Population structure of the sand dollar Echinarachnius parma in the subtidal zone of the northern Gulf of St. Lawrence, eastern Canada

1996 ◽  
Vol 74 (4) ◽  
pp. 698-709 ◽  
Author(s):  
A. Cabanac ◽  
J. H. Himmelman
Keyword(s):  
Growth Rate ◽  
Size Structure ◽  
Subtidal Zone ◽  
Size Distributions ◽  
Sand Dollar ◽  
Eastern Canada ◽  
Different Depths ◽  
Accelerated Growth ◽  
Sand Dollars ◽  
Water Turbulence

We examined changes in populations of Echinarachnius parma with depth on subtidal sediment slopes in the Mingan Islands. Size distributions showed the presence of two major groups measuring 1–21 and 37–62 mm in length, respectively. Intermediate-sized sand dollars were rare. Juveniles (< 28 mm in length) were extremely abundant at 16 and 20 m depth (460–660/m2) and decreased in number with decreasing depth, whereas the density of adults was relatively stable at different depths. Juveniles were more frequently buried (95%) than adults (30%). Analysis of growth lines and of shifts in juvenile cohorts indicated that growth rate increased with size up to a maximum between 20 and 40 mm and then decreased sharply. The bimodal size structure is possibly due to the accelerated growth rate at intermediate sizes. We hypothesize that sand dollars move to shallower water with increasing size to take advantage of food resources, possibly benthic diatoms, which are more abundant there. Large individuals are probably better adapted than juveniles to exploiting shallower water because they are less likely to be transported by water turbulence.

scholarly journals Spawning Potential Ratio (SPR) Approach as a Management Measure of Skipjack Sustainability Record from Cilacap Fishing Port, Central Java, Indonesia

2021 ◽  
Vol 13 (2) ◽  
pp. 199
Author(s):  
Yonvitner Yonvitner ◽  
Mennofatria Boer ◽  
Rahmat Kurnia
Keyword(s):  
Growth Rate ◽  
Size Structure ◽  
Size Distributions ◽  
Frequency Data ◽  
Central Java ◽  
Management Measure ◽  
Spawning Potential Ratio ◽  
The Indian Ocean ◽  
The Impact ◽  
Poor Management

Highlight Research:Spawning potential ratio (SPR) based on the length and frequency data is a substitution approach for data-poor management in fisheriesGonad maturity is an indicator to ensure recruitment and stock sustainability. Therefore important to evaluate the impact of fishing capture on the size and length of fishSpawning potential ratio of skipjack relatively low and potential medium impact on risk sustainability AbstractWhen data is limited, management measurement from fisheries makes it possible to use natural history data to analyze the potential spawning ratio (SPR). This research aimed to determine skipjack fish management measure from the Indian Ocean landed at Cilacap Fishing Port through the SPR approach. The study was conducted in December 2014 to March 2015 using length and reproduction data. The analysis consisted of the size structure, growth rate, and asymptotic length that were analyzed using FISAT II program and length at fifty percent maturity (Lm50). The SPR analysis used SPR software from the application in http://barefootecologist.com.au/lbspr. The size distributions of skipjack obtained were a length of 220-790 mm and an average dominant length of 311-371 mm. The asymptotic length obtained was 831.57 mm, with growth rate and natural mortality of 1.1 and 1.44 per year respectively. The population proportion of 50% reaching gonad maturity (Lm50) was found at a length of 494.75 mm and (Lm95 = 522.39 mm) with an M/k ratio of 1.309. The length selectivity level was caught 50% (SL50 = 317.36 mm) and 95% (SL95 = 373.1 mm). The spawning potential ratio (SPR) ranged from 2-4 with an average of 4% during observation. The SPR potential, which is lower from the standardized threshold of 40%, indicates many young fish populations are caught, and the potential for overfishing is high, high risk, and low sustainability.

scholarly journals Aged boreal biomass burning aerosol size distributions from BORTAS 2011

2014 ◽  
Vol 14 (17) ◽  
pp. 24349-24385 ◽  
Author(s):  
K. M. Sakamoto ◽  
J. D. Allan ◽  
H. Coe ◽  
J. W. Taylor ◽  
T. J. Duck ◽  
...  
Keyword(s):  
Size Distribution ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Climate Model ◽  
Sampling Period ◽  
Characteristic Size ◽  
Entrainment Rate ◽  
Size Distributions ◽  
Eastern Canada ◽  
Median Diameter

Abstract. Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ∼1–2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter), σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.05–0.18 μg m−3 ppbv−1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We estimate that the fresh-plume median diameter was in the range of 59–94 nm with modal widths in the range of 1.7–2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the plume dilution rates.

scholarly journals Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

2013 ◽  
Vol 10 (8) ◽  
pp. 5267-5280 ◽  
Author(s):  
F. H. Chang ◽  
E. C. Marquis ◽  
C. W. Chang ◽  
G. C. Gong ◽  
C. H. Hsieh
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Growth Rates ◽  
Specific Growth ◽  
Size Structure ◽  
Scaling Exponent ◽  
The East China Sea ◽  
Size Category ◽  
Grazing Mortality ◽  
Specific Growth Rates

Abstract. Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of −1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ∼0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by (1) differential grazing mortality of small versus large individuals, (2) differential growth rate of small versus large individuals, or (3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure.

scholarly journals Response of Bosmina size structure to the acidification and recovery of lakes near Sudbury, Canada

2016 ◽  
Vol 75 (s2) ◽  
Author(s):  
Andrew L. Labaj ◽  
Jennifer B. Korosi ◽  
Joshua Kurek ◽  
Adam Jeziorski ◽  
Wendel (Bill) Keller ◽  
...  
Keyword(s):  
Metal Contamination ◽  
Carapace Length ◽  
Size Structure ◽  
Chemical Recovery ◽  
Size Distributions ◽  
Environmental Controls ◽  
Invertebrate Predators ◽  
Successive Generations ◽  
Mining And Smelting ◽  
Acidification And Recovery

In response to biotic and abiotic cues, the cladoceran genus <em>Bosmina </em>can<em> </em>undergo changes in body size and appendage length and shape over successive generations. To improve our understanding of the environmental controls on <em>Bosmina</em> size structure, we used paleolimnological techniques to examine <em>Bosmina</em> size responses to the extreme acidification and metal contamination, and then subsequent chemical recovery, of lakes in the vicinity of mining and smelting operations near Sudbury, Canada. During the acidification period, <em>Bosmina </em>antennule and carapace length significantly increased in three of the five study lakes, while mucro length significantly decreased in four of the five lakes. However, despite the recent return to pre-impact pH levels, the size structure of the present-day <em>Bosmina</em> community still differs from the pre-impact size distributions. We suggest that the continued dominance of the food webs by small invertebrate predators (<em>e.g.</em>, cyclopoid copepods) is responsible for the persistent changes to <em>Bosmina</em> size structure.

The biogeography of origin and radiation: dendrasterid sand dollars in the northeastern Pacific

Paleobiology ◽  
1991 ◽  
Vol 17 (4) ◽  
pp. 325-339 ◽  
Author(s):  
Steven C. Beadle
Keyword(s):  
Coastal Waters ◽  
Pacific Coast ◽  
Sand Dollar ◽  
Central California ◽  
The Pacific ◽  
Northeastern Pacific ◽  
Place Of Origin ◽  
Transitional Forms ◽  
Sand Dollars ◽  
And Behavior

Under favorable circumstances, biogeographic and biostratigraphic data can be combined to identify accurately the time and place of origin of a given taxon, and to reconstruct the pattern of its subsequent radiation. This study considers the dendrasterid sand dollars, which are abundant today along the Pacific Coast of North America. The Neogene sand dollar record in this region is particularly good; in fact, sand dollars have traditionally been used as provincial index fossils.The dendrasterids originated in central California at the end of the Miocene; the oldest forms are dated at about 6.0–6.5 Ma. They spread south to Baja California during the Pliocene, and then north to Alaska during the Quaternary. This historical pattern is not an artifact of the record; it is consistent with independent paleogeographic evidence. The dendrasterids supplanted an older Mio-Pliocene sand dollar fauna; they are now completely dominant in the temperate coastal waters of the northeastern Pacific. They have reached this position in less than 7 m.y. since their first local appearance. The rapid rise of dendrasterids could be related to their aberrant morphology and behavior; these adaptations allow dendrasterids to suspension-feed, in a manner unique among living echinoids.Dendrasterids are characterized by “eccentric” test morphologies. Even the oldest species are highly eccentric; transitional forms are unknown. The first dendrasterids appear suddenly in the provincial “Jacalitos Stage,” above an unconformity which represents no more than about 1 m.y. They do not occur in the underlying units, although other fossil sand dollars are abundant. The dendrasterids may have arisen rapidly, through a heterochronic change in the development of older, noneccentric forms. Recent ontogenetic studies have documented the feasibility of this process.

High throughput MOVPE and accelerated growth rate of GaAs for PV application

2019 ◽  
Vol 509 ◽  
pp. 87-90 ◽  
Author(s):  
Akinori Ubukata ◽  
Hassanet Sodabanlu ◽  
Taketo Aihara ◽  
Ryuji Oshima ◽  
Takeyoshi Sugaya ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Throughput ◽  
Accelerated Growth

Growth, morphometrics and size structure of the Diadematidae sea urchin Centrostephanus rodgersii in northern New Zealand

2012 ◽  
Vol 63 (7) ◽  
pp. 624 ◽  
Author(s):  
Danilo Pecorino ◽  
Miles D. Lamare ◽  
Mike F. Barker
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Sea Urchin ◽  
Size Structure ◽  
Growth Line ◽  
Fluorescent Marker ◽  
Zealand Population ◽  
Ecological Changes ◽  
Eastern Australia ◽  
Size At Age

The sea urchin Centrostephanus rodgersii has increased its range in Eastern Australia resulting in important ecological changes. C. rodgersii may also have expanded its distribution range to northern New Zealand in the last five to six decades, although little is known about this process and of the biology of the species in New Zealand. We investigated morphometrics as well as growth using two techniques (growth line count in genital plates and tag–recapture using the fluorescent marker tetracycline). These methods allowed modelling of size at age of C. rodgersii in New Zealand, which we compared with populations recently established in Tasmania. The modelled growth rate was only slightly higher in the New Zealand population, and no differences in morphometrics were observed. The New Zealand population structure suggests that annual recruitment occurs regularly, with the population including a range of ages (3 to 10+ years).

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