Few studies have evaluated the joint effects of elevated temperature and pCO2 on marine organisms. In this study we investigated the interactive effects of Intergovernmental Panel on Climate Change predicted temperature and pCO2 for the end of the 21st century on key aspects of larval development of the American lobster, Homarus americanus, an otherwise well-studied, iconic, and commercially prominent species in the northeastern United States and Atlantic Canada. Our experiments showed that larvae (stages I–III) and postlarvae (stage IV) reared in the high temperature treatments (19 °C) experienced significantly lower survival, developed twice as fast, and had significantly higher oxygen consumption rates, than those in ambient treatments (16 °C). Larvae from the ambient temperature/high pCO2 (750 ppm) treatment had significantly longer carapace lengths, greater dry masses in stages I–III and higher C: N ratios in stage IV than larvae from all other treatments. Stage IVs raised in the high pCO2 treatment at 19 °C had significantly higher feeding rates and swimming speeds than stage IVs from the other three treatments. Together these results suggest that projected end-century warming will have greater adverse effects than increased pCO2 on larval survival, and changing pCO2 may have a complex effect on larval metabolism and behaviour. Understanding how the most vulnerable life stages of the lobster life cycle respond to climate change is essential in connecting the northward geographic shifts projected by habitat quality models, and the underlying physiological and genetic mechanisms that drive their ecology.
RFLP analysis of mitochondrial DNA (mtDNA) was used to study variation within and between ferox, sonaghen, and gillaroo, the local names of three types of brown trout, Salmo trutta L., which live sympatrically in Lough Melvin, northwest Ireland. They spawn in separate rivers or sections of rivers and thus maintain reproductive integrity by their innate homing behaviour. In this study, 12 restriction enzymes were used to survey 4.9% of the genome in 37 trout. Five of the enzymes were informative (AvaII, HaeIII, HinfI, MboI, and XbaI) and these were used to examine an additional 139 trout. Seven mtDNA haplotypes were found in the first 37 trout and one further haplotype, owing to variation at MboI sites, was found in the larger sample of trout. All of the ferox were monomorphic at all sites examined whereas six haplotypes were found among the gillaroo, three of which were unique to this group. Five haplotypes were found among the sonaghen, two of which were found only in this group. Sonaghen and gillaroo share three haplotypes but they are present in each at different frequencies. Relative to morphological, allozyme, and multilocus probe results, mtDNA provides the most discriminating marker system for these trout.
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