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Benthic Ecology - Science topic

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Hi folks,
My colleague has just asked me for advice regarding analyzing his BRUV (baited remote underwater video) dataset. It's a video camera fixed on a structure, used to record marine fishes passing by or attracted to the attached bait. It resulted in a wide dataset of species assemblage (lots of zeroes, lots of species columns). He has generated an NMDS ordination plot and ANOSIM to analyze his species assemblage dataset. He sees a spatial (geographic) separation of species composition through these methods.
Now, he wants to understand what drives this assemblage. He has additional benthic composition dataset (% coral, sand, rubble, etc.), current strength, depth, and more abiotic data. His coauthor is suggesting fitting envfit vectors on their NMDS and use the p-value of said vectors. I don't think this is a good idea, but I'm not well versed in this topic so I couldn't explain it sophisticatedly. I think because the vectors are "retrofitted" onto the ordination, the p-values are therefore not explanatory toward the species assemblage.
The alternative I could think of is running PERMANOVA or a model. The problem with the former is that the benthic composition dataset are related to each other (7 different variables, but all add up to 100%) so they're not independent of each other.
I'm wondering if anyone has any solution to this/or can add to the explanation. Would it be reliable to run a PERMANOVA? Should he be transforming his benthic composition dataset first? Or would he be better off creating a model, and if yes, which kind?
Thanks!
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You are right, doing anything parametric in NMDS-space is a silly idea. PERMANOVA won't help, it's asking a similar question to the ANOSIM you've done. To relate community composition to drivers (e.g. explanatory variables, singly or in combination) there are many methods available. If I was using PERMANOVA I'd probably go for DSTLM (distance-based linear modelling) though my preference would be to stick with the non-parametric approach underpinning ANOSIM and use a method such as BIOENV, which searches for subsets of explanatory variables that give the best match with the biotic similarity matrix.
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For community studies like species succession, variation in composition, especially for plankton and benthos, what are the appropriate statistical methods? One such method is MDS with cluster overlay. Similarly what else can be applied for such studies?
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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.
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Hello all,
This is a real dbRDA plot using real invertebrate abundance data (taxa-station matrix) with environmental data (substrate characteristics-station matrix) as predictor variables. The plot is produced in PRIMER v.7. Invertebrate data is 4th root transformed, Bray-Curtis similarity was used. Environmental data is normalized, Euclidean distance was used.
My question is: why is the vector overlay not centered at 0,0 in the plot? Interpreting this plot, one would conclude that every sampling station within the study area has values below the mean for predictor variables 2 and 13, which is impossible. Why would the center of the vector overlay be displaced -40 units? How can this be? Why is the plot centered on the dbRDA2 axis but the dbRDA1 axis?
Please let me know if anyone needs more information. Thank you!
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The analysis is fine. The position of the vector diagram relative to the ordination is arbitrary - it could just as easily be in a separate key. The diagram indicates the direction across the ordination plane in which values of the selected variables increase. The length of the lines indicates the amount of total variation in each variable is explained in the chosen ordination plane. If all of the variation is explained, the line reaches the circle.
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I am working with intertidal muddy sediments. In one of my sites the sediment was extremely muddy (high % of silt), oxic layer was shallow, and there were a lot of oligochaetes.
I would like to know how deep into the sediment they live/go, and in what areas of the sediment column they feed.
Does anyone have literature that I could study?
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10cm at Black sea shallow waters
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I am not understanding very well the dynamic of benthic exchange in coastal sites and if is a process that normally can occurrs fast (hours to days) or slowly (weeks to decades)?
I need this information to understand the variability of concentration in long-lived and short lived Radium isotopes in a coastal aquifer
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This sediment dwelling cnidarian was found within a benthic sediment grab at 170m depth north east of the Shetland Islands in the North Sea. Can anyone suggest a particular species?
Any help would be very much appreciated,
Ed Lavallin
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Hi Edward
Looks like Cavernularia pusilla (except for swelling in the proximal part of the rachis). Also compare your specimens with this species.
Regards
Melih
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It is hypothesized that harpacticoid copepods are the only meiofaunal organisms to develop larval stages because their nauplii share the same habitat as the adults. I am interested to know whether the nauplii (larvae) and copodite stages of harpacticoid copepods are pelagic or benthic compared to calanoid or cyclopoid copepods?
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Dear Moumita, as you know some marine harp. cop’s. are planktonic. So, for them there is no choice like to develop in plankton. Anyway in freshwater some copepods (cyclopoids) had been found in bottom conditions in wintering (look publ. of Natalia Kovalchuk in hydrobiological J. - in RG! But if I understand well we’re speaking about freshwater benthos! Thus, being involved about 40 years with alive samples of different habitats both fresh and brackish waters I'm absolutely sure that naup. & copep. of h. in freshwaters are mainly inhabited the same biotope as adult that is benthos, periphytos (if fast flow of stream) or submerged in case of lenthic basins! This provide much better survivance of youth as protect them against raptor cyclops!
Andrey
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After reading several articles I am a bit confused concerning the benthic species taken into account for the calculation of species richness and index like I2EC. In the description of I2EC (Grall & Glemarec, 2003) it is mentioned that fixed epifauna should not be counted. What about the vagile epifauna such as many molluscs of hard substrates (Nassarius, Chitons ...) ? I don’t understand why they are listed in mudflat case. What about Serpulidae species like Spirobranchus ?
Concerning the AMBI, normally used in soft sediment habitats, the list of ecological groups contains species like: Balanus trigonus, Nassarius sp., Actinia sp., Tethya sp., Polycarpa sp.
Looks like every study has its own recipe, and it is not possible to know which benthic species are taken into account by the authors for the calculation of each index.
In my opinion, different indices (AMBI, I2EC) must use different lists (infauna with or without epifauna), and each list should be clearly detailled to ensure reproductibility and comparison.
Can anyone enlighten me on this subject ?
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These are picked up from 5 to 8m water depth from coastal water.
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@Michael Martinez-Colon sir i am adding the SEM image of the above foraminifera, please help me out for identifying the species names.
2 years ago
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I am trying to analyse the degrees of influence of a few environmental factors on benthic mollusc assemblage structure using DistLM and dbRDA plots. After selecting the best model, I have used a forward-stepping selection proceedure based on Bray-Curtis distance measures to run both adj R^2and AIC selection criteria tests. Two things are odd - the results of both marginal tests came out almost identical for both adj R^2 and AIC, and there are no factors/values listed at all for either of the sequential tests! What have I done/what should I have done?
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Jen I have the same quetion like you!
Do you already know how to solve it?
Regards
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I'm measuring the shrimp diversity using diversity indexes such as Shannon, Simpson, Pielou and Simpson's dominance. I sampled three different sites during three seasons, so I have a total of 9 values for each index. My question is which statistical analysis could I use for testing if there is a significant difference between those values due to the sampling site or season or both?. Or if there is no need to use them and just make my conclusions based on the raw values of the indexes. Thank you for your attention. Best regards 
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You should start identifying the nature of the distribution of values of the index, i.e. Shannon index values are stricktly positive and continuos, so you should use some GLM model which allows for Gamma distribution.
Diversity (Shannon values) = a + Beta*Site + Beta*Season,
Diversity(Shannon ~ Gamma(µ, τ)
 E(Shannon) = µ_i   &   Var(Shannon) = µ_i2 / τ
ANOVA approach can ONLY be ok, if you have enough replication, otherwise It will assume normality and homogeneity, in the distribution of values of the Shannon index, and residuals, which we know is not true for small samples. Let me know if you need assistance.
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Marine benthos. scale 1mm. Processed from a muddy substrate.
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I agree with Ton. Probably Branchiostoma or another member of Amphioxiformes.
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I am developing a project investigation the effect of electromagnetic fields on benthic infauna, especially with respect to array and export cables associated with offshore energy installations . It would give my rationale some weight if I could provide existing measurements of EMF strength at the benthic in operational developments, does anybody know of any papers or monitoring reports that could help with this?
Many thanks!
Dan Henly 
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How can I select variables for PCA analysis from huge set of environmental data?
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Jayachandran,
You may use PC scores to reduce variables (i.e. the correlated ones). firstly, you should do a PCA on your parameters using predetermined number of PCs (lets say N= 10 PCs). Then check to see how many PCs are needed to describe 100% cumulative %variation (for example the first 5 out of 10 PCs). In each PC (1st to 5th) choose the variable with the highest score (irrespective of its positive or negative sign) as the most important variable. Since PCs are orthogonal in the PCA, selected variables will be completely independent (non-correlated).
Hope this helps you
Amir
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Can anybody explain possible effects of estuarine mixing on  benthic distribution, especially salinity and feeding behavior?
Which zone would be the benefit of high diversity?
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Dear Jayachandran,
you mean all living beings? reaction is too different. But working at the lab of the Danube and Limans (Estuaries) we found several interesting facts. Even desalinated the Estuary never lose completely its marutime or brackish water fauna. Look, please, my last presented publication about the Sassyk ciliates fauna! As well  what happened with this ineresting freshened basin after desalination are gathered in our book (as well my site). If estuary is of some large river and practically fresh, so marine fauna can penitrate over the deep relict river bad and it can be the very upper part of this type Estuary. Moreover  in this relic river bad is concentrated hydrogen sulphide that is suitable for anaerobic organismes od marine origin. I wrote about the Dnieper-Bug Estuary. As about tides it can stimulate exchange of the organismes but is not comfortable for a stable fauna. Therefore in the locality of the Estuary with abruptly changing regime it will be enough poor fauna, eg especially if salinity will be changing from 1-2 over 5-7 promille diapazone and back.
Extra interesting can be redistribution of the primary production of phytoplancton that can be consumpted in the deeper layers and in benthos...
I have enough much books on the question, so if necessary, call me by RG mailing, Will send.
Andrey
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I want to compare each communities' respiration (as measured in-situ in benthic chambers), per gram organic biomass. The problem is that biomass is order of magnitude different between communities and variations in biomass are much larger than variations in respiration between communities.
i.e. when subtracting a number by a large value = small value; when subtracting a small value = large value.
If I could, I would have done a controlled lab experiment using the same amount of biomass from each community and get rid of that artifact.
My question is:
Can I transform the biomass values in order to minimize variation between communities and - artifact? I don't care much about the actual values - I would just like to compare between them (which respires the most/least per gram organic biomass?)
also, which transformation should be used?: respiration is measured by the change in DIC concentration over time in side incubation chambers. 
I expect that production of DIC over time will increase with increasing organic biomass inside the chamber, however I'm not sure how these variables behave. I expect it not to be linear. Possibly logarithmic, however I can't really do a manipulative experiment to check that.
Is anyone familiar with a study that used this kind of normalization using transformed data? Who can I cite?
Thanks!
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Thanks everyone for your tips.
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Can foraminiferal paleontologists or interested colleagues help me to identify this species of agglutinated benthonic foraminifera from Paleogene of Egypt?? 
I suppose it is new species of Gaudryina...or not??
please be calm with my attached photos as i took it by my camera not attached with microscope,, so it may be low in resolution. Thank you.
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Dear Amr Zaky.
In spite of low resolution, but the image is clear where the last chamber is inflated. It may be hypotype of Gaudryina laevigata. Be sure it is distributed in many samples and in notable number, to be defined as new var. of Gaudryina laevigata.  best regard
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What is the method of sea star identification?
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Dear Jana Litt I need morphology identification manual. If have please share to me.
Thank you for response.
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Anything about their recovery as a community, the succession in assemblage, and their function in the recovery of the reef as a whole.
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Sorry, not me
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Tropical. Sampled from river. Scale=1mm
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I do not know if it will help you, but in my opinion foto 1 is an oligochaet (part of it without head), the other 3 images belong to Nereidae, but only foto 3 with a head, the others only middle (foto 4) or posterior (foto 2) parts.
The determination is almost impossible from these pictures, but the nereid polychaete could belong to the genera Nereis or Hediste. Alitta probably not, due to the missing prolongation of dorsal cirri in posterior segements (see foto 2).
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I'm looking at using meiofauna community data from eDNA analysis for benthic environmental monitoring.  I would like to filter the eDNA dataset to exclude non-benthic taxa but am struggling to find a source with this information.
Can anyone suggest a database or publication detailing meiobenthic taxonomic groups which I could use to filter the eDNA data.
Thanks
Paul 
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Dear Paul,
I'm not sure I understand your question. Are you looking for a database that can match your EDNA sequences to meiofauna species, or just a list of species that belong to meiofauna?
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Hello dear colleagues,
Did you agree with the identification of this benthic foram, is it Citharina or an other species? I have a doubt..
Thank you
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Dear Karoui-Yaakoub Narjess
I suggest to make an apertural view. 
apparently it is Planularia complanata (Reuss)
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About 10 individuals of this unusal species were found in a benthic sample of the Great Belt area (Baltic Sea) with water depth around 40 m and a salinity around 25 psu. Unfortunately I have no idea what taxonomical group it could be. Our first idea was, it is a part of a medusae, however, all individuals have the same shape and seem to be complete. For a priapulid it is quite unusal "open".
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I goit right now a tip from my colleague Carmen Pia Günther, it ist the pharynx of Echiurus echiurus! E. echiurus was also in the sample, very large individuals. Ton, your pharynx idea is not as far as I thought.
Thank you very much for your comments
Michael
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Collected from Gulf of Mannar Island,India.
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1762: a nemertean worm
1763, 1765, 1767: Ceramium
1823: a polychaete, possibly of the family Phyllodocidae
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Hi all,
recently from benthic samples we were able to collect interesting microgastropods (all less than 4 mm). There are six species attached herewith for identification. 4th species is that of a Nassarid and the first species looks like a Turritellid. Please help me to identify the species. All were collected in depths less than 10 meters. 
Best regards
Deepak
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Deepak:
By definition Micromolluscs are not allowed to exceed size of about 5mm for fully grown adults. You may like to have a look at this link for insights:
Best
Syed
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trochospiral with cylindric top.
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Amr:
We are not in a position to make out anything out of these images. Could you please supply well focused images with details of test composition.
Best
Syed
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Species of Marginulina with kind of radial ornamentation
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Before asking the community for help you need images that can be enlarged and clear. You should also indicate locality they are from and the age. These all look modern, but those trying to help you need better information. It would also be good to know what project these relate to and why you need determinations.
Malcolm
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I want to know the genus and species name for one of my friends, if possible.
The scale of each microscopic image is 200 μm.The images became re-size to upload. if you need to have more resolution, I can upload your mentioned fauna separately.
Thank you very much for your help.
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Nearly the half are foraminiferans. You need to submit depth, location information I guess for their identification.
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These are marine benthos.
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pic A could be a sipuncula, picture b is a polychaete from family Opheliidae, pic G is a Capitellid 
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Abundance, number of species and diversity
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Very interesting question. The bottom current has an effect on detrital input which in turn, may influence the feeding activities of macrobenthic polychaete community.
The following references may help you more.
Regards.
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sampling location Palkbay 
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He  Sekar the first image is a female Harpacticoid copepod, maybe belonging to Canthocamptidae family. The second image is an Isopod maybe genus Munna
Here an identification key
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They are found occasionally in grab samples from Kara and Laptev seas. Pictures of  paraffin embedded cross sections stained by hematoxylin and eosin.
Thanks in advance.
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Hi Valentin,
I'm not a specialist, but they look a lot like sipunculids (Phylum Sipuncula). 
Cheers,
Camilo
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I am interested to see if there has been any work on the ability of crustaceans and polychaetes to detect electromagnetic emissions from other organisms' nervous systems. This would be of interest in my study of epibenthic predators that burrow when prey is located as well as burrowing organisms that may retreat deeper when predators are detected. Any leads are appreciated!
All the best,
Justin Brundin
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...here another paper on the same topic.
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hi,i want to know the simple method of constructing  a abundance bio mass curves for benthic macro invertebrates.?
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Primer 7 is the best
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I need to estimate a benthic index from soft bottoms close to Esmeraldas, Ecuador and could appears new species
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Use Kristian Fauchald's pink book ( www.vliz.be/imisdocs/publications/123110.pdf) to identify all the animals to family level first. Then, search for appropriate papers for each family, with keys. Take care not to use identification keys for species from another part of the world, as you'll likely get wrong results. Fauvel's keys for example contain species from the Atlantic and Mediterranean coasts of France, and while they may be a good starting point for species from that area, they are now almost 90 years old and do not contain all species. Try to look for reasonably recent papers. Unfortunately I am not aware of any comprehensive key for the Pacific coast of South America... but you could try to contact Sergio Salazar-Vallejo from Mexico. He might have more dedicated literature for the area.
Hope that helps.
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benthic microalgae species
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Yes, you could use the relative abundance (RA). You could select, for example, 3-5 species with highest RA, or could set the lower limit of RA and all species with RA above that limit will considered as dominated.
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I picked the animal from benthic sample collected at the depth of about 40-50m in southern central Vietnam offshore waters. The size is 4-5mm. Thank you very much.
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Surely it is a Sipuncula
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The research project will be based on: To investigate the effect of pollution to benthic fauna. Please any help to clarify myself with my project
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You need to start with defining your actual questions Max. Even though you may be doing a generalised sampling program to identify patterns of abundance and community composition, you still need to think about WHY you are doing this. What will these data tell you? An excellent starting point is the paper by Neil Andrews and Bruce Mapstone -
Andrew NL, Mapstone BD (1987) Sampling and the description of spatial pattern in marine ecology. Oceanogr. Mar. Biol. Annu. Rev. 25: 39-90
I suggest you also read the papers that are in a special edition of Austral Ecology, Volume 18
Clarke KR (1993) Non-parametric multivariate analyses of changes in community structure. Aust. J. Ecol. 18: 117-143 is one example but the other papers will give you excellent insights into how to design and approach your sampling program.
Papers by Warwick, Clarke, John Gray, Somerfield et al. will provide numerous examples of how to design a sampling program for specific questions, what data need to be collected and subsequent analyses.
Hope this helps, Greg
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I have no recommended reading for this
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In each system is good if there are enough species with diferentes trophic categories, in your case, gastropods may indicate any change in the environment, i can recommend some diversity indices such as Pielou's evenness index, simpson index, shannon-wiener index, numbers Hill. A comparison of one or all of these measures of biodiversity can illustrate changes in water quality conditions within a local community. Water quality parameters like light penetration, dissolved oxygen and salinity can have dramatic impacts on levels of biodiversity. Association routines you can use as BIOENV or BIOSTEP to link all components (biotic and abiotic).
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Isolated from estuarine area (10 ppt) by agar plating (f/2 medium). Black small colonies formed after 4 weeks. The size of cells varies from 8 to 20 micron. Cells are attached together and benthic in culture.   
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If your algal culture is axenic, it is suggested to have DNA identification.
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I performed a multiple choice experiment to assess the food preference of the sea urchin Paracentrotus lividus in relation to 5 different food items. I have 15 replicates, each represented by a tank where the 5 food items were simultaneously offered to 1 sea urchin. For each tank, I measured the consumption of each food item after 48h.
Given the lack of independence within each replicate (the consumption of one food depends on the presence of other food sources), I would use a multivariate approach. The problem is that no treatments have been included in my experimental design (all replicates have the same condition) and it makes difficult choosing a proper statistical approach. Any suggestions?
Thanks 
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Simona
Bearing in mind your choices here can I recommend a book to you.  Non-parametric statistics for the behavioural sciences by Sidney Siegel.  Its a brilliantly laid out book that explains everything very clearly with worked examples and then gives a set of instructions rather like a recipe book.  its excellent for finding the right test for a situation and for the non statistically minded.  Ive used it all my career with hundreds of students ( no thousands !)
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I am currently modelling the potential distribution of the invasive Caprella mutica and native species of Caprellidae (for starters C. linearis) in the North Sea. From my own work I have obtained several offshore samples in the Dutch part of the North Sea. Furthermore I have received data from colleagues in other countries, but the total dataset is still very small. From literature I have obtained hundreds of presence-only observations (e.g. from Cook et al., 2007). But I found hardly any presence-absence data of Caprellidae.
Is there anyone that has this type of data from the North Sea and is interested in sharing this? Thank you for reading my question!
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Hi Joop
Maybe this will help: I just uploaded our recent paper on Caprella tuberculata in the Dutch part of the North Sea. It includes several references on Caprellids in this area.
Wim Vader responded to our paper and he presented an unpublished record of this species on the light vessel Noordhinder half a century earlier: Vader, W. 2015. Enkele amphipoden van het lichtschip Noordhinder in 1956. Het Zeepaard 75 (2) 53-54.
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I'm seeking information on the pH of urchin digestive tracts or stomachs under standard conditions (e.g. not acidified conditions). I'm aware there are values for larvae (Stumpp et al 2013) but, again, I need values for adults. 
Alternatively, I also need pH values for digestive tracts of bivalve larvae. I have values for adults.  Any help on this would be much appreciated!
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Veliger larvae has slightly acidic pH
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Photograph taken during underwater survey in West Coast of India. At 20m depth.
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I would think it is Favia favus (now know as Dipsastraea favus). (look at Veron JEN (2000). Corals of the World. Australian Inst Mar Sci  Vol.3 page 116 & 117)
It is not Favia maritima  (now known as Dipsastraea Blainville )as this species starts to show some form of poorly formed Paliform lobes and with Favia favus there are no such signs of Paliform lobes at all, it is clean. Your picture is of high quality so you can zoom in and have a look at the corallite structure very well.
The other point is that you can see that there is generally Intra-tentaclar budding (at the edges of the colony margins), a general indicator of the genus Favia.  
thanks 
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from Karachi  sea
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Post it to iNaturalist.org and ask the same question
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Hello, I am looking for recent (~1990s and forward) literature on invertebrate-moss associations in inland water ecosystems (lakes, streams, wetlands, canals, etc.).  Articles should focus on fully submerged or semi-aquatic moss and/or invertebrate species.  Articles in journals would be preferred, but easy-to-cite grey lit (e.g., USEPA technical reports) also would be appreciated -- anything that could stand in a soon-to-be-submitted manuscript that will have to pass through peer-review.  Also, any important literature citation on invertebrate-moss associations from other habitats (i.e., terrestrial), recent or historical, would be greatly appreciated.  Thanks a lot!
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Hi, the older experimental work showing impacts of suspended solids on moss fauna is here: Vuori K.-M. & Joensuu I. 1996: Impacts of forest draining on the macroinvertebrates of a small boreal headwater stream: do buffer zones protect lotic biodiversity ? -Biological Conservation 77, 87-95. Should be available on my RG site.  I,m also working with a manuscript on macroinvertebrates in altered and natural spring habitats with associated changes in bryophytes
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from intertidal rock of Karachi coast
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Hello Quddusi,
Sea anemones taxonomy is very difficult. It is based on external characters as well as internal characters and also the cnidom. Unfotunately, I was not able to see the image enlarged. It could be an acontiarian sea anemone, but you would have to dicover if it emits acontia when disturbed! Is this specimen alive? If so, try to do this using a small delicate brush on their tentacles!
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It was photographed at very shallow waters (the background algae is a species of Padina) of Mallorca Island (Mediterranean Sea) the body measures about 7 cm long.
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Olindias phosphorica...a jellyfish
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from the Caribbean
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K. Venkataraman: You may contact Dr Raghunathan of Zoological Survey of India in raghuksc@rediffmail.com.
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From Gulf of Mannar with a resident glass shrimp Ancylomenes sp. at a depth of 12 meters.
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You are welcome!
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They are collected from fouled structures at the southern caribbean
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Hi Maria
The above respondents are correct about seeking expert advice when it comes to bryozoan identifications because colony morphology is very unreliable for bryozoan identifications. Scanning electron microscopy of the zooid ultra-structures are essential for accurate diagnosis. Bryozoans from different ORDERS could have similar colony morphology! I would contact Judith Winston or perhaps Leandro Vieira who should be familiar with the regional bryzoan fauna. Below I have given my opinion but it should be treated conservatively because I don't have a good knowledge of the regional fauna.
Pic 1 - the redish crusts are potentially Watersipora and the white crusts are not legible enough to make any diagnosis (but these don't look like Membranipora)
Pic 2&3 - not legible enough but not Watersipora and I can see why Barnado suggests Schizoporella but can't be sure - The family Schizoporellidae is very diverse!
Pic 4&5 - both images look like the same species and I agree with Bugula  - from the colony colouration and morphology this could be Bugula neritina; a species that has been introduced to most known localities globally and commonly associated with harbours, ports or marinas.
Pic 6 - I'm not convinced this is a Bugula. There are a number of families that have this colony form but if I were to give an educated guess then I would say this species belongs to the family Candidae.
In closing I want to reiterate what Bernado said about examining the individual zooids - this is essential and therefore even educated guesses based on your images should be considered very very conservatively! Good luck
ps., also see www.bryozoa.net for all things bryozoan
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Can you identify young one of species of / genus?  Ophiothrix? collected form estuary, south west coast of India
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Sorry, looked at Picture only and missed sampling area. Ophiopholis is obviously not the right genus as it is limited to the Northern hemisphere. However, your specimen still reminds me of species within family Ophiactidae (to which genus Ophiopholis also belongs). Only gave picture of Ophiopholis aculeata as example for comparison. And please don’t call me ‘madam’, I am not 90 years old :-D.
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Sampled on the shallow waters of Admiralty Bay (King George Island, Western Antarctic Peninsula), max depth 90ft. (30m.)
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Hi
Eusiridae usually have way different claws (gnathopod 1 and 2), and Dexaminidae I'm used to also look different regarding the rear end. 
I attach an article of Epimeriidae from the Antarctic (Lorz and Brandt 2004), the most dominant Family in those waters.
Anyway, I hope you find out what family/ species it most probably belongs to, by using a key or sending it to a specialist. Let us all know when/ if you find out.
Regards, Halldis R.
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I want to know how the proteic values can influence predator's selectivity.
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Dear Riccardo,
I would like to recommend you the book "Production Hydrobiology" but fortunately it only in Russian. But I think you could write to Dr. Sergey Golubkov and Dr. Victor Bogatov who are the authors of this book and working for along time on trophic relationship in freshwater.
Best wishes,
Tatiana
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I am currently studying different species of starfish in Sogod Bay, Southern Leyte, Philippines as part of our Marine Biodiversity Project.
Please see attached picture.
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Apparently an ophidiasterid starfish, maybe Gomophia gomophia (Perrier 1875).
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I'm working on bioactivity of seaweeds. I have taken 5 kg amount of seaweed, extracted in the respective solvent, filtered and evaporated but I don't know that how much quantity of extracted material is required to isolate all compounds.
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It depends entirely on the type of extract you are looking for, what kind of activity, and detection limits of your equipment. Nevertheless, 5 kg is huge and should be more than enough for any compound.
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It is taken from the Red Sea at 20 m depth
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Looks like a corallimorpharian, family Discosomatidae (mushroom coral), but I could not find the species.
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I analysed some of my data from Caspian Sea basin. these data comprised form hard substrate of macrobenthic communities. I attached the results. in the attached file Time (1,2,3, and 4) represent season and Site (1 to 8) represent sampling sites.
anyone can help me to understand the results?
Thank you
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The SIMPER analysis calculates the contribution of each species (%) to the dissimilarity between each two groups.  It is calculated from the Bray-Curtiss dissimilarity matrix, the last two columns show the contributions for each species in descendant order, and it is accumulative.  For instance, the results compare first the invertebrate community composition between seasons across the different sites, and then between sites across the different seasons.   For example between seasons 1 and 2 the average dissimilarity of 40,3% indicates that the whole community differs in 40% between seasons 1 and 2.  The species with higher percentage are those who determine the group dissimilarity, in this case the first two species account for more than 50% of the dissimilarity of your groups 1 and 2, and if you consider the third species all of them will account together for more than 60%. Then, you should infer that species x y and Z are more typical from the season 1 or 2 maybe because they are comparatively more abundant for one of the seasons, also some of them could be absent for the other season.
Similarly, when you compare the community between sites (1 to 8) you will find there are some characteristic species accounting for differences between each pair of environments, maybe they are much more abundant in one environment than another.  Various of the average dissimilarities are rather low,  maybe the community is very similar across several environments,  although some dissimilarities are higher, such as between the sites 2 and 7 (51%)  with the first two species accounting for more than 70% of the dissimilarity
You can also run the analysis with the similarities instead of the dissimilarities and maybe you will find interest results to compare.
I hope it helps
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I surveyed 4 sites (A, B, C and D) during six times along a year. On each site I measured abundance in six sampling transects.  I have a total of 36 sampling units on each site.
Sites A and B are very impacted and sites C and D are reference with almost no human disturbance but topography is different A=C ≠ B=D (i.e. A and C present steep slope; B and D present gentle slope). I have 3 factors: Time (6 levels); Impact (2 levels) and Topography (2 levels). Data found to be normal and homocedastic. I´m interested in determining the relative contribution of Human disturbance and Topography to abundance variation of this species.
Is it possible lumping data together in order to perform two ANOVAS to determine the effect size attributed to each factor and then compare them?
I mean to perform a bifactorial ANOVA grouping data to compare Impact versus Reference sites and to calculate the effect size with its confidence intervals. To perform another bifactorial ANOVA grouping data to compare Gentle slope versus Steep slope and to calculate the effect size with its confidence intervals. Then comparing the effect size for each analysis in order to determine the relative contribution to variation of each factor
Note that: 1) variation due to time should be the same for both ANOVA; 2) in the first ANOVA the two sites on each level present different topography; 3) in the second ANOVA the two sites on each level present different disturbance.
  • If it’s not possible to do that, there is any other alternative to determine relative contribution of Impact and Topography to variations in abundance with this sampling design?
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I have a question. When you are mentioned that you made measures in six times along year, is these measures made at the same sites? If your reply is yes then you need to study the possibility to perform "repeated measures ANOVA". Additionally when you talk about slope, apparently the model is unbalanced since you can not obtain all the possible combinations between your factors. As marie mentioned in her answer you need to look the most important factors, this you can found using a variance contribution analyses.
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Your suggestions would be highly appreciable.
Thanks in advance.
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Hi,
For sorting purposes Rose Bengal is the best, but depends what  size fraction you have.  For identification, you could try a Methyl Blue stain. 
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Benthic realm and its biotic composition is highly important in glacio-marine fjords, specially when considering the cryosphere dynamics and the resulting phenomena (sedimentation, resuspension, freshwater influx, inter alia).
Also, in Antarctic seasonal bays (i.e. Mackellar Inlet  (King George Island, South Shetlands), where I've sampled macrobenthic communities for previous research (see: http://goo.gl/YOy16D)) pelagic realm also plays a key role in terms of primary production and its consequent influence on higher trophic levels.
It's certain that analysing the benthic composition is more predictive when trying to speculate future scenarios. I presumably assume that the Mackellar Inlet is mainly a benthic-controlled system. Nevertheless, in order to be sure of this hypothesis I should go further through an integrated analysis of both realms. 
The protocol that my colleagues usually execute is: macrobenthic survey (van Veen grab 0.05m2), collect plankton with plankton nets, and measure abiotic variables like temperature, pH, conductivity, turbidity and marine currents patterns (speed & direction).
I'd like to know if there's any specific protocol pointing straightforward to my question. What other measurements should I consider?
Thanks for the help. Cheers.
BSc. Bernabé Moreno
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I agree with the previous comments.  Stable Isoptopes can be very useful.  Carbon can be affected by methanogenesis, but particularly the sulfur signal can give some indication of benthic energy contributions, but you need to look at external and internal sources, isotope ratio of the various benthic infaunal species and nekton.  knowing the ecology of the organisms will help, such as filter feeding vs deposit feeding, benthic vs pelagic foraging by nekton (stomach contents and isotopes).  Is the system shallow and oxic enough for benthic photoautotrophy? any chance of looking at benthic oxygen (P/R) and nutrient fluxes?
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Can I have information or links on all information of (ecology, spatial distribution, and biology) of echinodermata of the Mediterranean sea?
- Biodiversity of echinodermata fauna.
- All research or articles of Paul Pallary.
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Thanks Fatima
Please, send these articles by mail
I have difficulties to download these documents from researshgate.
Sincerly
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The distribution of annelid species is based on what? Are there documents on this research?
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Have a look there:
QUIROZ-MARTINEZ, B., FRANÇOIS G. SCHMITT, F.G., DAUVIN, J.C., DEWARUMEZ, J.M., FOVEAU, A. & GARCIA, C.. Distribution patterns of annelid polychaetes species from the continental shelf (0-200 m) in the North Sea, English Channel, Irish Sea and Outer Bristol Channel. Italian Journal of Zoology 78(S1), 324- 332.
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