Bhavani Narayanaswamy:
> 2) In one of my samples in the Faroe-Shetland Channel I found a huge
> increase in the number of Spiophanes kroyeri. Depth = 800m, sediment
> is quite fine, temperature is about 0oC to 0.5oC. Relatively low TOC,
> organic content, heavy metals etc. Any suggestions as to why one
> should suddenly see a huge increase in this species? The same pattern
> is seen in both 1996 and 1998.
At the same site? Note I'm not sure how one can get an increase in a
sample which necessarily is a unique one off event. Additionally ONE
sample per site is impossible to analyse statistically.
Assuming the increase is present in several samples within a site and at
one time of year (interpreting the word 'pattern' here) - Does annual
recruitment when the S. kroyeri reach the critical size required for sieve
retention not fit the bill? Assuming there is a such a thing as an annual
pattern at that depth. But I suspect you don't think it's a recruitment
phenomenon. If it is just a spike in a single sample then one looks hard at
the physical/organic factors that would encourage 'abnormal' population
densities over those elsewhere. Otherwise your one sample has merely
'lucked' upon the higher densities of a rather patchy species - umm, three
years out of four!
--
Geoff Read <g.read at niwa.cri.nz>
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