共查询到20条相似文献,搜索用时 31 毫秒
1.
Igor Henrique Rodrigues-Oliveira Karine Frehner Kavalco Rubens Pasa 《Acta zoologica》2023,104(3):345-354
Psalidodon rivularis is a species of tetra endemic to the São Francisco River basin and, based on cytogenetic and molecular studies, represents a complex of species. The objective of the present work was to identify morphological differences in the body shape of seven populations of P. rivularis from the Upper and Middle São Francisco River basin through geometric morphometry. In all, we photographed 174 individuals on the right side of the body and 17 landmarks were digitized on each image. To study the effects of allometry on the shape, we performed regression analysis and, to study shape modulation at different collection points and sub-basins, the canonical variation analyses. We found differences in shape between collection points and sub-basins associated with relative body height and sub-orbital plate recoil, in addition to a significant influence of size on specimen shape (allometry) associated with the ventral skull, orbits and sub-orbital plate. We do not envision differences in body shape between males and females. Several works with fish relate body height with water velocity, while the sub-orbital plate recoil shows a taxonomic or ecological potential, marking the main difference between the populations of the Upper and Middle São Francisco River. 相似文献
2.
Augusto Frota Maria J. M. Ganassin Weferson J. da Graça 《Zeitschrift fur angewandte Ichthyologie》2021,37(1):145-149
This study reports the length-weight relationships (LWR) for seven endemic fish species from streams in the Ivaí (Characidium heirmostigmata, Corydoras lacrimostigmata, Curculionichthys oliveirai, Hisonotus pachysarkos, and Cambeva horacioi) and Ivaí and Piquiri (Apareiodon vladii and Planaltina kaingang) River basins, Paraná State, Brazil. Fish specimens measured and weighed were collected between November 1994 and July 2019, fixed with 10% formalin, and are preserved in 70% alcohol. Measurements were done for standard length (SL—0.1 cm precision) and total weight (TW—0.01 g precision). All coefficient of allometry obtained is within the general range for fishes representing useful tentatives for LWR parameters. We highlight the importance of information about the biology of the endemic fish species in a crucial area for the biodiversity conservation of the Upper Paraná River system. 相似文献
3.
The Sickle Darter Percina williamsi (Page and Near, 2007) is a species of fish endemic to the upper Tennessee River basin in eastern Tennessee, southwestern Virginia, and western North Carolina. Because of its narrow range and presumed decline in occupied sites over the last half century, it is being proposed for federal listing under the Endangered Species Act. We analyzed the current distribution of the Sickle Darter and temporal trends in its distribution in relation to temporal trends in environmental and habitat covariates for each of the historically occupied sub-basins (upper Clinch, Emory, upper French Broad, Little, Little Pigeon, Middle Fork Holston, North Fork Holston, Powell, South Fork Holston, and Watauga) with multiple linear regression modelling. A total of 154 Sickle Darters were observed at 15 sites throughout the upper Tennessee River Basin. Sickle Darters were observed in the Little River, Emory River, and Middle Fork Holston River sub-basins. A total of 133 unique historical occurrences were used for the spatiotemporal analyses. Sickle Darters have declined in 8 out of 10 historically occupied sub-basins. Our best model for the whole distribution scale (Mallow's Cp = −0.87; Adjusted R2 = .92) suggests that habitat fragmentation due to damming has had adverse effects on Sickle Darter populations across its distribution. Models were very similar for the sub-basin specific models as well. The results from this study highlight the drivers of decline in Sickle Darter distribution and outline the future research needs for this species that should be used to inform future conservation decisions regarding this species. 相似文献
4.
Habitat composition and connectivity within a stream vary with changing flows but the influence of changing flow on habitat
use by fish is not well understood. Meso- and microhabitat surveys were used to investigate habitat use by bullhead (Cottus gobio Linnaeus) in response to discharge variation in a small tributary of the Upper Severn, England. Mesohabitat mapping surveys
were carried out over a range of summer flows (0.016–0.216 m3 s−1) and were coupled with direct underwater observations (snorkelling) of fish location. Five mesohabitat types—glides, runs,
riffles, chutes and pools—were present in the reach at all flows surveyed and ‘backwaters’ were found at three flows. The
macro-morphology of the reach comprised six riffle–pool sequences divided into 27 mesohabitats with the maximum diversity
(23 mesohabitats) at intermediate flows (Q
43) and only 15 mesohabitats at Q
95. Despite low numbers of fish (N = 78), bullhead displayed a strong association (51% of the fish) with glides—relatively deep habitats having high rates of
velocity increase with flow. However, 54% of the fish were observed in two large, persistent mesohabitats, a glide (34%) and
a pool (20%), both located below a faster flowing mesohabitat. Habitat use curves based upon micro-habitat data showed bullhead
favoured low velocities (<0.30 m s−1), depths less than 0.30 m and a cobble substratum. This study illustrates the value of cross-scale investigations in linking
fish ecology, flow and physical habitat variability and suggests mesohabitat size, persistence and arrangement may influence
fish distribution. 相似文献
5.
Greg G. Sass Thad R. Cook Kevin S. Irons Michael A. McClelland Nerissa N. Michaels T. Matthew O’Hara Matthew R. Stroub 《Biological invasions》2010,12(3):433-436
Invasive silver carp (Hypophthalmichthys molitrix) populations have expanded greatly in the Upper Mississippi River System (UMRS) since their introduction in the early 1970s.
We conducted a Chapman-modified, continuous Schnabel mark-recapture population and biomass estimate for silver carp (106–901 mm)
in the La Grange reach, Illinois River during 2007–2008. We estimated a total of 328,192 (95% CI 231,226–484,474) silver carp
(2,544 per river km 1,792–3,756) comprising 705 (95% CI; 496–1,040) metric tons of biomass (5.5 metric tons per river km 3.8–8.1).
Long Term Resource Monitoring Program (LTRMP) data from the La Grange reach showed an exponential increase in silver carp
catches since 1998, with an intrinsic rate of increase approaching 84%. In 2008, silver carp comprised about 51% of the total
LTRMP annual fish collection. To our knowledge, this large river reach may contain the greatest ambient densities of wild
silver carp in the world. Our findings provide a target for reduction efforts and also emphasize the importance of the La
Grange reach as a source population for potential expansion of the species to the Laurentian Great Lakes. 相似文献
6.
Baoshan Ma Kaijin Wei Jin Xu Jianchao Lu Bin Xu Xiangyun Zhu 《Zeitschrift fur angewandte Ichthyologie》2020,36(5):748-749
Length-weight relationships (LWRs) and length-length relationships (LLRs) were evaluated for three endemic fish species sampled from the lower Yalong River and its biggest tributary (the Anning River), in China. Specimens were captured using set gillnet (mesh size 4 cm) and backpack electro-fishing (power output 400 W, depth fished 1 m, area covered 3 m2) from June to July 2018. LWRs and LLRs are presented for the following species (Sinogastromyzon sichangensis, Micropercops swinhonis and Percocypris pingi). 相似文献
7.
We re-visited a seven-stand boreal chronosequence west of Thompson, Manitoba, Canada, in which coarse woody debris (CWD) and
its instantaneous decomposition were measured in 2000. New CWD measurements were performed in 2007, and tree inventories updated
to provide mortality and snag failure data. These data were used to model CWD changes, compare methods of estimating decomposition,
and infer possible fragmentation rates. Measured CWD was between 9.7 (in both the 77- and 43-year-old stands) and 80.4 (in
the 18-year-old stand) Mg ha−1 in 2007. Spatial variability was high; at most stands CWD levels had not changed significantly from 2000 to 2007. Tree mortality
was a significant flux only in older stands, whereas snag fall rate varied by an order of magnitude, from 2.9% y−1 (0.2 Mg ha−1 y−1) in the 9-year-old stand to 9.8% y−1 (2.3 Mg ha−1 y−1) in the 12-year-old stand. A one-pool model based on these inputs underestimated actual 2000–2007 CWD decomposition in the
younger stands, suggesting that fragmentation could be an important part of the carbon flux exiting the CWD pool. We compared
three independent measures of annual decomposition (k): direct measurements of CWD respiration, rates based on the 7-year re-sampling effort described here, and rates inferred
from the chronosequence design itself. Mean k values arrived at via these techniques were 0.06 ± 0.03, 0.05 ± 0.04, and 0.05 ± 0.05 y−1, respectively. The four-pool model suggested that the transition rate between decay classes was 0.14–0.19 y−1; the model was most sensitive to initial CWD values. Although the computed k values implied a problem with chronosequence site selection for at least one site, the overall CWD trend was consistent with
a larger number of sites surveyed in the region. 相似文献
8.
Matthias Hofmann 《Journal of biological inorganic chemistry》2009,14(7):1023-1035
[Mo(SSCH3)(S2C2(CH3)2)2]
x
complexes with charges x between −3 and +3 were investigated by density functional theory computations as minimal nitrate reductase active-site models.
The strongly reduced species (x = −2, −3) exist preferentially as pentacoordinate sulfo complexes separated from a thiolate anion. The oxidized extremes
(x > 0) clearly prefer hexacoordinate complexes with an η2-MeSS ligand. Among the neutral and especially for the singly negatively charged species structures with η2-MeSS and η1-MeSS ligands are energetically close to the sulfo methyl sulfide complex without SS bonding. For x = −1 the three isomers lie in a 1.5 kcal mol−1 energy range. Putative mechanistic pathways for nitrate reduction from the literature were investigated computationally:
(1) reduction at a pentacoordinate sulfo complex, (2) reduction at the ligand, and (3) reduction at the molybdenum center
with an R–S–S ligand. All three pathways could be traced at least for some overall charges but no definite conclusion can
be drawn about the mechanism. Complexes with larger dithiolato ligands were also computed in order to model the tricyclic
metallopterin framework more accurately: the first heterocyclus (5,6-dihydro-2H-pyran) stabilizes the nitrate complex and the molybdenum oxo product complex by approximately 10 kcal mol−1 and also reduces the activation barrier (by approximately 5 kcal mol−1). The effect of the second (1,2,3,4-tetrahydropyrazin) and third heterocyclus (2-amino-3H-pyrimidin-4-one) on the relative energies is relatively small. For bigger models derived from an experimental protein structure,
nitrate reduction at a persulfo molybdenum(IV) complex fragment (mechanism 3) is clearly favored over the oxidation of a molybdenum-bound
sulfur atom (mechanism 2). Mechanism 1 could not be investigated for the big models but seems the least favorable on the basis
of the results from smaller models. 相似文献
9.
Gilmour KM Collier CL Dey CJ Perry SF 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(4):501-515
Fish compensate for acid–base disturbances primarily by modulating the branchial excretion of acid–base equivalents, with
a supporting role played by adjustment of urinary acid excretion. The present study used metabolic acid–base disturbances
in rainbow trout, Oncorhynchus mykiss, to evaluate the role played by cortisol in stimulating compensatory responses. Trout infused with acid (an iso-osmotic solution
of 70 mmol L−1 HCl), base (140 mmol L−1 NaHCO3) or saline (140 mmol L−1 NaCl) for 24 h exhibited significant elevation of circulating cortisol concentrations. Acid infusion significantly increased
both branchial (by 328 μmol kg−1 h−1) and urinary (by 5.9 μmol kg−1 h−1) net acid excretion, compensatory responses that were eliminated by pre-treatment of trout with the cortisol synthesis inhibitor
metyrapone (2-methyl-1,2-di-3-pyridyl-1-propanone). The significant decrease in net acid excretion (equivalent to enhanced
base excretion) of 203 μmol kg−1 h−1 detected in base-infused trout was unaffected by metyrapone treatment. Acid- and base-infusions also were associated with
significant changes in the relative mRNA expression of branchial and renal cytosolic carbonic anhydrase (tCAc) and renal membrane-linked
CA IV (tCA IV). Cortisol treatment caused changes in CA gene expression that tended to parallel those observed with acid but
not base infusion. For example, significant increases in renal relative tCA IV mRNA expression were detected in both acid-infused
(~2x) and cortisol-treated (~10x) trout, whereas tCA IV mRNA expression was significantly reduced (~5x) in base-infused fish. Despite changes in CA gene expression in acid- or base-infused fish, neither acid nor base infusion
affected CAc protein levels in the gill, but both caused significant increases in branchial CA activity. Cortisol treatment
similarly increased branchial CA activity in the absence of an effect on branchial CAc protein expression. Taken together,
these findings provide support for the hypothesis that in rainbow trout, cortisol is involved in mediating acid–base compensatory
responses to a metabolic acidosis, and that cortisol exerts its effects at least in part through modulation of CA. 相似文献
10.
P.-D. Plisnier H. Mgana I. Kimirei A. Chande L. Makasa J. Chimanga F. Zulu C. Cocquyt S. Horion N. Bergamino J. Naithani E. Deleersnijder L. André J.-P. Descy Y. Cornet 《Hydrobiologia》2009,625(1):117-134
The abundance of two main pelagic fish species in Lake Tanganyika (Stolothrissa tanganicae and Lates stappersii) has always been observed to fluctuate considerably at different time scales. The inverse correlation between the abundance
of these species has often been interpreted as the consequence of predator−prey relations (avoidance behaviour by the prey).
However, currently the two species often appear spatially segregated in the lake, S. tanganicae dominating in the north while L. stappersii is generally abundant in the south where it feeds mostly on shrimps. A fluctuating abundance of the species is nevertheless
observed. As these fish species have a major importance for the fisheries, we investigated the limnological variability in
relation to the short-term variability of fish catches. The abundance of S. tanganicae was positively correlated to plankton biomass (r = 0.65), while water transparency (r = 0.56), depth of mixed layer (r = −0.70) and oxygenated water appeared important drivers for the abundance of L. stappersii. Alternating “mixing” and “stable” states of the epilimnion related to seasonal and internal waves variability are probably
determinant for the short-term variability in abundance of S. tanganicae and L. stappersii. In the framework of this study, remote sensing has shown a potentially interesting application for fisheries research at
Lake Tanganyika. We observed a close correspondence between phytoplankton blooms at the time of trade winds changes and increased
catches of S. tanganicae in the south. The anti-correlated abundance of S. tanganicae and L. stappersii probably mainly reflects the underlying fluctuating limnological environment. Fisheries studies need to integrate limnological
and planktonic monitoring to better understand large and complex ecosystems such as Lake Tanganyika.
相似文献
P.-D. PlisnierEmail: |
11.
Nelusetta ayraudi (the ocean leatherjacket) is an endemic Australian monacanthid species distributed from North West Cape (Western Australia)
south to southern Queensland. The commercial and recreational fisheries targeting Nelusetta ayraudi have expanded substantially along the coast of New South Wales (NSW) in recent years but there exists little biological information
on which to base effective management of this growing fishery. World-wide, only a few studies have aged monacanthids. Of these,
researchers have interpreted periodic increments in bony structures such as vertebrae and anterior dorsal spines in preference
to those found in otoliths. In this study we estimated age of N. ayraudi by counting growth increments in sectioned otoliths. The periodicity of increment formation was validated using a vital stain,
(oxy-tetracycline), injected into young-of-the-year fish. Growth was rapid especially as juveniles with N. ayraudi attaining approximately 220 mm after 1 year and 340 mm after 2 years. No differences in growth rates were detected between
sexes or between fish captured at different latitudes (zones). The largest male (605 mm, Total Length—TL) and female (656 mm,
TL) were both recorded from northern NSW, with both sexes attaining the maximum age of 6+ years from northern and southern
NSW. The von Bertalanffy parameters describing growth for N. ayraudi were L¥ {L_\infty } = 591 mm (TL), k = 0.377 year−1 and t
o = −0.247 years. 相似文献
12.
Degradation of icefishes (Salangidae) in the Yangtze River basin of China: threats and strategies 总被引:1,自引:0,他引:1
Zhongsuo Wang Jieqiang Shi Chongren Xu Guangchun Lei 《Environmental Biology of Fishes》2009,86(1):109-117
The Yangtze River basin has been a major area in terms of icefish diversity conservation and fisheries. In the past two to
five decades, however, the wild icefish resources have degraded continuously in both the brackish estuary and freshwater portions
of the basin. Stocks have declined in all icefish fisheries, resulting in an annual fishing yield decrease from the maximum
of 4,000 metric tons to less than 1,300 metric tons in this river basin. The stocks decline significantly (t = −6.74, df = 1, p < 0.001) correlated with icefish fishing stress in the estuary. Meanwhile, species composition changed markedly with smaller
sized icefish species increased relative to the number of larger ones in terms of their relative abundances. Following the
stocks decline and size reduction, icefish commercial value decreased to the point that 91.9% of the traditional icefish-producing
waters (57 out of 62) terminated their icefish fisheries and some species became locally extinct. Based on the degradation
process, we suggest that these changes in stock size and species diversity are the result of overfishing and habitat loss
and degradation. We propose a number of measures aimed at the conservation and restoration of the wild icefish resources in
the Yangtze River basin. 相似文献
13.
Phosphorus (P) dynamics in the agriculturally-dominated Minnesota River (USA) were examined in the lower 40 mile reach in
relation to hydrology, loading sources, suspended sediment, and chlorophyll to identify potential biotic and abiotic controls
over concentrations of soluble P and the recycling potential of particulate P during transport to the Upper Mississippi River.
Within this reach, wastewater treatment plant (WWTP) contributions as soluble reactive P (SRP) were greatest during very low
discharge and declined with increasing discharge and nonpoint source P loading. Concentrations of SRP declined during low
discharge in conjunction with increases in chlorophyll, suggesting biotic transformation to particulate P via phytoplankton
uptake. During higher discharge periods, SRP was constant at ~0.115 mg l−1 and coincided with an independently measured equilibrium P concentration (EPC) for suspended sediment in the river, suggesting
abiotic control over SRP via phosphate buffering. Particulate P (PP) accounted for 66% of the annual total P load. Redox-sensitive
PP, estimated using extraction procedures, represented 43% of the PP. Recycling potential of this load via diffusive sediment
P flux under anoxic conditions was conservatively estimated as ~17 mg m−2 d−1 using published regression equations. The reactive nature and high P recycling potential of suspended sediment loads in the
Minnesota River has important consequences for eutrophication of the Upper Mississippi River. 相似文献
14.
Length–weight relationships of three fish species from the Tibet reach of the Lancang River,China
下载免费PDF全文
![点击此处可从《Zeitschrift fur angewandte Ichthyologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
T. B. Zhu X. G. Wang J. Huang D. G. Yang 《Zeitschrift fur angewandte Ichthyologie》2018,34(3):710-711
Length‐weight relationships (LWRs) were determined for three fish species, Schizothorax lantsangensis (Tsao, 1964), Schizothorax lissolabiatus (Tsao, 1964) and Schizopygopsis anteroventris (Wu & Tsao, 1989), from the Tibet reach of the Lancang River, China (N 29°06′–31°30′, E 96°57′–98°38′). Specimens were collected in April and September 2017. The specimens were caught with drifting gillnets (mesh size 2.5 cm and 7.0 cm). The b values of these three fish species ranged from 2.974 to 3.075. The high r2 values (all > .980) indicate that these relationships will be appropriate for use in fisheries management of these species. 相似文献
15.
Jeroen Speybroeck Joke Van Tomme Magda Vincx Steven Degraer 《Helgoland Marine Research》2008,62(3):257-268
Population dynamics and zonation of the amphipods Bathyporeia pilosa and B.
sarsi, co-occurring on some beaches, were studied through monthly sampling of eight cross-shore transects along the Belgian coast
(October 2003–October 2004). Their biomass and production were assessed for the first time. Abundance and biomass of B. pilosa were ten times higher along western ultra-dissipative transects than along slightly more reflective, eastern transects. For
B. sarsi (less prominent), differences between the two westernmost transects (2–5× higher) and all others were observed, whereas P/B
ratio was comparable for all. B. pilosa could reach two times higher abundance and biomass and higher levels of production (max B. sarsi = 7,580 g m−2 y−1; max B. pilosa = 16,040 g m−2 y−1), while the species was nearly absent from the eastern transects. Continuous reproduction and recruitment with three relative
peaks of the latter (February, July, October) were observed. Fecundity showed parallel temporal variation for both species,
peaking in February and September–October. Interestingly, the July relative “recruitment” peak could not be explained by relative
abundance of gravid females or fecundity, but was probably caused by adult mortality. Both species displayed comparable gonad
production (B. pilosa: P
g
= 0.73 mg/ind year; B. sarsi:
P
g
= 0.71 mg/ind year), but B. pilosa produced fewer yet larger embryos. Peak abundances were found at 436 ± 25 SD cm (B. pilosa) and 357 ± 40 SD cm (B. sarsi) above MLLWS, corresponding to a 40–62 m cross-shore distance between the peaks of both species. The occupied cross-shore
range was larger for B. sarsi than for B. pilosa (35–54 m), for females than for males (15–23 m), and for adults than for juveniles of B. pilosa (5–8 m). Both species displayed many comparable life history features. Differences in abundance and biomass may be related
to beach morphodynamics and zonation. 相似文献
16.
Length–weight relationship of five fish species from the Xiaonanhai reach of the Upper Yangtze River,southwest China
下载免费PDF全文
![点击此处可从《Zeitschrift fur angewandte Ichthyologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Length–weight relationships (LWRs) were determined for five fish species, including two endemic species [Platysmacheilus nudiventris (Luo, Le & Chen, 1977), and Rhinogobio cylindricus (Günther, 1888)] from the Xiaonanhai reach of the Upper Yangtze River in southwest China. Samples were obtained between July 2011 and October 2012 using various types of fishing gear and electroshock fishing techniques. For each species, the sample size, length range, weight range, LWR, 95% confidence intervals of a and b, and coefficient of correlation were determined. Length–weight relationships for two species were unknown to FishBase, and new maximum lengths are recorded for two species. 相似文献
17.
Robert R. Lane Christopher J. Madden John W. DayJr. Darrell J. Solet 《Hydrobiologia》2011,658(1):55-66
This article synthesizes several studies carried out at Fourleague Bay and connecting waterways of the western Terrebonne
interdistributary basin of the Mississippi River delta plain, which is strongly impacted by the Atchafalaya River. Hydrologic
and nutrient fluxes were measured over two tidal cycles in February, April, and September of 1982. Synoptic water quality
sampling of nutrients, sediments, salinity, and chlorophyll a was carried out from April 1986 to August 1991 (17 events), during 1994 (12 events), and from 2000 to 2002 (8 events). Hydrology
and nutrient dynamics of the region were controlled by winds associated with cold fronts and Atchafalaya River discharge during
winter–spring, and tidal forces during summer–fall. Less than 5% of the water discharged from the Atchafalaya River entered
Fourleague Bay, but nonetheless was the dominant source of nutrients, especially nitrate + nitrite (NO
x
), and sediments. Nitrate + nitrite concentrations entering Fourleague Bay ranged from 33.3 to 118.0 μM, with highest levels
occurring during peak river discharge. Fourleague Bay was a sink for DIN, with retention rates ranging from 184.4 to 704.2 μg-at m−2 h−1, but both a source and sink for DIP, with retention rates ranging from −2.7 to 14.9 μg-at m−2 h−1. Concentrations of DIN and DIP in the bay ranged from below detection limits to 49.0 and 29.1 μM, respectively, while chlorophyll
a ranged from 6.1 to 49.4 μg/l. In the wetlands surrounding Fourleague Bay, chlorophyll a generally mirrored NO
x
and TSS, and generally peaked 2–15 km from riverine sources. 相似文献
18.
Zhiying Tu Xi Yuan Jingcheng Han Xiaotao Shi Yingping Huang David Johnson 《Hydrobiologia》2011,675(1):119-127
Schizothorax chongi (locally known as Xilian Yu), a fish species commonly found in Yalong River, has been declining quickly in recent years.
One of the important factors, among many, is the interruption of the free flowing river by dams. To obtain data that can be
applied to the design of a fishway for S. chongi and other species in the community, a laboratory study of juvenile S. chongi’s swimming energetics and kinematics was conducted in a flume-type respirometer equipped with a high speed video camera system
to record swimming behavior. The aerobic metabolic rate, tail beat frequency (TBF) and tail beat amplitude (TBA) were measured
during steady swimming at varying flow rates for fish of similar mass. A power function accurately describes the relationship
between oxygen consumption rate (MO2) and swimming speed (U). The estimated standard metabolic rate (SMR) calculated from the power function was 445.34 mg O2 kg−1 h−1, similar to the experimental result of 431.5 mg O2 kg−1 h−1. The relationship between cost of transport (COT) and U was, characteristically, inverse bell-shaped, with COTmin = 44.6 J kg−1 m−1 at U
opt = 5.5 body lengths per second (bl s−1). There was a significant positive linear correlation between TBF and U. The slope of the correlation (0.33) was lower than for many other species, implying that S. chongi swim efficiently. The TBA, ranging from 0.15 to 0.2 bl, was found to be independent of U. Kinematic analyses indicates that S. chongi primarily depends on the caudal fin to generate forward thrust and employs three velocity-dependent swimming gaits. This
investigation provides data on the swimming ability of S. chongi that will add to the basic science required for fishway design. 相似文献
19.
Meso- and bathypelagic distribution and abundance of chaetognaths in the Atlantic sector of the Southern Ocean 总被引:1,自引:0,他引:1
We conducted multinet sampling during winter and summer in the Southern Ocean (Atlantic sector) to investigate the effect
of water mass, season and water depth on abundance and species composition of meso- and bathypelagic chaetognaths. Eukrohnia hamata (mean 115 ind. 1,000 m−3) and Sagitta marri (mean 51 ind. 1,000 m−3) were dominant, complemented by E. bathypelagica (mean 19 ind. 1,000 m−3) and E. bathyantarctica (mean 19 ind. 1,000 m−3) below 1,000 m. A further six species were identified, among them the rare bathypelagic species Heterokrohnia fragilis and the subtropical Eukrohnia macroneura that is new to the Antarctic. Water depth and season were the principal determinants of abundance and species composition
patterns, indicating vertical seasonal migration and vertical segregation of species. The life cycles of E. hamata and S. marri were studied additionally. Their maturity stages were vertically segregated and prolonged reproductive periods are suggested
for both species. 相似文献
20.
Motomi Genkai-Kato Miyuki Onishi Hideyuki Doi Kentaro Nozaki Kenji Yoshino Hitoshi Miyasaka Koji Omori 《Ecological Research》2008,23(6):1025-1032
We investigated the photosynthesis–light intensity (P–I) relationships of phytoplankton collected from a sublittoral sand
bank in the Seto Inland Sea, Japan, under different temperature conditions. In spite of low chlorophyll a concentration (<3 mg m−3), phytoplankton had considerably high photosynthetic potential (>10 mg C (mg chl a)−1 h−1) in the study area. Based on the P–I relationships, we conducted numerical simulation of areal primary production using published
data on water temperature, chlorophyll a concentration, and irradiance. The areal primary production ranged between 159 and 187 g C m−2 year−1. This production was within the range of typical values reported previously in deeper areas of the Seto Inland Sea. The productivity
in the sand bank area was discussed in relation to water current, allochthonous resource input, and fisheries. 相似文献