Publisher Summary The degree of match and mismatch in the time of larval production and production of their food has been put forward as an explanation of part of the variability in recruitment to a stock of fish. The magnitude of recruitment is not completely determined until the year-class finally joins the adult stock, and the processes involved probably begin early in the life-history of the fish when both their growth and mortality rates are high. The match/mismatch hypothesis is given in this chapter to cover the subsequent development through larval life up to metamorphosis, and possibly just beyond. The match/mismatch hypothesis has now been extended to the upwelling areas and oceanic divergences equatorward of 40° latitude on the basis that fish in these regions release batches of eggs more frequently when they are well fed and, more generally, that pelagic fish may modify their reproductive strategies such that they can feed and spawn at the same time. A delay in predation is of great importance, particularly when production peaks in early development. This model illustrates the difficulties that occur when growth and mortality are allowed to interact. On the other hand, there are three consequences of the match/mismatch hypothesis that are presented in this chapter. However, the limited conclusion drawn in this chapter is that, investigations of fish larvae should continue to be a part of the study of population dynamics of fishes.

Plankton Production and Year-class Strength in Fish Populations: an Update of the Match/Mismatch Hypothesis

Technical report series

Seventy years' observations of changes in distribution and abundance of zooplankton and intertidal organisms in the western English Channel in relation to rising sea temperature

Publisher Summary A common-sense view of the marine environment as a fluid medium would probably imply progressive changes and smooth gradients in physical properties. Sharp boundaries, however, are actually quite widespread and are generally known as “fronts” or “convergences” from one major aspect of the associated circulation. In the days of classical oceanography, these terms were applied mainly to wholesale oceanic features, such as the Antarctic Convergence, or Polar Front, which runs around the whole globe between the latitudes 50° and 60° S. Over the two or three past decades, however, increasing attention has been paid to a variety of hydrographic structures, all of them being termed “fronts”, ranging from the above-mentioned planetary features to small river plumes. The harvest of new fronts became especially large in the late seventies, when satellite-borne infrared radiometry, originally devised for night mapping of cloud patterns in meteorological surveys, underwent technical improvements which allowed it to be efficiently used for sea-surface temperature monitoring. As a result, the limit between what should and what should not be called a front can sometimes appear rather fuzzy. With regard to frontal structures in north-west European waters and their influence on pelagic ecosystems, the tide turns out to be both the common ultimate cause of a number of phenomena and the source of their variety.

Aspects of the Biology of Frontal Systems

The subject of ocean turbulence is in a state of discovery and development with many intellectual challenges. This book describes the principal dynamic processes that control the distribution of turbulence, its dissipation of kinetic energy and its effects on the dispersion of properties such as heat, salinity, and dissolved or suspended matter in the deep ocean, the shallow coastal and the continental shelf seas. It focuses on the measurement of turbulence, and the consequences of turbulent motion in the oceanic boundary layers at the sea surface and near the seabed. Processes are illustrated by examples of laboratory experiments and field observations. The Turbulent Ocean provides an excellent resource for senior undergraduate and graduate courses, as well as an introduction and general overview for researchers. It will be of interest to all those involved in the study of fluid motion, in particular geophysical fluid mechanics, meteorology and the dynamics of lakes.

https://assets.cambridge.org/97805218/35435/frontmatter/9780521835435_frontmatter.pdf

The Turbulent Ocean

The amplitude and phase of tidal characteristics in the English Channel have been described both using numerical models (Grijalva, 1962; Hyacinthe & Kravtchenko, 1967) and a hydraulic model on a rotating table (Chabert d'Hieres & le Provost, 1970). The aim behind the development of the numerical model described here is first to derive an accurate representation of the principal lunar semi-diurnal (M2) tide in the English Channel and then to use the currents generated by the tidal input to determine the tidal circulation patterns and residual flow through the English Channel. A test of the model must be its ability to reproduce the known clockwise eddy in Lyme Bay and the south-ward flow either side of Portland Bill. If these known tidal residuals can be reproduced then the model may help to elucidate residuals in other regions where the flow is unknown. In addition to deriving the mean tidal velocities, horizontal distributions for the mean squared and cubed values are calculated and the importance of these distributions in determining the nature of the bottom and the degree of stratification of the water column in summer is demonstrated.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315400021792

Tidal residuals in the English Channel

Radioactive wastes and sewage discharged into coastal waters may be largely dispersed by tidal streams. Before authorization for sea discharges can be granted by responsible authorities representing public interests, as much information as possible must be obtained on water movement in the chosen area. Comprehensive data on tidal conditions around the British Isles can be found from the Admiralty Tidal Stream Atlases (Hydrographic Department). The method by which these currents are measured is explained in the Admiralty Manual of Hydrographic Surveying (Hydrographic Department, 1948). Further, special surveys using sea surface drifters and current meters are usually necessary to provide additional information in the neighbourhood of a proposed release. The purpose of this note is to point out that further relevant information can be obtained using numerical models and that these results should also be taken into account when decisions have to be made.

Tidal eddies and coastal discharge

Temperature, salinity and nutrient structure at a station, E1, in the English Channel 22 miles from Plymouth have been described for many individual years (see Armstrong & Butler, 1968, for example). By averaging the results gathered over many years (1903–61) the mean seasonal changes in the vertical distributions have been obtained (Pingree & Pennycuick, 1975). In this paper these distributions have been extended to incorporate data to 1975 and as well as presenting up-to-date mean distributions for temperature, salinity and inorganic phosphate, the mean distributions for silicate and nitrate are included. The purpose of the present work is to interpret the observed mean seasonal changes in the inorganic nutrient distributions in the light of recent measurements giving continuous variations of chemical properties (Armstrong & Lafond, 1966), and in particular, from the knowledge gained from continuous vertical chlorophyll ‘a’ determinations (Lorenzen, 1966; Holligan & Harbour, 1977; Pingree, Holligan & Head, 1977).

The influence of biological activity and physical stability in determining the chemical distributions of inorganic phosphate, silicate and nitrate

Data on the distribution of dinoflagellates in the surface waters around the British Isles in July 1977 were analysed by correspondence analysis. Four communities of dinoflagellates were recognized, and the occurrence of each was related to various environmental parameters. The vertical stability of the water column is considered to be the most important factor in determining the relative abundance of individual species.

The distribution of dinoflagellates around the british isles in july 1977: a multivariate analysis

A numerical model, developed in polar coordinates, illustrates barotropic flow over banks and around islands. Steady-state flow patterns over circular banks with diameters of a few kilometers to several hundred kilometers illustrate the progressive importance of the Earth's rotation in determining the flow pattern. The flow patterns are asymmetric so that an oscillating flow over banks and around islands results in Eulerian residual currents. When the far field flow is circular clockwise, the effects due to bottom friction and the Earth's rotation work in the same sense and the Eulerian residual currents are directed clockwise (in the Northern Hemisphere) in the shoaling regions. When the far field flow is circular anticlockwise, these two effects are opposed and, if bottom friction dominates, the Eulerian current pattern becomes anticlockwise. Rotary flow conditions occur in a number of regions, and the broad conclusions presented here are predicted to apply around banks and islands (like the Isles of Scilly and the Channel Isles) which are situated in rotary semidiurnal tidal flow conditions.

Linda Maddock

Papers

Tidal residuals in the English Channel

Tidal eddies and coastal discharge

The influence of biological activity and physical stability in determining the chemical distributions of inorganic phosphate, silicate and nitrate

The distribution of dinoflagellates around the british isles in july 1977: a multivariate analysis

Rotary currents and residual circulation around banks and islands