On the population dynamics of dab, sole and flounder within bridgwater bay in the lower severn estuary, England

Henderson, Peter; Holmes, R. H. A.

doi:10.1016/0077-7579(91)90036-z

Cited by 47 publications

(40 citation statements)

References 9 publications

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“…The water intakes are in front of a rocky promontory within Bridgwater Bay; to the east are the 40 km 2 Stert mud £ats. The Crangon crangon were sampled from water varying in depth from about 8 to 18 m. A full description of the intake con¢guration and sampling methodology is given in Henderson & Holmes (1991) and Henderson & Seaby (1994). Methodology has not changed over the 25 years of study.…”

Section: Methodsmentioning

confidence: 99%

A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon (Crustacea: Caridea) in the Bristol Channel

2006

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The results of a 25-year study of the population dynamics of the common shrimp, Crangon crangon, in the Bristol Channel are presented. The population size varied seasonally, with maximum abundance occurring in early autumn at the completion of annual recruitment. The number of recruits changed greatly between years, and was positively correlated with both average water temperature from January to August, and river flow rate, and negatively correlated with the Winter North Atlantic Oscillation Index. A wide range of other physical and biotic variables was found to have no significant impact on C. crangon abundance. The positive relationship between temperature and C. crangon abundance observed for the Atlantic coast during this study is the opposite of that found for southern North Sea populations. Similar contradictory responses have been noted previously for flatfish such as sole, Solea solea. This suggests that global variables may act to produce different outcomes for Atlantic and North Sea populations of the same species. Over-winter mortality was found to vary with population size so that the adult C. crangon population in spring was found to be remarkably stable, and little influenced by temperature or other variables. The mortality rate increased with population size producing clear evidence of density-dependent control. It is suggested that this stability is linked to the constant limited availability of suitable habitat, with individuals unable to find shelter vulnerable to a range of predatory fish. Given the pivotal role of C. crangon within the northern European estuarine ecosystems, this stability may be a critical component for the overall stability of the system. A particular feature of this study was the exceptional recruitment observed in October 2002. This did not result in any subsequent increase in adult C. crangon numbers, possibly because there was a synchronous increase in a wide range of predators. While the adult population has remained stable and showed no temporal trend, there has been an increase in both the average magnitude and between year variability in recruitment, which can be related predominately to the recent increase in water temperature. The difficulty of predicting the response of this population to continued climate warming is discussed. If temperature continues to rise, the present power law describing the increase in recruitment with temperature must inevitably break down. If this were to occur, the future trajectory of the C. crangon population could not be predicted, and the continued stability of this ecosystem would no longer be assured.

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Section: Methodsmentioning

confidence: 99%

A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon (Crustacea: Caridea) in the Bristol Channel

2006

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“…Many species of flatfishes have specific nursery areas and environmental requirements ( Dorel et al ., 1991 ; Henderson and Holmes, 1991), while other species utilize a wide range of habitats and substrata ( Nash et al ., 1991 ). Some juveniles appear to settle in one area or on a specific substrate and then move to other conditions as they grow ( Burke et al ., 1991 ; Kramer, 1991; Reichert and van der Veer, 1991).…”

Section: Introductionmentioning

confidence: 99%

Comparison of models for defining nearshore flatfish nursery areas in Alaskan waters

Norcross

Blanchard

Holladay

1999

Fisheries Oceanography

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Because it is unrealistic to assess fishes in all locations, models are needed to characterize the nursery habitats of flatfish species. Descriptive habitat models of species presence and categorical analysis regression tree (CART) models of species abundance have been developed in previous studies. Based on collections around Kodiak Island, Alaska in 1991 and 1992, these models have been developed for: age‐0 flathead sole (Hippoglossoides elassodon); age‐0 Pacific halibut (Hippoglossus stenolepis); age‐1 yellowfin sole (Pleuronectes asper); and age‐0 rock sole (Pleuronectes bilineatus). In 1995, collections were made in bays along the Alaska Peninsula (an area never before sampled for juvenile flatfishes) and were compared with the previous models developed for Kodiak Island in 1991 and 1992. Very simple descriptive models for Kodiak Island ( Norcross et al., 1995 , Neth. J. Sea Res. 34: 161–175) accurately predicted the abundance along the Alaska Peninsula of flathead sole (78%), Pacific halibut (96%), yellowfin sole (75%) and rock sole (99%) in specific depth ranges and on specific substrate types. More complex CART models of species abundance ( Norcross et al., 1997 , Fish. Bull. (US) 95: 504–520) were more precise but not as accurate as the descriptive models because some parameters were not always available at the test locations. Flathead sole were found at temperatures ≤ 8.9°C on mud and mixed mud substrates in similar proportions in 1995 (66%) as in 1991–92 (71%). Similarly, Pacific halibut were ≤ 7.9 km inside bays and at depths ≤ 40 m in 93% of the sites of this study, compared with 89% previously. Seventy‐five per cent of yellowfin sole were at depths ≤ 28 m on mixed substrates in both study periods. Rock sole were found on sand and muddy sand substrates at temperatures above 8.7°C in 52% of the sites in present and 69% of the sites in previous studies. This field test demonstrated that both descriptive and CART models were very useful at identifying juvenile habitat parameters, but are insufficient for areas not previously sampled. The resource‐selection models verified the importance of a subset of parameters used in earlier models and provided a statistical means (78–87% correct) for prediction of fish distribution in similar areas of the eastern North Pacific.

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“…Indeed, each of the species of marine estuarine-opportunist found at Oldbury was also recorded at Hinkley Point. The presence at Hinkley Point of considerable numbers of the juveniles of all of those marine species, that were likewise abundant as juveniles in the Severn Estuary, demonstrates that, for several species, protected inshore, and more marine, waters act as alternative nursery areas to inshore, sheltered estuarine waters, both in south-west England (see also Henderson & Holmes, 1991;Henderson & Seaby, 1994) and elsewhere (e.g. Potter et al, 1990).…”

Section: Faunal Composition Of Inshore Waters Of the Inner Bristol Chmentioning

confidence: 99%

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

et al. 1997

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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.

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On the population dynamics of dab, sole and flounder within bridgwater bay in the lower severn estuary, England

Cited by 47 publications

References 9 publications

A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon (Crustacea: Caridea) in the Bristol Channel

A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon (Crustacea: Caridea) in the Bristol Channel

Comparison of models for defining nearshore flatfish nursery areas in Alaskan waters

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

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