Can Myxosporean parasites compromise fish and amphibian reproduction?

Research into fish and amphibian reproduction has increased exponentially in recent years owing to the expansion of the aquaculture industry, the need to recover fishery populations, the impact of endocrine disruptors on the aquatic environment and the global decline of amphibian populations. This review focuses on a group of parasites, the Myxozoa, that affect fish and amphibian reproduction. Lists of the myxosporeans that specifically infect gonads are provided. Most of these are parasitic of freshwater hosts, and most amphibian cases are reported from testes. Sex specificity and sex reversal are discussed in relation to gonadal parasitism. The immune response of the fish to the infection is described, and the contribution of the immunoprivilege of gonads to host invasion is emphasized. The pathological effect of these parasites can be significant, especially in aquacultured broodstocks, on some occasions, leading to parasitic castration. Although myxosporean parasites are currently not very frequent in gonads, their impact could increase in the future owing to the transactions in the global market. Their easy release into the aquatic environment with spawning could make their spreading even more feasible. In the absence of commercial drugs or vaccines to treat and prevent these infections, there is an urgent need to develop specific, rapid and reliable diagnostic tools to control and manage animal movements. In addition, much effort is still to be made on deciphering the life cycle of these organisms, their invasion strategies and their immune evasion mechanisms

The influence of ants on soil and water losses from an orange orchard in eastern Spain

Herbicide applications have greatly reduced plant cover, and increased soil erosion on a new orange orchard planted on valley slopes in eastern Spain. This has increased the importance of soil fauna, such as ants, in regulating soil erosion processes. Ants increase water infiltration rates by forming soil macropores during nest construction, but new soil brought to the surface by ant activity could increase the sediments available for erosion. Simulated rainfall experiments were conducted on 20 paired plots (20 with ant activity and 20 controls) to study the impact of ants on surface water flow and sediment movement in an intensively managed orange orchard near Valencia, Spain. Simulated rainfall was applied to each plot at a rate of 55 mm/h on a 0.25 m2 area for 1 h. We found a reduction of soil bulk density, an increase in soil organic matter, and an increase in macropore flow in ant-affected soils, as compared to soil without ant activity. These ant-induced soil changes increased water infiltration rates and runoff discharge. However, the fresh, unconsolidated soil brought to the surface during nest construction resulted in greater soil loss on two plots than their ant-free controls. Ants can be an important factor in soil erosion processes when surface vegetation is removed by intensive herbicide use. © 2008 The Authors

THE ROAD TO CIVIL WAR: AN INTERACTIVE THEORY OF INTERNAL POLITICAL VIOLENCE

Opportunity structure theories of civil war onset argue that certain societal preconditions lower the costs of rebel mobilization. This approach, however, has not provided an account of how these structures transform lower level political violence into civil war because civil war is treated as a conceptually distinct category of violence. This paper proposes an internal theory of political violence based on the interactions of regimes and challengers. The escalation and de-escalation of political violence is viewed as the product of comparative rates of adaptation. Equal rates of adaptation produce civil war, while unequal rates, termination.Civil war, Internal conflict, Conflict escalation, Conflict resolution,