The plankton food web of the Bizerte Lagoon (South-western Mediterranean): II. Carbon steady-state modelling using inverse analysis

Grami, Boutheina; Niquil, Nathalie; Hlaili, Asma Sakka; Gosselin, Michel; Hamel, Dominique; Mabrouk, Hassine Hadj

doi:10.1016/j.ecss.2008.03.009

Cited by 28 publications

(37 citation statements)

References 58 publications

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“…Ecological Network Analysis (ENA), increasingly used coupled with a calculated set of flows driven from modelling exercises [33], [44], allows characterisation of emergent properties and overcomes the difficulties of comparing different food webs solely on the basis of the magnitude of flows [45].…”

Section: Discussionmentioning

confidence: 99%

Functional Effects of Parasites on Food Web Properties during the Spring Diatom Bloom in Lake Pavin: A Linear Inverse Modeling Analysis

et al. 2011

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This study is the first assessment of the quantitative impact of parasitic chytrids on a planktonic food web. We used a carbon-based food web model of Lake Pavin (Massif Central, France) to investigate the effects of chytrids during the spring diatom bloom by developing models with and without chytrids. Linear inverse modelling procedures were employed to estimate undetermined flows in the lake. The Monte Carlo Markov chain linear inverse modelling procedure provided estimates of the ranges of model-derived fluxes. Model results support recent theories on the probable impact of parasites on food web function. In the lake, during spring, when ‘inedible’ algae (unexploited by planktonic herbivores) were the dominant primary producers, the epidemic growth of chytrids significantly reduced the sedimentation loss of algal carbon to the detritus pool through the production of grazer-exploitable zoospores. We also review some theories about the potential influence of parasites on ecological network properties and argue that parasitism contributes to longer carbon path lengths, higher levels of activity and specialization, and lower recycling. Considering the “structural asymmetry” hypothesis as a stabilizing pattern, chytrids should contribute to the stability of aquatic food webs.

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Section: Discussionmentioning

confidence: 99%

Functional Effects of Parasites on Food Web Properties during the Spring Diatom Bloom in Lake Pavin: A Linear Inverse Modeling Analysis

et al. 2011

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“…1O). The bacteria and small algal prey are always present in coral reefs (27,28); thus, Symbiodinium in coral reefs likely encounter prey cells on a continuous basis.…”

Section: Resultsmentioning

confidence: 99%

Heterotrophic feeding as a newly identified survival strategy of the dinoflagellate Symbiodinium

Jeong

Yoo

Kang

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

166

120

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Survival of free-living and symbiotic dinoflagellates (Symbiodinium spp.) in coral reefs is critical to the maintenance of a healthy coral community. Most coral reefs exist in oligotrophic waters, and their survival strategy in such nutrient-depleted waters remains largely unknown. In this study, we found that two strains of Symbiodinium spp. cultured from the environment and acquired from the tissues of the coral Alveopora japonica had the ability to feed heterotrophically. Symbiodinium spp. fed on heterotrophic bacteria, cyanobacteria (Synechococcus spp.), and small microalgae in both nutrient-replete and nutrient-depleted conditions. Cultured free-living Symbiodinium spp. displayed no autotrophic growth under nitrogen-depleted conditions, but grew when provided with prey. Our results indicate that Symbiodinium spp.'s mixotrophic activity greatly increases their chance of survival and their population growth under nitrogen-depleted conditions, which tend to prevail in coral habitats. In particular, free-living Symbiodinium cells acquired considerable nitrogen from algal prey, comparable to or greater than the direct uptake of ammonium, nitrate, nitrite, or urea. In addition, freeliving Symbiodinium spp. can be a sink for planktonic cyanobacteria (Synechococcus spp.) and remove substantial portions of Synechococcus populations from coral reef waters. Our discovery of Symbiodinium's feeding alters our conventional views of the survival strategies of photosynthetic Symbiodinium and corals. mixotrophy | zooxanthella | coral bleaching | food web | Heterosigma

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“…The concentration of dissolved organic carbon (doc) was obtained considering that 1 µM of doc is equal to 12 mg C m -3 (Grami et al, 2008). The detrital organic carbon (det) was estimated as total POC, determined from water column, minus the total carbon biomass of all plankton communities.…”

Section: Areal Carbon Stocksmentioning

confidence: 99%

“…However, ecosystem-level studies in the South of the Mediterranean Sea are very scarce. Indeed, only one study using the LIM approach has modelled the plankton trophic pathways in the semi-enclosed Bizerte Lagoon (Grami et al, 2008), but studies on nearby marine ecosystems are non-existent. So, in the present study, we have applied the approach LIM-MCMC to characterize the trophic food-web status and its associated structural and functional properties in inshore (Lagoon and Channel of Bizerte) and offshore (Bay of Bizerte) coastal waters located in the south-west of the Mediterranean Sea.…”

Section: Introductionmentioning

confidence: 99%

Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): An ecological network analysis

Meddeb

Grami

Chaalali

et al. 2018

Progress in Oceanography

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The study is the first attempt to (i) model spring food webs in three SW Mediterranean ecosystems which are under different anthropogenic pressures and (ii) to project the consequence of this stress on their function. Linear inverse models were built using the Monte Carlo method coupled with Markov Chains to characterize the food-web status of the Lagoon, the Channel (inshore waters under high eutrophication and chemical contamination) and the Bay of Bizerte (offshore waters under less anthropogenic pressure). Ecological network analysis was used for the description of structural and functional properties of each food web and for inter-ecosystem comparisons. Our results showed that more carbon was produced by phytoplankton in the inshore waters (966-1234 mg C m-2 d-1) compared to the Bay (727 mg C m-2 d-1). The total ecosystem carbon inputs into the three food webs was supported by high primary production, which was mainly due to >10 µm algae. However, the three carbon pathways were characterized by low detritivory and a high herbivory which was mainly assigned to protozooplankton. This latter was efficient in channelling biogenic carbon. In the Lagoon and the Channel, foods webs acted almost as a multivorous structure with a tendency towards herbivorous one, whereas in the Bay the herbivorous pathway was more dominant. Ecological indices revealed that the Lagoon and the Channel food webs/systems had high total system throughput and thus were more active than the Bay. The Bay food web, which had a high relative ascendency value, was more organized and specialized. This inter-ecosystem difference could be due to the varying levels of anthropogenic impact among sites. Indeed, the low value of Finn's cycling index indicated that the three systems are disturbed, but the Lagoon and the Channel, with low average path lengths, appeared to be Highlights ► Herbivorous and multivorous food-webs were the dominant carbon pathways in the Bay and the Lagoon/Channel, respectively during the study period. ► Indices used, showed that the Lagoon and the Channel seemed to be more stressed, more active, and less organized compared to the Bay of Bizerte. ► Inverse modelling combined with ecological networks analysis may offer an effective tool for management and assessment of ecosystems health, and to diagnose the occurrence of anthropogenic pressures.

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The plankton food web of the Bizerte Lagoon (South-western Mediterranean): II. Carbon steady-state modelling using inverse analysis

Cited by 28 publications

References 58 publications

Functional Effects of Parasites on Food Web Properties during the Spring Diatom Bloom in Lake Pavin: A Linear Inverse Modeling Analysis

Functional Effects of Parasites on Food Web Properties during the Spring Diatom Bloom in Lake Pavin: A Linear Inverse Modeling Analysis

Heterotrophic feeding as a newly identified survival strategy of the dinoflagellate Symbiodinium

Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): An ecological network analysis

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