The Breeding Ecology Of Pink Salmon (oncorhynchus Gorbuscha Walbaum) From The Carp River, Eastern Lake Superior

Although inadvertently introduced to North American\u27s Laurentian Great Lakes, pink salmon (Oncorhynchus gorbuscha) now constitute the world\u27s only self-perpetuating freshwater population of this species. Their proliferation and growing impact on the extant fish fauna are elevating the species to one of considerable importance here. Despite this, the reproductive ecology of Great Lakes populations remains largely unknown. This study of the pink salmon breeding in the Carp River, a tributary to eastern Lake Superior, is a response to the need for this information. Considered are their upstream migration patterns, fish size and condition variation, migrant reproductive maturity and gonadal investment, male spawning performance, the determinants of male and female length of breeding life, rates of carcass recovery, and the wandering of spawners to other streams. Contrasts between Carp River and anadromous populations and between even- and odd-year runs into the same study stream are also emphasized.;Plasticity in the life histories of salmonid species is associated with the occurrence of alternative male breeding patterns. Because pink salmon display essentially invariable life histories, they seem unlikely to demonstrate similar breeding pattern diversity. Nonetheless, in behaviour studies some Carp River males were seen to participate in spawnings by attempting to sneak fertilizations rather than by competing for access to females in characteristic salmonid fashion. These same individuals also resembled females in shape. Such behaviour was seen only at high spawner densities when single large males were apparently unable to monopolize nesting females. Consistent with these observations, morphological studies confirmed the occurrence of males which in shape resembled females more than did other males. Secondary sexual character development (hump size) was reduced in these individuals, likely as a result of their reduced condition. These female-like males did not differ from typical males in age, level of maturity, investment of biomass in testis, or length of breeding life. Thus, the occurrence of an alternative male breeding pattern in this population is interpreted as being a facultative response by males to reduced competitive ability

Plant capitalism and company science: the Indian career of Nathaniel Wallich

The career of the Danish-born botanist Nathaniel Wallich, superintendent of the Calcutta Botanic Garden from 1815 to 1846, illustrates the complex nature of botanical science under the East India Company and shows how the plant life of South Asia was used as a capital resource both in the service of the Company's economic interests and for Wallich's own professional advancement and international reputation. Rather than seeing him as a pioneer of modern forest conservation or an innovative botanist, Wallich's attachment to the ideology of ‘improvement’ and the Company's material needs better explain his longevity as superintendent of the Calcutta garden. Although aspects of Wallich's career and botanical works show the importance of circulation between Europe and India, more significant was the hierarchy of knowledge in which indigenous plant lore and illustrative skill were subordinated to Western science and in which colonial science frequently lagged behind that of the metropolis

In ovo exposure to o,p -DDE affects sexual development but not sexual differentiation in Japanese medaka (Oryzias latipes).

Despite being banned in many countries, dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) continue to be found in fish tissues at concentrations of concern. Like o,p -DDT, o,p -DDE is estrogenic and is believed to exert its effects through binding to the estrogen receptor. The limited toxicologic data for o,p -DDE suggest that it decreases fecundity and fertility of fishes. We conducted an egg injection study using the d-rR strain of medaka and environmentally relevant concentrations of o,p -DDE to examine its effects on sexual differentiation and development. The gonads of exposed fish showed no evidence of sex reversal or intersex. However, other gonad abnormalities occurred in exposed individuals. Females exhibited few vitellogenic oocytes and increased atresia. Male testes appeared morphologically normal but were very small. Gonadosomatic index values for both sexes were lower for exposed fish. Our observations of abnormal female and very small male gonads after in ovo o,p -DDE exposure may be indicative of effects on early endocrine processes important for normal ovarian and testicular development