The distribution of benthic macrofauna associations in the Bristol Channel in relation to tidal stress

Sediment bed types and benthic faunal associations in the Bristol Channel, U.K., are shown to be directly related to the tidally averaged M2 bed stress as determined from a hydrodynamical numerical model. The correlation provides an important preliminary to an understanding of the physical control of community structure and function

Water and Fine-Sediment Circulation

[Extract] This chapter provides an introduction to Volume 2 of the Treatise, which deals with water and fine-sediment circulation in estuaries and the coastal zone. Chapters 2.02, 2.03, 2.04, and 2.05 are concerned primarily with buoyancy and its consequences for circulation and include topics such as stratification, turbulence, estuarine circulation, surface fronts, plumes, and mixing. Chapters 2.06, 2.07, 2.08, 2.09, and 2.10 consider barotropic and wind-driven motions, especially tides, winds, and waves. Coastal and estuarine interactions, incorporating river plumes on the shelf and coastal oceanography, are dealt with in Chapters 2.11 and 2.12. Chapters 2.13, 2.14, and 2.15 describe biological interactions and sediments and particularly hydrodynamic interactions with biota and sediments. Finally, Chapters 2.16 and 2.17 deal with measurement and modeling techniques for estuarine and coastal waters

The prediction of nutrients into estuaries and their subsequent behaviour: application to the Tamar and comparison with the Tweed, U.K.

Some of the techniques used to model nitrogen (N) and phosphorus (P) discharges from a terrestrial catchment to an estuary are discussed and applied to the River Tamar and Tamar Estuary system in Southwest England, U.K. Data are presented for dissolved inorganic nutrient concentrations in the Tamar Estuary and compared with those from the contrasting, low turbidity and rapidly flushed Tweed Estuary in Northeast England. In the Tamar catchment, simulations showed that effluent nitrate loads for typical freshwater flows contributed less than 1% of the total N load. The effect of effluent inputs on ammonium loads was more significant (∼10%). Cattle, sheep and permanent grassland dominated the N catchment export, with diffuse-source N export greatly dominating that due to point sources. Cattle, sheep, permanent grassland and cereal crops generated the greatest rates of diffuse-source P export. This reflected the higher rates of P fertiliser applications to arable land and the susceptibility of bare, arable land to P export in wetter winter months. N and P export to the Tamar Estuary from human sewage was insignificant. Non-conservative behaviour of phosphate was particularly marked in the Tamar Estuary. Silicate concentrations were slightly less than conservative levels, whereas nitrate was essentially conservative. The coastal sea acted as a sink for these terrestrially derived nutrients. A pronounced sag in dissolved oxygen that was associated with strong nitrite and ammonium peaks occurred in the turbidity maximum region of the Tamar Estuary. Nutrient behaviour within the Tweed was very different. The low turbidity and rapid flushing ensured that nutrients there were essentially conservative, so that flushing of nutrients to the coastal zone from the river occurred with little estuarine modification