Predation control of zooplankton dynamics: a review of observations and models
Daewel, U. ; Hjoello, S.S. ; Huret, M. ; Ji, R. ; Maar, M. ; Niiranen, S. ; Travers-Trolet, M. ; Peck, M.A. ; Wolfshaar, K.E. van de - \ 2014
ICES Journal of Marine Science 71 (2014)2. - ISSN 1054-3139 - p. 254 - 271.
central baltic sea - sprat sprattus-sprattus - southern benguela system - individual-based models - large marine ecosystem - mussel mytilus-edulis - planktonic food-web - long-term dynamics - early-life stages - north-sea
We performed a literature review to examine to what degree the zooplankton dynamics in different regional marine ecosystems across the Atlantic Ocean is driven by predation mortality and how the latter is addressed in available modelling approaches. In general, we found that predation on zooplankton plays an important role in all the six considered ecosystems, but the impacts are differently strong and occur at different spatial and temporal scales. In ecosystems with extreme environmental conditions (e.g. low temperature, ice cover, large seasonal amplitudes) and low species diversity, the overall impact of top-down processes on zooplankton dynamics is stronger than for ecosystems having moderate environmental conditions and high species diversity. In those ecosystems, predation mortality was found to structure the zooplankton mainly on local spatial and seasonal time scales. Modelling methods used to parameterize zooplankton mortality range from simplified approaches with fixed mortality rates to complex coupled multispecies models. The applicability of a specific method depends on both the observed state of the ecosystem and the spatial and temporal scales considered. Modelling constraints such as parameter uncertainties and computational costs need to be balanced with the ecosystem-specific demand for a consistent, spatial-temporal dynamic implementation of predation mortality on the zooplankton compartment.
Early Detection of Ecosystem Regime Shifts: A Multiple Method Evaluation for Management Application
Lindegren, M. ; Dakos, V. ; Groger, J.P. ; Gardmark, A. ; Kornilovs, G. ; Otto, S.A. ; Mollmann, C. - \ 2012
PLoS ONE 7 (2012)7. - ISSN 1932-6203
central baltic sea - early-warning signals - catastrophic shifts - marine ecosystems - leading indicator - slowing-down - climate - dynamics - time - reorganization
Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Using real monitoring data of a key ecosystem component, we here apply multiple early-warning indicators in order to assess their ability to forewarn a major ecosystem regime shift in the Central Baltic Sea. We show that some indicators and methods can result in clear early-warning signals, while other methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face of ecosystem change.
Dietary overlap between the potential competitors herring, sprat and anchovy in the North Sea
Raab, K.E. ; Nagelkerke, L.A.J. ; Boeree, C. ; Rijnsdorp, A.D. ; Temming, A. ; Dickey-Collas, M. - \ 2012
Marine Ecology Progress Series 470 (2012). - ISSN 0171-8630 - p. 101 - 111.
engraulis-encrasicolus l. - central baltic sea - clupea-harengus - feeding-behavior - intraguild predation - trophic interactions - population-dynamics - mediterranean sea - fish eggs - irish sea
European anchovy Engraulis encrasicolus increased its abundance and distribution in the North Sea during the mid-1990s and may consume similar zooplankton to and/or compete with other occupants of the North Sea like herring Clupea harengus and sprat Sprattus sprattus. The diets of adult anchovy, sprat and juvenile herring of comparable sizes, sampled close in time and space, were compared to understand how the 3 species prey on zooplankton and establish whether their diets overlap or not. Anchovy was found to be more generalist, consuming a higher diversity of prey items. Herring was more specialized, with low diversity of food items. Sprat was intermediate between anchovy and herring. The dietary overlap between anchovy and sprat was highest, followed by herring and sprat before anchovy and herring. The mean weight of stomach contents did not differ between species. We conclude that of the 3 species, anchovy is likely to be the least affected by changing plankton communities.
Effects of temperature and population density on von Bertalanffy growth parameters in Atlantic herring: a macro-ecological analysis
Brunel, T.P.A. ; Dickey-Collas, M. - \ 2010
Marine Ecology Progress Series 405 (2010). - ISSN 0171-8630 - p. 15 - 28.
cod gadus-morhua - clupea-harengus-harengus - central baltic sea - climate-change - north-sea - marine fish - dependent growth - body condition - top-down - size
The effect of temperature and population density on the growth of Atlantic herring Clupea harengus was studied using a comparative approach applied to 15 North Atlantic populations. The von Bertalanffy (VB) equation was applied to describe mean growth of individuals in each population, both averaged over the whole period studied and for each cohort. Water temperature was a determinant factor for herring growth at the species level: North Atlantic herring in cold water areas exhibited a lower growth coefficient (k), longer lifespan and a higher asymptotic weight (winf) than those living in warmer water. The average winf of herring was positively correlated to the density of biomass of that population. This relationship was most likely due to the negative correlation found between population density and mean temperature. At the within-population level, when looking at the temporal variability in growth parameters amongst cohorts, winf was still negatively correlated to temperature, but the positive correlation between k and temperature was no longer significant. In a single population, the temperature range is probably too narrow to have an identifiable effect on growth. The effect may be confounded by other factors such as density dependence. On the basis of this macroecological pattern, global warming should enhance growth of the youngest age-classes, but reduce the growth of older individuals and shorten the lifespan of herring