A Lagrangian study of plankton trophodynamics over a diel cycle in a eutrophic estuary under upwelling influence

2017 ◽  
Vol 98 (7) ◽  
pp. 1547-1558 ◽  
Author(s):  
Suzana G. Leles ◽  
Gleyci A. O. Moser ◽  
Jean L. Valentin ◽  
Gisela M. Figueiredo
Keyword(s):  
Food Web ◽  
Sampling Period ◽  
Small Cells ◽  
Guanabara Bay ◽  
Predator Prey ◽  
Trophic Links ◽  
Lagrangian Study ◽  
Predation Control ◽  
Atlantic Coastal

A Lagrangian study was conducted in a eutrophic estuary (Guanabara Bay, Brazil) to investigatein situplankton trophodynamics under the influence of the cold, nutrient-rich South Atlantic Coastal Water in a short-term temporal variability (scale of hours). We tested the hypothesis that the base of the plankton food web is composed of small cells and that microzooplankton is the main consumer of this assemblage. Samples of pico-, nano- and microplankton, as well as copepods, were collected during spring, when the entry of upwelling water in the Bay is commonly observed, and near the surface every 3 h during the 1-day sampling period. Potential predation of dinoflagellates, ciliates, copepod nauplii, copepodites and adult copepods was estimated based on predator-prey size relationships. The main trophic links in the Guanabara Bay food web for the period analysed were nanophytoplankton-copepods, nanophytoplankton-ciliates, and autotrophic dinoflagellates-heterotrophic dinoflagellates. According to microphytoplankton availability, adult copepods could not satisfy their food requirement, and nanophytoplankton represented an important supplementary food source. In fact, diel variations of nano- and microplankton biomass were opposite to that of copepods suggesting predation control by the latter on the former. The trophodynamics of Guanabara Bay, under the influence of upwelling water, resulted in marked differences from other eutrophic estuaries around the world.

scholarly journals Protozooplankton characterization of two contrasting sites in a tropical coastal ecosystem (Guanabara Bay, RJ)

2007 ◽  
Vol 55 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Eli Ana Traversim Gomes ◽  
Viviane Severiano dos Santos ◽  
Denise Rivera Tenenbaum ◽  
Maria Célia Villac
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
Food Web ◽  
Warm Season ◽  
Descriptive Study ◽  
Cold Season ◽  
Guanabara Bay ◽  
Trophic Conditions ◽  
Plankton Dynamics

Much time and resources have been invested in understanding plankton dynamics in Guanabara Bay (Brazil), but no attention has been devoted to the protozooplankton. To fulfill this lacuna, abundance and composition of protozooplankton were investigated from January to December - 2000 in fortnightly surface water samplings at two distinct water quality sites (Urca - closer to the bay entrance, more saline and cleaner waters; Ramos - inner reaches, hypereutrophic waters). The density at Urca (10³ - 10(5) cell.l-1) was one to three orders of magnitude lower than at Ramos (10(4) - 10(5) cell.l-1). A seasonal trend for nanoplankton and protozooplankton was more evident at Urca, but both sites had lower densities during the colder period. Small heterotrophic dinoflagellates (20-30 mm) were dominant in over 50% of the samples. The protozooplankton abundance and composition reflected the distinct trophic conditions states found at the bay. During the wet-warm season, non-oligotrich ciliates were representative of Ramos site with Gymnodiniaceae dinoflagellates, while tintinnids and heterotrophic dinoflagellates were predominantly found at Urca mainly during the dry-cold season. This first descriptive study towards the understanding of the intricate relationships among the microbial food web components reveals that protozooplankton can be a good indicator of water quality conditions at the bay.

Predator–Prey Relationships for Juvenile Chinook Salmon, Oncorhynchus tshawytscha, Feeding on Zooplankton in "in situ" Enclosures

1983 ◽  
Vol 40 (3) ◽  
pp. 287-297 ◽  
Author(s):  
Karl K. English
Keyword(s):  
Growth Rates ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Fish Growth ◽  
Juvenile Salmon ◽  
Predator Prey ◽  
Juvenile Chinook Salmon ◽  
Successful Search ◽  
Juvenile Chinook

Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5–6 g juvenile salmon. Mean growth rate was 1.8% wet body weight/d over 6 wk. Weekly growth rates ranged from 3.9%/d while food was abundant, to −0.5%/d when food was scarce. Zooplankton concentration inside and outside enclosures without fish were not significantly different. Organisms associated with the sides of the enclosures (non-pelagic) were not a major contributor to the growth of the juvenile chinook. There was a strong relationship between the fish growth rates and the abundance of 1.4- to 4.5-mm zooplankton. Rates of successful search varied directly with the size and inherent contrast of a prey item. The minimum rate of successful search was 2.3 m3/h for salmon feeding on 1.4- to 4.5-mm zooplankton. This rate of successful search, while far greater than previously suspected, is still within the visual capabilities of the juvenile salmon. The enclosed salmon grew rapidly on zooplankton concentrations that were 1/1000 of those required to sustain similar growth rates in tank experiments.Key words: predator–prey relationship, planktivorous salmonid, marine, "in situ" enclosures, search efficiency

scholarly journals Nestedness of trophic links and biological traits in a marine food web

Ecosphere ◽  
2015 ◽  
Vol 6 (9) ◽  
pp. art161 ◽  
Author(s):  
M. C. Nordström ◽  
K. Aarnio ◽  
A. Törnroos ◽  
E. Bonsdorff
Keyword(s):  
Food Web ◽  
Biological Traits ◽  
Marine Food Web ◽  
Trophic Links ◽  
Marine Food

scholarly journals Food‐web interaction strength distributions are conserved by greater variation between than within predator–prey pairs

Ecology ◽  
2019 ◽  
Vol 100 (10) ◽  
Author(s):  
Daniel L. Preston ◽  
Landon P. Falke ◽  
Jeremy S. Henderson ◽  
Mark Novak
Keyword(s):  
Food Web ◽  
Interaction Strength ◽  
Predator Prey ◽  
Strength Distributions

Coupled predator-prey oscillations in a chaotic food web

2009 ◽  
Vol 12 (12) ◽  
pp. 1367-1378 ◽  
Author(s):  
Elisa Benincà ◽  
Klaus D. Jöhnk ◽  
Reinhard Heerkloss ◽  
Jef Huisman
Keyword(s):  
Food Web ◽  
Predator Prey

Food web dynamics in an Australian Wet Tropics river

2010 ◽  
Vol 61 (8) ◽  
pp. 909 ◽  
Author(s):  
Thomas S. Rayner ◽  
Bradley J. Pusey ◽  
Richard G. Pearson ◽  
Paul C. Godfrey
Keyword(s):  
Food Web ◽  
Wet Season ◽  
Food Web Structure ◽  
Spatial And Temporal Scales ◽  
Trophic Links ◽  
Energy Inputs ◽  
Longitudinal Connectivity ◽  
Wet Tropics ◽  
High Degree ◽  
Prey Items

In Australia’s Wet Tropics rivers, perennial base flows punctuated by wet season floods drive instream responses across a range of spatial and temporal scales. We combined gut-content and stable-isotope analyses to produce preliminary webs depicting trophic links between fish, their main prey items and basal productivity sources. We then used these webs to test the applicability of general food web principles developed in other tropical systems. Although a range of sources appeared to underpin fish productivity, a large portion of total energy transfer occurred through a subset of trophic links. Variability in food web structure was negatively correlated with spatial scale, being seasonally stable at river reaches and variable at smaller scales. Wet Tropics rivers are similar to those in other tropical areas, but exhibit some unique characteristics. Their high degree of channel incision improves longitudinal connectivity, thereby allowing fish to move between mesohabitats and target their preferred prey items, rather than shifting their diet as resources fluctuate. However, this also inhibits lateral connectivity and limits terrestrial energy inputs from beyond the littoral zone.

scholarly journals Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

2009 ◽  
Vol 364 (1524) ◽  
pp. 1659-1663 ◽  
Author(s):  
Kevin D. Lafferty ◽  
Armand M. Kuris
Keyword(s):  
Food Web ◽  
Trematode Species ◽  
Snail Species ◽  
Native Community ◽  
Free Living ◽  
Predator Prey ◽  
Living Species ◽  
Secondary Parasite ◽  
Disproportionate Number ◽  
Secondary Extinction

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica , resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria , is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

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