Spelling suggestions: "subject:"glacial""
1 |
The breeding season distribution, foraging trip characteristics and habitat preference of northern fulmars, Fulmaris glacialisEdwards, Ewan William James January 2015 (has links)
The role of seabirds as indicators of marine conditions is widely acknowledged. As top predators they are vulnerable to environmental change. The study of spatial ecology has been identified as critical to the conservation of seabirds. The studies described within this thesis have for the first time explored in detail the spatial distribution of breeding fulmars. A combination of geolocation (GLS) and GPS tracking during incubation and chick rearing found that fulmars ranged further and for longer during incubation, with little difference between the sexes (Chapter 2). GLS tracking data from this period suggested that some birds were foraging at the Mid Atlantic Ridge, far surpassing the assumed maximum foraging range of this species whilst breeding. This was confirmed from the GPS track of one bird. Search behavior during the trip suggests that this bird exploited prey resources associated with fronts at the Charlie Gibbs Fracture Zone (Chapter 4). Whilst foraging far from the breeding site may allow birds to avoid competition and exploit predictable prey patches, this wide ranging behaviour may expose birds to threats such as fisheries bycatch. The majority of female fulmars tracked during the pre laying exodus foraged within the Norwegian Sea (Chapter 3), where it is estimated that 20,000 fulmars die annually on longlines. A double-tagging study, the first in the North Atlantic region and the first on a petrel species, used a state-space model to estimate the error in GLS data from fulmars and reconstructed the most probably route travelled. These data indicate that during this early period of the breeding season when distribution was virtually unknown, fulmars from a Scottish colony were foraging widely within three broad biogeographical regions. Meanwhile, fine-scale GPS tracking data was collected at three colonies during the chick rearing period. When combined with environmental and fisheries data within a model this facilitated investigation into the habitat preference of fulmars, finding associations between fulmar presence and fisheries activity, as well as oceanography (Chapter 5). This thesis describes how the use of telemetry has for the first time linked breeding season foraging characteristics with spatial distribution and habitat. Tracking has revolutionized our knowledge of fulmar distribution, behavior and habitat preference during the breeding season.
|
2 |
Terpenoids from the marine sponge Aplysilla glacialis and the nudibranch Cadlina luteomarginataTischler, Mark January 1989 (has links)
A chemical study of the pink encrusting sponge Aplysilla glacialis collected in Barkley Sound, B.C., has led to the isolation and structure elucidation of terpenes which are believed to be derived biogenetically from the hypothetical "spongian" precursor. In addition, the first example of a diterpene from a sponge containing a "marginatane" skeleton has been found.
Cadlinolide A (75) was isolated and its structure elucidated by a combination of spectroscopic interpretation, chemical degradation, and confirmed by a single crystal x-ray diffraction analysis. The structure of a related metabolite, cadlinolide B (76). was also isolated and elucidated by spectroscopic interpretation and conversion to the known metabolite tetrahydroaplysulphurin-1 (72). The structure of a nor-diterpene, aplysillolide A (101) was determined by spectroscopic interpretation and chemical interconversion along with its dehydrated analogue, aplysillolide B (102). Glaciolide (110). a degraded and highly rearranged diterpene was solved by extensive NMR analysis of both the parent compound and its chemically interconverted derivatives. Glaciolide (110) represents only the second known example of a metabolite containing a "glaciane" skeleton. Marginatone (112) is the first example of a diterpene containing a "marginatane" skeleton from a sponge. The "marginatane" skeleton was first encountered in a metabolite, marginatafuran (111), isolated from the nudibranch Cadlina luteomarginata which is generally found in the same location as Aplysilla glacialis. The structure of cadlinolide C (131), containing both methyl ester and γ lactone moieties, was elucidated by spectroscopic interpretation. This compound is believed to be an isolation artifact
Examination of the chemical constituents of the nudibranch Cadlina luteomarginata found feeding on the sponge Aplysilla glacialis yielded a mixture of terpenes mcluding cadlinolide A (75). glaciolide (110) and tetrahydroaplysulphurin-1 (72). Compound 72 was previously isolated from a New Zealand sponge.
A review of "spongian" and "marginatane" derived metabolites from sponges and nudibranchs as well as a review of Cadlina luteomarginata terpenoids is presented.
[Formulas omitted] / Science, Faculty of / Chemistry, Department of / Graduate
|
3 |
Hybridation entre Calanus finmarchicus et C.glacialis (Copepoda)Parent, Geneviève 19 April 2018 (has links)
L’hybridation est un phénomène observé tant chez les plantes que chez les animaux, mais qui n’avait toutefois jamais été détecté chez le zooplancton marin. Cette thèse vise à caractériser l’hybridation entre Calanus glacialis et C. finmarchicus afin d’évaluer son impact sur la dynamique des populations dans l’ouest de l’Atlantique. De plus, les méthodes d’identification morphologique et génétique sont comparées et combinées afin de tester leur capacité à discriminer les espèces parentales et les hybrides. Dans le deuxième chapitre, une grande variabilité spatio-temporelle du chevauchement de la longueur de prosome entre les espèces C. glacialis et C. finmarchicus est montrée pour les copépodites de stade V. Ce chevauchement de taille entraine une identification erronée et donc, une sous-estimation considérable de l’abondance de C. glacialis dans l’estuaire du Saint-Laurent et sur la côte du Labrador. Au troisième chapitre, la présence d’hybrides est d’abord établie. Il existe une grande variabilité spatiale dans la fréquence des hybrides dans la zone hybride, soit de l’archipel canadien arctique au golfe du Maine, chez le stade copépodite V. De plus, la longueur de prosome des hybrides varie en fonction des génotypes dans l’aire d’étude. Dans le quatrième chapitre, il est mis en évidence que la phénologie reproductive des femelles adultes hybrides est intermédiaire à celles des espèces parentales dans l’estuaire du Saint-Laurent. En revanche, le succès reproducteur et le phénotype des femelles adultes hybrides sont similaires à ceux de leur ancêtre maternel. Les hybrides représentent une faible proportion de la production totale d’œufs de mars à juillet. Ainsi, malgré la présence de flux génique entre C. glacialis et C. finmarchicus, les espèces parentales conservent leur intégrité et sont isolées temporellement dans la zone hybride. Les effets sur la dynamique des populations des espèces parentales semblent minimes. Les recherches à vernir devraient tenter de révéler l’hybridation entre ces espèces dans d’autres zones et d’investiguer l’effet des variations de phénologie reproductive et d’advection sur l’abondance d’hybrides. L’hybridation entre d’autres espèces de zooplancton marin semble également plausible. / Hybridization is a phenomenon observed in plants and animals which to date has never been detected in marine zooplankton. This thesis aims to characterise hybridization between Calanus glacialis and C. finmarchicus in order to evaluate the impact on species population dynamics in the West Atlantic. In addition, morphological and genetic identification were compared and combined to test their potential for discrimination of parental species and hybrids. In the second chapter, a great spatio-temporal variability in overlap in prosome length between C. glacialis and C. finmarchicus is shown for stage V copepodites. This overlap in prosome length has the consequence of misidentifying and thus, considerably underestimating C. glacialis’ abundance in the St. Lawrence Estuary and on the Labrador Coast. In the third chapter, it is shown that hybrids exist, and that there is substantial spatial variability in their frequency in the hybrid zone, from the Canadian Arctic Archipelago to the Gulf of Maine, for the copepodite stage V. Moreover, hybrid size varied as a function of genotypic composition. In the fourth chapter is shown that hybrid adult females have an intermediate reproductive phenology to that of their parental species in the St. Lawrence Estuary. Contrastingly, fitness and phenotypes of hybrid adult females are similar to those of their maternal ancestor. Hybrids represent a small proportion of total egg production from March to July. Thus, although gene flow occurs between these species, parental species are maintained and mainly isolated temporally within the hybrid zone. The effects of hybridization on species population dynamics are probably minor. Future studies should aim to study hybridization between these species in other zones and the effects of variation in their reproductive phenology and advection on hybrid abundance. Hybridization between other marine zooplankton species is also likely.
|
4 |
The cost of locomotion in North Atlantic right whales (<italic>Eubalaena glacialis</italic>)Nousek McGregor, Anna Elizabeth January 2010 (has links)
<p>Locomotion in any environment requires the use of energy to overcome the physical</p><p>forces inherent in the environment. Most large marine vertebrates have evolved</p><p>streamlined fusiform body shapes to minimize the resistive force of drag when in</p><p>a neutral position, but nearly all behaviors result in some increase in that force.</p><p>Too much energy devoted to locomotion may reduce the available surplus necessary</p><p>for population-level factors such as reproduction. The population of North Atlantic</p><p>right whales has not recovered following legal protection due to decreased fecundity,</p><p>including an increase in the intercalf interval, an increase in the years to first calf and</p><p>an increase in the number of nulliparous females in the population. This reproductive</p><p>impairment appears to be related to deficiencies in storing enough energy to meet the</p><p>costs of reproduction. The goal of this study was to determine whether increases in</p><p>moving between prey patches at the cost of decreased foraging opportunities could</p><p>shift these whales into a situation of negative energy gain. The first step is to</p><p>understand the locomotor costs for this species for the key behaviors of traveling and</p><p>foraging.</p><p>This study investigated the cost of locomotion in right whales by recording the</p><p>submerged diving behaviors of free-ranging individuals in both their foraging habitat</p><p>in the Bay of Fundy and their calving grounds in the South Atlantic Bight with a</p><p>suction-cupped archival tag. The data from the tags were used to quantify the oc-</p><p>currence of different behaviors and their associated swimming behaviors and explore</p><p>three behavioral strategies that reduce locomotor costs. First, the influence that</p><p>changes in blubber thickness has on the buoyancy of these whales was investigated</p><p>by comparing the descent and ascent glide durations of individual whales with differ-</p><p>ent blubber thicknesses. Next, the depth of surface dives made by animals of different</p><p>sizes was related to the depth where additional wave drag is generated. Finally, the</p><p>use of intermittent locomotion during foraging was investigated to understand how</p><p>much energy is saved by using this gait. The final piece in this study was to deter-</p><p>mine the drag related to traveling and foraging behaviors from glides recorded by</p><p>the tags and from two different numerical simulations of flow around whales. One, a</p><p>custom developed algorithm for multiphase flow, was used to determine the relative</p><p>drag, while a second commercial package was used to determine the absolute mag-</p><p>nitude of the drag force on the simplest model, the traveling animal. The resulting</p><p>drag estimates were then used in a series of theoretical models that estimated the</p><p>energetic profit remaining after shifts in the occurrence of traveling and searching</p><p>behaviors.</p><p>The diving behavior of right whales can be classified into three stereotyped be-</p><p>haviors that are characterized by differences in the time spent in different parts of the</p><p>water column. The time budgets and swimming movements during these behaviors</p><p>matched those in other species, enabling the dive shapes to be classified as foraging,</p><p>searching and traveling behaviors. Right whales with thicker blubber layers were</p><p>found to perform longer ascent glides and shorter descent glides than those with</p><p>thinner blubber layers, consistent with the hypothesis that positive buoyancy does</p><p>influence their vertical diving behavior. During horizontal traveling, whales made</p><p>shallow dives to depths that were slightly deeper than those that would cause ad-</p><p>ditional costs due to wave drag. These dives appear to allow whales to both avoid</p><p>the costs of diving as well as the costs of swimming near the surface. Next, whales</p><p>were found to glide for 12% of the bottom phases of their foraging dives, and the</p><p>use of `stroke-glide' swimming did not prolong foraging duration from that used by</p><p>continuous swimmers. Drag coefficients estimated from these glides had an average</p><p>of 0.014 during foraging dives and 0.0052 during traveling, values which fall in the</p><p>range of those reported for other marine mammals. One numerical simulation deter-</p><p>mined drag forces to be comparable, while the other drastically underestimated the</p><p>drag of all behaviors. Finally, alterations to the behavioral budgets of these animals</p><p>demonstrated their cost of locomotion constitutes a small portion (8-12%) of the</p><p>total energy consumed and only extreme increases in traveling time could result in a</p><p>negative energy balance. In summary, these results show that locomotor costs are no</p><p>more expensive in this species than those of other cetaceans and that when removed</p><p>from all the other stressors on this population, these whales are not on an energetic</p><p>`knife edge'.</p> / Dissertation
|
5 |
Variation in the prey field of North Atlantic right whales (Eubalaena glacialis) in Roseway BasinDavies, Kimberley 08 August 2012 (has links)
‘Critical Habitat’ is the habitat required to close the life history of an endangered species and is a fundamental requirement for species recovery for two reasons; the role of habitat in population limitation and viability must be determined, and the habitat must be protected. The North Atlantic right whale is an endangered species that annually migrates to the Grand Manan Basin and Roseway Basin Critical Habitats to feed on diapausing calanoid copepods that are typically aggregated at depths of 100 to 150 m. In this thesis I quantify spatial and temporal variation in the copepod prey field and occupancy of right whales in Roseway Basin, and use this information to identify the location and extent of right whale Critical Habitat. To accomplish this, I measured copepod abundance and energy density (kJ m-3) using optical, acoustic and net collection methods during 2007 to 2009. Oceanographic processes that affect variation in the copepod prey field include slope water intrusions, water mass density, gyre-like circulation and frontal features. Aggregations of diapausing copepods are maintained on the southern slope of Roseway Basin by cross-isobath tidal advection, and are advected along-isobath by the residual flow. Tidal advection at a front, coupled with along-isobath advection and shear in the horizontal currents serve to accumulate copepods along the slope where aggregations are maintained for at least 7 days. The abundance, stage-structure, species composition and aggregation locations of copepods, as well as the hydrography and circulation, were variable among the three years of the study. A 20 year time series of right whales, copepods and hydrography revealed that interannual whale occupancy in the Critical Habitats is variable and can be explained by prey field variation only in Roseway Basin. Factors other than the local prey field affect the number of whales that occupy Grand Manan Basin. Variation in the right whale prey field could not be explained by temperature and phytoplankton-dependent growth in the Scotia - Fundy -Gulf of Maine region. The results of this thesis assisted in establishing the Roseway Basin right whale Critical Habitat in 2008, and the cross-disciplinary nature of the study also provides new insights into the relationships between biology and physics in Scotian Shelf - Gulf of Maine basins.
|
6 |
Satellite monitored dive characteristics of the northern right whale, Eubalaena glacialisNieukirk, Sharon L. 07 December 1992 (has links)
The western North Atlantic population of the northern right whale (Eubalaena
glacialis) was severely depleted by whaling over the last century. Despite over fifty
years of protection, fewer than four hundred individuals are believed to exist in the
North Atlantic. Relatively little is known about the diving behavior, respiratory
physiology, or diel activity of these whales, although such information could be useful
in predicting population abundance and distribution in relation to food or
environmental variables. Dive behavior data can be collected visually, but collection
is limited to daylight hours, calm weather, and fortuitous encounters with study
animals. Satellite-monitored radio tags offer the opportunity to collect data on
individual whales' diving behavior continuously, over long distances and periods of
time, and at relatively low cost.
Thirteen North Atlantic right whales were tagged and monitored in the Gulf of
Maine between 1989 and 1991. One male was tagged in 1989; two adult males, six
adult females (two with calves) and one juvenile were tagged in 1990; one adult
female (with a calf) and two juveniles were tagged in 1991. The duration of
monitoring for the whales varied from <1 day to 43 days. Characteristics of the
radio tags were different over each year in order to evaluate different attachment
mechanisms and methods of collecting and summarizing data for dive duration, dive
frequency, and time submerged. These data were then used to describe the dive
behavior and to predict aspects of the respiratory physiology for these whales.
The number of dives, their duration, and the time submerged varied
considerably among individual whales and between years. Over all, the whales spent
79% of their time underwater. However, most dives were short (i.e., 95% were
<14 min; the mean dive duration was 92.3 sec), although dives of 30-40 min
duration were observed for several individuals. In general, the number of dives a
right whale made was inversely related to the average duration of its dives within a
time interval. Furthermore, over a given time interval, the number of times a whale
dove was a better predictor of the percent time it was submerged than was the
average duration of its dives.
There was no evidence of diel variation in dive behavior (i.e., number of
dives, average dive duration, or percent time submerged) among these whales. Age,
sex, and reproductive status may have affected dive behavior, although these trends
were not statistically significant due to the small number of study animals and
individual behavioral variability. Males tended to dive more often and averaged
shorter dives than females. Females with calves dove more often and averaged
shorter dives than females without calves. Juvenile females dove less often but
averaged longer dives than adult males or females with calves.
It was predicted that the aerobic dive limit of an "average" right whale was
approximately 14 min. Ninety-five percent of the dives recorded for the 11
monitored right whales were < 14 min. Furthermore, there was no evidence of
recuperative periods (i.e., prolonged periods at the surface) after long dives. These
observations were consistent with the idea that the North Atlantic right whales dove
within their aerobic scope. They further suggest that physiological parameters alone
probably have little influence on dive characteristics, except to set an upper limit on
the duration of a dive.
Satellite telemetry provides an opportunity to monitor the movements and
behavior of free-ranging animals, and overcome many of the short-comings associated
with traditional, human-based visual techniques for tracking and studying such
animals. Although the tags used in this study were prototypes and varied in their
design from year to year, several right whales were monitored simultaneously and
were tracked over thousands of kilometers. Advances in tag miniaturization,
attachment, and software will likely extend the time tags stay attached and the detail
of the behavioral and environmental variables that can be monitored. As testimony to
the power of this technology, this application of satellite telemetry to monitor great
whales yielded one of the most extensive, long-term, continuously-monitored data sets
yet recorded on the diving behavior of a baleen whale. / Graduation date: 1993
|
7 |
Variabilidade espacial e temporal do fitoplâncton na zona de arrebentação da praia do Cassino (RS, Brasil): relação com os depósitos de lama e nutrientes dissolvidosPiedras, Fernanda Reinhardt January 2012 (has links)
Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2012. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-11-19T12:24:44Z
No. of bitstreams: 1
fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5) / Approved for entry into archive by Angelica Miranda (angelicacdm@gmail.com) on 2013-11-20T21:40:54Z (GMT) No. of bitstreams: 1
fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5) / Made available in DSpace on 2013-11-20T21:40:54Z (GMT). No. of bitstreams: 1
fernanda.pdf: 1386021 bytes, checksum: e67fec86c13546d730d06a2d26086f69 (MD5)
Previous issue date: 2012 / Na zona de arrebentação de praias arenosas e expostas ocorrem acumulações de diatomáceas, as quais são importantes produtores primários. Visando entender se existe uma variação espacial e temporal do fitoplâncton na zona de arrebentação da Praia do Cassino, foram analisadas semanalmente cinco estações no período de deposição lama (maio a julho de 2009), e posteriormente (agosto de 2009 a abril 2010) três estações quinzenalmente ao longo de 21 km. As relações entre variáveis ambientais e a composição e biomassa do fitoplâncton foram comparadas, verificando-se que a deposição de lama influenciou a transparência da água, mas não foi detectada diferença significativa entre os valores médios de nutrientes e de clorofila a nas estações ao longo do ano. As diatomáceas foram dominantes, destacando-se a contribuição de cêntricas unicelulares do microplâncton e Skeletonema spp., e das penadas Asterionellopsis glacialis e Pseudo-nitzschia sp. Porém, a densidade de A. glacialis encontrada neste ano foi menor do que em anos anteriores, enquanto os gêneros planctônicos Skeletonema e Pseudo-nitzschia apareceram em alta densidade. Em laboratório foram realizados experimentos curtos com enriquecimento de nutrientes inorgânicos dissolvidos testando-se ao todo sete proporções de silicato, nitrato e fosfato, com objetivo de determinar sua influência sobre as microalgas da Praia do Cassino. Como resultado, a biomassa fitoplanctônica exibiu um aumento significativo nos tratamentos com adição de nitrato, independentemente da proporção adicionada, indicando que o nitrato é o nutriente mais importante no controle da biomassa e do crescimento das diatomáceas da Praia do Cassino. / In the surf zone of exposed sandy beaches significant accumulations of diatoms occur, which are important primary producers. In order to determine the spatial and temporal variability of phytoplankton in the surf zone, five and three stations were studied in the period with mud deposition (weekly sampling, May to July 2009) and without (every two weeks, August 2009 to April 2010), respectively, along 21 km of Cassino Beach. The relationships among environmental variables and phytoplankton composition and concentration were compared. The influence of mud was evident on the water transparency, but not on the mean values of nutrients and chlorophyll a. The diatoms were dominant, emphasizing the contribution of the unicellular centric microplankton and Skeletonema spp., and the pennates Asterionellopsis glacialis and Pseudo-nitzschia spp. However, the density of A. glacialis found in this study was lower than in previous years. Moreover, the planktonic species Skeletonema and Pseudo-nitzschia appeared in high density. In laboratory, short experiments were performed with dissolved inorganic nutrient enrichment by testing seven proportions of silicate, nitrate and phosphate, in order to determine their influence on the microalgae from Cassino Beach. In both experiments, density showed a significant increase (mainly diatoms) in the treatments with nitrate addition, regardless of the proportion added, showing that nitrate is the most important nutrient controlling diatoms density and growth at the sandy Cassino Beach.
|
8 |
Herbivory and plant community structure in a subarctic altitudinal gradientMoen, Jon January 1993 (has links)
The object of this thesis was to study plant community structure, especially in relation to vertebrate herbivory, in an altitudinal gradient in the Fennoscandian mountain chain. A sowing experiment in a high alpine Ranunculus glacialis population showed that seeds germinated better in cleared microsites than under established individuals. This is contrasted with a hypothesis that predicts positive plant-plant interactions in high alpine environments. It was concluded that plant-plant interactions in die studied population varied from neutral to negative, whereas no indications for positive interactions were found. An exclosure experiment in a snow-bed showed that a lemming population consumed 33 % of the available graminoids and 66 % of the mosses from August to June during a population peak. The results shows that grazing needs to be considered as a structuring factor in snow-bed vegetation. The vegetation in exclosures in another snow-bed changed from a graminoid-dominated to a herb-dominated plant community during a long-term (six years) experiment No changes of the same magnitude were seen in a tall herb meadow on a lower altitude. Survival of transplanted adult shoots from the tall herb meadow was equally high in the snow-bed as on the meadow, and germination was also high on bare ground in the snow-bed. Grazing seemed to be a more important structuring factor in the snow-bed than in the more productive tall herb meadow. Raising the grazing pressure during one growing season by introducing microtine rodents into enclosures did not cause any large short-term effects on plant community structure in a tall hob meadow or in a snow-bed. Marked shoots showed that some preferred plant species had a high shoot mortality, but biomass for pooled categories of plants was not significantly affected. It was predicted that the tall herb meadow would be more grazing sensitive than die snow-bed, but productivity on the meadow seemed to be sufficiently high for the plants to compensate for the grazing during the growing season. A greenhouse experiment showed that voles, when grazing freely, have the potential to deplete productive field layer vegetation contrary to predictions from plant defence theories. A nitrogen-based defence did not prevent heavy shoot mortality for toxic tall herbs. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 5 uppsatser.</p> / digitalisering@umu.se
|
9 |
Taxonomy, distribution and aspects of the biology of some deep-living copepods in B.C. inlets and adjacent waterKoeller, Peter Arthur 02 February 2021 (has links)
The bathypelagic copepods Spinocalanus brevicaudatus, Scaphocalanus brevicornis and Heterorhabdus tanneri have established relatively large, permanent breeding populations in Bute and Jervis Inlet, British Columbia. They are found only rarely in the shallower Strait of Georgia. The preference shown by Spinocalanus brevicaudatus and Scaphocalanus brevicornis was attributed to the deep living habits of breeding adults. The reason for H. tanneri's preference of deep water was not apparent from the distribution study.
Two general patterns of vertical distribution were seen among the calanoid capepods in the inlets. The common interzonal species such as Calanus glacialis preferred a definite depth interval near mid-water. The deep-living species such as Spinocalanus brevicaudatus were found throughout the water column below the thermocline, in about equal numbers. Maximum numbers usually occurred in the depth interval immediately below the thermocline.
Only females of Metridia pacifica showed a strong diurnal migration pattern in July. This migration became less intense near the head of Bute Inlet. The vertical distribution and migration patterns of Spinocalanus brevicaudatus, Scaphocalanus brevicornis and H. tanneri appeared to increase the chances of secual encounters in these relativelyt rare species.
The interzonal and deep-living species showed contrasting life-histories. The interzonal species exhibited a well-defined breeding season, with adults maturing in the winter, and young appearing in the spring. The deep-living species did not show a yearly breeding cycle. Females dominated the population at all times of year, and a relatively small percentage of males and females were always present.
A reduction in the male:female sex ratio occurred during or after the last moult in Spinocalanus brevicaudatus and Scaphocalanus brevicornis. In the animals the male has reduced mouth parts and probably dies soon after mating. H. tanneri males do not have reduced mouth parts. This species had a sex ratio close to unity at all times.
An increase in total copepod numbers was observed with increasing distance from the head of Bute Inlet. An increase in the percentage of juveniles in the population of most species was also observed with increasing distance from the inlet head.
Spinccalanus brevicaudctus, Scaphocalanus brevicornis and H. tanneri are redescribed. Comantenna columbiae is described for the first time. / Graduate
|
Page generated in 0.4013 seconds