Reduced peroxisomal import triggers peroxisomal retrograde signaling

1. Download : Download high-res image (184KB)
2. Download : Download full-size image

     

Biological invasions and eutrophication reshape the spatial patterns of stream fish size spectra in France

Aim

The global patterns of body size distributions are affected by global environmental changes (GEC), but our knowledge of the interaction effects between GEC and natural drivers is still limited. In this study, we aimed to test the effects of these interactions on fish community size spectra, that is, the variation in a community property across the body size range of individuals in the community.

Location

One thousand and ninety-five stream locations across France between 2015 and 2018.

Methods

We fitted size spectrum slopes for each fish community based on individual biomass size and using binning and maximum-likelihood methods through regression models across size classes and negative log-likelihood functions, respectively. Interactions between natural drivers and GEC were tested using model-averaging and the best models were selected with information criterion.

Results

Our results demonstrated that size spectra were steeper (i.e. higher proportion of small-bodied individuals) in warmer than colder locations, as expected by temperature-size rules. However, eutrophication (total phosphorus concentration) and biological invasions (percentage of non-native individuals) modulated the effect of temperature, with flatter size spectrum slopes in streams with more nutrients and higher proportion of non-native individuals. In addition, fish size spectrum slopes were generally steeper in upstream than in downstream locations, and this effect was more pronounced in stream locations with more nutrients. Finally, size spectrum slopes were flatter in species-rich communities when nutrient concentration was high.

Main Conclusions

Our study highlights that accounting for GEC, such as eutrophication and biological invasions, can help understanding the complex patterns of fish body size distributions in ecological communities.     

Weasel (<Emphasis Type="Italic">Mustela nivalis</Emphasis>) decline in NE Spain: prey or land use change?

In this note, we reported the decline of weasel populations in NE Spain between the end of the last century and present. Our results suggested a delayed numerical response of weasels to wood mice abundance during the first study period (1995–1998), but no response at all in the second and longer period (2008–2015). Small mammals’ outbreaks triggered weasel’ populations in the first period, but they did not in the second period. Other factors may be invoked to explain the recent lack of numerical responses of weasels to mice. Population declines of small mammals have been noted in the study area in recent years, whereas an increase of casual predation records of weasels by generalist raptors has been documented. Both trends seemed to be related to the effects of the process of natural afforestation experienced by Mediterranean areas due to land abandonment. Top-down increased predation may add to bottom-up decreasing prey availability to explain current weasel declines.     

The response of fish size and species diversity to environmental gradients in two Neotropical coastal streams

Hydrobiologia - This study investigated the effects of environmental variation on fish diversity patterns in two coastal streams in northwestern Ecuador. Specifically, we examined the role of...