You can edit almost every page by Creating an account. Otherwise, see the FAQ.

Baltic Sea Food Web

From EverybodyWiki Bios & Wiki





The Baltic Sea is a relatively young mediterranean sea of the Atlantic Ocean. It developed during the last ice age. Due to high fresh water input and only a small connection to the North Sea, its salinity is rather low compared to other marine environments and eventually the water shifted from marine to brackish water. As a result of multiple changes in Baltic Sea water since the last ice age being fresher or more marine, the environmental conditions were not stable enough to develop a high biodiversity in flora and fauna evolutionary (“stability-time hypothesis”)..[1]. The relatively low species number in the Baltic Sea compared to other oceans leads to a relatively simple marine food web structure making the Baltic Sea particular suitable for food web studies of marine ecosystems. The Baltic Sea represents one of the best studied marginal seas in the world and seems to fulfill the requirements for data availability to generate food web models. Additionally, compared to a fully marine ecosystem, there are fewer trophic links to be analyzed in the Baltic Sea due to its low biodiversity. Nevertheless, the influence of abiotic and biotic interactions varies spatially and temporally in the Baltic Sea which adds a high degree of complexity to the food web dynamics[2].

General aspects[edit]

Compared to other ocean basins, the Baltic Sea is very small; nevertheless, it consists of several large basins which are separated by sills, a high fresh water input creates a pronounced salinity gradient with higher salinity in the north-western Baltic Sea to almost fresh water in the north-eastern Baltic Sea. Within its sub-basins, different food web structures developed caused by a different community composition within the sub-basins[3]. These differences are induced mainly by the salinity gradient. Other processes influencing the food web structure are for example the spreading of oxygen minimum zones (affecting especially the benthic zone), global warming, or human perturbations like fishery, eutrophication or marine pollution (environmental stressors). The three major basins are the Baltic Proper with excess to the North Sea via the Kattegat and Skagerrak, the Bothnian Sea and the Bothnian Bay in the northern Baltic. The Bothnian Bay is characterized by low salinity, high terrigenous input of dissolved organic carbon (DOC), mainly via rivers and is generally considered an oligotrophic system with low phosphorus concentrations. The adjacent Bothnian Bay shows intermediate salinity and is characterized as mesotrophic as the Baltic Proper the southernmost basin with the highest salinity of the three basins. Through this south-north gradient of salinity and nutrient availability the species diversity declines towards north and the composition of the species present changes. Additionally, the magnitude of energy and material flow through the food web differs between the basins[4]. In general, primary production and utilization of nutrients as an energy source dominate in the pelagic zone. This energy can reach benthic organisms passively by sedimentation or can be taken up actively by the benthos, for example during suspension feeding[5] (for more details about the connection between the pelagic and the benthic food web see benthic-pelagic coupling). The Baltic Sea is inhabited by many generalist species, meaning that they can occupy a relatively wide range of ecological niches. The low species richness makes the Baltic Sea especially sensitive to environmental stress. The removal of a species due to local or global extinction can have a more pronounced effect in the species poor Baltic Sea compared to other marine environments with higher diversity, because its ecological function may not be provided by multiple other species[6]. Changes in the species composition will eventually affect the Baltic Sea food web.

Carbon flow[edit]

The description of food web structures can be used for better understanding prey-predator interactions and the flow of carbon in spatial separated ecosystems like the Baltic Sea. The food web structure and processes within the food web can be analyzed quantitatively by estimating the carbon flow within the carbon cycle, which describes the flow of organic matter, and therefore energy flow through the organisms. Nutrients such as nitrogen and phosphorus are of interest as well, since a relative shortage of this nutrients compared to carbon can affect primary production, and hence, the consumer by limiting for example the growth of zooplankton. As a feedback, the relative recycling of these nutrients may limit the primary production[7]. The decline of species diversity towards the north of the Baltic Sea and the shift of the species composition of the community result in different storage strategies and flow patterns of carbon, nitrogen and phosphorous, which can be influenced by e.g. nutrient availability and predation intensity. This results in differences in food web structures and biochemical flow pattern within the Baltic Sea from south to north. Network analysis provides tools to bring concepts such as species richness and biodiversity together to analyze ecosystems as a number of compartments (e.g. bacteria, mesozooplankton, pelagic producers, etc.), which are interconnected by flows of energy and matter from one compartment to another. To estimate the carbon flow within a food web, the requirement for a mass balance of a steady state for each compartment have to be fulfilled. Therefore, the consumption has to equal the production.

The carbon flow in the food webs of the three northernmost sub-basins of the Baltic Sea is estimated to be the highest in the Baltic Proper (due to high nutrient levels and more saline environment), relatively lower in the Bothnian Sea and lowest in the Bothnian Bay (due to low nutrient availability and low salinity). The mass balance for this three major basins of the Baltic Sea deviates from steady state, which means that the incoming energy does not equal the outgoing energy[8]. Consumption, production, respiration and flow to detritus show highest values in the Baltic Proper, followed by intermediate values for the Bothnian Sea and lowest values in the Bothnian Bay, which is reflected the far lower biomass in the Bothnian Bay and the overall trend of decreasing biomass from south to north in the Baltic Sea, e.g. fish catches decrease progressively from Baltic Proper to Bothnian Bay[9]. Concerning the food web structure, the average trophic level is very similar among the three basins for comparable compartments of the food web. Some differences are for example a higher average trophic level for meiofauna in the Bothnian Bay and a lower average trophic level of demersal fish for the Gulf of Bothnia[10]. These changes might occur due to the different dominance of a species within a food web compartment when the overall biodiversity decreases from south to north, and not only to differences in the species’ diet.

The input of carbon for primary producers though dissolved organic carbon (DOC) and sediment exceeds all outflow of carbon for each of the compartments of the food web. That means, the requirements for a steady state are not fulfilled and a considerably accumulation of carbon will take place. In the Baltic Proper 45g C/(m2 * yr), in the Bothnian Bay 25g C/(m2 * yr), in the Bothnian Sea 18g C/(m2 * yr) were not consumed by any organism in the pelagic zone[11]. Additionally, a considerably accumulation of carbon in the sediment is assumed[12], even though there is no evidence of such high accumulation of organic matter in the Baltic Sea today by field data. The differences in carbon flow between the basins might be influenced by different carbon contents in marine and limnic organisms and the high input of organic matter in the Bothnian Bay by river discharge. Nevertheless, the steady state requirement is not fulfilled in these estimations, maybe due to an underestimating of the microbial loop and missing intermediate trophic levels (e. g. heterotrophic nanoflagellates for the microheterotrophic compartment), which can lead to the imbalance in this model. Thus, higher bacterial consumption of DOC and higher consumption of primary producers by zooplankton would lead to higher respiration, which presumably would be enough to take up the surplus of carbon in the pelagic zone and balance the flow of carbon in the Baltic Sea food web.

In a more complex model, more food web compartments can be added (e. g. the microbial food web with pools of DOC, virus, bacteria, flagellates and microzooplankton)[13]. In addition, the fish community can be depicted more in details, which in total leads to a more complex structure of the food web, but allows a more realistic estimation of basin-wide carbon flow that might fulfill mass balance requirements[14]. In order to fulfill the steady state requirements for the mass balance approach, the bacterial production have to be lower in the Bothnian Bay and Bothnian Sea and increase in the Baltic Proper[15]. The supply of autochthonous particulate organic carbon (POC) is highest in the south and decreases towards the north[16]. Respiration seems to be the highest loss factor from the pelagic food webs in all basins, followed by sedimentation. The respiration of bacteria exceeds 50% of the total respiration in the Bothnian Sea and Bothnian Bay[17], which highlights the increase of relative importance of the microbial food web from south to north in Baltic Sea. The sensitive analysis shows that an increase in bacterial production results in an increase in zooplankton, which declined relatively from south to north. The relative differences in bacterial production between the basins lead to differences in carbon flow between the basins. The flow of POC from primary production to the classic food chain and the microbial food web is similar among the basins, but the demand for POC from primary production decreased towards north. Therefore, the relative importance of total DOC in relation to other carbon sources increases towards the north[18].

Top-down control[edit]

Among other, top-down effects are important forces to control the abundance and the biomass of Baltic Sea species. It cascades down the trophic levels from piscivorous fish to phytoplankton: piscivorous fishes control the abundance and species composition of planktivorous fishes, that control the abundance and species composition of zooplankton, that controls phytoplankton. This control happens through the direct effect of predation, but other effects like bottom-up control e. g. by nutrient availability, abiotic pressures like the salinity gradient in the Baltic Sea or seasonally and long-scale variations in temperature are important as well. Through this cascade of top-down control, there exist a strong coupling between fishes with high trophic positions and lower trophic positions, that can vary in its strength of predation pressure. For example, due to the special salinity conditions in the Baltic Sea, predators like cod or sprat can vary in their importance spatially. In the Baltic Sea, the main piscivores are humans (due to fishery) and seals, the main piscivorous fishes are cod and salmon with different abundances in different sub-basins, the main planktivorous fishes are herring, sprat, smelt and stickleback and the main zooplankton taxa are calanoid copepods, cladoerans and rotifers[19]. In general, the Baltic Sea is a planktivorous dominated system with herring as the main planktivorous predator. The most important piscivorous fish in the Baltic Sea is cod. Its most important prey items are herring and sprat, but cod is the main predator for clupeids as well[20]. Together with oceanographic conditions, it controls the biomass of clupeids via top-down control. In addition, clupeids and other planktivorous fishes are feeding on cod eggs, resulting in a depression of clupeids during an increase in cod stocks and a depression of cod stocks during an increase in clupeid abundance[21]. Cods feeding on clupeids reducing the predation pressure on their own eggs at the same time. As a result, the system can shift from a clupeid-dominated to a cod-dominated system. The selectivity of planktivorous organisms like herring, clupeids and mysids control the abundance and the species composition of zooplankton: An increase in planktivory correlates with a decrease in zooplankton biomass[22]. In addition, this top-down predation pressure can alter the behaviour of the zooplankton; for example, the copepod Eurytemona performs a diel vertical migration to avoid predation by clupeids. The quantitative determination of top-down processes is still under discussion because a large number of interactions are involved in modulating the biomass of a species: not only predation, but as well competition, mortality, cannibalism, oceanographic conditions and seasonal variations.

Benthic-pelagic coupling[edit]

In most food web studies of the Baltic Sea the benthic and the pelagic component of the food web are investigated separately. But for understanding the realised energy flow and transfer of organic matter it becomes necessary to study the coupling of these components as well. A quantification of transfer from benthic to pelagic energy and biomass is difficult, but recent studies have shown that stable isotope analysis can be used for identifying the energy source. With these studies it is possible to estimate that 30-70% of energy (depending on the sub-basin) in the pelagic system ultimately derived from the benthic environment[23]. The coupling probably is the strongest in shallow waters due to the higher porximity of the benthic and the pelagic compartment of the food web, so its influence on the Baltic Sea food web can assumed to be relatively high compared to other ocean basins. Energy and organic matter flow from the pelagic to the benthic food web happen though settlement of pelagic biomass on the sea floor as fecal pellets, sloppy feeding or sinking of dead organisms, providing an energy source for benthic organisms. On the other hand, energy and organic matter can flow from the benthic to the pelagic food web though active movement of organisms (seasonal or daily migration or ontogenetically) like mysids or amphipods which act as important linkers between the benthic and pelagic component of the food web, or passively through resuspension of benthic material. Some predators like herring can perform prey switching: herring can shift from the benthic to the pelagic habitat for feeding[24]. Due to the key position of herring in the Baltic Sea food web, the benthic energy can propagate through the pelagic food web via predation of herring by e. g. seals, birds and piscivorous fishes. Therefore, herring act as a vector for benthic energy. Due to the coupling of the benthic and the pelagic environment, the spreading of oxygen minimum zones in the Baltic Sea not only influences benthic organisms. Depending on the diversity of diet and the energy source of pelagic organisms, it can as well influence the pelagic community severely and modulate the strength of benthic-pelagic coupling spatially due to reduction of benthic organisms as an energy source[25]. For example, herring that can feed opportunistically on nektobenthos shows a reduced growth rate when feeding on planktonic organisms only[26]. Due to the central position of herring in the Baltic Sea food web, this lower uptake of energy compared to a benthic diet influences other pelagic organisms that feed on herring as well.

Changes in food web structure[edit]

Fishery[edit]

Commercial fishery can cause immense perturbations in the Baltic Sea food web structure. Fishery acts as a top-down control of the trophic chain with humans acting as highly selective piscivores. Fishery can amplify or attenuate natural fluctuations in Baltic Sea fish communities, e. g. by the reduction of cod stocks, and therefore creating a lack of piscivorous predators, leading to a community shift towards clupeid species and herring and a general dominance of planktivorous fish in the Baltic Sea[27]. To compensate for the reduction in fish stocks, fishery management is performed by gear restrictions, catch quotas and stock enhancement[28]. Hence, large-scale stocking programmes in the Baltic Sea released several million salmon, sea trouts and whitefish and several hundred thousand rainbow trouts so far to compensate for reduced spawning areas and to restore the fish community[29].

Invasive species[edit]

Species invasion is a global issue that is enhanced by progressing globalization. In the marine realm, especially shipping traffic causes increasing number of invasive species in marine habitats due to ballast water release or attachment of species on the outside of vessels. Due to the Baltic Sea's geography, invasive species can even have a higher effect in the Baltic Sea compared to the open ocean: surrounded by land masses, which cause a relatively high input of terrestrial material and only a limited natural exchange with the open ocean through the Skagerrak, the Baltic Sea is limited in its capacity to cope with perturbations[30] A prominent invader in the Baltic Sea is the ctenophore Mnemiopsis leidyi that is known to be invasive in the Black Sea since the 1980s. The first time it was recorded in the western Baltic Sea in 2006 and spread towards the east during its planktonic life stage. It is mainly feeding on early life stages of commercially important fishes like cod and sprat, but occasionally it feeds on zooplankton as well. Especially cod is one of the top predators in the Baltic Sea. So, a reduction of cod stocks due to predation and competition for food resources with M. leidyi has not only negative impacts on commercial fishery but directly influences the Baltic food web[31]. The reduction in cod abundance releases predation pressure from its prey, that is mainly consisting of molluscs and planktivorous fishes. The decrease in biomass of a top predator like cod could lead to a shift of the food web initiated by higher trophic levels and propagates to lower trophic levels.

Another example for an invasive species altering the Baltic Sea food web is the cladoceran crustacean Cercopagis pengoi, which originates from the Ponto-Caspian region but arrived in the Baltic Sea in the 1990s and established permanent populations in several basins[32][33][34]. It mainly feeds on micro- and mesozooplankton, and thereby competes with young herrings and other pelagic fishes like smelt and sprat. The competition is especially high in summer and autumn when C. pengoi is the most abundant. The signature of the stable isotope δ15N can be used as an indicator for the trophic position of a species, because it is enriched of about 3.4‰ relative to its respective diet. The analysis of δ15N of young herrings has shown an increase from 2.6‰ before the invasion of C. pengoi to 3.4‰ after the invasion[35]. C. pengoi shows lower δ15N which indicates a shift in the herring’s diet from mainly copepods and native cladocerans to predation on C. pengoi as well. The trophic position of a species is directly linked to energy gain and flow. Herring and other pelagic fishes occupy a central position in the Baltic Sea food web so a change in their diet from mainly mesozooplankton to mesozooplankton and C. pengoi can influence large parts of the food web. But because C. pengoi is not only prey for herring and other planktivorous fishes but as well a potential competitor for food, the changes in the Baltic Sea food web caused by its invasion is still under discussion[36]

References[edit]

  1. Sanders, H. L. (1968). "Marine benthic diversity". The American Naturalist. 925: 234–282.
  2. Sandberg, J., Elmgren, R., Wulff,F. (2000). "Carbon flow in Baltic Sea food webs: a re-evaluation using a mass balance approach". Jurnal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  3. Elmgren, R. (1984). "Trophic dynamics in the enclosed, brackish Baltic Sea". Rapp PV Reun Cons Int Explor Mer. 183: 152–169.
  4. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  5. Elmgren, R. (1984). "Trophic dynamics in the enclosed, brackish Baltic Sea". Rapp PV Reun Cons Int Explor Mer. 183: 152–169.
  6. Elmgren, R. (1984). "Trophic dynamics in the enclosed, brackish Baltic Sea". Rapp PV Reun Cons Int Explor Mer. 183: 152–169.
  7. Sterner, R.W., Hessen, D.O. (1994). "Algal nutrient limitation and the nutrition of aquatic herbivoures". Annu. Rev. Ecol. Syst. 251: 1–29. doi:10.1146/annurev.es.25.110194.000245.CS1 maint: Multiple names: authors list (link)
  8. Sandberg, J., Elmgren, R. and Wulff, F. (2000). "Carbon flows in Baltic Sea food webs—a re-evaluation using a mass balance approach". Journal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  9. Sandberg, J., Elmgren, R. and Wulff, F. (2000). "Carbon flows in Baltic Sea food webs—a re-evaluation using a mass balance approach". Journal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  10. Sandberg, J., Elmgren, R. and Wulff, F. (2000). "Carbon flows in Baltic Sea food webs—a re-evaluation using a mass balance approach". Journal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  11. Sandberg, J., Elmgren, R. and Wulff, F. (2000). "Carbon flows in Baltic Sea food webs—a re-evaluation using a mass balance approach". Journal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  12. Sandberg, J., Elmgren, R. and Wulff, F. (2000). "Carbon flows in Baltic Sea food webs—a re-evaluation using a mass balance approach". Journal of Marine Systems. 25 (3–4): 249–260. doi:10.1016/S0924-7963(00)00019-1.CS1 maint: Multiple names: authors list (link)
  13. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  14. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  15. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  16. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  17. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  18. Sandberg, J. (2007). "Cross-ecosystem analyses of pelagic food web structure and processes in the Baltic Sea". Ecological Modelling. 201 (3–4): 243–261. doi:10.1016/j.ecolmodel.2006.09.023.
  19. Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  20. Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  21. Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  22. Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  23. Kiljunen, M., Peltonen, H., Lehtiniemi, M., Uusitalo, L., Sinisalo, T., Norkko, J., Kunnasranta, M., Torniainen, J., Rissanen, A. J., Karjalainen, J. (2020). "Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs". Limnology and Oceanography. 65 (8): 1706–1722. doi:10.1002/lno.11413.CS1 maint: Multiple names: authors list (link)
  24. Kiljunen, M., Peltonen, H., Lehtiniemi, M., Uusitalo, L., Sinisalo, T., Norkko, J., Kunnasranta, M., Torniainen, J., Rissanen, A. J., Karjalainen, J. (2020). "Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs". Limnology and Oceanography. 65 (8): 1706–1722. doi:10.1002/lno.11413.CS1 maint: Multiple names: authors list (link)
  25. Kiljunen, M., Peltonen, H., Lehtiniemi, M., Uusitalo, L., Sinisalo, T., Norkko, J., Kunnasranta, M., Torniainen, J., Rissanen, A. J., Karjalainen, J. (2020). "Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs". Limnology and Oceanography. 65 (8): 1706–1722. doi:10.1002/lno.11413.CS1 maint: Multiple names: authors list (link)
  26. Arrhenius, F., Hansson, S. (1993). "Food consumption of larval, young and adult herring and sprat in the Baltic Sea". Marine Ecology-Progress. 96: 125–137. doi:10.3354/meps096125.CS1 maint: Multiple names: authors list (link)
  27. ] Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  28. ] Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  29. ] Rudstam, L. G., Aneer, G., Hildén, M. (1994). "Top-down control in the pelagic Baltic ecosystem". Dana. 10: 105–129.CS1 maint: Multiple names: authors list (link)
  30. Caddy, J. F. (1993). "Toward a comparative evaluation of human impacts on fishery ecosystems of enclosed and semi‐enclosed seas". Reviews in Fisheries Science. 1 (1): 57–95. doi:10.1080/10641269309388535.
  31. Haslob, H., Clemmesen, C., Schaber, M., Hinrichsen, H. H., Schmidt, J. O., Voss, R., Kraus, G., Köster, F. W. (2007). "Invading Mnemiopsis leidyi as a potential threat to Baltic fish". Marine Ecology Progress. 349: 303–306. doi:10.3354/meps07283.CS1 maint: Multiple names: authors list (link)
  32. Ojaveer, H., Lumberg, A. (1995). "On the role of Cercopagis pengoi (Ostroumov) in Pärnu Bay and the part of the Gulf of Riga ecosystem". Proc. Esionian Acad. Sci. Ecol. 5 (112): 20–25.CS1 maint: Multiple names: authors list (link)
  33. Gorokhova, E., Aladin, N., Dumont, H. (2000). "Further range extensions of Cercopagis genus (Crustacea, Branchiopoda, Onychopoda) with notes on taxonomic composition and ecology". Hydrobiologia. 429: 207–218. doi:10.1023/A:1004004504571.CS1 maint: Multiple names: authors list (link)
  34. Bielecka, L., Zmijewska, M. I., Szymborska, A. (2000). "A new predatory cladoceran Cercopagis (Cercopagis) pengoi (Ostroumov 1891) in the Gulf of Gdańsk". Oceanologia. 42 (3).CS1 maint: Multiple names: authors list (link)
  35. Gorokhova, E., Hansson, S., Höglander, H., & Andersen, C. M. (2005). "Stable isotopes show food web changes after invasion by the predatory cladoceran Cercopagis pengoi in a Baltic Sea bay". Oecologia. 143 (2): 251–259. doi:10.1007/s00442-004-1791-0. PMID 15688211.CS1 maint: Multiple names: authors list (link)
  36. Gorokhova, E., Hansson, S., Höglander, H., & Andersen, C. M. (2005). "Stable isotopes show food web changes after invasion by the predatory cladoceran Cercopagis pengoi in a Baltic Sea bay". Oecologia. 143 (2): 251–259. doi:10.1007/s00442-004-1791-0. PMID 15688211.CS1 maint: Multiple names: authors list (link)


This article "Baltic Sea Food Web" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Baltic Sea Food Web. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.