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  • Zooplankton  (3)
  • EBM  (1)
  • National Institute of Oceanograhy and Fisheries (NIOF)  (2)
  • Oxford University Press  (2)
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (4)
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  • 2005-2009  (4)
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  • 1
    Publication Date: 2022-05-25
    Description: © 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License. The definitive version was published in ICES Journal of Marine Science: Journal du Conseil 67 (2010): 379-394, doi:10.1093/icesjms/fsp242.
    Description: In principle, measurements of high-frequency acoustic scattering from oceanic microstructure and zooplankton across a broad range of frequencies can reduce the ambiguities typically associated with the interpretation of acoustic scattering at a single frequency or a limited number of discrete narrowband frequencies. With this motivation, a high-frequency broadband scattering system has been developed for investigating zooplankton and microstructure, involving custom modifications of a commercially available system, with almost complete acoustic coverage spanning the frequency range 150–600 kHz. This frequency range spans the Rayleigh-to-geometric scattering transition for some zooplankton, as well as the diffusive roll-off in the spectrum for scattering from turbulent temperature microstructure. The system has been used to measure scattering from zooplankton and microstructure in regions of non-linear internal waves. The broadband capabilities of the system provide a continuous frequency response of the scattering over a wide frequency band, and improved range resolution and signal-to-noise ratios through pulse-compression signal-processing techniques. System specifications and calibration procedures are outlined and the system performance is assessed. The results point to the utility of high-frequency broadband scattering techniques in the detection, classification, and under certain circumstances, quantification of zooplankton and microstructure.
    Description: The work was supported by the US Office of Naval Research (Grant # N000140210359).
    Keywords: Broadband acoustic scattering ; Internal waves ; Oceanic microstructure ; Zooplankton
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 2
    Publication Date: 2022-05-26
    Description: This paper is not subject to U.S. copyright. The definitive version was published in ICES Journal of Marine Science: Journal du Conseil 67 (2010): 1-9, doi:10.1093/icesjms/fsp221.
    Description: Effective marine ecosystem-based management (EBM) requires understanding the key processes and relationships controlling the aspects of biodiversity, productivity, and resilience to perturbations. Unfortunately, the scales, complexity, and non-linear dynamics that characterize marine ecosystems often confound managing for these properties. Nevertheless, scientifically derived decision-support tools (DSTs) are needed to account for impacts resulting from a variety of simultaneous human activities. Three possible methodologies for revealing mechanisms necessary to develop DSTs for EBM are: (i) controlled experimentation, (ii) iterative programmes of observation and modelling ("learning by doing"), and (iii) comparative ecosystem analysis. We have seen that controlled experiments are limited in capturing the complexity necessary to develop models of marine ecosystem dynamics with sufficient realism at appropriate scales. Iterative programmes of observation, model building, and assessment are useful for specific ecosystem issues but rarely lead to generally transferable products. Comparative ecosystem analyses may be the most effective, building on the first two by inferring ecosystem processes based on comparisons and contrasts of ecosystem response to human-induced factors. We propose a hierarchical system of ecosystem comparisons to include within-ecosystem comparisons (utilizing temporal and spatial changes in relation to human activities), within-ecosystem-type comparisons (e.g. coral reefs, temperate continental shelves, upwelling areas), and cross-ecosystem-type comparisons (e.g. coral reefs vs. boreal, terrestrial vs. marine ecosystems). Such a hierarchical comparative approach should lead to better understanding of the processes controlling biodiversity, productivity, and the resilience of marine ecosystems. In turn, better understanding of these processes will lead to the development of increasingly general laws, hypotheses, functional forms, governing equations, and broad interpretations of ecosystem responses to human activities, ultimately improving DSTs in support of EBM.
    Keywords: Comparative marine ecosystem analysis ; Decision-support tools ; EAM ; EBM ; Ecological modelling ; Ecosystem approaches to management ; Ecosystem-based management
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    National Institute of Oceanograhy and Fisheries (NIOF)
    Publication Date: 2021-05-19
    Description: Bardawil Lagoon is a shallow oligotrophic hypersaline lake, located at the northern periphery of Sinai peninsula-Egypt, connected to SE Mediterranean Sea through two main openings known as Boughazes. Distribution of zooplankton in Bardawil Lagoon during 2004 was studied, not only in space and time but also with reference to species assemblages and environmental factors. Copepoda, Protozoa, and Mollusca were dominating the lagoon zooplankton community during the period of study with 58 identified forma. Zooplankton stock peaked during August and October with severe depletion in spring. Spatially, the maximum density occurred near the sea opening I. The lowest density and species richness were noticed at stations with high salinity. The community composition was highly changed with time series. Twenty new taxa were recorded during the study, whereas thirty three taxa disappeared from the lagoon along twenty years.
    Description: تعتبر جونة البردويل بحيرة عالية الملوحة، فقيرة فى الانتاجية الاولية، وقليلة العمق. وتقع هذه الجونة فى اقصى شمال جزيرة سيناء-مصر. وتتصل بجنوب شرق البحر المتوسط من خلال فتحتين. وقد تمت دراسة توزيع الهائمات الحيوانية خلال عام 2004 شهريا. وسجل 58 نوعا من الهائمات الحيوانية. وكانت مجدافيات الارجل والاوليات الحيوانية والرخويات هى الاكثر سيادة فى البحيرة. وبخاصة فى شهرى أغسطس وأكتوبر، بينما كان هناك فقر كبير فى كثافة هذه الكائنات فى ربيع ذلك العام. كما كانت أعلى كثافة للهائمات الحيوانية فى المحطات القريبة من البوغاز الغربى. وبينت الدراسة ان الملوحة كانت هى العامل المُحدد لتغير كثافة وتنوع الهائمات الحيوانية حيث تناسبت معها عكسيا. ظهر عشرون نوعا فى جونة البردويل أثناءالدراسة لم يتم تسجيلهم من قبل بينما اختفى ثلاثة وثلاثون نوعا على مدار عشرون عاما.
    Description: The Chief Editor: Prof. Fatma Aly Abd El-Razek E-mail: fatma_abdelrazek@hotmail.com
    Description: Published
    Description: Hypersaline lagoon
    Keywords: Hydrobiology ; Zooplankton ; Salinity ; Zooplankton ; Salinity ; Lagoons
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
    Format: 210540 bytes
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  • 4
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    National Institute of Oceanograhy and Fisheries (NIOF)
    Publication Date: 2021-05-19
    Description: Diel vertical migration of different zooplankton groups in Dekhaila Harbor was studied monthly from May 2003 to April 2004. Generally, more groups were found in the surface layer (0-10 m.) than the deeper one (10-20 m.). Some zooplankton groups undergo significant vertical migration at certain time of the year, others showed no clear differences in distribution patterns and exhibited no directed movement patterns. Some species stayed a part of the day within certain layer of the water column, others were randomly dispersed in the whole water column during different hours. Responses appear to depend also on the life stages of each zooplankton group, as well as other ecological conditions such as temperature, light and amount of food. Population budget indicates that the abundance of some groups was greater at the morning time, others at the sunset time. While the noon time often showed lower density. The time of the day which showed the lowest count of each group is known as the day deficit, which is probably due to diel horizontal migrations.
    Description: استهدف البحث دراسة الهجرة الرأسية اليومية لمجتمع الهائمات الحيوانية في ميناء الدخيلة الذي يقع داخل خليج المكس على ساحل البحر المتوسط غرب الإسكندرية , حيث أجريت هذه الدراسة على عينات شهرية جمعت لمدة عام في الفترة من مايو 2003 إلي إبريل 2004 من عمقين 0-10 ,10-20متر كل ساعتين خلال ساعات النهار و ذلك من محطة ثابتة . و قد تميز مجتمع الهائمات الحيوانية بكثافة عالية في الطبقة العليا0-10م أكبر من الطبقة العميقة 10-20م و يرجع ذلك إلي زيادة شدة الأستضاءة و التركيز العالي للكلوروفيل في هذه الطبقة و بينت بعض المجاميع هجرة رأسية واضحة في وقت معين من العام بينما لم تبد أخري أي نوع من الهجرة الرأسية. كما أن بعض الأنواع تركزت في وقت معين من النهار في طبقة معينة من الماء بينما تواجدت أنواع أخري على عمق معين طوال ساعات النهار المختلفة و يعزي ذلك إلي الاختلاف في كمية الضوء و درجة الحرارة . كما أظهرت بعض هذه الكائنات كثافة عالية خلال ساعات الصباح و البعض الآخر عند ساعات الغروب بينما كان وقت الظهيرة غالبا يمثل الكثافة المنخفضة . وكذلك فقد دلت النتائج على وجود وقت معين من النهار تكون فيه كثافة كل مجموعة أقل ما يمكن و علل ذلك بسبب الهجرة الأفقية اليومية , كما أبدت بعض المجاميع توزيعا معين اعتمد على المرحلة العمرية لها و أيضا على الظروف البيئية السائدة مثل الحرارة و الضوء و كمية الغذاء الموجود بالماء. وعموما فقد اعتمدت الهجرة الرأسية لكل كائن على سرعته والاختلافات الفسيولوجية بين الأجيال المختلفة.
    Description: The Chief Editor: Prof. Fatma Aly Abd El-Razek E-mail: fatma_abdelrazek@hotmail.com
    Description: Published
    Description: Ecological factors, Diel migration
    Keywords: Hydrobiology ; Zooplankton ; Vertical migrations ; Ecology
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
    Format: 1066272 bytes
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