for dry and wet weather from three steep upstream urban catchments with different economic, age and ethnic profiles. Results show, for example, that total daily solids per capita from the low income and ageing populations are almost twice that from high income or ethnic populations. Relative differences are verified through independent questionnaires. The relationship between solids stored in sewers prior to storms, antecedent dry weather period and the proportion of roof to total catchment area is quantified. A full solids' flush occurs when storm flows exceed three times the peak dry weather flow. The data presented will assist urban drainage designers in managing pollution caused by the discharge of sewage solids

Plasma levels of gonadotropin and 17 alpha 20 beta dihydroxy-4-pregnen-5one in relation to spawning behaviour of rainbow trout (Oncorhynchus mykiss)

Manipulation of the opportunity to spawn was used to investigate the relationship between endocrine events, egg viability and spawning behaviour in female rainbow trout. Females were prevented from spawning by isolating them from males and gravel for up to 21 days after ovula- tion. Blood samples were taken before pairing with a male, at the onset of nesting activity, and at the completion of spawning. Plasma hormone levels of gonadotropin (GtH) and 17α,20β-dihydroxy-4-pregnen-3-one (17,20P) were measured by specific radioimmunoassays. There were no qualitative or quantitative differences in the spawning behaviour of females paired on the day of ovulation or 7. 14, or 21 days after ovulation. There was a general decrease in the viability of eggs with increasing retention times. In females paired on the day of ovulation, or after 7 or 14 days, GtH levels increased with the onset of nesting behaviour and declined as fish reached the post-spawning condition. By day 21, GtH levels before pairing were significantly higher than prepairing levels in the other three treatment groups, and did not increase at the onset of nesting, or decrease in post-spawning fish. Plasma 17,20P remained high in prepairing and nesting samples of all four groups and declined to low levels in fish in post-spawning condition. In females paired on the day of ovulation there was a significant increase in 17,20P from the prepairing to the nesting stage. These results suggest that 1,20P plays a key role in the synchronization of behavioural and maturational events at the time of spawning

Social organisation and competition for refuges and nest sites in Coryphopterus nicholsii

The ability of larger males to control resources and monopolise spawnings is thought to explain the benefits of protogyny in some animals. Here we describe the breeding and non-breeding social organisations of a temperate protogynous goby, Coryphopterus nicholsii, in the light of this prediction. Our results confirm that C. nicholsii has a stable social organisation, based on the year-round defence of a territory by both females and males. As predicted, larger individuals of both sexes were more likely to defend territories than smaller ones. These territories always included one or more shelter rocks, which were used as refuges by both sexes throughout the year, and also as nest sites by males in the breeding season. We then use experimental manipulation of shelter rock availability to examine the influence of intraspecific competition on territory establishment by smaller males. Following the removal of resident, non-nesting males, territories were quickly taken over. In addition, artificial reefs and nest sites were quickly colonised. Therefore, it appears that suitable shelter rocks are limited. Furthermore, intraspecific competition is strongly size-specific in C. nicholsii and determines which individuals gain access to shelter rocks. The presence of these social conditions is consistent with the prediction that the ability of larger males to monopolise more than one mate affects the occurrence of protogyny in some animals, and may clarify the occurrence of protogyny in C. nicholsii

Endocrine changes associated with spawning behavior and social stimuli in a wild population of rainbow trout (Salmo gairdneri). II. Females

Rainbow trout (Salmo gairdneri) were collected from a natural spawning population at Pennask Lake, B.C. Blood samples taken from female trout at different stages of spawning were assayed by radioimmunoassay for gonadotropin (GtH), estradiol-17 beta (E2), androgens, including testosterone (T), and 17α-hydroxy-20 β-dihydroprogesterone (17,20-P). Plasma levels of androgen and estradiol were highest in females sampled shortly before ovulation (ogreeno females) and declined in ovulated and sexually active females, reaching lowest levels in postspawning fish. Concentrations of 17,20-P rose markedly in ovulated females allowed to dig nests and interact with sexually active males. Plasma GtH levels were similar in green unovulated females and ovulated fish prevented from spawning, but showed a marked increase in actively nest building ovulated fish. The results demonstrate that social stimuli affect plasma levels of 17,20-P and perhaps GtH. The functional significance of the endocrine responses to social factors is not clear, but it is suggested that increased hormone levels may contribute to an acceleration or synchronization of breeding, or be responsible for causing and maintaining more vigorous sexual activity

Gametic isolation in guppies (Poecilia reticulata)

Post-mating reproductive isolating mechanisms may be among the earliest reproductive barriers to emerge among incipient species. Trinidadian guppy, Poecilia reticulata, populations in the Caroni and Oropouche drainages in Northern Trinidad exhibit marked genetic divergence and provide an ideal system in which to search for these barriers. We inseminated virgin females with equal amounts of sperm from two males, a ‘native’ male from the female's own population and a ‘foreign’ male from the other drainage. Artificial insemination ensured that mating order and mate choice did not affect the outcome. Paternities were assigned to the resulting broods using microsatellite markers. As predicted, sperm from native males had precedence over foreign sperm. Moreover, this effect was symmetrical for both drainages. In contrast, we detected no native sperm precedence in controls, in which females received sperm from the same and another population within the same drainage. Our results show that gametic isolation can arise between geographically proximate, though genetically divergent, populations of a single species and highlight the potential role of this process in speciation

Endocrine changes associated with spawning behavior and social stimuli in a wild population of rainbow trout (Salmo Gairdneri). I. Males.

Rainbow trout (Salmo gairdneri) were collected from a natural spawning population at Pennask Lake, B.C. Blood samples were taken from male trout at different stages of spawning and assayed by radioimmunoassay for gonadotropin (GtH), testosterone (T), 11-ketotestosterone (11-KT), and 17α-hydroxy-20β-dihydroprogesterone (17,20-P). Testosterone and 11-KT were detected in the plasma of males in spawning condition: 11-KT was at a higher concentration than T and declined to undetectable levels in postspawning fish. There were striking increases in plasma GtH and 17,20-P in males actively courting nest building females. The increase in 17,20-P was evidently not dependent upon an elevation of the pituitary hormone: 17,20-P remained low in males placed with sexually inactive, unovulated females even though GtH levels rose above levels measured in males isolated from females. The significance of the social control of hormone levels is not clear. There is some evidence that 17,20-P and/or GtH may cause an increase in quantity of the milt, and thus the endocrine response to a sexually active female may serve to synchronize maximum male fertility with oviposition readiness in the female

Social organisation and competition for refuges and nest sites in Coryphopterus nicholsii

The ability of larger males to control resources and monopolise spawnings is thought to explain the benefits of protogyny in some animals. Here we describe the breeding and non-breeding social organisations of a temperate protogynous goby, Coryphopterus nicholsii, in the light of this prediction. Our results confirm that C. nicholsii has a stable social organisation, based on the year-round defence of a territory by both females and males. As predicted, larger individuals of both sexes were more likely to defend territories than smaller ones. These territories always included one or more shelter rocks, which were used as refuges by both sexes throughout the year, and also as nest sites by males in the breeding season. We then use experimental manipulation of shelter rock availability to examine the influence of intraspecific competition on territory establishment by smaller males. Following the removal of resident, non-nesting males, territories were quickly taken over. In addition, artificial reefs and nest sites were quickly colonised. Therefore, it appears that suitable shelter rocks are limited. Furthermore, intraspecific competition is strongly size-specific in C. nicholsii and determines which individuals gain access to shelter rocks. The presence of these social conditions is consistent with the prediction that the ability of larger males to monopolise more than one mate affects the occurrence of protogyny in some animals, and may clarify the occurrence of protogyny in C. nicholsii