Preliminary overview of exotic and invasive marine species in the Dutch Caribbean

The marine exotic species of the Dutch Caribbean are less well-known than its terrestrial exotics. So far, only 27 known or suspected marine exotic species, some of which are also invasive are documented for one or more islands of the Dutch Caribbean. Four of these were documented only once or were only present for a certain period of time and are no longer present. Six of the species are marine epidemic diseases. As very little is known about these diseases, they might actually be native, but based on the literature and their ecological signature we regard them as special cases of invasive species. In addition to these documented species, 76 other exotic species that have already been observed elsewhere in the Caribbean may already be present or can be expected to arrive in the Dutch Caribbean in the near future. The marine communities of the Dutch Caribbean have suffered major changes based on a handful of marine exotic and/or invasive species, particularly in the special case of (opportunistic) pathogens. In certain cases experience shows that after decades, the affected systems/species may show slow signs of recovery from initial impacts (e.g. the green turtle fibropapillomas), while in other cases the impact may be long-lasting and recovery doubtful (e.g. sea fan mortality). Compared to terrestrial exotic species, eradication and control have been proven difficult or impossible for marine exotics. Therefore, management practices aimed at controlling unwanted species introductions should focus on preventing the arrival of such species by ships-- that transport exotics in their ballast water or as fouling communities on their hulls-- and (accidental) introductions from aquaculture or the aquarium trade. Busy harbors can be expected to be the areas where most marine exotics likely establish first. Because of dispersal of marine exotics is facilitated by ocean currents, local approaches to prevent their arrival or reduce their numbers will be less effective compared to similar efforts for terrestrial species. In the case of marine exotics and invasives, it is paramount that prevention, control and management efforts should be regionally integrated. We conclude this report by listing a number recommendations on how to develop effective management approaches with which to address the impacts and risks associated with marine exotic species. This research is part of the Wageningen University BO research program (BO-11-011.05-004) and has been financed by the Ministry of Economic Affairs, Agriculture and Innovation (EL&I) under project number 4308202004

KWIN nu ook als app

KWIN, Kwantitatieve Informatie Veehouderij, verscheen de afgelopen 25 jaar als lijvig handboek, zowel op papier als digitaal. Dit najaar is daar een serie apps bij gekomen, waarmee adviseurs en veehouders zelf saldo- en kostprijsberekeningen kunnen maken. De apps zijn beschikbaar voor de pluimvee-, varkens- en rundveehouderij

Elephants can determine ethnicity, gender, and age from acoustic cues in human voices

Animals can accrue direct fitness benefits by accurately classifying predatory threat according to the species of predator and the magnitude of risk associated with an encounter. Human predators present a particularly interesting cognitive challenge, as it is typically the case that different human subgroups pose radically different levels of danger to animals living around them. Although a number of prey species have proved able to discriminate between certain human categories on the basis of visual and olfactory cues, vocalizations potentially provide a much richer source of information. We now use controlled playback experiments to investigate whether family groups of free-ranging African elephants (Loxodonta africana) in Amboseli National Park, Kenya can use acoustic characteristics of speech to make functionally relevant distinctions between human subcategories differing not only in ethnicity but also in sex and age. Our results demonstrate that elephants can reliably discriminate between two different ethnic groups that differ in the level of threat they represent, significantly increasing their probability of defensive bunching and investigative smelling following playbacks of Maasai voices. Moreover, these responses were specific to the sex and age of Maasai presented, with the voices of Maasai women and boys, subcategories that would generally pose little threat, significantly less likely to produce these behavioral responses. Considering the long history and often pervasive predatory threat associated with humans across the globe, it is likely that abilities to precisely identify dangerous subcategories of humans on the basis of subtle voice characteristics could have been selected for in other cognitively advanced animal species

Revisiting the martensite/ferrite interface damage initiation mechanism:The key role of substructure boundary sliding

Martensite/ferrite (M/F) interface damage plays a critical role in controlling failure of dual-phase (DP) steels and is commonly understood to originate from the large phase contrast between martensite and ferrite. This however conflicts with a few, recent observations, showing that considerable M/F interface damage initiation is often accompanied by apparent martensite island plasticity and weak M/F strain partitioning. In fact, martensite has a complex hierarchical structure which induces a strongly heterogeneous and orientation-dependent plastic response. Depending on the local stress state, (lath) martensite is presumed to be hard to deform based on common understanding. However, when favourably oriented, substructure boundary sliding can be triggered at a resolved shear stress which is comparable to that of ferrite. Moreover, careful measurements of the M/F interface structure indicate the occurrence of sharp martensite wedges protruding into the ferrite and clear steps in correspondence with lath boundaries, constituting a jagged M/F interfacial morphology that may have a large effect on the M/F interface behaviour. By taking into account the substructure and morphology features, which are usually overlooked in the literature, this contribution re-examines the M/F interface damage initiation mechanism. A systematic study is performed, which accounts for different loading conditions, phase contrasts, residual stresses/strains resulting from the preceding martensitic phase transformation, as well as the possible M/F interfacial morphologies. Crystal plasticity simulations are conducted to include inter-lath retained austenite (RA) films enabling the substructure boundary sliding. The results show that the substructure boundary sliding, which is the most favourable plastic deformation mode of lath martensite, can trigger M/F interface damage and hence control the failure behaviour of DP steels. The present finding may change the way in which M/F interface damage initiation is understood as a critical failure mechanism in DP steels

Toekomst intensieve veehouderij in Zuid-Holland

De intensieve veehouderij in Zuid-Holland is de afgelopen tien jaar gehalveerd. De Provinciale Staten willen de intensieve veehouderij in Zuid- Holland te convergeren naar een diervriendelijke, duurzame en meer extensieve bedrijfsvoering. De provincie kan zich hiervoor richten op veehouderijsystemen die voldoe