On the life history ofTurnerella mertensiana (Rhodophyta,Gigartinales)

Turnerella (Gigartinales) withT. mertensiana known from northern Japan was studied to determine its life history. Carpospores cultured from foliose female plants gave rise on germination to crustose plants containing tetrasporangia, as noted previously inT. pennyi from the Atlantic. The crusts were slow to develop and required 3–5 years to achieve reproductive maturity. Tetraspores liberated in culturedT. mertensiana gave rise on germination eventually to thalli similar to gametophyticT. mertensiana. Thus this species may be said to adhere to the pattern of life history in which a large, foliose gametophyte alternates with a small crustose tetrasporophyte. The erect filaments of the small sporophytes branch laterally and tetrasporangial mother cells are found there, exemplifying an unusual method for crustose species to produce tetrasporangia.     

Oxygen uptake through water during early life in Channa punctatus (Bloch) (Pisces; Ophicephaliformes)

Oxygen uptake in relation to body size during the early life of the fish Channa punctatus shows a significant two-component curve: one related to the fully aquatic phase and the other to the bimodal phase of respiration. The onset of the air-breathing habit around the 18–20th day after hatching brings about a 45% drop in O₂ uptake through the gill/skin in water.     

Studies on the life cycle of Pallisentis nagpurensis Bhalerao, 1931 (Pallisentidae; Acanthocephala) parasitic in the fish Ophiocephalus striatus (Bloch)

The life cycle of Pallisentis nagpurensis involves the fish Ophiocephalus striatus as the final host and the copepod Cyclops strennus as the intermediate host. The embryonated eggs are adapted to float in water. The development of the acanthors up to the stage of infective acanthellae takes place in the haemocoel of the cyclops in 15–20 days. The juveniles develop to maturity in the intestine of the fish after about 50 days. Incompletely developed juveniles penetrate the intestinal wall adjacent to the liver and then encyst in the peripheral tissues of the liver. Cannibalism among the fish seems to help the establishment of the encysted worms for normal development within the intestine. The life-cycle of the worm is neatly geared to the feeding habits of the host fish. A number of transport hosts have also been observed. Study has also been made on the morphology of various developmental stages of the worm.     

Riverine life history of the amphidromous goby Sicyopterus japonicus (Gobiidae: Sicydiinae) in the Ota River, Wakayama, Japan

To understand the riverine life history of the amphidromous goby, Sicyopterus japonicus, studies were conducted in the Ota River, Wakayama, Japan. They were distributed from 3 to 23 km upstream from the river mouth, and abundance was higher in the middle reaches than in the upper and lower reaches. Fish were not observed in rapids during winter, suggesting a seasonal change of habitat. Body length ranged from 24 to 120 mm SL. Both females and males ranged from 1 to 6 years old, and males had larger asymptotic length than females. Condition factor showed two peaks in July and November, which appeared to correspond to the spawning season and preparation for over wintering. Gonad somatic index increased in summer with a peak in August indicating a summertime spawning season that was confirmed by collections of the newly hatched larvae migrating downstream. Eggs of 0.5 mm diameter were attached to stones and newly hatched larvae made continuous vertical movements of sinking and upward swimming and the distance of each movement was longer in freshwater than in seawater. The newly hatched larvae were collected at nighttime (19:00–24:00) mainly in August. Those larvae were very small (mean: 1.4 mm TL) with a yolk sac and no eye pigmentation. Low wintertime temperatures are likely an important determinant of the spawning and recruitment seasons and seasonal changes of activity of this species that lives at much higher latitudes than all other species of the subfamily.     

The Maturity Index,the evolution of nematode life history traits,adaptive radiation and cp-scaling

Nematodes are increasingly being used in environmental studies. One of the potential parameters to measure the impact of disturbances and to monitor changes in structure and functioning of the below-ground ecosystem is the nematode Maturity Index; an index based on the proportion of colonizers (r-strategists s.l.) and persisters (K-strategists s.l.) in samples. In this paper the original allocation of nematode taxa on the colonizer-persister scale, and the tolerance and sensitivity of colonizers and persisters are discussed from an evolutionary viewpoint. The phenomenon that neither relative egg size nor body length is an unequivocal character to scale nematodes suggests that the main selection for life history traits occurred independently in the major evolutionary branches. This revised version was published online in June 2006 with corrections to the Cover Date.     

The life history and production of Asellus aquaticus (Crustacea: Isopoda) in the River Ely, South Wales

SUMMARY. A population of the isopod Asellus aquaticus was studied for sixteen months in the organically polluted River Ely. South Wales. There were two complete generations each year. The overwintering population released young (the spring-brood) over the period April-June. These animals in turn produced their own offspring (summer-brood) in late July-October. Each generation died after breeding and the overwintering population was comprised entirely of animals from the summer-brood.
Seasonal patterns of mortality were related to water flow, temperature and life-cycle stage. Individual growth rates were affected by both temperature and life-cycle stage.
Annual population production (P) was 195.68 g wet wt m^-2, mean annual biomass (B) was 32.98 g wet wt m^-2 and the annual P/B ratio was 5.93.     

The life history and production of the leech Helobdella stagnalis (Hirudinea:Glossiphonidae) in the River Ely, South Wales

SUMMARY. A population of the glossiphonid leech Helobdella stagnalis was studied over a period of 16 months in the organically polluted River Ely, South Wales. There were two generations each year. The overwintering population released young (the spring-brood) in June. The spring-brood in turn produced their own offspring (summer-brood) in August.
Seasonal patterns of mortality were related to flow, temperature and life-cycle stage. Individual growth rates were dependent upon both temperature and life-cycle stage.
Annual population production (P) was 7.56 g wet wt m^-2, mean annual population biomass (B) was 1.43 g wet wt m^-2 and the annual P/B ratio was 5.29.     

Observations on the life history of Limnodrilus hoffmeisteri (Annelida,Tubificidae) from the Little Calumet River in temperate North America

The reproductive period for L. hoffmeisteri as observed in the Little Calumet River (41°34′22″N. 87°28′30Prime;W) occurs from early fall through late spring. The period is marked by the development of the reproductive organs in the early fall months, followed by the development of sperm products within the sperm sac. The female organs appear to mature in middle to late winter with the appearance of nutritive granules followed by the developing eggs in early spring. This cycle is completed in early to late spring with the appearance of cocoons containing developing embryos. It is also apparent that a low level of reproductive activity occurs throughout the rest of the year. This is usually observed in worms with developed sperm sacs and sperm products, having matured penis and some developed egg sacs with nutritive granules. Eggs have not been observed during this low level of reproductive activity.     

Biology and life history of Dabry's sturgeon, Acipenser dabryanus, in the Yangtze River

Dabry's sturgeon, Acipenser dabryanus, is a relatively small (130 cm, 16 kg) and now rare sturgeon restricted to the Yangtze River Basin. It behaves as a resident freshwater fish, does not undertake long distance migrations (except for spawning), and lives in a variety of habitats. It historically spawned in the upper Yangtze River, but the spawning sites are unknown. Acipenser dabryanus reaches maturity earlier than do other Chinese sturgeons, which gives the species aquaculture potential, and artificial spawning has been carried out. However, the native population in the Yangtze has sharply declined in the last two decades due to overfishing, pollution and habitat alteration and destruction, especially since the construction of the Gezhouba Dam, which was built in 1981 across the Yangtze River at Yichang, Hubei Province. Since 1981, Dabry's sturgeon rarely occurs below the Gezhouba Dam because downstream movements are blocked. Clearly, conservation of Dabry's sturgeon must be emphasized. Conservation methods may include protecting habitats, controlling capture and stock replenishment.     

Condition, length–weight and length–length relationships of the Asian striped catfish Mystus vittatus (Bloch, 1794) (Siluriformes: Bagridae) in the Mathabhanga River, southwestern Bangladesh

The present study describes the annual condition as well the length–weight (LWR) and length–length relationships (LLR) of the Asian striped catfish, Mystus vittatus (Bloch, 1794) (Siluriformes: Bagridae), an important fishery in the Mathabhanga River (SW Bangladesh). A total of 2438 specimens (3.60–9.60 cm standard length) used in this study was caught with traditional fishing gear from January to December 2004. Overall, the allometric coefficient b of the LWR was close to the isometric value (b = 3.058), although it suggested negative allometric growth for males (b = 2.959) whilst positive allometric growth for females (b = 3.134). The results further indicated that the LLRs were highly correlated (r² > 0.989, P < 0.001). The monthly gonadosomatic index showed that the reproductive period of M. vittatus began in April, and ended in August when the highest values of the Fulton's condition factor (K) indicated their recovery. These results will be useful for fishery managers to impose adequate regulations for sustainable fishery management not only in the Mathabhanga River of Bangladesh but also in neighbouring countries.     

Distribution of the Forest Dormouse Dryomys nitedula (Pallas, 1779) (Rodentia, Myoxidae) in Europe

A spot distribution map of Dryomys nitedula in Europe is presented, based on a critical evaluation of published information from the various countries of Europe. In addition, maps which are numbered to identify localities were prepared for regions where Dryomys nitedula distribution was largely unknown until now. The species has a unique distribution, ranging from the Alps in the west to the foothills of the Urals in the east, and from southern Latvia in the north as far south as Calabria and Peloponnisos. The species' reported vertical range is from sea level in the Balkans to the subalpine belt in the Alps. The presence of Dryomys nitedula in Europe can be traced back to the beginning of the Pleistocene, but its recent distributional area does not coincide with climatic factors, nor with the distribution of vegetation communities. Possible competition with Eliomys quercinus is discussed as a factor affecting the peripheral range distribution of Dryomys nitedula.     

Aspects of the life history of Rhodophysema elegans (Rhodophyta,Peyssonneliaceae)

The life history of Rhodophysema elegans is described from laboratory culture and the field in Newfoundland, Canada. Sexual plants are lacking and tetraspores germinate to produce new tetrasporangial plants. Approximately 30–35 chromosomes were counted in vegetative cells of successive generations. There was no evidence of chromosome pairing in the early stages of division of tetrasporangial initials, indicating that the tetrasporangia are apomeiotic.     

Geographic variation in Leporinus friderici (Bloch) (Pisces: Ostariophysi: Anostomidae) from the Paraná-Paraguay and Amazon River basins

Morphological variation among populations of Leporinus friderici (Bloch), an anostomid fish of widespread neotropical distribution, has been hypothesized but never conclusively demonstrated. We used multivariate procedures to examine patterns of morphometric variation among populations of L. friderici from three South American biogeographic regions: the Paraná-Paraguay River and Amazon River basins of Brazil, and the Marowijne River basin of Suriname. Samples from the southern Paraná-Paraguay basin are completely distinct from the northern Amazonian and Suriname regions in principal components analysis, primarily on the basis of body elongation and orbit differcnces. Samples from the two northern regions were separated in a size-free canonical variates analysis by differences in relative body depth. These results emphasize a need for further studies of neotropical fish species with similar distribution patterns.