Effects Of Preservation On Wet Weight Dry-Weight Nitrogen And Carbon Contents Of Calanus-Helgolandicus (Crustacea Copepoda)

The lengths, wet and dry weights, nitrogen and carbon contents of fresh, frozen and formaldehyde-fixed specimens of Calanus helgolandicus (Claus) were determined. Samples were collected during May 1980 in the Celtic Sea. Individual Copepodite Stages 3, 4, 5, and Adult Male and Female Stage 6 were measured and analysed, and 36 linear regression equations derived for these variables together with mean values, standard deviations and 95% confidence limits. The range of nitrogen values in the fresh material, expressed as a percentage of dry weight, ranged from 8.08%±0.80 (Copepodite Stage 3) to 10.89%±0.27 (adult female); carbon values changed from 41.6%±3.05 (mean ±95% confidence limits) for Copepodite Stage 3 to 50.97%±2.63 in Copepodite Stage 5. The adult females had a high nitrogen and relatively low carbon content, while the converse was true for Stage 5 copepodites. There was a loss of dry weight from the frozen samples (57%) and the fixed samples (38%) compared with the mean of the fresh dry weight of all stages. The material lost from the copepods was rich in nitrogen, thus, artificially high percentage carbon values were determined from the frozen and fixed samples (52.0 to 60.3% and 44.7 to 58.5%, respectively).

Estimation of atmospheric nutrient inputs to the Atlantic Ocean from 50°N to 50°S based on large-scale field sampling: Iron and other dust-associated elements

Atmospheric inputs of mineral dust supply iron and other trace metals to the remote ocean and can influence the marine carbon cycle due to iron's role as a potentially limiting micronutrient. Dust generation, transport, and deposition are highly heterogeneous, and there are very few remote marine locations where dust concentrations and chemistry (e.g., iron solubility) are routinely monitored. Here we use aerosol and rainwater samples collected during 10 large-scale research cruises to estimate the atmospheric input of iron, aluminum, and manganese to four broad regions of the Atlantic Ocean over two 3 month periods for the years 2001–2005. We estimate total inputs of these metals to our study regions to be 4.2, 17, and 0.27 Gmol in April–June and 4.9, 14, and 0.19 Gmol in September–November, respectively. Inputs were highest in regions of high rainfall (the intertropical convergence zone and South Atlantic storm track), and rainfall contributed higher proportions of total input to wetter regions. By combining input estimates for total and soluble metals for these time periods, we calculated overall percentage solubilities for each metal that account for the contributions from both wet and dry depositions and the relative contributions from different aerosol types. Calculated solubilities were in the range 2.4%–9.1% for iron, 6.1%–15% for aluminum, and 54%–73% for manganese. We discuss sources of uncertainty in our estimates and compare our results to some recent estimates of atmospheric iron input to the Atlantic.