摘要:

Data are presented for a wide variety of different measurements and observations made on representatives of the lampreyGeotria australiscaught during the first four months after they had left the sea in seven successive years. Comparisons have been made with the trends shown by similar data obtained from animals subsequently held in the laboratory for a number of months to provide information on the subsequent pattern of changes and the duration of the spawning run. In comparison with anadromous holarctic species, the gonads at the beginning of the upstream migration in July were very small. The eggs, which did not yet contain yolk platelets, measured only 190 μm in diameter and took until October of the following year to reach 1120 μm, which is comparable to the size of the mature eggs of other lampreys. This indicates that the spawning run ofG. australislasts for the exceptionally long period of 16 months, which is consistent with the time of appearance of young larvae. At the commencement of the spawning run, the mean lengths and weights ofG. australiswere approximately 655 mm and 250 g. Hepatosomic (c. 0·8%) and heart ratios (c. 0·18%) were significantly lower than those of other species. The relatively long length of the trunk, which was associated with a very high mean myomere number (78·8), helped to compensate for a small body depth and permitted the production of a large number of eggs (mean fecundity 57,943). The intestine underwent rapid atrophy immediately after the animal entered fresh water, even though the gonads were not developing rapidly at this time. Migratory movements in the river were most marked on nights when water levels were rising, the temperature lay between 12 and 14.5°C, rain was falling and extensive cloud cover or the dark phase of the moon was pr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06106.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Beach seines, gill nets and otter trawls were used during 1979–81 to sample extensively the fish fauna of the Peel‐Harvey estuarine system. Approximately 145,000 individuals were caught, representing 29 familes and 55 species. The Clupeidae, Teraponidae, Mugilidae, Apogonidae, Atherinidae and Gerreidae were the dominant families, each contributing at least 8.9% to the total catch and together contributing 86.2%. Seasonal catch data and length‐frequency distributions were used to help clarify the way in which the estuary was utilised by fish. Nine of the 15 most abundant fish species were marine species which entered the estuary for variable periods while the other six were represented by populations in which the individuals were capable of passing through the whole of their life cycle within the estuary. In order of abundance, the nine marine species wereHyperlophus vittatus, Pelates sexlineatus, Aldrichetta forsteri, Mugil cephalus, Torquigener pleurogramma, Favonigobius lateralis, Pranesus ogilbyi, Gymnapistes marmoratusandSillago schomburgkii, while the six species with estuarine populations wereApogon rueppellii, Atherinosoma elongata, Nematalosa vlaminghi. Atherinosoma wallacei, Cnidoglanis macrocephalusandAmniataba caudavittatus.The extent and seasonality of the distribution of the species within the estuary and associated river systems varied considerably. Evidence is also presented to show that fish tend to move further away from the shallow banks near the shore with increasing age and size. The fish fauna of the Peel‐Harvey is compared with those of Cockburn Sound and the estuaries of the Swan‐Avon and Blackwood rivers in Western Australia and with Botany Bay in eastern

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06107.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

St Paul's Rocks are a remote group of islets, barely 400 m across, in the equatorial mid‐Atlantic (o°55'N 29°21'W). The results of a primarily zoological survey of the Rocks, carried out in September 1979 by the Cambridge Expedition to Saint Paul's Rocks, are reported. In addition, earlier studies of the Rocks' biology are discussed in the light of recent research. The terrestrial fauna is dominated by three species of sea‐bird and a land crab. Also reported from on land are a few species of insects, ticks and spiders, an endemic pseudoscorpion, and a centipede; the majority of these species are associated with the seabirds.The islets are devoid of tracheophytes, bryophytes and lichens.The marine ecology of the Rocks is discussed with respect to habitat. Five habitats are distinguished in the supralittoral and littoral zones; the fauna and to a limited extent the flora of each is described. Sublittorally the Rocks consist almost entirely of steep escarpments extending to 60 m depth and beyond. The shallow sublittoral (<60 m deep) is divided into four habitats: (1)Palythoazone; (2)Caulerpazone; (3) sub‐Cauferpazone, and (4) areas of unstable substrates. ThePalythoazone occupies a band extending from the base of the littoral to a depth ofc. 5m and is dominated by a mat‐forming hexacoral,Palythoa caribaeorum.Below this zone to a depth ofc. 33 m the rock faces are thickly invested by a species of green‐alga,Caulerpa racemosa.At depth thisCaulerpadominated zone is succeeded by an invertebrate dominated community. Unstable substrates are represented by a few pockets of coarse sand and some patches of rubble. The communities in each of these habitats are described. A primarily taxonomic review of the deep‐water fauna is also included. Finally, the influence of ocean currents on the zoogeographical relationships of the Rocks' fauna is bri

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06108.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of flooding on the behaviour of most mammals has not been studied, even though in tropical areas there are well delineated wet and dry seasons which produce flood conditions on a regular basis. Fossorial mammals can be expected to be particularly vulnerable to flooding because of the absolute dependence on a sub‐surface existence and poor climbing ability.Behaviour of the East‐African mole‐rat,Tachyoryctes splendens, was studied under flood conditions and compared with published field work conducted under non‐flood conditions. Four completely excavated burrow systems were obviously abbreviated (2–9 m in length), although the nest area did not appear to be affected. Live‐trapped animals released on the surface travelled as far as 80 m before attempting to dig; surface speed was generally slow (7 m/min). Animals generally (83% of the trials) excavated towards the increase in slope on the study area; total digging time before closure of the tunnel ranged from 7–49 min. In swimming trials, animals were not hesitant to enter water but swimming endurance was short (range 115‐550s).Flooding may be a very disruptive but not an entirely negative aspect of the biology of Tachyoryctes. Dispersal may be instigated and even assisted by providing surface routes over edaphic barriers and moist soils which are r

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06109.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The gill areas and their component measurements of 16 species of North American crab and seven species of British decapod crustaceans have been analysed in relation to body mass using the method of logarithmic transformation.A wide range of relationships was found, each of which is typical for a given species. The slope,b, of the log/log regression lines varied from 0·5 to 1·0, the lower values being most commonly found in the Macrura. For the North American species the average slope is about 0·8 whereas for British brachyurans the relationship was close to linear (b=0·97).The analysis shows that the increase in gill surface body size is mainly due to the increasing area for individual platelets or gill lamellae.Comparison of weight‐specific gill areas for animals of the same body weight suggests that the most active species have larger gill areas. For some of these species the values (900mm2/g) approximate to those of active fish.As plots for interspecific relationships derived from average values for many individual species have slopes which are not typical for any of the component species, it is concluded that caution must be exercized when interpreting such interspecific plots in Allometric st

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06110.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Light and electron microscopic techniques were employed to examine the kidneys of three species of pelagic seabird which had high tissue cadmium and mercury levels. Direct examination and comparison with the kidneys of cadmium and mercury dosed starlings showed that the seabirds had patchy nephrotoxic kidney lesions. It was suggested that these lesions were due to natural exposure of the animals to high levels of metals, particularly cadmium through their diet. Pathological features included necrosis and degeneration of the proximal tubular epithelium together with the direct observation of obstruction of the more distal neprhon segments by necrotic cellular debris. Abnormalities of the glomerular podocytes and Bowman's capsule cells were also observed. There was a high degree of similarity between the type and distribution of kidney lesions in the seabirds and the laboratory metal dosed starlings. The significance of this kidney damage and its possible effects on the birds survival prospects are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06111.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Plasma levels of prolactin and FSH in free‐living Pied flycatchers were studied in relation to breeding stage, clutch size and diurnal variations. In the female, the concentration of prolactin started to increase during the egg‐laying and reached maximal values at the end of the incubation period. After hatching prolactin levels decreased. Male Pied flycatchers showed an increase in plasma levels of prolactin at the time when they returned to their home‐territories, i.e. at the end of the incubation period. Males still occupying secondary territories at this time had low levels of prolactin. In the males, as in the females, plasma levels of prolactin decreased after hatching.Male Pied flycatchers showed at all times higher plasma levels of FSH than did females. In both sexes FSH levels were high during the early part of the breeding season and started to decrease after the egg‐laying period. After hatching time plasma levels of FSH were below the sensitivity of the assay. No differences in FSH were found between males occupying secondary territories and males in home‐territories.In incubating females FSH, but not prolactin, showed a distinct unimodal daily cycle.No differences were found in plasma levels of prolactin and FSH between females incubating different sized

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06112.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Ultrastructural observations were made of the non‐lactating and lactating mammary gland of the Weddell seal, and measurements of several cell components were compared with those in other species to determine whether there are any morphological modifications within the gland to explain the unusual milk composition and very rapid growth of sucking young in this species.The mammary parenchyma in non‐lactating and lactating Weddell seals is almost identical morphologically to that found in other mammals. Although the relative volumes of most organelles are similar to those in other eutherians, the relative volume of rough endoplasmic reticulum (RER) is reduced in the Weddell seal. In addition, the absolute and relative volumes of Golgi vacuoles are smaller in the Weddell seal, probably associated with the low lactose and water content of the milk. The synthesis and secretion of milkspecific proteins and fat droplets by mammary secretory cells in the Weddell seal appear to be identical to other eutherians. Relatively small numbers of fat droplets less than 1 μm diameter are present in epithelial cells, alveolar lumina and milk samples, and there is a far greater contribution by large fat droplets to the total fat volume of Weddell seal milk than milk from other mam

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06113.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY