The relationship between body size, sediment grain size and the burying ability of juvenile plaice, <i>Pleuronectes platessa</i> L.

Changes in habitat use with increasing conspecific density are well-documented, but such patterns are likely to be dynamic over the lifespan of the organism and responsive to changes in the environment. In the laboratory, we examined how habitat selection was mediated by ontogeny (6, 8 and 12 mo) and temperature (4 and 9°C) in 2 juvenile, marine flatfish species: Pacific halibut Hippoglossus stenolepis and northern rock sole Lepidopsetta polyxystra. In a set of initial trials at 9°C, groups of same-aged juvenile flatfish (6, 8 or 12 mo) of either halibut or rock sole were given the choice of 2 habitats -fine sand (preferred) and coarse gravel (unpreferred) -at 1 of 6 densities (0.4 to 12.2 fish m -2 ). A second set of trials was conducted at 4°C using 8 mo juvenile fish of both species over the same range of densities. At 9°C, density-dependent habitat selection was observed among all treatment groups. As juveniles increased in age in the 9°C treatments, both species began occupying the less-preferred gravel habitat at lower densities. However, at 4°C, density-dependent habitat selection varied between species. Sand habitat supported higher densities of juvenile Pacific halibut at 4°C whereas no change was observed in northern rock sole. Juvenile Pacific halibut activity was also lower than rock sole at 4°C, suggesting that competitive interactions (e.g. interference, territoriality etc.) and/or physiological demands of halibut is sufficiently reduced at this temperature to increase the carrying capacity of the preferred habitat. Together, these results indicate that temperature, ontogeny and density interact to yield unique habitat selection patterns in fish, mechanisms that may be important in area-abundance relationships.KEY WORDS: Density-dependence · Habitat selection · Carrying capacity · Pacific halibut · Northern rock sole Resale or republication not permitted without written consent of the publisher

Section: Ontogeny and Temperature Effectscontrasting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Density-dependent habitat selection in marine flatfish: the dynamic role of ontogeny and temperature

Laurel¹,

Stoner²,

Hurst³

2007

“…Similar behavioral studies of crangonid shrimp predation on post-settled flatfish have been conducted with experimental systems that lacked a substrate ( Van der Veer & Bergman 1987, Ansell & Gibson 1993, Gibson et al 1995. Moreover, Crangon crangon predation rates on juvenile plaice Pleuronectes platessa were unaffected by the presence or absence of sand (Ansell & Gibson 1993), indicating that sediments provide an inadequate refuge for newly settled flatfish because of their relatively poor burying capabilities (Gibson & Robb 1992, Phelan et al 2001. In this study, interactions between shrimp and flounder were recorded with a monochrome video camera connected to a video recorder.…”

Section: Methodsmentioning

confidence: 91%

Effect of temperature on the functional response and foraging behavior of the sand shrimp Crangon septemspinosa preying on juvenile winter flounder Pseudopleuronectes americanus

Taylor¹,

Collie²

2003

Predator-prey dynamics between the sand shrimp Crangon septemspinosa and juvenile winter flounder Pseudopleuronectes americanus were examined in laboratory experiments to assess the joint effects of varying prey density and temperature on shrimp foraging behavior and flounder mortality. The functional response of shrimp to 6 densities of flounder was determined at 2 temperatures (10 and 16°C). The behavioral mechanisms underlying the shrimp's functional response were quantified with visual observations and compared to the foraging parameters predicted by continuous-time functional response models. Shrimp consumption rates increased significantly with increasing flounder density, irrespective of water temperature. At low flounder densities, however, significantly more flounder were consumed at 16°C than at 10°C. Analysis of proportional mortality of flounder across prey density and general functional response models revealed a sigmoidal, Type III functional response at 10°C, and a hyperbolic, Type II functional response at 16°C. Model parameter estimates and visual observations of shrimp foraging behavior suggest that the variable functional responses at different temperatures are the result of cold temperatures decreasing predator activity at low flounder densities, and conversely, shrimp maintaining high attack rates at low flounder densities when exposed to warm temperatures. These findings indicate that shrimp are capable of driving flounder populations to local extinction during warm water conditions. The recent warming trend experienced in northwest Atlantic estuaries, and its impact on trophic dynamics, may therefore explain the failure of the winter flounder stocks to recover in these areas.

“…This is believed to be related to the inability of the smaller fish to bury themselves in coarse sedi m e n t~ and hence take advantage of reduced drag forces induced by bottom currents, lower predation levels and potentially reduced metabolic rates (Riley & Holford 1965, Berghahn 1986, Gibson & Robb 1992, Plhl & van der Veer 1992, Ansell & Gibson 1993. Differences in sediment con~position have also been shown to influence the distribution patterns of gobiid fish, also as a result of predator related mortalities (Evans & Tallmark 1984, 1985, Tallmark & Evans 1986).…”

Section: Other Variablesmentioning

confidence: 99%

Factors affecting spatial variability in seine net catches of fish in the surf zone of False Bay, South Africa

Bm¹,

Ba²,

Sj³

1996

Ichthyofaunal assemblages at 11 surf zone localities along the perimeter of False Bay South Afnca were sampled by seine netting at monthly intervals between July 1991 and J u n e 1993 Sampllng localit~es were selected to encompass as wide a range of physical vanables as possible incorporatlng sheltered, exposed, sandy and mixed-shore habitats, thus providing a colnprehensive assessment of the factors lnfluenclng surf zone fish assemblages Data collected at each site were averaged over the 2 yr p e i~o d in order to highlight the influence of various physical environnlental vanables on the abundance and co~nmunity structure ot these assemblages Athenr~a brevlceps, Liza rlchardsonii and Rhahdosarg~ls gloh~ceps were numeiically domlnant at all sites together providing between 69 and 99%) of the catches Overall catches of juvenile flsh exceeded that ot adult fish, making up almost 53 of the catch Fish abundance (no ind per 100 m') and number of species recorded at each site ranged from 6 to 199 and from 12 to 31 respectivel) Multivdriate analyses Indicated that the deglee of wave exposure the presencc of emergent rock on the shore dnd turbid~ty were responsible for most of the s p a t~a l vanab~lity in abundance and community structure observed Although of lesser importance abundance of detached macrophytes salinity dnd water temperature also played a role in structuring fish assemblages Species specific preferences for varying combinations of these var~ables are responsible for fluctuations in the structure and overall abundance of assemblages in different a r e a