Coexistence of multiple food chains in a heterogeneous environment: Interactions among community structure, ecosystem functioning, and nutrient dynamics

1996 ◽  
Vol 134 (2) ◽  
pp. 153-188 ◽  
Author(s):  
Michel Loreau
Keyword(s):  
Community Structure ◽  
Ecosystem Functioning ◽  
Nutrient Dynamics ◽  
Food Chains ◽  
Heterogeneous Environment

scholarly journals Stochastic Assembly Leads to Alternative Communities with Distinct Functions in a Bioreactor Microbial Community

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Jizhong Zhou ◽  
Wenzong Liu ◽  
Ye Deng ◽  
Yi-Huei Jiang ◽  
Kai Xue ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Diversity ◽  
Microbial Community Structure ◽  
Community Assembly ◽  
Ecosystem Functioning ◽  
Dominant Role ◽  
Microbial Biodiversity ◽  
Stochastic Assembly

ABSTRACTThe processes and mechanisms of community assembly and its relationships to community functioning are central issues in ecology. Both deterministic and stochastic factors play important roles in shaping community composition and structure, but the connection between community assembly and ecosystem functioning remains elusive, especially in microbial communities. Here, we used microbial electrolysis cell reactors as a model system to examine the roles of stochastic assembly in determining microbial community structure and functions. Under identical environmental conditions with the same source community, ecological drift (i.e., initial stochastic colonization) and subsequent biotic interactions created dramatically different communities with little overlap among 14 identical reactors, indicating that stochastic assembly played dominant roles in determining microbial community structure. Neutral community modeling analysis revealed that deterministic factors also played significant roles in shaping microbial community structure in these reactors. Most importantly, the newly formed communities differed substantially in community functions (e.g., H2production), which showed strong linkages to community structure. This study is the first to demonstrate that stochastic assembly plays a dominant role in determining not only community structure but also ecosystem functions. Elucidating the links among community assembly, biodiversity, and ecosystem functioning is critical to understanding ecosystem functioning, biodiversity preservation, and ecosystem management.IMPORTANCEMicroorganisms are the most diverse group of life known on earth. Although it is well documented that microbial natural biodiversity is extremely high, it is not clear why such high diversity is generated and maintained. Numerous studies have established the roles of niche-based deterministic factors (e.g., pH, temperature, and salt) in shaping microbial biodiversity, the importance of stochastic processes in generating microbial biodiversity is rarely appreciated. Moreover, while microorganisms mediate many ecosystem processes, the relationship between microbial diversity and ecosystem functioning remains largely elusive. Using a well-controlled laboratory system, this study provides empirical support for the dominant role of stochastic assembly in creating variations of microbial diversity and the first explicit evidence for the critical role of community assembly in influencing ecosystem functioning. The results presented in this study represent important contributions to the understanding of the mechanisms, especially stochastic processes, involved in shaping microbial biodiversity.

scholarly journals Impacts of exotic mangrove forests and mangrove deforestation on carbon remineralization and ecosystem functioning in marine sediments

2010 ◽  
Vol 7 (2) ◽  
pp. 2631-2671 ◽  
Author(s):  
A. K. Sweetman ◽  
J. J. Middelburg ◽  
A. M. Berle ◽  
A. F. Bernardino ◽  
C. Schander ◽  
...  
Keyword(s):  
Community Structure ◽  
Ecosystem Functioning ◽  
Mangrove Forest ◽  
Mangrove Forests ◽  
Short Term ◽  
Benthic Respiration ◽  
Faunal Abundance ◽  
Carbon Remineralization ◽  
And Control ◽  
Mangrove Biomass

Abstract. To evaluate how mangrove invasion and removal can modify benthic carbon cycling processes and ecosystem functioning, we used stable-isotopically labelled algae as a deliberate tracer to quantify benthic respiration and C-flow through macrofauna and bacteria in sediments collected from (1) an invasive mangrove forest, (2) deforested mangrove sites 2 and 6 years after removal of above-sediment mangrove biomass, and (3) two mangrove-free, control sites in the Hawaiian coastal zone. Sediment oxygen consumption (SOC) rates were significantly greater in the mangrove and mangrove removal site experiments than in controls and were significantly correlated with total benthic (macrofauna and bacteria) biomass and sedimentary mangrove biomass (SMB). Bacteria dominated short-term C-processing of added microalgal-C and benthic biomass in sediments from the invasive mangrove forest habitat. In contrast, macrofauna were the most important agents in the short-term processing of microalgal-C in sediments from the mangrove removal and control sites. Mean faunal abundance and short term C-uptake rates in sediments from both removal sites were significantly higher than in control cores, which collectively suggest that community structure and short-term C-cycling dynamics in habitats where mangroves have been cleared can remain fundamentally different from un-invaded mudflat sediments for at least 6-yrs following above-sediment mangrove removal. In summary, invasion by mangroves can lead to large shifts in benthic ecosystem function, with sediment metabolism, benthic community structure and short-term C-remineralization dynamics being affected for years following invader removal.

scholarly journals Struktur komunitas Echinodermata pada ekosistem lamun Desa Taula’a Kecamatan Bilato, Kabupaten Gorontalo

DEPIK ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 207-216
Author(s):  
Hardiyanti Yusuf ◽  
Miftahul Khair Kadim
Keyword(s):  
Community Structure ◽  
Water Depth ◽  
Coastal Area ◽  
Food Chains ◽  
Total Abundance ◽  
Equitable Distribution ◽  
Water Parameters ◽  
Seagrass Ecosystem ◽  
Evenness Index ◽  
Index Of Diversity

Abstract. Echinodermata is playing an important role in food chains in waters ecosystem; however, there was no report on the Echinodermata structure in the seagrass ecosystem of Taula’a village, Gorontalo district. Hence, the objective of the study was to  to determine the community structure of Echinoderms in the seagrass ecosystem of coastal area of Taula’a village, Bilato, Gorontalo regency. The research was conducted from January to April 2019. There were 3 observation stations chosen purposively. The sample of Echinoderms was observed at low tide using methods of quadrats and transects of 1×1 m. In addition, the water parameters were also measured i.e the temperature, the salinity, the pH, the water depth, the substrate and the water flow. Furthermore, diversity, dominanc and Evenness index were analyzed using software PAST 3.22. The results showed that there were 13 species of Echinoderms representing 4 classes, namely Ophiuroidea, Asteriodea, Echinodea dan Holothuroidea in which the highest total abundance was on 1st station and the lowest total abundance was on the 2nd station.  The index of diversity was in the medium category, the index of domination was in the low category, the index of evenness showed an equitable distribution and the index of uniformity was very high.Keywords : Echinoderms, community, seagrass, Past 3.22 Abstrak. Echinodermata memiliki peranan penting dalam rantai makanan pada ekosistem laut, namun demikian struktur komunitasnya di ekosistim lamun Desa Taula’a Kabupaten Gorontalo belum pernah dilaporkan. Oleh karena itu peneilitan ini bertujuan  untuk mengetahui struktur komunitas Echinodermata pada ekosistem lamun di wilayah pesisir Desa Taula’a, Bilato Kabupaten Gorontalo. Penelitian dilaksanakan pada bulan Januari hingga April 2019. Terdapat 3 stasiun pengamatan yang dipilih secara purposive. Pengamatan sampel Echinodermata dilakukan pada saat surut dengan menggunakan transek kuadran 1×1 m. Selain itu dilakukan juga pengukuran terhadap parameter air yaitu suhu, salinitas, pH, kedalaman, substrat dan arus. Nilai indeks keanekaragaman, indeks dominansi dan indeks kemerataan dianalisis menggunakan software PAST 3.22. Hasil penelitian menunjukkan sebanyak 13 spesies Echinodermata ditemukan yang mewakili 4 kelas yaitu Ophiuroidea, Asteriodea, Echinodea dan Holothuroidea dimana kelimpahan total tertinggi pada stasiun I dan terendah pada stasiun II.  Indeks keanekaragaman kategori sedang, indeks dominasi rendah, indeks kemerataan menunjukkan penyebaran yang merata dan indeks keseragaman yang sangat tinggi. Kata kunci: Echinodermata, komunitas, Lamun, Past 3.22

scholarly journals Responses of Ammonia-Oxidising Bacterial Communities to Nitrogen, Lime, and Plant Species in Upland Grassland Soil

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Deirdre C. Rooney ◽  
Nabla M. Kennedy ◽  
Deirdre B. Gleeson ◽  
Nicholas J. W. Clipson
Keyword(s):  
Community Structure ◽  
Plant Species ◽  
Bacterial Communities ◽  
Ecosystem Functioning ◽  
Fragment Length Polymorphism ◽  
Nitrogen Addition ◽  
Grassland Soil ◽  
Agricultural Improvement ◽  
Seminatural Grasslands ◽  
Upland Grassland

Agricultural improvement of seminatural grasslands has been shown to result in changes to plant and microbial diversity, with consequences for ecosystem functioning. A microcosm approach was used to elucidate the effects of two key components of agricultural improvement (nitrogen addition and liming) on ammonia-oxidising bacterial (AOB) communities in an upland grassland soil. Plant species characteristic of unimproved and improved pastures (A. capillarisandL. perenne) were planted in microcosms, and lime, nitrogen (NH4NO3), or lime plus nitrogen added. The AOB community was profiled using terminal restriction fragment length polymorphism (TRFLP) of theamoAgene. AOB community structure was largely altered byNH4NO3addition, rather than liming, although interactions between nitrogen addition and plant species were also evident. Results indicate that nitrogen addition drives shifts in the structure of key microbial communities in upland grassland soils, and that plant species may play a significant role in determining AOB community structure.

Biodiversity, community structure and ecosystem function on kelp and wood falls in the Norwegian deep sea

2021 ◽  
Vol 657 ◽  
pp. 73-91
Author(s):  
RP Harbour ◽  
CR Smith ◽  
C Simon-Nutbrown ◽  
M Cecchetto ◽  
E Young ◽  
...  
Keyword(s):  
Community Structure ◽  
Ecosystem Function ◽  
Deep Sea ◽  
Ecosystem Functioning ◽  
Secondary Production ◽  
Anthropogenic Impacts ◽  
Management Strategies ◽  
Terrestrial Ecosystems ◽  
Kelp Forests ◽  
Biological Trait

Fjordic systems in temperate and Arctic regions often feature extensive kelp forests at their shallow coastal margins as well as extensive terrestrial forests. Detrital export from these shallow-water and terrestrial ecosystems is an important source of carbon for deep-sea communities in the form of kelp and wood falls. Benthic landers with experimental substrates (wood blocks and kelp parcels) were deployed for 10 mo at a depth of 530 m in a deep Norwegian fjord to investigate and compare macro- and megabenthic community structure, biodiversity and ecosystem functioning on kelp and wood falls. Results revealed that while wood and kelp falls can support a similar number of species and abundance of fauna, they support significantly different faunal communities. Biomass and secondary production on both wood and kelp substrates were significantly greater than in the control samples. Secondary production estimates were similar or higher than those reported from soft-sediment ecosystems at shallower European marine sites. Biological trait analysis showed that macrofaunal assemblages were distinct between the kelp and wood, providing evidence for differences in ecosystem function between the substrates. This case study from a deep-sea fjord in Norway provides clear evidence that while wood and kelp organic falls can support similar abundances of fauna, the associated benthic biodiversity, community structure and ecosystem functioning can be dramatically different between these substrates. The work presented here aims to provide information that is useful in assessing the extent of anthropogenic impacts on deep fjord ecosystems with respect to informing future conservation and management strategies.

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