Prey-size selection by brown trout (Salmo trutta L.) in a stream in northern Spain

Pedro A Rincón; Javier Lobón-Cerviá

doi:10.1139/z99-031

Prey-size selection by brown trout (Salmo trutta L.) in a stream in northern Spain

Canadian Journal of Zoology ◽

10.1139/z99-031 ◽

1999 ◽

Vol 77 (5) ◽

pp. 755-765 ◽

Cited By ~ 15

Author(s):

Pedro A Rincón ◽

Javier Lobón-Cerviá

Keyword(s):

Water Column ◽

Brown Trout ◽

Relative Abundance ◽

Prey Size ◽

Size Composition ◽

Northern Spain ◽

Size Frequency Distribution ◽

Size Classes ◽

Size Selection ◽

Size Frequency

Brown trout in the River Negro in northern Spain preferentially ate larger aquatic prey items (found throughout the water column). A model based on size-dependent prey encounters was able to account for this trend and to generate accurate predictions of the consumption of aquatic prey of different sizes. In contrast, the same model failed to predict the size composition of terrestrial prey (restricted to the upper layers of the water column) eaten bv the trout. Trout ignored the larger (more profitable) terrestrial prey, and the consumption of prey of a given size class was more dependent on their relative abundance than on their size. However, the smallest prey were rejected. We suggest that trout were switching, i.e., overexploiting the most abundant prey, because of perceptual limitations mediated by large differences in relative abundance of the different size classes of terrestrial prey. The size-frequency distributions of the available terrestrial prey were always greatly dominated (75-90%) by the two smallest size classes (1-2 and 2-3 mm long), prey over 4 mm long being extremely scarce, while size distributions of aquatic prey were less skewed. Overall, active choice guided by energetic optimization criteria appeared to be of limited importance in determining the size composition of prey eaten by this population of brown trout Our results also indicate that the operating mechanisms of prey-size selection are probably not independent of the characteristics of the size-frequency distribution of the available prey.

Download Full-text

Prey-size selection by brown trout (Salmo trutta L.) in a stream in northern Spain

Canadian Journal of Zoology ◽

10.1139/cjz-77-5-755 ◽

1999 ◽

Vol 77 (5) ◽

pp. 755-765 ◽

Cited By ~ 5

Author(s):

Pedro A. Rincón ◽

Javier Lobón-Cerviá

Keyword(s):

Brown Trout ◽

Salmo Trutta ◽

Prey Size ◽

Northern Spain ◽

Size Selection

Download Full-text

Consumption and prey size selection of the nematode Caenorhabditis elegans by different juvenile stages of freshwater fish

Nematology ◽

10.1163/15685411-00002793 ◽

2014 ◽

Vol 16 (6) ◽

pp. 631-641 ◽

Cited By ~ 15

Author(s):

Sebastian Weber ◽

Walter Traunspurger

Keyword(s):

Caenorhabditis Elegans ◽

Freshwater Fish ◽

Common Carp ◽

Prey Size ◽

Size Classes ◽

Size Selection ◽

Ninespine Stickleback ◽

Nematode Abundance ◽

Juvenile Stages ◽

Selection Of

Meiofauna, and nematodes in particular, play an essential role in the diet of certain juvenile freshwater fish. However, the specific consumption and prey size selection of fishes on nematodes is largely unrecognised. In this study, the effects of different juvenile stages of widely distributed common European freshwater fish, gudgeon (Gobio gobio), roach (Rutilus rutilus), ninespine stickleback (Pungitius pungitius), and two strains of common carp (Cyprinus carpio (scaled) and C. carpio (mirror)), on abundances of the nematode Caenorhabditis elegans were investigated in controlled laboratory experiments with a known number of prey. Gudgeon, carp (scaled), and carp (mirror) consumed significant amounts of nematodes, whereas the roach and ninespine stickleback did not. Both strains of common carp reduced nematode abundance dependent on the size of the fish, with smaller fish causing a greater reduction than medium-size or large fish, although fish of all sizes fed significantly on nematodes of all size classes (<0.5, 0.5-1.0 and >1.0 mm). While the gudgeon also reduced nematode abundance dependent on the size of the fish, with increasing body length there was a dietary shift towards larger nematode size classes (0.5-1.0 and >1.0 mm). Morphometric analysis of the branchial basket indicated that the mesh width of gudgeon and both strains of common carp, but not of roach and ninespine stickleback, is suitable for feeding on specific size classes of nematodes. Together, the results showed that nematodes are used as a food source for different juvenile stages of certain species of freshwater fish.

Download Full-text

Prey size selection in invasive (Hemigrapsus sanguineus and H. takanoi) compared with native (Carcinus maenas) marine crabs

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315419000985 ◽

2019 ◽

Vol 100 (1) ◽

pp. 73-77

Author(s):

Mark M. Bouwmeester ◽

Andreas M. Waser ◽

Jaap van der Meer ◽

David W. Thieltges

Keyword(s):

Resource Competition ◽

Size Range ◽

Prey Size ◽

Carcinus Maenas ◽

Hemigrapsus Sanguineus ◽

Crab Species ◽

Size Classes ◽

Size Selection ◽

Size Preference ◽

Selection Of

AbstractIntroductions of predators can have strong effects on native ecosystems and knowledge of the prey size selection of invasive predators is pivotal to understand their impact on native prey and intraguild competitors. Here, we investigated the prey size selection of two invasive crabs (Hemigrapsus sanguineus and Hemigrapsus takanoi) recently invading European coasts and compared them with native shore crabs (Carcinus maenas) which are known to feed on similar prey species. In laboratory experiments, we offered different size classes of native blue mussels (Mytilus edulis) to different size classes of the crab species in an effort to identify the respective prey size preferences and potential overlap in prey size range of native and invasive crabs. In all three species, the preferred prey size increased with crab size reflecting general predator–prey size relationships. Prey size preference did not differ among the crab species, i.e. crabs showed similar mussel size preference in relation to carapace width. Given that additional morphological measurements showed that both of the invasive crab species have much larger claws relative to their body size compared with the native species, this finding was surprising and may relate to differential claw morphologies or structural strength. These results suggest that the invasive crabs exert predation pressure on the same size classes of native mussels as the native crabs, with potential effects on mussel population dynamics due to the high densities of the invaders. In addition, the overlap in prey size range is likely to result in resource competition between invasive and native crabs.

Download Full-text

Muscle Tissue Growth and Muscle Fibre Dynamics in the Tropical Loliginid Squid Photololigo sp. (Cephalopoda: Loliginidae)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f94-081 ◽

1994 ◽

Vol 51 (4) ◽

pp. 830-835 ◽

Cited By ~ 21

Author(s):

N. A. Moltschaniwskyj

Keyword(s):

Muscle Fibre ◽

Frequency Distribution ◽

Muscle Tissue ◽

Tissue Growth ◽

Muscle Fibre Types ◽

Muscle Fibres ◽

Size Frequency Distribution ◽

Continuous Growth ◽

Size Classes ◽

Size Frequency

Growth of somatic tissue in Photololigo sp. was examined in terms of muscle fibre recruitment and growth. Muscle blocks and muscle fibres were measured and size frequency distributions compared between different size-classes of squid. Muscle blocks increased in size as individuals grew. The size frequency distribution of the muscle blocks suggested that this increase was due to both the generation of new muscle fibres and an increase in the size of existing muscle fibres. The size frequency distribution of muscle fibres was very similar in all size-classes of squid examined, and the presence of small muscle fibres in all individuals suggested that fibre recruitment may be continuous. Growth of muscle tissue, by muscle fibre growth and recruitment, provides a mechanism to explain constant growth throughout the life cycle described for tropical squid. Two structural types of muscle fibres, mitochondria-poor and mitochondria-rich, are present in juvenile and adult squid. A weak relationship between the ratio of the two muscle fibre types and dorsal mantle length suggests that generation of mitochondria-rich fibres may not be influenced by growth.

Download Full-text

Catchability of the southern rock lobster Jasus edwardsii. II. Effects of size

Marine and Freshwater Research ◽

10.1071/mf01244 ◽

2002 ◽

Vol 53 (8) ◽

pp. 1149 ◽

Cited By ~ 12

Author(s):

P. E. Ziegler ◽

C. R. Johnson ◽

S. D. Frusher ◽

C. Gardner

Keyword(s):

Frequency Distribution ◽

Rock Lobster ◽

Size Frequency Distribution ◽

Frequency Distributions ◽

Size Classes ◽

Size Frequency ◽

Jasus Edwardsii ◽

Behavioural Interactions ◽

Males And Females ◽

Relative Selectivity

For most of the year, the size-frequency distribution of trap-caught southern rock lobster, Jasus edwardsii, reflected size-specific catchability rather than the size-frequency distribution of the population in a scientific reserve in Tasmania, Australia. The size-frequency distributions of the population on the ground and of lobsters captured in traps were similar only during a few months, typically during moulting and mating. Small males and females were usually under-represented in traps. Catchability generally increased with size, but varied with sex and season. During moulting and mating, size-specific catchability and relative selectivity of larger animals were similar to or lower than for smaller animals. The relative pattern of catchability throughout the year was similar for most size classes within each sex. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions could explain the lower catchability of smaller lobsters. Relative selectivity estimates using tag–recapture and size-specific catchability data provided generally similar results.

Download Full-text

Effects of Predation and Trophic Conditions on the Reproduction of Tylototriton verrucosus (Caudata: Salamandridae) in Darjeeling

Russian Journal of Herpetology ◽

10.30906/1026-2296-1997-4-2-163-169 ◽

2011 ◽

Vol 4 (2) ◽

pp. 163-169 ◽

Cited By ~ 1

Author(s):

Ritwik Dasgupta

Keyword(s):

Frequency Distribution ◽

Primary Productivity ◽

Egg Size ◽

Zooplankton Abundance ◽

Trophic Conditions ◽

Size Frequency Distribution ◽

Size Frequency ◽

High Predation ◽

Hatchling Size ◽

Predation Rates

The facts that small hatchlings emerged from small eggs laid under high predation levels prevailing at the lower altitudes of distribution of this species in Darjeeling while larger hatchlings emerged from larger eggs laid under lower levels of predation at higher altitudes, show that predation is not selected for large egg and initial hatchling size in this salamandrid species. Metamorphic size was small under high predation rates because this species relied on crypsis for evading predators. Egg and hatchling size are related inversely to levels of primary productivity and zooplankton abundance in lentic habitats. Hatchling sizes are related positively to egg size and size frequency distribution of zooplankton. Small egg and small hatchling size have been selected for at the lower altitudes of distribution of this salamandrid in Darjeeling because predation rates increased in step with improvement in trophic conditions at the lower altitudes.

Download Full-text

SIZE FREQUENCY DISTRIBUTION BIASES IN HORSESHOE CRAB MOLT ASSEMBLAGES: IMPLICATIONS FOR THE FOSSIL RECORD

10.1130/abs/2016cd-274346 ◽

2016 ◽

Author(s):

Shelly J. Wernette ◽

◽

Scott Evans ◽

Christine Hall ◽

Mary L. Droser ◽

...

Keyword(s):

Frequency Distribution ◽

Fossil Record ◽

Horseshoe Crab ◽

Size Frequency Distribution ◽

Size Frequency

Download Full-text

Linking population size structure, heat stress and bleaching responses in a subtropical endemic coral

Coral Reefs ◽

10.1007/s00338-021-02081-2 ◽

2021 ◽

Author(s):

Liam Lachs ◽

Brigitte Sommer ◽

James Cant ◽

Jessica M. Hodge ◽

Hamish A. Malcolm ◽

...

Keyword(s):

Heat Stress ◽

Size Structure ◽

Temporal Trends ◽

Early Recovery ◽

Size Frequency Distribution ◽

Frequency Distributions ◽

Community Organisation ◽

Size Frequency ◽

Eastern Australia

AbstractAnthropocene coral reefs are faced with increasingly severe marine heatwaves and mass coral bleaching mortality events. The ensuing demographic changes to coral assemblages can have long-term impacts on reef community organisation. Thus, understanding the dynamics of subtropical scleractinian coral populations is essential to predict their recovery or extinction post-disturbance. Here we present a 10-yr demographic assessment of a subtropical endemic coral, Pocillopora aliciae (Schmidt-Roach et al. in Zootaxa 3626:576–582, 2013) from the Solitary Islands Marine Park, eastern Australia, paired with long-term temperature records. These coral populations are regularly affected by storms, undergo seasonal thermal variability, and are increasingly impacted by severe marine heatwaves. We examined the demographic processes governing the persistence of these populations using inference from size-frequency distributions based on log-transformed planar area measurements of 7196 coral colonies. Specifically, the size-frequency distribution mean, coefficient of variation, skewness, kurtosis, and coral density were applied to describe population dynamics. Generalised Linear Mixed Effects Models were used to determine temporal trends and test demographic responses to heat stress. Temporal variation in size-frequency distributions revealed various population processes, from recruitment pulses and cohort growth, to bleaching impacts and temperature dependencies. Sporadic recruitment pulses likely support population persistence, illustrated in 2010 by strong positively skewed size-frequency distributions and the highest density of juvenile corals measured during the study. Increasing mean colony size over the following 6 yr indicates further cohort growth of these recruits. Severe heat stress in 2016 resulted in mass bleaching mortality and a 51% decline in coral density. Moderate heat stress in the following years was associated with suppressed P. aliciae recruitment and a lack of early recovery, marked by an exponential decrease of juvenile density (i.e. recruitment) with increasing heat stress. Here, population reliance on sporadic recruitment and susceptibility to heat stress underpin the vulnerability of subtropical coral assemblages to climate change.

Download Full-text

Blocks Size Frequency Distribution in the Enceladus Tiger Stripes Area: Implications on Their Formative Processes

Universe ◽

10.3390/universe7040082 ◽

2021 ◽

Vol 7 (4) ◽

pp. 82

Author(s):

Maurizio Pajola ◽

Alice Lucchetti ◽

Lara Senter ◽

Gabriele Cremonese

Keyword(s):

Frequency Distribution ◽

Power Law ◽

Size Frequency Distribution ◽

Surface Stresses ◽

Size Frequency ◽

The One ◽

Power Law Index ◽

Comet 67P ◽

South Polar ◽

Degree Of Fragmentation

We study the size frequency distribution of the blocks located in the deeply fractured, geologically active Enceladus South Polar Terrain with the aim to suggest their formative mechanisms. Through the Cassini ISS images, we identify ~17,000 blocks with sizes ranging from ~25 m to 366 m, and located at different distances from the Damascus, Baghdad and Cairo Sulci. On all counts and for both Damascus and Baghdad cases, the power-law fitting curve has an index that is similar to the one obtained on the deeply fractured, actively sublimating Hathor cliff on comet 67P/Churyumov-Gerasimenko, where several non-dislodged blocks are observed. This suggests that as for 67P, sublimation and surface stresses favor similar fractures development in the Enceladus icy matrix, hence resulting in comparable block disaggregation. A steeper power-law index for Cairo counts may suggest a higher degree of fragmentation, which could be the result of localized, stronger tectonic disruption of lithospheric ice. Eventually, we show that the smallest blocks identified are located from tens of m to 20–25 km from the Sulci fissures, while the largest blocks are found closer to the tiger stripes. This result supports the ejection hypothesis mechanism as the possible source of blocks.

Download Full-text