scholarly journals Implications of extremely high recruitment: crowding and reduced growth within spatial closures

2019 ◽  
Vol 611 ◽  
pp. 157-165 ◽  
Author(s):  
ND Bethoney ◽  
KDE Stokesbury
Keyword(s):  
High Recruitment

scholarly journals Characteristics of the Norwegian Coastal Current during Years with High Recruitment of Norwegian Spring Spawning Herring (Clupea harengus L.)

PLoS ONE ◽  
2015 ◽  
Vol 10 (12) ◽  
pp. e0144117 ◽  
Author(s):  
Øystein Skagseth ◽  
Aril Slotte ◽  
Erling Kåre Stenevik ◽  
Richard D. M. Nash
Keyword(s):  
Clupea Harengus ◽  
Coastal Current ◽  
Norwegian Coastal Current ◽  
High Recruitment

Survival and recruitment in the population ecology of the endangered Bombina pachypus (Amphibia: Anura)

2018 ◽  
Vol 39 (3) ◽  
pp. 265-274
Author(s):  
Claudio Angelini ◽  
Andrea Tiberi ◽  
Bruno Cari ◽  
Filippo Giachi
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Breeding Site ◽  
Juvenile Dispersal ◽  
Relative Contribution ◽  
Annual Population ◽  
Conservation Concern ◽  
Local Recruitment ◽  
Effective Conservation ◽  
High Recruitment

Abstract Global amphibian decline is a subject of great conservation concern, yet often basic demographic information is absent, which prevents the understanding of population trends and the planning of effective conservation management. We analysed capture-mark-recapture data from six populations of the endangered Bombina pachypus in order to understand the relative contribution of survival and recruitment to population growth, and to assess if any differences exist among populations in terms of their population dynamics. We found that survival was rather high and generally constant among sites, and recruitment was low, with the exception of two single years at one site. Population growth depended on survival on all sites, except the years following high recruitment at one site. Annual population size was generally lower than 30 individuals, but in one site it was estimated to be larger than 50. Our findings suggest that juvenile survival is more important for population dynamics than recruitment from the larval to the juvenile stage. We also suggest that the low recruitment rates we recorded was a result of juvenile dispersal, and that when populations exhibited high recruitment it was due to occasional successful migration or local recruitment. This pattern could represent a way to counterbalance the risk of inbreeding in populations composed of few individuals, a common characteristic of populations of B. pachypus. Finally, we suggest that conservation measures for B. pachypus should be planned at the landscape scale, and should not be limited solely to the breeding site and its close surroundings.

Upwelling Bays: How Coastal Upwelling Controls Circulation, Habitat, and Productivity in Bays

2020 ◽  
Vol 12 (1) ◽  
pp. 415-447 ◽  
Author(s):  
John L. Largier
Keyword(s):  
Ocean Acidification ◽  
Wind Stress ◽  
Coastal Waters ◽  
Coastal Upwelling ◽  
Coastal Currents ◽  
Local Wind ◽  
Phytoplankton Blooms ◽  
Local Extrema ◽  
High Recruitment

Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a circulation in the bay, which is also influenced by local wind stress and thermal bay–ocean density differences. Three types of bays are recognized based on the degree of exposure to coastal currents and winds (wide-open bays, square bays, and elongated bays), and the characteristic circulation and stratification patterns of each type are described. Retention of upwelled waters in bays allows for dense phytoplankton blooms that support productive bay ecosystems. Retention is also important for the accumulation of larvae, which accounts for high recruitment in bays. In addition, bays are coupled to the shelf ecosystem through export of plankton-rich waters during relaxation events. Ocean acidification and deoxygenation are a concern in bays because local extrema can develop beneath strong stratification.

Evidence for continuous iteroparity in a temperate-zone frog, the red-crowned toadlet, Pseudophryne australis (Anura : Myobatrachidae)

2002 ◽  
Vol 50 (2) ◽  
pp. 151 ◽  
Author(s):  
K. Thumm ◽  
M. J. Mahony
Keyword(s):  
Adaptive Response ◽  
Breeding Site ◽  
Breeding Sites ◽  
Reproductive Loss ◽  
Nesting Sites ◽  
In Captivity ◽  
Large Clutch ◽  
Variance In Reproductive Success ◽  
High Recruitment

The breeding behaviour of the red-crowned toadlet, Pseudophryne australis, was observed both in the field and in captivity. Female and male red-crowned toadlets were active in the field throughout the year. New egg masses were observed all year except mid-winter. Females returned in a gravid condition repeatedly to the breeding site over years and presumably deposited eggs, and a captive female has laid 34 clutches over 7.25 years. P. australis has evolved continuous iteroparity in a region where most frogs breed once a year, seasonally, in reliable long-lasting ponds or permanent creeks. We suggest that the comparatively extreme iteroparity observed is a result of the limitations imposed on the species in the choice of oviposition time, due to unpredictable rainfall, and of the limited availability and suitability of nesting sites. Further, iteroparity may have evolved because there is high variance in reproductive success, or particularly high recruitment losses incurred as a result of the desiccation of embryos or larvae in the ephemeral breeding sites. The adaptive response is to lay small clutches often and to gamble that follow up rains will occur on some occasions to enable recruitment. The alternative, to lay a large clutch of eggs at one time and have the ephemeral pond dry because there was no follow-up rain, would lead to total reproductive loss.

scholarly journals Modelling stock–recruitment relationships to examine stock management policies

2007 ◽  
Vol 64 (5) ◽  
pp. 870-877 ◽  
Author(s):  
A. Kimoto ◽  
T. Mouri ◽  
T. Matsuishi
Keyword(s):  
Prediction Error ◽  
Management Strategies ◽  
Fish Stock ◽  
Data Sets ◽  
Stock Management ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Management Policies ◽  
Leave One Out ◽  
High Recruitment

Abstract Kimoto, A., Mouri, T., and Matsuishi, T. 2007. Modelling stock–recruitment relationships to examine stock management policies. – ICES Journal of Marine Science, 64: 870–877. Simulation studies are used widely for fish stock management. In such studies, forecasting future recruitment, which can vary greatly between years, has become an essential part of evaluating management strategies. We propose a new forecasting algorithm to predict recruitment for short- or medium-term stochastic projections, using a stock–recruitment relationship. We address cases in which the spawning stock has dropped below previously observed levels, or in which predicted recruitment is situated close to the maximum observed level. The relative prediction error of seven existing algorithms was compared with that of the new model using leave-one-out cross-validation for 61 data sets from ICES, the Japanese Fisheries Agency, and PICES. The new algorithm had the smallest prediction error for 49 of the data sets, but was slightly biased by the precautionary treatment of predictions of high recruitment.

Performance of native and introduced grasses for low-input pastures. 2. Herbage production

2005 ◽  
Vol 27 (1) ◽  
pp. 41 ◽  
Author(s):  
D. L. Garden ◽  
C. M. Waters ◽  
A. B. Smith ◽  
M. R. Norton ◽  
G. C. Auricht ◽  
...  
Keyword(s):  
Experimental Period ◽  
Perennial Grasses ◽  
Preference Ranking ◽  
Good Growth ◽  
Relative Preference ◽  
Brief Assessment ◽  
C3 Grasses ◽  
Stocking Rates ◽  
High Recruitment ◽  
Sampling Times

A total of 62 perennial grasses were evaluated for herbage production under low-fertiliser conditions at eight sites in the temperate zone of southern Australia from 1999 to 2001. A brief assessment of relative preference ranking by sheep was also made at the end of the experimental period. Four sites were in the high rainfall areas of south-east Australia, two in the drier mixed farming areas of western NSW, and two sites in Mediterranean southern Australia. Seven standard cultivars were included in the comparisons. Plants were grown from seed in glasshouses and transplanted to the field as spaced plants at 6–8 weeks age. Plants were harvested at irregular intervals by clipping to determine herbage production. Relative preference was determined by enclosing sheep in the experimental area at high stocking rates and estimating the amount of herbage grazed after 1, 3 and 5 days. Herbage production data were analysed using a multi-environment trial approach in which the environments comprised all combinations of sites and sampling times over the 3-year period. Overall, 73.6% of the total genetic variation for herbage production was accounted for. Average seasonal comparisons revealed good herbage production from Eragrostis curvula cv. Consol in both winter and summer, but in spring, several Dactylis glomerata lines were the most productive. Consol was not generally preferred by sheep, while D. glomerata lines were. Apart from cv. Consol, C4 species, including Bothriochloa macra, Chloris truncata, Enteropogon acicularis and Dichanthium sericeum had low herbage production in winter and spring, and had low acceptability to grazing sheep. These particular grasses were also not highly ranked for production in summer, although other C4 lines, notably selections of Themeda australis, Paspalidium jubiflorum and P. constrictum were. Few native C3 grasses had superior herbage production, although selections of Elymus scaber, Austrodanthonia fulva and A. duttoniana showed good growth rates. When considering further evaluation, grasses with very high recruitment (e.g. A. caespitosa) may need to be included, and the acceptability of grasses to sheep should also be assessed.

scholarly journals Limpet disturbance effects on barnacle recruitment are related to recruitment intensity but not recruit size

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9190
Author(s):  
Julius A. Ellrich ◽  
Takefumi Yorisue ◽  
Kyosuke Momota
Keyword(s):  
Field Experiment ◽  
Pacific Coast ◽  
Demographic Variable ◽  
Balanus Glandula ◽  
Disturbance Effects ◽  
The Pacific ◽  
Population Establishment ◽  
First Time ◽  
High Recruitment ◽  
Chthamalus Dalli

Intertidal limpets are important grazers along rocky coastlines worldwide that not only control algae but also influence invertebrates such as common barnacles. For instance, grazing limpets ingest settling barnacle cyprid larvae (hereafter cyprids) and push cyprids and barnacle recruits off the substrate. Such limpet disturbance effects (LDEs) can limit barnacle recruitment, a key demographic variable affecting barnacle population establishment and persistence. In this study, we examined limpet (Lottia cassis) disturbance to barnacle (Chthamalus dalli, Balanus glandula) recruitment on the Pacific coast of Hokkaido, Japan, as information on limpet-barnacle interactions from this region is missing. We investigated, for the first time, whether barnacle size and recruitment intensity influence LDEs on barnacle recruitment. Small barnacles may be less susceptible to LDEs than larger barnacles, because small size may reduce the propbability of limpet disturbance. Moreover, recruitment intensity can influence LDEs, as high recruitment can compensate for LDEs on barnacle recruitment density. In Hokkaido, C. dalli cyprids are smaller than B. glandula cyprids, and C. dalli recruitment is higher than B. glandula recruitment. Thus, we hypothesized that LDEs on C. dalli recruitment would be weaker than those on B. glandula recruitment. To test our hypothesis, we conducted a field experiment during which we manipulated limpet presence/absence on the interior surfaces of ring-shaped cages. After four weeks, we measured barnacle recruitment and recruit size on the interior surfaces of the cages and found negative LDEs on C. dalli and B. glandula recruitment and recruit size. As hypothesized, the LDEs on C. dalli recruitment were weaker than the LDEs on B. glandula recruitment. Additionally, C. dalli recruits were smaller than B. glandula recruits. However, the LDEs on C. dalli recruit size were as strong as the LDEs on B. glandula recruit size, indicating that the smaller C. dalli recruits are not less susceptible to LDEs than B. glandula recruits. Since C. dalli recruitment was higher than B. glandula recruitment, we propose that the higher C. dalli recruitment compensated for the LDEs on C. dalli recruitment. Our findings indicate that the detected differences in LDEs on barnacle recruitment are related to barnacle recruitment intensity but not recruit size.

scholarly journals Population study and habitat preferences of Pinang Jawa (Pinanga javana) in Mt. Slamet, Central Java, Indonesia

2019 ◽  
Vol 20 (3) ◽  
pp. 712-718 ◽  
Author(s):  
RIZMOON NURUL ZULKARNAEN ◽  
NISYAWATI NISYAWATI ◽  
JOKO RIDHO WITONO
Keyword(s):  
Population Study ◽  
Population Biology ◽  
Abiotic Factors ◽  
Habitat Preferences ◽  
Central Java ◽  
Crown Cover ◽  
Lack Of Information ◽  
Hill Slope ◽  
Palm Species ◽  
High Recruitment

Abstract. Zulkarnaen RN, Nisyawati, Witono JR. 2019. Population study and habitat preferences of Pinang Jawa (Pinanga javana) in Mt. Slamet, Central Java, Indonesia. Biodiversitas 20: 712-718. Conservation effort of Pinang Jawa is hampered due to lack of information on its ecology and population biology. The species is an endemic palm species to Java. The study aimed to assess the population study and habitat preference of Pinang Jawa in Mt. Slamet, Central Java. The research design used a purposive sampling method with a plot measuring 10x10 m. The observation plot was successfully made with a total of 183 plots. The result showed that the population was dominated by adult palm (mature) with the number of 1023 individuals on the southern slope of Mt. Slamet. Individuals growth dominated in hill slope. Population structure was dominated by individuals with stem heights of 6.1-8.1 m and stem diameters of 7-8.9 cm. The stem height and stem diameter class distribution showed that high mortality rate occurs in the seedlings stage class, although this stage should be high recruitment due to the seed production is perennial continuously. Predators were identified as the main threat for seedlings of Pinang Jawa. The result of statistical analysis clearly provides reveals that abiotic factors in which influencing the density of Pinang Jawa was slope, litter thickness, and crown cover.  

Population structure of the invasive species Leucaena leucocephala (Fabaceae) in a seasonal semi-deciduous forest, southern Brazil

2015 ◽  
Vol 63 (7) ◽  
pp. 590
Author(s):  
Janete T. Costa ◽  
Inês C. B. Fonseca ◽  
Edmilson Bianchini
Keyword(s):  
Invasive Species ◽  
Leucaena Leucocephala ◽  
Deciduous Forest ◽  
Recruitment Rate ◽  
Invasive Species Management ◽  
Southern Brazil ◽  
Disturbed Areas ◽  
Forest Remnant ◽  
Negative Exponential ◽  
High Recruitment

Biological invasions are one of the great threats of our time, and the accumulation of knowledge of invasive species is essential for invasive species management. In this study, aspects of the population ecology of Leucaena leucocephala (Lam) de Wit were investigated in a seasonal semi-deciduous forest remnant (23°15ʹ28ʹʹS, 51°01ʹ52ʹʹW – centre of the remnant) in Southern Brazil to evaluate whether the species is invading the remnant. In the first season, 1974 individuals, distributed heterogeneously in the remnant, were sampled. The population height structure fitted a negative exponential growth curve function (r2 = 0.9), indicating that the population was persisting through recruitment. The population also had a grouped spatial pattern and high recruitment rate. The species invaded the disturbed areas of the remnant. Gradual eradication is recommended for L. leucocephala for the remnant.

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