Life history of Corophium curvispinum G. O. Sars (Crustacea,Amphipoda) living on macrophytes in Lake Balaton

Samples of the amphipod Corophium curvispinum were collected from Myriophyllum spicatum twice a month during the vegetation period. The animals were sexed, their length measured and the eggs of females were counted. Length frequency histograms served to follow the life history of C. curvispinum.Reproduction lasts from May to October. The animals born in May–June reproduce in the same year while the summer-autumn generation reproduces the following year. The life span is about 1 year. The highest fecundity was found in June, the lowest in October.     

Life history, aspects of reproductive biology and production of Corophium orientale (Crustacea: Amphipoda) in Monolimni lagoon (Evros Delta, North Aegean Sea)

Monthly samples of Corophium orientale were collected during February 1998–February 1999 in both parts of Monolimni lagoon (0.3 < Sal. < 6 psu, 2 < Temp. < 28.5 °C). Corophium orientaleshowed a semiannual life cycle. In the southern part, breeding occurred from early spring to mid autumn having three peaks, in early spring, early summer and early autumn, and three cohorts were produced, a spring cohort, a summer cohort and an overwintering one. In the shallower innermost northern part of Monolimni lagoon, breeding peaked in mid-spring and, also, in early autumn, and two discrete cohorts, a spring and an overwintering one, were produced. A lack of large individuals, attributed to a temporary size – selective predation by migrating shorebirds, was observed during summer. That lack possibly contributed to the hiatus in reproduction. Photoperiod seemed to be a more important cue than temperature in the initiation of the reproductive cycle, while extremely low salinities (<1 psu) did not deter breeding. Females attained maturity at a smaller size in late spring and, especially, in summer than in early spring at lower temperatures. Brood size was a function of females body size. Females, matured during summer at high temperatures, showed the lowest brood size, body length ratio. Mean brood size was small (12–13 early embryos) and embryo loss during development high (54%), possibly due to a negative effect of low salinities. A 1:1 sex ratio existed in the small body length classes, but females preponderated in the large ones. The spring cohort in the southern part, which developed at moderate temperatures, showed the highest growth rate (40 m day^–1). Secondary production of C. orientalecalculated by Hyness method gave a mean annual density of 4562.5 and 9327.6 ind. m^–2, a mean annual crop (B) of 1.03 and 2.67 g DW m^–2, an annual production (P) of 6.91 and 22.54 g DW m^–2 and a P/B ratio of 6.7 and 8.4 in the northern and southern part of the lagoon, respectively.     

Range extension of the predatory cladoceranBythotrephes longimanus Leydig 1860 (Crustacea,Onychopoda) in Western Europe

The long-spined waterfleaBythotrephes longimanus Leydig 1860 (Crustacea, Onychopoda), a predatory cladoceran, new for the Belgian fauna, has been recorded in the water storage reservoir Broechem. Several possible methods of entry ofB. longimanus into lakes far outside its known distribution area are discussed.     

The North-American amphipods, Melita nitida Smith, 1873 and Incisocalliope aestuarius (Watling and Maurer, 1973) (Crustacea: Amphipoda: Gammaridea), introduced to the Western Scheldt estuary (The Netherlands)

The American amphipod species Melita nitida andIncisocalliope aestuarius have been found in the WesternScheldt estuary (the Netherlands). This is the first record of these species inthe north-east Atlantic. Shipping is the most likely vector of introduction.Thedistribution of both species is investigated and compared with the distributionand the microhabitat of co-occurring amphipod species. Melitanitida is known from both the east and west coast of North Americaand I. aestuarius originates from the east coast of NorthAmerica. Until now neither has been reported from other parts of the world. Inthe Netherlands both species are restricted to the mesohaline part of theWestern Scheldt. Melita nitida occurs predominantly underPacific oysters at the underside of boulders, mainly sublittorally.Incisocalliope aestuarius is associated to hydrozoans.Bothmicrohabitats are hardly utilized by other amphipod species. Therefore, thetheory that the existence of many empty niches in north-western Europeanbrackish waters make this environment particularly susceptible to invasions ofalien species is corroborated. The application of hard substrates in a regionoriginally predominated by soft bottoms moreover facilitates the introductionofexotic species. The species community on hard substrates in the mesohaline partof the Western Scheldt contains a high proportion of introduced species:approximately one third of the macrofauna species is of allochthonous origin.     

The spring-time abundance and feeding ofEurytemora affinis (Poppe) in Volkerak-Zoommeer,a newly-created freshwater lake system in the Rhine delta (The Netherlands)

Eurytemora affinis, a calanoid copepod, has been encountered in Volkerak-Zoommeer (Rhine delta region, S.W. Netherlands) both before this lake system was isolated in 1987 from the estuarine influence, and after. It was the main particle-feeding crustacean at all the 3 sampling stations in March–April 1990 when it reached densities of up to 215 ind.l^–1. Its decline from mid April onwards, and low densities through summer, coincided with increase in cladocerans, especiallyDaphnia spp. (D. pulex andD. galeata), a decrease in seston (<33m) and chlorophyll concentrations and in primary production rates. The clearance rates (CR) ofEurytemora measured in the spring period varied enormously (0.6–24 ml.ind^–1.d^–1) depending mainly on size (0.44–1.06 mm), food concentration (0.8–2.2 mg C.l^–1), and the water temperature which varied only narrowly (8.0–9.0°C). Mean ingestion rates of the animals measuring 0.68±0.02 mm during the study was 6.7±3.2 gC.ind^–1.d^–1; and assimilation efficiency varied between 27 and 53% (mean: 41±9%). The weight specific CR (SCR) varied between 0.96 and 6.4 litre.mg^–1 body C.d^–1. Pooled regression of SCR on the animal's body weight at the 3 study stations revealed a significant inverse relationship. Also daily ration and specific assimilation ofE. affinis varied greatly and inversely with the body weight. This calanoid contributed from about 50 to 100% to the zooplankton community grazing rates and assimilation rates, the former often exceeding the phytoplankton primary production.     

The ultrastructure of the sinus gland of Gammarus oceanicus (Crustacea: Amphipoda)

Summary The sinus gland of Gammarus oceanicus, like that of other crustaceans, is composed of three elements: neurosecretory axons, glial cells and stromal sheath. Five neurosecretory axon types are identified on the basis of granule diameter, shape, and electron density, and axon matrix density. Exocytosis appears to be the major release mechanism of neurosecretory material. The preterminal regions of neurosecretory axons contain axoplasmic reticulum and neurotubules. Their arrangement in the axon and relationship with one another suggest a transport function. Multilamellar bodies are found in the terminal regions of neurosecretory axons. They arise from mitochondria and may be involved in granulolysis.The technical assistance of G.A. Bance, statistical assistance of D. MacCharles and D.W. Hagen, and financial support provided by the University of New Brunswick Research Fund to K.H. are gratefully acknowledged     

The subterranean genus Niphargus (Crustacea, Amphipoda) in the Middle East: A faunistic overview with descriptions of two new species

The Middle East is at the southeastern borderline of the range of the subterranean amphipod Niphargus. The review of new and published data identified two new species and set the guidelines for the future research in the area. The genus in this part of the world seems to be insufficiently studied. The taxonomic status of Niphargus valachicus, population identified as N. spoeckeri and some populations, identified as N. nadarini, need to be reviewed. According to present data, we expect the highest diversity in Western Turkey. The eventual new records of the genus in the Middle East can be expected from those areas where even the longest periods of drought in the recent geological history did not affect the water supply.     

Gut passage times in Gammarus pulex (Crustacea,Amphipoda) and aspects of summer feeding in a stony stream

Gut passage times in Gammarus pulex (Crustacea, Amphipoda) were calculated by counting and measuring voided faecal pellets. Following feeding on elm leaves conditioned in a stream, or summer fine detritus from the same source, calculated gut passage times were usually short, about 2 h or less at 15 °C. Using harder oak and beech leaves, not previously conditioned in the stream, apparent gut passage times were much longer, 8–48 h, but since intermittent feeding occurred these figures are not comparable to the others.In connection with summer feeding of the animal in the stream, the microbiological status of the fine detritus there was studied. It contained fungal hyphae, which were mostly empty, viable fungal spores of terrestrial derivation, and bacteria, all largely carried on fragments of vascular plant tissues. In experiments, such fungal spores (of Aureobasidium pullulans and of Mucor sp.), incorporated into fine detritus, were not digested by the animal. The bacterium Bacillus cereus was present in the fine detritus and when the latter was consumed it survived passage through the gut of the animal. Using B. cereus as a proportion marker it was concluded that other unicellular bacteria in the fine detritus were not digested either. In other experiments, not immediately related to the summer season, nutrient extraction by the animal from hyphae of the fungus Nectria lugdunensis was examined; it probably occurs through sub-microscopic pores connecting the cells. This mode of extraction may apply when the animal consumes vascular plant tissues.     

High abundance of Trochospongilla horrida (Porifera, Spongillidae) in the Rhine (Germany) 1992–1995

Trochospongilla horrida (Porifera, Spongillidae) was the dominant freshwater sponge in the Rhine between Karlsruhe and Bonn between 1992 and 1995 are reported. It showed an annual life cycle, with an inactive phase during winter. The life cycle was controlled by temperature. Gemmules were produced in high numbers, and played a significant role as resting bodies. Their role as distribution units was negligible because they were tightly fixed to the substratum. Trochospongilla horrida preferred relatively stable habitats, not affected by fluctuations in water level; it was restricted to habitats with a slightly alkaline pH. Laboratory experiments showed a delayed germination of the gemmules, which explains why the highest abundance of the species occured considerably after the first hatching colonies.     

Significant extension in northern Australia of the known geographic range of the Shield Shrimp Triops australiensis (Crustacea: Notostraca)

The program BIOCLIM predicts the total geographic distribution of species, based upon the biogeoclimatic characteristics common to the localities at which they are known to occur. Field studies in the Northern Territory have located the Shield Shrimp Triops australiensis at localities substantially north of its known and predicted geographic distribution.     

The membrane systems of the cardiac muscle cell of Tmetonyx cicada O. Fabricius (Crustacea,Amphipoda)

Summary The membrane systems of the cardiac muscle cell of the amphipod Tmetonyx cicada (O. Fabricius) are described. The sarcolemma invaginates and forms a transverse network of tubules at the level of the Z band. Narrow longitudinal tubules branch from the network and connect to another transverse network of tubules at the H band level, where dyadic and triadic junctions are formed with the sarcoplasmic reticulum. Adjacent myofibrils are normally separated by a well developed double layer of the sarcoplasmic reticulum. In areas where the myofibrils closely approach the outer sarcolemma, peripheral couplings have been found at the level of the H band.     

Distribution and aspects of population dynamics of the zebra mussel,Dreissena polymorpha (Pallas, 1771), in the lake IJsselmeer area (The Netherlands)

Summary The distribution, settling and growth of the zebra mussel, Dreissena polymorpha Pallas, in Lake IJsselmeer and Lake Markermeer in The Netherlands were studied from 1980 to 1985. In these lakes D. polymorpha is the most important food source for wintering diving ducks. The study was part of an investigation into the carrying capacity of the lakes for these birds.     

Two new species of Caprella (Crustacea:Amphipoda:Caprellidea) collected from sandy bottoms in the Strait of Gibraltar

Two new species of the genus Caprella (Crustacea:Amphipoda:Caprellidea) are described based on specimens collected from the Strait of Gibraltar (Southern Spain and Northern Africa). Both species were found living in sandy bottoms. Caprella pseudorapax n. sp. is very close to the species C. rapax (Mayer, 1890) and C. lilliput (Krapp-Schickel & Ruffo, 1987). Caprella sabulensis n. sp. resembles C. cavediniae (Krapp-Schickel & Vader, 1998).     

Distribution of four narrowly endemic Niphargus species (Crustacea: Amphipoda) in the western Dinaric region with description of a new species

The distribution of four morphologically similar and narrowly endemic Niphargus species living mainly in surface waters of the western Dinaric region was studied. The study area consists of limestone and marls-sandstone (flysch) patches. The variable chemical structure of the flysch affects water conductivity and carbonatic hardness. N. timavi inhabits surface and subterranean waters of low conductivity and carbonatic hardness, both on limestone and flysch. N. spinulifemur is restricted to surface waters with high conductivity and higher carbonatic hardness, exclusively on flysch areas. N. vinodolensis sp. n., described herein, lives both on karst and flysch, where waters exhibit intermediate values of conductivity and carbonatic hardness. N. krameri inhabits surface and subterranean waters with high conductivity and high carbonatic hardness, both on limestone and flysch. This species is in the course of morphological differentiation with three morphological races, probably due to low dispersal ability. The studied species probably do not constitute a monophylum. The easternmost species, N. vinodolensis shows (morphologically, molecularly) close relations with the northeast-Italian N. elegans and with middle-Dalmatian N. illidzensis dalmatinus. It is possible that they differentiated from a common ancestor which inhabited the dry bottom of the northern Adriatic, exposed during the last glacial. We assume that the reasons for the high degree of endemism are historical changes of hydrographical regimes and sea transgressions–regressions. Poor migratory abilities in a geologically diverse landscape restricted further dispersal.     

A late Burdigalian gobiid fish,<Emphasis Type="Italic">Gobius brevis</Emphasis> (<Emphasis Type="SmallCaps">Agassiz</Emphasis>, 1839), in the Upper Hydrobia Beds in the middle Upper Rhine Graben (W-Germany)

Gobius brevis (Agassiz, 1839) was hitherto exclusively based on articulated skeletons. It first appears in the late Early Miocene (late Burdigalian, Karpatian) and is widespread throughout the Middle Miocene. Its previously known zoogeographical distribution was the western Paratethys and the Styrian Basin in Austria. We here report on articulated skeletons ofG. brevis with otoliths in situ from a temporary outcrop at Edenkoben, located in the middle Upper Rhine Graben, Germany. The strata are assigned to the basal part of the Upper Hydrobia Beds. The otoliths in situ are identical with those ofGobius latiformis Reichenbacher, 1992, which is an otolith-based species occurring in the Karpatian and Middle Miocene of the western Paratethys; henceG. latiformis has to be regarded as a younger synonym ofG. brevis (Agassiz, 1839). The skeletons ofG. brevis from Edenkoben differ from other articulated freshwater or brackish water MioceneGobius species in the number of vertebrae, more elongate body shape, and number of fin rays. Also the otoliths ofG. brevis differ in their overall shape from these species. However, the in situ preserved otoliths ofG. brevis in the Edenkoben locality show a more primitive evolutionary stage than the Middle Miocene otoliths ofG. brevis (formerly described asG. latiformis). Thus, the gobiid fishes from Edenkoben belong to the oldest representatives ofG. brevis and must be late Burdigalian in age.Gobius brevis probably migrated into the middle Upper Rhine Graben from the Paratethys area.      

Observations on the seasonal and yearly occurrence and the distribution ofAtyaephyra desmaresti (Millet, 1831) (Crustacea,Decapoda, Natantia) in The Netherlands

Summary The seasonal occurrence ofAtyaephyra desmaresti in The Netherlands has been studied by sampling the cooling-water filtering screens of power stations situated along the rivers Rhine and Meuse. The shrimps were only found in large numbers at the two power stations with vegetation in the cooling-water intake areas. Fluctuations in the seasonal occurrence showed great similarity for these two localities. Highest numbers of shrimps were impinged in November. High numbers also occurred in September, while a lower peak in numbers was found in May.Changes in the numbers of records during the last 30 years in The Netherlands were compared with climatological fluctuations (severe or mild winters), indicating that this mainly southern-European species is living here at the limits of its ecological and geographical range.The distribution in The Netherlands reveals thatAtyaephyra desmaresti mainly occurs in freshwater habitats, although it tolerates higher chlorinities.     

Ranging Behavior of Proboscis Monkeys (Nasalis larvatus) in the Lower Kinabatangan, Northern Borneo

I studied the ranging behavior of proboscis monkeys (Nasalis larvatus) at two sites in the Lower Kinabatangan Region of northern Borneo. I collected data on ranging behavior via scan sampling during group follows. Groups of Nasalis larvatus had ranges overlapping those of other groups in each area. I observed no territorial behavior. Groups of Nasalis larvatus occasionally swam across the Kinabatangan River, and frequently across its tributaries. The home range size of a focal one-male group (SU1) was 220.5 ha. The group traveled farther on days when the proportion of young leaves in the diet was higher. In addition, SU1 used particular areas when they fed on flowers and fruits. Apparently, rainfall and phenology did not influence ranging patterns.