Article Impact assessment of nuclear power plant discharge on zoopla...
The zooplankton density estimated in this study ranged from 354-771 cells per ml. That means it is 354000-771000 cells per liter. If you see the available literature from Indian coasts as well as from the same Kalpakkam coast, zooplankton density generally will be in the range of 200000-600000 cells per 10000 liters of seawater. Even many authors have reported similar densities for 100000 liters of seawater. So its unimaginable how such huge numbers were arrived.
Generally, a phytoplankton bloom with 700000 cells per liter density can be seen in naked eye as a distinct layer of green, brown or red colour on sea surface. So, with this high density of zooplankton reported in this paper, the sea will be full of zooplankton. With this density, if you take one liter of seawater, 20-30 % of the volume will be occupied by zooplankton considering the presence of gelatinous species encountered by the authors in this study. Practically, it is just impossible.
Numerical estimation of planktonic species are performed by many, but it is indeed a sorry state of affair that many of such reports are the results of extrapolated data obtained from very least volume of water sample and that too without establishing a mean data. Normally manual or instrumental enumeration of species assemblages, if performed on only 0.5 to 1 ml of water sample, results in amplification of the data when extrapolated to a litre of water and often the data exceeds what would have been actually present there.
With this being written, it is also possible for many workers to simply misidentify the more mature copepodite stages of mesozooplankton as adults and that too often yields exorbitant densities.
Keeping the above statements in mind, we need to consider the fact that aquatic system in highly dynamic and data procured from one such environment can only be contested upon by being at the same site at the same time, which practically is impossible since the planktonic assemblages vary significantly based on the circadian rhythm as well as the biogeochemistry of the ambient ecosystem. Also the presence of warm discharge water at the vicinity of nuclear power plants might have triggered such a phytoplanktonic bloom as befitting the number of zooplankton reported.
Unless consistent data of similar magnitude get reported, it will not be prudent to discard (no matter how outrageous it appears) nor incorporate such reports in the more practical data pool used by the more concerned personnel. Doing either without the absolute evidence to disregard the other will simply lead to impractical vilification and unwanted situations. In cases such as this, ignorance is a bliss.
Regards,
Dr. Abhishek Mukherjee
Agreed to Dr. Abhisekh's point of view. Ignorance is a bliss. However, for information of others, I have been involved in marine ecological work in the same stretch of Kalpakkam coast since 2006 and we have got regular data for all these years. We have never observed any such unusual zooplankton densities. The possibility of phytoplankton bloom and its impact on zooplankton population is mostly ruled out due to many reasons. The intake of power plant has been designed in such a way that the hot water from outfall is never recirculated in to the system. That means, heated water never travels more than a few hundred meters. Same has also been confirmed by many studies. Mostly the heat dissipates beyond 200-300 meters and we never observed any bloom or significantly high densities of phyto- or zooplankton in that area. The sampling locations in the study are much beyond the out fall area as well.
Anyway, apart from every other possibility, the data presented in the paper may be of some minor technical error of calculation as well.
Ajit Kumar Mohanty
Your reply is the very reflection of my answer. If you know that based on your personal experience on working on an aspect of a certain ecosystem that a new data presented might be flawed, then its better not to promote the data through criticism on a platform which is unlikely to change the fate of the publication. Because you know the data to be somehow contradictory or deviatory to what your experiences have taught you, all you need is to ignore the data and spread awareness through your own works without influencing someone else to support your stance on the topic. The ones to have committed the error are more unlikely to be swayed towards correcting their faults based on your, although professionally essential and astute, criticisms.
The people that know your ethics and quality of work shall always look up to you for quality, there is no use being tangled in situations which will serve you to no end.
Thank you for the opportunity to exchange some good and critical thoughts.
With regards
Dr. Abhishek Mukherjee
Though, zooplankton swarming sometime results in a high density but such a high density is never recorded from Gulf of Mannar.
With reference to the size of zooplankton in general, the reported mean density of 354-771 cells per ml. by the authors is an wonder. Imagine that one ml of water with 354 zooplankton cells in it. Who is to be blamed- the editor or the authors?
The amount of abundance calculated in the unit area is quite high! The amount collected in the collector after the horizontal tows may be correct, but I think there was some confusion during the calculations. Did you ask the authors?
All best
Fatih
Plankton swarms are not usual in water rich in nutrients - coastal or otherwise continental waters.
I am also agreeing the query of Dr. Ajit Kumar Mohanty and other researchers. Its purely a blender typographical mistake. We are doing regular seasonal survey in both Tamil Nadu and Pondicherry coasts for the past 25 years. We never experienced this type of zooplankton abundance. Better the authors recheck the values and correct it.
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