Movements, abundance, age composition and growth of bass, Dicentrarchus labrax, in the Severn Estuary and inner Bristol Channel

The movements, abundance, age composition and growth of bass, Dicentrarchus labrax (L.), in the Severn Estuary and inner Bristol Channel have been described from regular samples offish taken from power-station intake screens between 1972 and 1977. Bass began to move into the estuary during late August or September and reached peak abundance between September and early November. The tendency for fish to move seawards in the late autumn and winter may be related to declining water temperatures in the estuary. Likewise, differences in abundance between years appear to be related to annual differences in temperature. Although the populations were dominated by the 0 + age class, successively decreasing numbers of the next four age classes and occasional 5 + fish were also present. Respective mean standard lengths of bass in the estuary at the end of their first to fifth years of life were approximately 65 mm (≡ 4·5 g), 130 mm (≡ 37·9 g), 190 mm (≡ 121·1 g), 250 mm (≡ 280·4 g) and 290 mm (≡ 441.5 g). Growth occurred predominantly between May and September, with the mean standard length of 1 + fish increasing from approximately 65 mm (≡ 4·5 g) to 130 mm (≡ 37·9 g)

Oxygen consumption, ventilatory frequency and heart rate of lampreys (Lampetra fluviatilis) during their spawning run

1. The standard rate of oxygen consumption, ventilatory frequency and heart rate of adult Lampetra fluviatilis were measured during the light phase of the photoperiod and at times corresponding to various stages in the upstream migration. 2. All three parameters increased during the spawning run but only in mature individuals were significant differences found between the sexes. 3. The regression coefficients for the logarithmic relationship between oxygen consumption and body weight of immature animals were 0.912 and 0.925 at 9.5 and 16 degrees C respectively. 4. Both the standard rate of oxygen consumption and the amount of oxygen taken up during activity increased greatly during the hours of darkness. 5. Oxygen consumption, ventilatory frequency and, to a lesser extent, heart rate increased significantly at 9.5 degrees C over the 100–20% range of saturation with air. 6. Below 20% saturation with air, lampreys no longer remained attached by their oral disc for prolonged periods and the ventilatory frequency rose even more rapidly to reach a maximum of 175 beats/min at 12.5%. Exposure to 7.5% resulted in death within 5–8 h

Pathogen-sugar interactions revealed by universal saturation transfer analysis

Many pathogens exploit host cell-surface glycans. However, precise analyses of glycan ligands binding with heavily modified pathogen proteins can be confounded by overlapping sugar signals and/or compounded with known experimental constraints. Universal saturation transfer analysis (uSTA) builds on existing nuclear magnetic resonance spectroscopy to provide an automated workflow for quantitating protein-ligand interactions. uSTA reveals that early-pandemic, B-origin-lineage severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike trimer binds sialoside sugars in an "end-on" manner. uSTA-guided modeling and a high-resolution cryo-electron microscopy structure implicate the spike N-terminal domain (NTD) and confirm end-on binding. This finding rationalizes the effect of NTD mutations that abolish sugar binding in SARS-CoV-2 variants of concern. Together with genetic variance analyses in early pandemic patient cohorts, this binding implicates a sialylated polylactosamine motif found on tetraantennary N-linked glycoproteins deep in the human lung as potentially relevant to virulence and/or zoonosis

Seasonal catches, size and meristic data for sprat, Sprattus sprattus, in the Severn Estuary

While the sprat, Sprattus sprattus (L.), may live for up to a total of six years, at the end of which time the total length can exceed 150 mm, the fishery in British waters is based primarily on the second, third and fourth year classes (Robertson, 1936, 1938; De Silva, 1973). Historically, the sprat was a major contributor to the fishery of the Bristol Channel and Severn Estuary (Matthews, 1933; Lloyd, 1942). Although this fishery has declined during recent decades, the sprat has remained an important component of the teleost fauna of the region. This point is illustrated by the observation that S. sprattus was by far the most abundant of all teleosts in plankton samples taken throughout the Bristol Channel between the spring and autumn of 1974 (Russell, 1980). While length–frequency data were provided by Russell (1980) for these recently spawned sprat and there is comparable information for those sprat which form the basis of the commercial fishery in the Bristol Channel (Lloyd, 1942), no such data are available for those members of the population which are known sometimes to enter the Severn Estuary in considerable numbers (Lloyd, 1941)

Distribution, abundance and size composition of mullet populations in the Severn Estuary and Bristol Channel

The following three species of grey mullet (Mugilidae) are recorded by Wheeler (1978) for the waters of north-western Europe: thick-lipped mullet, Chelon labrosus (Risso, 1826); thin-lipped mullet, Liza ramada (Risso, 1826) and golden mullet, Liza aurata (Risso, 1810). Liza ramada was obtained in relatively large numbers during the course of extensive sampling of the material collected on the intake screens of power stations in the Bristol Channel and Severn Estuary (for details of other studies see e.g. Claridge & Gardner, 1977, 1978; Titmus, Claridge & Potter, 1978; Abou-Seedo & Potter, 1979; Claridge & Potter, 1983, 1984). Since there is apparently no detailed information on the biology of the thin-lipped mullet in the estuaries of north-western Europe based on regular frequent collections, the power station material was used to provide data on seasonal and annual abundance, size composition, growth and lip depth of this species in the Severn Estuary and Bristol Channel. Comparisons have been made between these data and those obtained for C. labrosus from the same environments and more particularly from outside the area at Pembroke where much larger collections of this latter species were taken

Consistency of seasonal changes in an estuarine fish assemblage

Data on the abundance of all fish species collected at weekly intervals from the intake screens of the Oldbury-upon-Severn Power Station in the inner Severn Estuary, U. K., between 1972 and 1977, have been analysed using classification and multi-dimensional scaling (MDS) ordination techniques. The results show that in each year the structure of the fish community in the shallows of the estuary underwent similar cyclical changes. These changes were largely attributable to a sequential immigration and emigration of different species, particularly estuarine-dependent marine species, and were not driven directly by variations in water temperature, salinity or freshwater discharge from the river. However, comparisons between the data for years with the driest and wettest winters show that the pattern of change in faunal composition was modified under extreme environmental conditions

Seasonal, annual and regional variations in ichthyofaunal composition in the inner Severn Estuary and inner Bristol Channel

Monthly samples of fish from the intake screens of power stations at Oldbury and Berkeley in the inner Severn Estuary and Hinkley Point in the inner Bristol Channel, were used to analyse the community structures of the ichthyofauna in these regions. Marine species that use the estuary as a nursery area (marine estuarine-opportunists) were very abundant in the shallow inshore waters at Oldbury. Diadromous species were more abundant in the offshore and deeper waters at Berkeley than at Oldbury. Only one of the two species that complete their life cycles in the estuary was even moderately abundant in the inner estuary and the 15 freshwater species were relatively rare. Bass and particularly the sand goby complex were more numerous in the protected, inshore waters than the more offshore waters of the estuary. With the yellow and silver stages of the European eel, the reverse situation pertained. Seasonal changes in faunal composition were more pronounced in the inshore shallow than in more offshore deeper waters of the estuary. This largely reflected the sequential immigration of large numbers of the juveniles of marine estuarine-opportunist species into the former area for relatively short periods. Although the ichthyofaunal composition in the shallows at Oldbury underwent the same pattern of cyclical variation in each of five consecutive years, the degree of intra-annual variability differed, reflecting interannual differences in the recruitment strengths of the 0+ age classes of the different marine estuarine-opportunists. These cyclical changes were not correlated strongly with either salinity or water temperature. The faunal composition of the protected inshore, more marine waters of the inner Bristol Channel differed from those in both inshore and offshore regions of the inner estuary. The species which typified the fauna of the Channel were bib, poor cod, five-bearded rockling, sole and conger eel. Although the first four of these species were relatively more abundant in these waters than in the estuary, their juveniles often made extensive use of the shallows at Oldbury. This study emphasizes that, for some marine species, the protected inshore, and more marine, waters in the Bristol Channel can act as alternative nursery areas to those provided by the inshore shallows of the Severn Estuary

Abundance, seasonality and size of Atlantic salmon smolts entrained on power station intake screens in the Severn Estuary

Atlantic salmon smolts were sampled from the intake screens of the Oldbury power station in the inner Severn Estuary at weekly intervals between July 1972 and June 1977. These catches, and those taken over nearly three years from the nearby Berkeley power station, demonstrated that the abundance of smolts in the estuary peaked in autumn (October) and, to a far greater extent, in spring (April and May). However, small numbers of smolts were occasionally found in all other months of the year except July. Standard length-frequency distributions of smolts remained unimodal throughout the year. Lengths ranged from 76 to 187 mm, mean 130·2 ±1·87 mm (95% CL), and wet weights ranged from 5·4 to 68·0 g, mean 26·9 ±1·17 g. The mean monthly standard length of smolts increased slightly between the autumn of one year and the spring/early summer of the next year, suggesting that, on average, the former were six months younger than the latter. The condition factor was significantly greater in autumn (1·40) than in spring (1·23). It is estimated that the total number of salmon smolts entrained annually on the screens at Oldbury during the five years ranged from 92 to 791, with a mean of 405. Total estimated numbers at Berkeley ranged from 196 to 788 per annum. The numbers at Oldbury are lower than those estimated for the downstream migrants of the Twaite shad, another anadromous species, and far lower than those of the most abundant of the marine fish species that use the Severn Estuary as a nursery area