Plankton response to weakening of the Iberian coastal upwelling

Coastal upwelling regions, which are affected by equatorward‐wind variability, are among the most productive areas of the oceans. It has been suggested that global warming will lead to a general strengthening of coastal upwelling, with important ecological implications and an impact on fisheries. However, in the case of the Iberian upwelling, the long‐term analysis of climatological variables described here reveals a weakening in coastal upwelling. This is linked to a decrease of zonal sea level pressure gradient, and correlated with an observed increase of sea surface temperature and North Atlantic Oscillation. Weakening of coastal upwelling has led to quantifiable modifications of the ecosystem. In outer shelf waters a drop in new production over the last 40 years is likely related to the reduction of sardine landings at local harbors. On the other hand, in inner shelf and Ria waters, the observed weakening of upwelling has slowed down the residual circulation that introduces nutrients to the euphotic layer, and has increased the stability of the water column. The drop in nutrient levels has been compensated by an increase of organic matter remineralization. The phytoplankton community has responded to those environmental trends with an increase in the percentage of dinoflagellates and Pseudonitzschia spp. and a reduction in total diatoms. The former favors the proliferation of harmful algal blooms and reduces the permitted harvesting period for the mussel aquaculture industry. The demise of the sardine fishery and the potential threat to the mussel culture could have serious socio‐economic consequences for the region.     

Plant stages with biotic,indirect defences are more palatable and suffer less herbivory than their undefended counterparts

Plants have evolved several anti‐herbivory strategies, including direct defences, such as mechanical and chemical defences, and indirect or biotic defences, such as the recruitment of defending animals. We examined whether the investment plants make in direct defences differs between those which do and do not invest in biotic defences, by comparing standing herbivory and palatability of congeneric species with and without indirect defences at two ontogenetic stages: before and after the onset of indirect defences. We used Cordia alliodora and Croton suberosus as the species with indirect defences and Cordia elaeagnoides and Croton pseudoniveus as the species without indirect defences. We predicted that herbivores would prefer to eat species and stages with indirect defences to those without them. As predicted, we found that herbivores preferred species and ontogenetic stages with indirect defences in all cases. Overall, however, natural levels of herbivory were lower in species with indirect defences. We conclude that indirect defences offer effective protection against herbivores and posit that their recruitment allows plants to reduce investment in other defence mechanisms. Our results support the notion that plants trade‐off between direct and indirect defensive strategies. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 536–543.     

Breeding success and predation on artificial nests of the endemic pigeons Bolle's Laurel Pigeon Columba bollii and White-tailed Laurel Pigeon Columba junoniae in the laurel forest of Tenerife (Canary Islands)

Breeding success and nest predation effects on the two Canarian endemic pigeons, Bolle's Laurel Pigeon Columba bollii and White-tailed Laurel Pigeon C. junoniae, were studied during 1995 in five zones of laurel forest on Tenerife Island. Nest predation was the more important cause of nesting failure of both species (88%), but principally affecting the White-tailed Laurel Pigeon. Experiments using artificial nests showed a greater predation on the ground than in trees and a lower predation in the February-March period than in June-July and September-October. The abundance of predators, estimated by bait consumption, showed a similar seasonal pattern, while fruit availability decreased over time from the first to third period. Predators identified by automatic cameras showed that Black Rat Rattus rattus was the major nest predator of both pigeons. These general patterns of nest predation affect the White-tailed Laurel Pigeon, which breeds on the ground mainly during April-July, much more than Bolle's Laurel Pigeon, which breeds in trees, especially in February-June. All seems to indicate that rats are the key factor causing the scarcity of the White-tailed Laurel Pigeon on Tenerife.     

Assessing the risk of freshwater fish introductions into the Iberian Peninsula

1. Preventing the introduction of species likely to become invaders is the best management option to deal with biological invasions. A data set consisting of native, introduced and species not currently present in Iberian Peninsula (n = 167 species) was used to identify freshwater fish species that are likely to be introduced and become successful invaders in the near future. 2. Principal component analysis (PCA) of species traits was used to determine species likely to be introduced, assuming that the traits of species introduced in the future will resemble those of previously introduced species. The likelihood of introduction was calculated as the proportion of neighbour species (in the space defined by the PCA) that have been introduced to the Iberian Peninsula and, together with metrics related to different stages of invasion, was used to construct a region‐specific risk index (Iberian risk index). 3. Introduced species had higher index values compared with native species or species currently absent from the region. The Iberian risk index was positively related to the results of an independent risk analysis for freshwater fish as well as to the geographical spread of species previously introduced to the Iberian Peninsula. 4. Iberian risk index values were used to establish a cut‐off value for estimating the probability of a successful invasion. This threshold value was used to construct a list of 20 species to be included in a ‘watch list’ to prevent freshwater fish invasions in the Iberian Peninsula.     

Deep phylogeny,net primary productivity,and global body size gradient in birds

Body size is evolutionarily constrained, but the influence of phylogenetic relationships on global body size (i.e. body mass) gradients is unexplored. We quantify and map the family‐level phylogenetic and non‐phylogenetic structure of the global gradient of birds, evaluating the extent to which it is influenced by phylogenetic inertia in contrast to heat conservation, resource availability, starvation resistance, niche conservatism, or interspecific competition. Phylogenetic eigenvector regression (PVR) partitioned the global bird body size gradient into phylogenetically autocorrelated (PA) and phylogenetically independent (PI) components. Simple, piecewise, and partial regressions were used to investigate associations between the PA and PI components of body size and environmental correlates, and to quantify independent and overlapping contributions of environment, phylogenetic autocorrelation, and species richness to the body size gradient. Two‐thirds of the geographic variation in bird body size can be explained by phylogenetic relationships at the family level. The global variation in body size, independent of phylogenetic relationships, is most strongly associated with net primary productivity, which is consistent with ‘starvation resistance’. However, the New and Old worlds have very different patterns. We found no independent association of species richness with body size. Despite major unresolved regional differences, deep phylogenetic relationships, heat conservation, and starvation resistance probably operate in concert in shaping the global bird body size gradient in different parts of the world. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.