Comparison of five methods for estimating growth of Calanus helgolandicus later developmental stages (CV�CVI)

The activity of the enzymes aminoacyl-tRNA synthetases (AARS) in adult females and males and copepodites stage V of Calanus helgolandicus was studied at the L4 time-series station in the English Channel from June 2002 to December 2003. AARS activity was explored as an index of somatic growth in the laboratory as well as in the field by comparison with other methods of measuring growth: (1) the direct method (Heinle in Chesapeake Sci 7:59�74, 1966), (2) the weight increment (WI) method, (3) the Hirst and Bunker (HB) equation (Limnol Oceanogr 48(5):1988�2010, 2003) and (4) the egg production (EPR) method. AARS activity showed a significant correlation with the direct measurement of growth in the laboratory (R 2=0.55). However, the correlation was lower for growth assessed either with the WI or the HB approaches in the field (R 2=0.05�0.17). Female AARS activity showed a positive correlation with specific EPR during the reproductive season (R 2=0.40) but no relationship was found during the non-reproductive period

Elevation and habitats: the potential of sites at different altitudes to provide refuges for phytophagous insects during climatic fluctuations

Uplands are expected to provide refuges for species subject to lowland habitat loss and projected climate changes. Here, we argue that upland populations also provide refuges when lowland sites are subject to climatic fluctuations and extreme events and that species with populations dispersed over adjoining uplands and lowlands spread their risk of extinction. A proviso is that development is sufficiently lagged with altitude but that development rates are compatible. Emergence patterns and development of the butterfly Anthocharis cardamines and its larval host plant Cardamine pratensis show these characteristics, and coupled with the butterfly’s capacity to migrate between isolated populations present a case where upland and lowland populations can act as sources when one or the other area is adversely affected by extreme events