- Bert W Hoeksema added an answer:Is habitat complexity or live coral cover more related to reef fish abundance and diversity?While literature supports the live coral cover, field observations were contradictory as I observed dense reef fishes in an area which is scarce of live corals.
This may strongly depend on the fish and the coral species. Small fish can hide inbetween coral branches. Some small associated fish species (crypto-ichthyofauna) are host specific, like small gobies in Acropora corals. If the reef architecture is less complex, there will be more space for large fish. Then, it depends on whether these fishes are just temporary or territorial.Following
- Menakhem Ben-Yami added an answer:What were the causes of fish kills in your lakes, rivers, coastal waters and oceans?Fish kills can be defined as any sudden and unexpected mass mortality of wild or cultured fish over a short period of time. It could be due to pollution or contamination of waters or a combination of natural and human induced stresses in the environment. Climate change (rise of temperature) and projected increase in the frequency of algal blooms may also increase fish kills.
Fish kills can occur due to a number of reasons including the following: abrupt change of temperatures (winter fish kills/summer fish kills), accidental spills; acid mine drainage (AMD), acid sulfate soils (wetlands and floodplains), algal blooms (cyanobacteria, dinoflagellates), ammonia (NH3) toxicity, anoxia, black water events, bush fire ash, crowding, climate change (rise of temperature), cold water pollution, cold stress, dam operation, dissolved solids, diseases, droughts, environmental stress, eutrophication, floods, herbicides, high temperature stress, hydrogen sulphide (H2S) toxicity, hypoxia, life cycle event, low temperature stress, metals (toxic), municipal sewage, oil spills, nutrient pollution, overturn of lakes, pesticides, pH (low), parasites, power generation water discharge, red tide, salinity, spawning activities, toxins, turbidity, underwater explosions and upwelling.
Fish kills are very visible events which cause considerable interest and concern to the public. Fish kills could be an indicator of environmental stress, a declining of aquatic ecosystems health or water quality problems or water pollution or contamination of water etc.
Question: What were the causes of fish kills in your lakes, rivers, coastal waters and oceans?
Anoxy in the Sea of Galilee. Happens when due to upwelling of anoxic water caused by prolonged winds blowing offshore and pushing surface water layer away from the coast. MB-YFollowing
- Emiko K. Resende added an answer:In what way will invasive plant and animal species affect native animal fauna of the freshwater aquatic ecosystems?
Aquatic biodiversity is increasingly affected and declined through various factors including increasing of temperature due to climate change, anthropogenic effects, invasive species slowly adapted in a particular environmental condition and replaced native species etc.
Pantanal floodplain was invaded by asian clam, Limnoperna fortunnei, but due a natural oxygen depletion caused as a consequence of floodwater spread trough the plain and consequent terrestrial plant decomposition, a natural control is occuring preventing the overpopulation of this asian clam.Following
- Dan Minchin added an answer:What is the best way of sampling aquatic macroinvertebrates in crocodile infested rivers?I would not mind getting advice on sampling both in shallow and deep rivers in Africa.
Much depends on the invertebrates that you intend to study. However, remote sampling would be what I would consider but there may be problems with snagging on submerged objects such as waterlogged dead trees. Should the density of the invertebrates be high then sampling using a basket dredge or Van-Veen type grab might just be sufficient for your study. Diving may be an option under some circumstances but whether this something that you would be covered on your life -insurance policy is something else.Following
- Rukaiah Al-Ammar added an answer:Can anyone identify this freshwater phytoplankton?It co-occurred with Microcystis aeruginosa.
Its Dictyosphaerium sp.Following
- Sunil J Wimalawansa added an answer:What are the main factors responsible for self purification of rivers?Self purification of rivers is a natural process. What is the limit of pollution load of rivers to get self purified?
Very interesting topic and good answers. Rivers have been flowing for thousands or years; mostly in a sustainable manner. However, anthopogenic interventions can cause major problems to the fauna and flora though alternations of the quality of water. These alao dramatically affect not only all living creatures in the river, but also all water bodies supplied by this polluted river.
For example, when the levels of either phosphates or nitrogen, or both increase as runoff of fertilizer, reserviour water get hyper eutrophication. This is the commonest cause for dangerous algae blooms; some of th which produces toxins that can harm animals and humans. Basically we the human created most of these pollution and as a result we all suffer from unintended consequences.
Sunil Wimalawansa (email@example.com)Following
- Ssanyu Asiyo added an answer:How can we standardise the units of observed nutrients data in mg/l to kg/ha in the process of to calibrating SWAT model?SWAT model was set for nutrients analysis. We are at the point of calibrating the nutrient outputs using the observed data. The model NO3 and total phosphorus are given in kg/ha while our field observations of river nutrients N03 and total phosphorus are in mg/l. We have failed to reach a resolution on standardising the all values in the same units.Thank you PaulFollowing
- Joshua A. Israel added an answer:Does anybody know about the creation of artificial spawning grounds for fish below dams? Any case studies with or without success?Fish passage through large dams is usually a real problem. Creating spawning grounds below dams, using the water which comes out of the turbines might be a solution. I know about very few cases and wonder if there is a real experience in our community?Creating spawning habitat below dams is occurring for salmonids in tributaries to the Sacramento and San Joaquin rivers in California. This tends to occur below dams in lower elevation areas, outside of historic spawning areas. There remain limitations to their long term benefits due to warm water temperatures in the Fall when chinook salmon want to spawn, and fish passage may be another consideration in the long term for fish reaching spawning grounds with suitable water quality. Monitoring and research articles are available from this type of activity on the American River, Mokelumne River, and Merced River. You should be able to find it with a good search engine.Following
- Parviz Tavakoli-kolour added an answer:What things will increase the vulnerability of Kish Island coral reefs?See above.Dear elham,
some anthropogenic and natural stress affected Iranian coral reefs in Persian Gulf, coral reef condition of Kish Island is better than the other islands (Larak and Qeshm), Please take a look at Mohammadizadeh et al. (2013) coral reefs and community around Larak island (Persian Gulf) in my RG, and also Kavousi et al. (2011) in Zoological studies, vol. 50(3): 276-283.Following
- A. BANAOUI added an answer:When algae cells in the culture system are not in the exponential growth stage, how can we calculate the growth rate?As we known, in the exponential growth stage algal growth can be explained by an exponential equation. However, when algae cells in the culture system are not in the exponential growth stage and instead in the stationary stage or death stage, how can we calculate the growth rate?Enough explication given by Pr. frank
- Yuliya Vystavna added an answer:Heavy metals between sediment and water?I have analyzed the concentration of heavy metals in water as well as the intertidal sediment. I have not been able to find literature as to why the heavy metal content in sediment is more than the water. Can anyone help me? I would also like to know the permissible range for various heavy metals in marine water sample and sediment.I had the same problem. In our case heavy metals were deposited in the sediments and represented the 'historical pollution'. They were deposited during the period of the intensive industrial activity. At present time, after the significant reduction of the industrial wastewaters and run-off discharges, the sediments are still enriched in heavy metals, but the surface water shows the low level of the contamination. You can see in Vystavna et al. 2012 and Vystavna et al. 2013 publications, if you are interesting in it.Following
- Armando ORTEGA Salas added an answer:Sex-determination and primary sex ratios in non sex-changing gobies: do you have info?My lab and collaborating labs are working with issues related to sex role dynamics and operational sex ratios, based on studies of temperate gobies. In this context, we're looking for information on sex determination and primary sex ratios (i.e., egg sex ratios) in temperate (or other) non sex-changing gobies. Sex determination is, as many may know, highly variable in fishes but I haven't been able to detect information about how it works in gobies that don't change sex (which I believe most high-latitude gobies don't do). I'm also very curious about any info on sex ratios in eggs/embryos, provided that sex can be identified at this early stage in temperate gobies (I honestly don't know). I'm struggling to find relevant info via ISI or similar sources. Any advice on sources or other info greatly appreciated!
Best wishes.Look a t our papers: ). A. A. Ortega-Salas, H. Reyes-Bustamante & H.Reyes B. (2013). Sex reversal, growth, and Survival in the guppy Poecilia reticulala (Cyprinodontiformes: Poeciliidae) under laboratory conditions. Research Journal of the Costa Rican Distance Education University. ISSN: 1659-4266 Vol. 5(2), Diciembre, 2013.
A. A. Ortega-Salas, H. Reyes-Bustamante & H.Reyes B. (2013). Sex reversal, growth, and Survival in the swordtail fish Xiphophorus helleri (Cyprinodontiformes: Poeciliidae) in laboratory conditions. Research Journal of the Costa Rican Distance Education University. ISSN: 1659-4266 Vol. 5(2), Diciembre, 2013.Following
- Jose Jimenez added an answer:About the new legislation on invasive species in Spain: what is your opinion?The expected new Royal Decree regulating the Spanish Católogo Invasive Species was published this past Saturday August 3 in the BOE and as expected has not left anyone indifferent. Just enough to read expert opinions conservation scientists, environmentalists or fishing and hunting forums, to give just two examples.My opinion is...don't fix what isn't brokenFollowing
- Charlotte L Johansson added an answer:How true is it that turf algae prevents settlement of coral larvae?It is experimentally proved that turf algae in combination with sediment prevents the settlement of coral larvae. My field observations are contradictory to it. I observed lot of new recruits on hard substrate which has been covered with turf algae and sediment. Is there any other factor which could aid the settlement of coral larvae on a turf algal substrate?The spat also run the risk of being consumed when herbivores target the adjacent turf. Perhaps the success of the spat is only determined by luck..Following
- Fikrat Hassan added an answer:Does nitrogen concentration increase in a lake after the death of nitrogen fixing cyanobacteria?During nitrogen limitation periods, nitrogen fixing cyanobacteria fix atmospheric nitrogen. Nitrogen is stored in cyanobacterial cells, is there any study cases that document an increase in nitrogen concentration after the death or disappearance of nitrogen fixing cyanobacterial species?Many factors effects the nitrogen cycle in lake, one of these factors is Cyanophyceae blooming.Following
- Manohar Sehgal added an answer:Who methylates mercury in the open ocean water column?Methylmercury concentrations of up to a few hundred femtomoles have been measured in the oxic water column of various ocean basins [1-15]. Maximum concentrations are found in the oxygen minimum zones. Oxygen is consumed here by bacteria during the remineralization of sinking organic matter. Yet only anaerobic bacteria and archaea have been shown to be capable of methylating mercury .
1. Mason, R.P. and W.F. Fitzgerald, Alkylmercury species in the Equatorial Pacific. Nature, 1990. 347(6292): p. 457-459.
2. Mason, R.P. and W.F. Fitzgerald, Mercury speciation in open ocean waters. Water Air & Soil Pollution, 1991. 56(1): p. 779-789.
3. Mason, R.P. and W.F. Fitzgerald, The distribution and biogeochemical cycling of mercury in the Equatorial Pacific-Ocean. Deep-Sea Research Part I-Oceanographic Research Papers, 1993. 40(9): p. 1897-1924.
4. Cossa, D., J.M. Martin, K. Takayanagi, and J. Sanjuan, The distribution and cycling of mercury species in the western Mediterranean. Deep-Sea Research Part Ii-Topical Studies in Oceanography, 1997. 44(3-4): p. 721-740.
5. Mason, R.P., K.R. Rolfhus, and W.F. Fitzgerald, Mercury in the North Atlantic. Marine Chemistry, 1998. 61(1–2): p. 37-53.
6. Mason, R.P. and K.A. Sullivan, The distribution and speciation of mercury in the South and equatorial Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 1999. 46(5): p. 937-956.
7. Monperrus, M., E. Tessier, D. Amouroux, A. Leynaert, P. Huonnic, and O.F.X. Donard, Mercury methylation, demethylation and reduction rates in coastal and marine surface waters of the Mediterranean Sea. Marine Chemistry, 2007. 107(1): p. 49-63.
8. Cossa, D., B. Averty, and N. Pirrone, The origin of methylmercury in open Mediterranean waters. Limnology and Oceanography, 2009. 54(3): p. 837-844.
9. Sunderland, E.M., D.P. Krabbenhoft, J.W. Moreau, S.A. Strode, and W.M. Landing, Mercury sources, distribution, and bioavailability in the North Pacific Ocean: Insights from data and models. Global Biogeochemical Cycles, 2009. 23: p. 14.
10. Heimbürger, L.E., D. Cossa, J.-C. Marty, C. Migon, B. Averty, A. Dufour, and J. Ras, Methyl mercury distributions in relation to the presence of nano- and picophytoplankton in an oceanic water column (Ligurian Sea, North-western Mediterranean). Geochimica Et Cosmochimica Acta, 2010. 74(19): p. 5549-5559.
11. Cossa, D., L.E. Heimbürger, D. Lannuzel, S.R. Rintoul, E.C.V. Butler, A.R. Bowie, B. Averty, R.J. Watson, and T. Remenyi, Mercury in the Southern Ocean. Geochimica Et Cosmochimica Acta, 2011. 75(14): p. 4037-4052.
12. Lehnherr, I., V.L. St. Louis, H. Hintelmann, and J.L. Kirk, Methylation of inorganic mercury in polar marine waters. Nature Geosci, 2011. 4(5): p. 298-302.
13. Cossa, D., M. Harmelin-Vivien, C. Mellon-Duval, V. Loizeau, B. Averty, S. Crochet, L. Chou, and J.F. Cadiou, Influences of Bioavailability, Trophic Position, and Growth on Methylmercury in Hakes (Merluccius merluccius) from Northwestern Mediterranean and Northeastern Atlantic. Environmental Science & Technology, 2012. 46(9): p. 4885-4893.
14. Hammerschmidt, C.R. and K.L. Bowman, Vertical methylmercury distribution in the subtropical North Pacific Ocean. Marine Chemistry, 2012. 132–133(0): p. 77-82.
15. Wang, F., R.W. Macdonald, D.A. Armstrong, and G.A. Stern, Total and Methylated Mercury in the Beaufort Sea: The Role of Local and Recent Organic Remineralization. Environmental Science & Technology, 2012.
16. Parks, J.M., A. Johs, M. Podar, R. Bridou, R.A. Hurt, S.D. Smith, S.J. Tomanicek, Y. Qian, S.D. Brown, C.C. Brandt, A.V. Palumbo, J.C. Smith, J.D. Wall, D.A. Elias, and L. Liang, The Genetic Basis for Bacterial Mercury Methylation. Science, 2013.A humble argument from a student of chemistry where no excellence is proclaimed:
Chemically, the reactive form of Hg in auatic environments is Hg(II)[ Already very well established].
Methylation means the addition of methyl carbanion [ CH3(-)] so as to form [Hg(CH3)]^+.
In the aqutic conditions, SULPHATE REDUCING BATERIA have been identified as the most important Hg- METHYLATING ORGANISMS.
The COBALMIN BEING THE PRINCIPAL SOURCE OF METHYYL GROUP.
But Pls. let me continue with the argument.
It is also reported that all not all sulphate reducing bacteria methylate mercury. Studies show that more methyl mercury is produced when these bateria are growing fermentively than when they are reducing sulphate.
HOWEVER, SULPHATE ADDITION IS ALSO KNOWN TO STIMULATE METHYLATION UNDER LIMITING CONDITIONS.
So there can be a possibility that:
[I] At low sulphate, methylation is stimulated by sulphate addition as this enhances the activity of sulphate reducers but
[II] At high SULPHIDE concentrations, Hg bioavailability becomes limited by SULPHIDE COMPLEXATION which decreases the methylation rate. In many culture experiments, HgS precipitation occurs when the concentration of Hg is quite high.Following
- Tim Sandle added an answer:Isolation of Bacteria in Surface WaterI am looking for a good method to isolate bacteria that degrade pharmaceuticals in surface water. I am doing a study on degradation of neutral, basic and acid pharmaceuticals in waste water, river water and lake water.R3A agar is fairly effective for subculuturing, especially in making the transition from a low nutrient environment. R3A also helps with the recovery of isolates from R2A agar.Following
- Anne Watson added an answer:What is the best method for germinating propagules trapped using AstroTurf mats along river banks?I have used AstroTurf mats to trap propagules (seeds and vegetative fragments) deposited over winter along river banks. The propagules deposited on these mats will be used in a germination trial to assess abundance and species richness of viable propagules. I have reviewed the methods used in similar studies, such as those by Gurnell, Goodson, and Cockel. The authors in these various studies germinated propagules directly on the mat in a seedling tray, which in some instances was supplemented with sterile soil when needed. Other studies assessing sediment deposition and propagules wash the mats and germinate in seed trays.
As I am not assessing sediment is there any benefit to washing the mats prior to germination, so that they germinate in sterile compost rather than directly on the turf mats? I.e. Will it aid the germination of propagules?Dear Zarah
What you do depends on the question you are asking...if you want to know how hydrochory influences germination, then keep the mats intact and inundate them in trays. This presumes you were using the mats to duplicate the normal ground surface. How much water you use will also depend on your question. If you are looking for a flood response, then they should be completely covered, but how long you leave them for will depend on what the normal flood regime is for your study river.
Washing the mats could remove small seeds that may be important. I found that Astroturf mats trapped more small seeds than 'normal' litter traps. Once again - you really need to define the question you are askingFollowing
- John Gallagher added an answer:What is the difference between "carbon sequestration" and "net ecosystem production (NEP)"? Or are they the same?There are so many approaches to measure NEP (e.g. statistical, biogeochemical, remote sensing etc.). How is NEP associated to carbon sequestration?
Biologically fixed carbon could be retained by the system at a varying scale (from seconds to 1000s of years). Which one can be considered as real sequestration?I tackled this question in a chapter for a book in press the effects of climate change and aquaculture on subaquatic ecosystems blue carbon sequestration and storage
Its in aquaculture ecosystems wiley blackwell ed Mustafa S. And I'm currently writing a paper about the intrinsic assumptions in blue carbon research that is relevant to definitions it will first be in ICOMSA 2014 proceedings as one of the keynote addresses. It has to be in by the end of June , so watch that space.
Yes the literature at times is confusing here is my take.
First, when you see NEP net ecosystem production substitute NCP net community production which is the excess production from the ecosystem at its landscape scale. Even in the papers headed by the major researchers in blue carbon (Duarte et al 2005) these twi terms have been interchangeable betWeen the figures and the txt just to confuse you. NECP is another term used it is the net ecosystem community production. This is not like the NCP and NEP. The NECP removes the production exported from the ecosystems landscape, the NCP and NEP is inclusive of the material exported from the ecosystems landscape.
I think things can be made clearer by the following equations
NCP = GPP - cR i.e. Gross primary production of plant and the community respiration, the plant s and animals, microflora
NPP = GPP - pR i.e. The plant respiration
NECP = (GPP - cR - E ) = S. Where E is the amount exported S the amount stored in the ecosystems landscape unit.
Often to measure one or the other production values it is necessary to substitute one form each equation, depending on the method of measurement.
In the last equation is is assumed that all the exported carbon is respired so the NECP is very much smaller than the NCP the excess production of the ecosystem stored in biomass and sediments and the detrital material exported, which may may not be mineralised back to the surface waters. The latter is something I discuss in the chapter and paper
Hope this clears things up for youFollowing
- Levent Artüz added an answer:Can anyone help me identify this organisms?I have many doubts. The sample is from about 170 m depth, and was retained on a sieve of 63 um (it is meiofauna). Any idea about the family or genera?Following
- Andreas Kunzmann added an answer:What methodologies have you applied to estimate the tourism carrying capacity in underwater SCUBA diving trails of marine protected areas?Recently, a number of different approches have been proposed to estimate the carrying capacity of SCUBA divers in MPA. However, methodologies and their analysis may give a number of results depending on the characteristics of the marine environment and the factors taken into consideration. There is some published research but still I beleive some other valuable work and points of view should be taken into consideration.I suggest that you get in contact with some international NGOs about that. TNC and CI are involved in this kind of studies. Also the CTI network should be able to help you.Following
- Andrey V. Dolgov added an answer:What types of weights do you use on board research vessels at the sea?I need some information on weights for marine investigations. Can you inform me - what types of weights do you use aboard research vessels at the sea? Are there any weights with resolution 0.1 g or higher? We used Pols with such resolution long time at PINRO, but now Pols is not exist. I will grateful if you can provide model name and producer (and site where it will be possible to see it).thank you again! We tried to buy similar model in MAREL, but this model is not in the list on the MAREL site now. Probably we need to contact to MAREL representative on this model. Thank you!Following
- Robert S. Prezant added an answer:Would the gustatory preference serve as a factor when a predator chooses its prey?During one of the discussions in our ecology class, we got to talk about the influence of the intertidal snail, L. littorea, on the structure of the algal community. It serves as a keystone species, which preys upon the green algae and prevents the competitive displacement of the red algae. It allows the co-existence between two different species, which helps in maintaining the biodiversity and organization in the marine environment. I was just wondering, is it possible for the intertidal snail to have a gustatory preference, which could be another factor as to why it chooses to prey on green algae rather than red algae? Would this hold true for other species?
Literature is dominated by studies that discuss "preference" in predator-prey interactions. Dominance of particular species within a given habitat can, of course, reflect long term evolutionary trends but in many cases those "trends" can lead to less desirable prey. Preference, in a sense, can then yield repulsion. That is, potential predators will reject or avoid even some dominant organisms because of anti-predator secretions (or toxins). Often these inhibitory substances are packaged in "carriers", such as glycoproteins or mucopolysaccharies (i.e. mucus) that are not revealed until tasted; other times potential prey can release secondary metabolites or allelochems that influence potential predators gustatory preference (thus, really inhibiting predation) thus yielding "co-existence".Following
- David Beaune added an answer:Looking for expert in Coral reef aquaculture for knowledge sharing..I had a plan for start coral transplantation in aquarium environment..i had try so many mainstream idea, but it like doesn't work..need advice :(What species do you want?Following
- João Pedro Barreiros added an answer:Does anyone have any information about the African halfbeak Hyporhamphus picarti (Actinopterygii, Hemiramphidae) in the Mediterranean Sea?I wonder if this species has been described in the Mediterranean lagoons or coastal areas.Dear João
Never saw around here. In fact not a single species of Hemiramphidae was detected in the Azores so far. Latest check-list is from 2010.
- J.H. Martin Willison added an answer:How can I study the diatom by EM?Study and identification of algae.I think the document at the following source should provide you with all the information you need:
- Abinandan Sudharsanam added an answer:Can anyone identify this cyanobacteria? These are observed in the allen and nelson enrichment media..Tried these with axenic condition ??Following
- Antonio Camacho added an answer:Is there a special name for the aquatic environment of a pond or lake which is under the ice?I'm looking for the term analogous to "subnivean." Now I know if I read that question, I'd answer it by saying, "really cold water", but I'm looking for something a bit more scientific than that!I suggest using the word subglacial as a general rule. Lakes permanently covered by ice, such as the case of Lake Vostok in Antarctica, as many others, are referred as such. Maybe the problem would be when the ice-cover is not permanent, then this term can be confuse, so for those case may be using "temporally ice-covered lakes (or ponds)" could be more convenient. Morever, "melting ponds" is a name that has been widely used, for example, to name ponds that are formed over icefields (or icepacks) such as those covering polar seas, though they represent liquid-water bodies over the ice.Following
- Edward Howard James Morrison added an answer:Can anyone identify this wetland plant please?Found in Kenya/East Africa.Hi all,
Many thanks indeed for the generous responses and my sincere apologies for the hideous delay in my acknowledging them; I have to admit I'd entirely forgotten I'd posted the picture and request on RG.
I believe it is indeed M. aquaticum and am very grateful for your contributions and insights!
About Aquatic Ecosystems
marine and freshwater aquatic ecology and hydrobiology