Monitoring the growth and survival of larval herring on B.C. central coast

Herring spawning on British Columbia’s central coast takes place in the early spring. Strength of a year class is largely dependent on successful recruitment from the larval stage to the adult population. The potential temporal and spatial overlap of herring larval distribution with spring bloom dynamics can be a major determining factor in the success of larvae in finding suitable prey, with delayed feeding potentially leading to mass mortality. Consequently the phenology and productivity of plankton blooms, as well as the interannual variability in spawning at active sites can be significant. Reporting on data since 2012, we observe that although spawn timing does vary from year to year, this variation is less than that associated with spring bloom timing. The prey conditions experienced by larvae are therefore expected to vary significantly from one year, and site, to the next. In fact, larval growth at 38% of sites sampled wa

Simulating forest productivity along a neotropical elevational transect: temperature variation and carbon use efficiency

A better understanding of the mechanisms controlling the magnitude and sign of carbon components in tropical forest ecosystems is important for reliable estimation of this important regional component of the global carbon cycle. We used the JULES vegetation model to simulate all components of the carbon balance at six sites along an Andes-Amazon transect across Peru and Brazil and compared the results to published field measurements. In the upper montane zone the model predicted a lack of forest vegetation, indicating a need for better parameterization of the responses of cloud forest vegetation within the model. In the lower montane and lowland zones simulated ecosystem productivity and respiration were predicted with reasonable accuracy, although not always within the error bounds of the observations. Model-predicted carbon use efficiency in this transect surprisingly did not increase with elevation, but remained close to the ‘temperate’ value 0.5. Upper montane forests were predicted to allocate ~50% of carbon fixation to biomass maintenance and growth, despite available measurements showing that they only allocate ~33%. This may be explained by elevational changes in the balance between growth and maintenance respiration within the forest canopy, as controlled by both temperature- and pressure-mediated processes, which is not yet well represented in current vegetation model