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| Trenkel, Verena; Berger, Laurent. |
| Fisheries acoustic instruments provide information on four major groups in aquatic ecosystems: fish with and without swim bladder (tertiary and quaternary consumers), fluidlike zooplankton (secondary consumers) and small gas bearing organisms such as larval fish and phytoplankton (predominantly primary producers). We entertain that this information is useable to describe the spatial structure of organism groups in pelagic ecosystems. The proposal we make is based on a multi-frequency indicator that synthesises in a single metric the shape of the acoustic frequency response of different organism groups, i.e. the dependence of received acoustic backscattered energy on emitting echosounder frequency. We demonstrate the development and interpretation of the... |
| Tipo: Text |
Palavras-chave: Acoustics; Frequency response curve; Monitoring; EOF; Ecosystem state. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00128/23886/21848.pdf |
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| Chevillot, Xavier; Pierre, Maud; Rigaud, Arthur; Drouineau, Hilaire; Chaalali, Aurelie; Sautour, Benoit; Lobry, Jeremy. |
| For decades, global climate change has directly and indirectly affected the structure and function of ecosystems. Abrupt changes in biodiversity have been observed in response to linear or sudden modifications to the environment. These abrupt shifts can cause long-term reorganizations within ecosystems, with communities exhibiting new functional responses to environmental factors. Over the last 3 decades, the Gironde estuary in southwest France has experienced 2 abrupt shifts in both the physical and chemical environments and the pelagic community. Rather than describing these shifts and their origins, we focused on the 3 inter-shift periods, describing the structure of the fish community and its relationship with the environment during these periods. We... |
| Tipo: Text |
Palavras-chave: Ecosystem state; Fish diversity; Estuary; Generalised linear mixed models; GLMM; Time series; Shift; Inter-shift periods. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00334/44567/44282.pdf |
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| Goatley, Christopher H. R.; College of Marine and Environmental Sciences, James Cook University; Australian Research Council Centre of Excellence for Coral Reef Studies; christopher.goatley@jcu.edu.au; Fox, Rebecca J.; College of Marine and Environmental Sciences, James Cook University; Australian Research Council Centre of Excellence for Coral Reef Studies; Division of Evolution, Ecology and Genetics, Australian National University; School of Life Sciences, University of Technology Sydney; rebecca.fox-1@uts.edu.au; Bellwood, David R.; College of Marine and Environmental Sciences, James Cook University; Australian Research Council Centre of Excellence for Coral Reef Studies; david.bellwood@jcu.edu.au. |
| Around the world, the decreasing health of coral reef ecosystems has highlighted the need to better understand the processes of reef degradation. The development of more sensitive tools, which complement traditional methods of monitoring coral reefs, may reveal earlier signs of degradation and provide an opportunity for pre-emptive responses. We identify new, sensitive metrics of ecosystem processes and benthic composition that allow us to quantify subtle, yet destabilizing, changes in the ecosystem state of an inshore coral reef on the Great Barrier Reef. Following severe climatic disturbances over the period 2011-2012, the herbivorous reef fish community of the reef did not change in terms of biomass or functional groups present. However, fish-based... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Disturbances; Ecosystem state; Herbivory; Management; Monitoring; Processes; Resilience; Sediment; Thresholds. |
| Ano: 2016 |
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