Zooplankton investigations in the Firth of Clyde

Adams, J. A.

doi:10.1017/s0269727000005017

Cited by 3 publications

(2 citation statements)

References 32 publications

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“…Firstly, algorithms for shear-induced aggregation of diatom-dominated microplankton create a sinking loss which is greatest when this microplankton is most abundant. Secondly, losses to mesozooplankton were calculated as grazing pressure derived (Tett and Walne, 1995) from climatological zooplankton data (Adams, 1986). This grazing was applied to the whole of the diatom-dominated microplankton but only to the heterotrophic part of the flagellate-dominated microplankton, on the grounds that the phytoflagellate component of the latter was too small for capture by copepods.…”

Section: Trophic State Control Investigated With a Dynamic Modelmentioning

confidence: 99%

Eutrophication and some European waters of restricted exchange

Tett

Gilpin

Svendsen

et al. 2003

Continental Shelf Research

168

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Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002) concerns 'Oceanographic Applications to Eutrophication in Regions of Restricted Exchange'. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfjärden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q. It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex 'research' model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socio-economic issues that need to be taken into account in managing the trophic status of RREs

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Section: Trophic State Control Investigated With a Dynamic Modelmentioning

confidence: 99%

Eutrophication and some European waters of restricted exchange

Tett

Gilpin

Svendsen

et al. 2003

Continental Shelf Research

168

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show abstract

“…The site is particularly suited to population dynamic studies since it is mostly landlocked and experiences limited advective exchange with Atlantic waters to the west (Edwards et al 1986), thus minimizing the confounding influences of immigration and emigration. M. norvegica is found in the deeper regions, especially the Arran Deep, which reaches depths of between 140 and 200 m. The Clyde Sea exhibits many of the physical and biological features that characterize North Atlantic waters (Jones et al 1995), and it contains the majority of the zooplankton species found within the North Atlantic biome (Colebrook 1978;Adams 1986). Zooplankton studies of the Clyde Sea are therefore likely to reflect patterns that occur throughout the North Atlantic and its periphery.…”

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confidence: 99%

Synchronization in the molting and spawning activity of northern krill (Meganyctiphanes norvegica) and its effect on recruitment

Tarling

Cuzin-Roudy

2003

Limnology & Oceanography

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The molting, spawning, and recruitment of northern krill (Meganyctiphanes norvegica) were analyzed over an annual cycle (1999)(2000) in the Clyde Sea (west coast of Scotland). Results supported the hypothesis of a functional relationship between egg production and molt development for the duration of the reproductive season (March to August), with one reproductive cycle being made up of two molt cycles. Females remained in reproductive condition throughout the reproductive season, and the timing of their spawning and molting was synchronized at the population level throughout this period. A semiempirical model predicted that the krill population produced an egg pulse every 20 to 26 d (depending on temperature), and three cohorts were evident in net samples taken later in the year. The likely date on which the first cohort was spawned was around 26 d after the main phytoplankton bloom, suggesting that the bloom triggered egg development in all adult females. Such a synchronized spawning period was observed directly in adult females 26 d after a bloom in March 2000. A total of three cohorts over the 6-month reproductive season is less than the maximum of seven that would be possible if spawning occurred at a periodicity of between 20 and 26 d, suggesting that larval recruitment was not always successful. Analysis showed that successful recruitment was only achieved when chlorophyll a levels were adequate during both the period of egg maturation in the ovary and the subsequent development of larvae, especially the furcilia stages.

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Seasonal movements and behaviour of basking sharks from archival tagging: no evidence of winter hibernation

Sims¹,

Southall²,

Richardson³

et al. 2003

Mar. Ecol. Prog. Ser.

197

194

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Habitat selection processes in highly migratory animals such as sharks and whales are important to understand because they influence patterns of distribution, availability and therefore catch rates. However, spatial strategies remain poorly understood over seasonal scales in most species, including, most notably, the plankton-feeding basking shark Cetorhinus maximus. It was proposed nearly 50 yr ago that this globally distributed species migrates from coastal summerfeeding areas of the northeast Atlantic to hibernate during winter in deep water on the bottom of continental-shelf slopes. This view has perpetuated in the literature even though the 'hibernation theory' has not been tested directly. We have now tracked basking sharks for the first time over seasonal scales (1.7 to 6.5 mo) using 'pop-up' satellite archival transmitters. We show that they do not hibernate during winter but instead undertake extensive horizontal (up to 3400 km) and vertical (> 750 m depth) movements to utilise productive continental-shelf and shelf-edge habitats during summer, autumn and winter. They travel long distances (390 to 460 km) to locate temporally discrete productivity 'hotspots' at shelf-break fronts, but at no time were prolonged movements into open-ocean regions away from shelf waters observed. Basking sharks have a very broad vertical diving range and can dive beyond the known range of planktivorous whales. Our study suggests this species can exploit shelf and slope-associated zooplankton communities in mesopelagic (200 to 1000 m) as well as epipelagic habitat (0 to

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Zooplankton investigations in the Firth of Clyde

Cited by 3 publications

References 32 publications

Eutrophication and some European waters of restricted exchange

Eutrophication and some European waters of restricted exchange

Synchronization in the molting and spawning activity of northern krill (Meganyctiphanes norvegica) and its effect on recruitment

Seasonal movements and behaviour of basking sharks from archival tagging: no evidence of winter hibernation

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