Effects of temperature,size, and food on the growth of <Emphasis Type="Italic">Membranipora membranacea</Emphasis> in laboratory and field studies

In the rocky subtidal ecosystem of the western North Atlantic outbreaks of the introduced epiphytic bryozoan Membranipora membranacea cause defoliation of kelp beds and facilitate the introduction of other non-native benthic species. We quantified size- and temperature-dependent growth rates of M. membranacea colonies in the field and the laboratory for durations of 8–23 days. Also, we examined the interaction between food abundance and temperature on growth rates of newly settled colonies in the laboratory. Growth rates were positively related to temperature and increased exponentially with size of colonies over the ranges examined (5.7–16.2°C and 0.5–192 mm, respectively), and were significantly higher in the field than in the laboratory. There was an interactive effect between food and temperature on the size and growth rates of colonies, with the most pronounced effects of food limitation on colonies grown at the warmest temperatures, and no effect of food on colonies grown at the coldest temperatures. Quantifying the growth rates of introduced species is essential to understanding their population dynamics, particularly when outbreaks can have severe impacts on the native community.     

Sexual conflict in a polygynous primate: costs and benefits of a male-imposed mating system

Fundamental reproductive interests dictate that females generally benefit most from mate selectivity and males from mate quantity. This can create conflict between the sexes and result in sexual coercion: male use of aggression to garner mating success at a cost to females. Potential fitness costs of sexual coercion, however, can be difficult to measure. Here, we demonstrate benefits to males and costs to females of female defense polygyny in wild hamadryas baboons, cercopithecoid primates in which females are coercively transferred among social units by males, restricting both female choice and bonding among female kin. Of all coercive transfers (takeovers) of females with young infants, 67 % were followed by infant mortality, which was significantly more likely to occur after takeovers than at other times. As expected, infant mortality decreased time to subsequent conception but lengthened intervals between surviving infants. Following infant survival, whether a female had experienced a takeover after the previous birth was a significant predictor of subsequent interbirth interval, with interbirth intervals of females remaining with the same male between births being significantly shorter than those of females incurring takeovers between births. Together, these results reveal that takeovers increase the chance of infant mortality while delaying subsequent conception. Male-driven female defense polygyny in this species is thus costly to females in two ways. These results demonstrate that reproductive strategies benefitting males can evolve despite substantial costs to females. These costs may be mitigated over the long term, however, by female counterstrategies and protective behavior by males.     

Environmental public health tracking: piloting methods for surveillance of environmentally related diseases in England and Wales

An effective environmental public health tracking system integrates data and intelligence on environmental hazards, exposures, and health outcomes to focus interventions on reducing the impact of environmental contamination on public health. Most work in this area in the UK has focused on assessing data on hazards that are relatively easy to obtain. However, most hazards will present no actual risk and information on exposure is required to make an effective risk assessment. Obtaining exposure data is technically challenging, expensive, and potentially raises ethical concerns. Consequently, the Health Protection Agency is exploring methods for targeting geographical zones for efficient detailed environmental assessment (including exposure assessment). This paper describes and assesses three methods (indirect standardization, statistical process control (SPC) and kernel density contouring) for the surveillance of potentially environmentally related diseases for this purpose. While the evaluation demonstrates the utility of the three methods, particularly SPC, the comparison was limited due to ethical approval issues.