Zooplankton Ecology - Science topic

Aahed Alhamamy Thank you so much for your wonderful response. You provided exactly the kind of guidance I was seeking.

Thanks, and have a nice day.

It's too late, but I will be interested

Yes, You can use many methods of cluster or ordenation analysis. May be the assay with PRIMER software could help you and select the methods that you want.

I not so familiar with the probes used although I have used them but I might suggest developing some calibration plots using standard wet chemistry extractions with acetone or even the hot methanol extraction.

Most probably this is male rotifer of Hexartha. I am now in Australia, my laboratory is in Bangladesh. So, you please go through the literature that I cannot do from here. Consult with Fresh water Biology of WArd and Whipple.

Thank's for all help me to identify that cell.

terrible fotos - but after postabdomen, and body shape it looks like D. deserti .... see foto Hudec 1993.  D. similis is really different   igor

hi Salah MAhdi ;

thanks for al this articles 

greetings

It does not look to me neither as a cladoceran, nor copepod or ostracod. Because of the separated eyes and bifurcated caudal appendix, it reminds me of a juvenile isopod, but it's not sure at all from that picture. I can't see the suckers if it would be and Argulidae, but I have no experience with them.

Strangely enough, no previous answers actually target the question - what negative consequences may arise with increase in copepod abundance?:) I would not seriously consider oxygen depletion in the epilimnion of the large lake....But this is a very good question. It is commonly assumed that the more zooplankton - the better (=higher trophic efficiency, etc.), but this is not just this simple...

What comes to my mind as a possible negative consequence of the situation that is described is:

- possible blooms of infectious deceases and pathogens that copepods may carry as primary or intermediate hosts;

- food web alterations for other primary consumers (competition) or secondary consumers (cascading effects);

- increased grazing of algae that are important food source for benthos relying on high sedimentation;

- transfer of algal toxins (if any) to higher trophic levels should the copepods bioaccumulate these toxins.

All very good advice!  I dissected flounder juveniles and knew what species the single eyeballs in the gut were from.  I was able to infer how many of that species had been ingested! Good Luck!

it helps a lot sir..thank you for the time and for identifying it..have a good day to you sir.

The Ludox density gradient centrifugation is probably the most appropriate method for your purpose.

Dear Lennart,

may be i can help you. Cannot do now any complicated work because gathering with family for Suth-East Asia (Thailand, Indonesia, East Timor, Malaysia and after that into East Africa). This country science is over so may be will try smth other. It all cost 6 month period, but I will try to be in permanent contact with colleagues, except of climbing Cota Cinabalu etc. So, I'm attaching for you my database for ciliates. Please, do not distribute, as it will be for a patent attaining (still have no time to prepare). We are using it (one of a lot of databases) for calculating structural and functional parameters of communities. Open it like txt file. For help look attached file. Can send you program, but it needs experience to use. Moreover, the database for the Baltic Sea should be improved.

Previously we use some sub-program I wrote for the prim. pro. decomp. of benthos, and peryphiton but now V. Pliashechnik elaborated Excel program to do it.

Frankly,

Andrey

Hi Brian

There is some literature also from other counties on daphnids spending the winter as adult females. For instance, Larsson & Wathne (2006) reported adult females during winter in oligotrophic mountain lakes.  They claimed that females that produced ephippia in the autumn have less reserve energy at that time, than those  spending the winter as adults. Furthermore, Lampert et al. (2010) hypothesized that females can exhibit a mixed strategy, first produce ephippia, then spend the winter in an active state. Hamrova et al. (2011), however, found strong clonal variation among populations regarding their reproductive strategy during unfavourable conditions. Thus, high food density appears not to be a prerequisite for adult females under ice in winter, but perhaps rich winter conditions may improve the survival of the adults during winter. Larsson & Wathne (2006) reported high mortality towards the end of the winter in oligotrophic, alpine lakes and assumed that this is due to lack of reserve energy in support of your hypothesis.

References

Hamrova et al. BMC 2011 11:231

Larsson & Wathne (2006) Arch Hydrobiol 167: 265-280

Lampert et al. (2010) in oligotrphic mountain lakes. Limnol. Oceanogr., 55(5): 1893–1900.

Bror

I've been happy with the Olympus SZX for freshwater zooplankton. I have also used the Nikon series that is similar to the SZX. In my opinion both are great but the SZX will save you money and you get the same quality. We switched out the LED base to a different version though, because we wanted a to be able to tilt the light source with a mirror to adjust the contrast. Which really helped for identification.

ThankLena and Edgar. Extremely helpful! :)

Larisa,

 look like some simple Difflugia. But needs to be measured and from different points of wiev ! Look, please, some articles about Vorochevo lakes and Svidovets lakes from my site, altitude about 660 m, and 1400 m. I studied it enough well, but hardly to identify from this photo. Testate amoebae needs to see their oral form and collar< important is if flattend body, some "neck" like Pontigulasia. Can ask Volodia Pliashechnik from Uzhgorod (he has site) or if need perfect qualification call Prof. Vassil Golemansky. Anyway perfet key of mazei & tsiganov in Russian. i made the very good PDF, just put for smbd like reply for question.

important if this lake has some water flows in & out. if no, will be like swampy area with special faunal list...

Andrey

50 g of I₂ (metal), 50 g of KI, 50 g of CH₃COONa, about 1 g of phenol, q.s DW to 1 l. Add to sample by small portions until it look like strong tea. Conserved samples can hold out from several month to year in cold place (it may be need to add conserving agent if sample color become pale).

Rotifers without rigid shell (Asplanchna, delicate Trichocerca et al.) will distort.

Dear Reliana, read these articles 

This looks like a small specimen of Pyrostremma agassizi.

It's often difficult to identify illoricate rotifers which can require to be observed alive and active in order to see them with their appendages extended (foot, head, antenna, spur).

Your rotifer could be a bdelloid and you should look at the trophus to confirm that.

If so, the following papers can be usefull :

Heiarchial cluster analysis, component analysis can be done to study the direct and the indirect interaction and interrealtion between the zooplankton community and the fish growth rate.... SPSS and SYSTAT can be used for the same...

This organism lacks median spines unlike Keratella taurocephala. 

It is rather difficult to separate between Lobonema and Lobonemoides without observing canal structure. As far as my experience, however, it would be Lobomemoides robustus. They are very abundant in the Gulf of Thailand targeting commercial fisheries.

thank u Pal

1st one Subeucalanus attenuatus??

Dear Valentina,

In the attachment please find copies of papers, which may be interesting for you.

Take into account that they are quite old, and some of the taxonomic information (species names) have changed.

Best regards,

Slawek

perhaps you might find an answer in the enclosed aricles, including the thesis by Virro.

why  they are typical of eutrophic  and meso-to oligotrophic conditions has apparently been left to the curiosity of other specialists. at a guess, feeding habits or feeding efficiency, since they may appear in fairly high numbers, but guesses are not good enough for publication (and therefore not as answers to your question)

It depends on the zoogeographical region, freshwater or brackish or salt. General keys are based on the most typical (in author's opinion) species. In first approximation such general keys can be used, but you should support tham by specialised keys, e.g. with regional or world fauna books. In post soviets countries f. ins.  when identifying Rotifers we use normally perfect Kutikova book, when have to do with Chidoridae – Smirnov Fauna of the world (1971) (in Russian). As well, Cyclopoidea by Monchenko, Harpacticoidea by Borutzky etc. So, you should define more accurately you interest.

Andrey

This appears to be a pelagic polychaete with an everted proboscis.  Identification of genus/species would likely require details of the jaws and arrangement of the setae which is not possible from the photo.  Perhaps someone is familiar with the species already?

Thanks very much for Mustapha and Eugenia's kindly answer. After comparing the specimen and the image of Chaemorpha, I think it really should belong to genus Chaemorpha.

Hello Alessandra,

I strongly advise you look into William Peterson's work with the NOAA Northwest Fisheries Science Center. His research has been integral on the effect of the Pacific Decadal Oscillation (PDO) on zooplankton community composition with emphasis on fisheries management. 

Just like temperature, zooplankton community composition can be used as a metric for stock success, individual growth, and overall fecundity. PDO phase shifts correlate with variation in seasonal upwelling and temperature regimes, resulting in zooplankton community changes that dramatically impact energetic constraints on foraging fishes with carryover effects for piscivorous species. Zooplankton community composition has also been used as a proxy for ecosystem health and assessment of susceptibility to climate change in more recent years. 

Bill Peterson would definitely be the person I would try and contact for specifics on the how's and why's of how these metrics are applied to fisheries analysis and policy.

Cheers,

-Thomas

You should select your depth range based of actual pycnocline layer.

Hello Stefania, you can take also a look at these two studies  performed in the MED, one focusing on biocumulation of PAHs in Zooplankton and the other on non-DL PCBs and OCPs in plankton. Maybe interesting for you. Regards.Javier

Aha, I misunderstood. Some do test that, you could e.g. make a t test between grazed and control treatments. But i usually do not. Maybe I would if there is no clear grazing effect to be able to state "no significant grazing" Regarding the shrinking I would not worry for short (over night?) incubations. But several common colony forming species do split up in response to copepod grazing. E.g Skeletonema (Bergkvist et al 2012 L&O) Phaeocystis (Long et al 2007 PNAS), and Alexandrium Selander et al 2011 PNAS). At least for Skeletonema and Alexandrium the response typically takes longer than an over night grazing experiment to develop fully. If you do total bio volume it should not matter anyway, the cells are still there. So this probably added more confusion than solution, but I think normally stats is not necessary to prove grazing in a grazing experiment, rather to prove differences in grazing between treatments, prey etc. Best wishes /Erik

Well, I distinctly remember this radiolarian species extending down to Devonian. Please do check up literature.

We have been doing quite a lot of work on this topic.  If you go to my lab's web page:

and Click on publications (although not totally up to date) - there are several of those papers there.  See papers especially with Adam Jeziorski as an author.  See also our recent Proc Roy Soc Paper:

John Smol

Thanks a lot Alexey!

Best regards

Renato

I have done some permanent slides using microscope slide and cover slip and nail varnish. If the object is not too big (most cases on mesozooplankton it is too large) then it should work nicely. Just but a little drop of fixated (4% formaldehyde or lygol or spirit+clycerin) plankton species on microscope slide and cover it with cover slip and then cover the edges of covr slip with nail varnish (transparent is the best and some companies make better varnish than others). Let the varnish dry and your slide would be ready to preserve!

I am fairly sure that it is a cycloid fish scale, as others have suggested. We frequently encounter them in plankton-net samples. They (1) get knocked off of fish that are caught by the plankton net and (2) exist in sediment largely as the result of predation events; sedimented scales may be easily re-suspended into the water column, where they may be collected by plankton nets.

It looks like lipid droplets with carotenoid coloration

The definition of the pictures is low. Nevertheless it doesn't seem to be organisms.

It looks like pieces of detritus usually found within the suspended particulate matter.

Contact Prof. B.K. Sharma, Dept of Zoology, Northeastern Hill University, Shillong. He may be able to help.

thank u harris.

Hi everyone.

I can just give you some titles of studies where there tested

1. the fatty acid differnces of phytoplankton under changing nutrient ratios (Bi, Arndt & Sommer 2014: Linking elements to biochemicals: effects of nutrient supply ratios and growth rates on fatty acid composition of phytoplankton species)

2.The differences (Fatty Acid composition) of between phytoplankton species for copepod development (Arndt & Sommer 2014: Effect of algal species and concentration on development and fatty acid composition of two harpacticoid copepods, Tisbe sp. and Tachidius discipes, and a discussion about their suitability for marine fish larvae")

It might help you.

Dinoflagellate Prorocentrum cf. rhathymum [I can see the diagnostic small spine on at least one cell)

You can use Lugol for that.

I think some of these link could be useful

Hi Lennart, inverse relationship between these metrics is well documented, particularly for zooplankton inhabiting brackish water, or, water of varying salinity (in time) such as in classic estuaries.  Before adding my 2 cents worth, can you tell me more about what is meant by "increasing"?  I take it you mean diversity has changed over time yes? What time scales, hours/days/weeks or by season/ year-to-year? Have you noticed a concomitant change in any environmental variables?

Dear Shaun,

To my point of view, we first need to know if you want the biomass by family or genus  category, or by the entire zooplankton community. I will answer to the most accurate level of biomass estimation: the family/genus level. I suggest also to use the digital imaginig system (probably another system than zooscan that s pretty expensive) but rather a commercial scanner like Epson V700 and plastic tray) and estimate biomass with a software like silhouette digitizer, the software proposed by Joanna Strzelecki or zooImage. The last one is able to accurately recognise semi-automatically mesozooplankton up to the family genus level (see Grosjean et al. 2004) and use conversion factors to estimate biomass.  Its possible to automatically discriminate particles other than zooplankton but you will need to dilute quite a lot your sampling to avoid the overlapping between copepods and chain forming diatoms. So you will need to use sometime the method proposed by Kalevi Salonen. You can also use the method of José Pedro Marín to preprocess and clean your sample..Its quite accurate compare to traditional methods. Time to dominate the entire system and software: 2 months. But u will save time for the next surveys.. Hope it will also help you.

All the best

Pascal

Stefan,

the shape of the cephalotorax is not a reliable character to identify these species. As suggested by Ian, you should focus on legs and furcal branchs ornementation.

Note that the taxonomy of Acanthocyclops robustus is not up to date in both Rybak & Bledzki 2005 and Einsle’s 1996 guides. Most of the time, specimens identified as A. robustus are in fact A. trajani.

See :

Sulistiyowati, I personally find it quite difficult identifying zooplankton from photographic images, my first impulse is to zoom in as one would on a good stereo zoom microscope, which is not always possible with low resolution photos.  The exception being of course when one views a familiar species, one that is easily distinguished from others in the sample.  To this end, let us hope there is someone out there that may recognise the specimens posted by Priscilia!

Are you looking for  days after hatching?  I don't think there is a method to determine that.  However, you can stage the animals and if you know the average temperature you could estimate the "time post hatching"

Sorry. I am a marine biologist

This nice paper will give you some quite relevant info.

How zooplankton feed: mechanisms, traits and trade-offs

Thomas Kiørboe

DOI: 10.1111/j.1469-185X.2010.00148.x

Lennart, which zooplankton groups do you consider as microzooplankton (it differs)?

Danny Grunbaum at the University of Washington had a 3D video setup and did some really neat modeling/observational work with plankton. His web page is at http://faculty.washington.edu/random/.

Hi

It is desirable that you use sieves of different mesh sizes in order to obtain a number of size-fractionated subsamples.

These articles may be of your help:

1. http://www.msrc.sunysb.edu/MedFlux/pdfs/Liu_etal.pdf

2. http://aslo.net/lo/toc/vol_52/issue_3/0966.pdf

Best

Dola

Hi there! Look I have the idea of studying lakes, different lakes with different environmental histories (natural + anthrop.), considering their pelagic biota an then studying the biota's responses(physiological to molecular and functional) under simulations of future enviromental conditions (°C, pH, etc). I think should be interesting to connect these observations with current and previous genetic diversity of lakes.

Hi,

PCA is an option, for sure. However, it is often the case that there are a considerable amount of zeros in the data, which I guess is also the case with plankton where there is considerable variation in species competition within the season. This means that the ecological gradient of species occurrence is relatively long and under such circumstances PCA is not a good method for analysis (unless the data is transformed prior to analysis, see Legendre & Gallacher 2001 in Oecologia).

I would suggest that (given that your data is abundances and not presence/absence) that you first use some dissimilarity index to calculate the ecological resemblance between your samples (i.e., using vegdist in the vegan package in R). Then you can use Non-metric Multidimensional Scaling to gain a graphical representation of the original ecological space in, say 2-dimensions. This can be done using the monoMDS function in the vegan package in R.

I hope this helps.