Japanese macaques (Macaca fuscata) social development: Sex differences in Juvenile behavior

We have quantitatively documented the development of sex differences in the behavior of juvenile Japanese macaques (1 to 2 years of age). Mothers treated their offspring differently by sex, i.e., mothers of males broke contact with them more frequently than did mothers of females. Juvenile males played more, and mounted other macaques more frequently; juvenile females groomed their mothers more and were also punished by other group members more frequently than were males. Males showed a pattern of decreasing interactions with their mothers, but females increased the frequency of their maternal interactions. These patterns appear to presage the life histories of the sexes. However, comparisons with other species of nonhuman primates indicate that although sex differences in behavior are common, the variability among species severely limits cross-specific generalizations.     

Interspecific variation in sustained swimming ability of late pelagic stage reef fish from two families (Pomacentridae and Chaetodontidae)

 Characteristics of the pelagic stages of reef fishes have generally been investigated at the family level, which may mask important differences among species. Here the variation in sustained swimming ability of the late pelagic stages is examined among species, within two families (Pomacentridae and Chaetodontidae). The pomacentrids displayed a 7.5-fold difference in sustained swimming ability across 24 species, while the chaetodontids displayed a 2-fold difference across 10 species. The variation within the Pomacentridae was not related to pelagic larval duration, post-settlement habitat or taxonomy. There was, however, a significant correlation between sustained swimming ability and total length (TL) of individuals (r=0.435, P<0.0001). Differences in the mean distance swum by pomacentrid species, however, was most strongly related to differences in mean wet weight (r=0.814, P<0.0001). When the mean distance swum by species was scaled with respect to mean TL there was still a strong correlation with mean wet weight (r=0.644, P<0.005). Among chaetodontid individuals TL and sustained swimming ability were not correlated (r=−0.004, P=0.978). Furthermore, sustained swimming ability was not significantly related to the trans-oceanic distribution of species in either family. The variation in sustained swimming ability, however, may contribute to explanations of the observed levels of gene flow within populations. Accepted: 24 November 1997     

The role of nurse plants in the establishment of shrub seedlings in the semi-arid subtropical Andes

In the nurse plant syndrome, or nurse association, seedlings (beneficiaries) are associated with adult shrubs/trees (benefactors). This phenomenon has been documented in several regions of the planet. Abiotic stress amelioration (one mechanism of facilitation) is one of the causes of this association. Most of the studies addressing the nurse syndrome have been conducted on spatial scales of a few hectares and have focused on only one or a few species. Moreover, there is an almost complete lack of studies addressing the incidence and characteristics of the nurse phenomenon in the arid Andes of South America. We undertook a first approximation to the study of facilitation in these ecosystems. The study was conducted at local and regional scales and involved the assessment of the spatial distribution of juveniles (seedlings and saplings) of 51 populations of 16 shrub and 12 cactus species in relation to shrub cover at 20 localities of the Prepuna (subtropical Andes of Bolivia and Argentina, 20–26°S). In terms of spatial distribution, the juveniles of most of the populations of shrubs studied were distributed both under the shrubs and in open spaces, thereby showing an apparent indifference to microhabitat. Globose and opuntioid cacti were preferentially distributed below the canopies of shrubs and were usually more associated with the dominant shrub species, which stood out as better potential nurses. The pattern was consistent throughout the region, including the more mesic and arid localities. The fact that Prepuna woody species are capable of establishing in open spaces would confer this region a greater resilience. Our findings further suggest that community dynamics in arid and semi-arid environments are more variable than previously thought.     

Rotation screen prevents fish damage in hydroelectric power stations

Downstream migrations of fish over a rotation screen were studied at a hydroelectric power station in Hadamar/Hessen, Germany. This study monitored and evaluated the functionality and efficiency of the rotation screen in order to prevent fish from entering the Kaplan turbine. During one autumn and two spring tests, a total of 1,629 specimens representing 25 species including eel and salmon smolt migrated over the screen. The smallest fish (dace, bleak, three-spined stickleback, and perch) from standard lengths ≤30 mm were carried by scoop buckets mounted on the rotation screen. The tests confirmed in all cases that the migration activity of fish depended unambiguously on the diurnal cycle (P < 0.05). Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Assessing the diversity and abundances of larvae and juveniles of coral reef fish: a synthesis of six sampling techniques

Due to an increasing emphasis for fish population survey and regulation, efficient tools for evaluating the abundance and diversity of fish from various life stages are needed, especially for coral reef species that present a high taxonomic diversity. The characteristics of six different techniques used for sampling pelagic larvae (a plankton-net and two light-traps), newly settled juveniles (one type of artificial reef), and older juveniles (an underwater seine net in seagrass and macroalgal beds, and rotenone poisoning in coral patches) are described in this study. Larvae belonging to 70 families and juveniles belonging to 34 families were collected. An analysis of similarity (ANOSIM) showed that the taxonomic composition of assemblages collected with the plankton-net and the two light-traps were overlapping but clearly different, due to the higher occurrence of Gobiidae in the plankton-net and of Pomacentridae in both light-traps. Larvae being 2–4 mm standard length (SL) dominated in the plankton-net, whereas larvae being 9–11 mm SL dominated in both light-traps. Pomacentridae juveniles were more abundant in rotenone samples, whereas Labridae dominated in the underwater seine. Juvenile fish collected with the artificial reefs, the underwater seine, and rotenone poisoning largely overlapped in size, with mean sizes of 22, 38, and 33 mm SL, respectively. Seven families were caught by the six sampling techniques, but with unequal success. This study provides ecologists and managers with a unique review of six techniques for sampling a wide range of developmental stages of young fish in different habitats of a coral reef lagoon.

Annual rhythms of swimming behaviour and seawater adaptation in young baltic salmon,Salmo salar,associated with smolting

Synopsis Sexually immature and sexually mature precocious male Baltic salmon,Salmo salar, parr from Umeälven (Ume river) were tested for rheotactic behaviour and adaptation to seawater before, during, and after the time period for smolt migration. Size of fish at the beginning of the experiment in January was on average 13.5 cm. Rheotactic behaviour was tested in annular stream tanks with photocells to measure upstream and downstream movements. Samples of fish were given a Seawater challenge test at monthly intervals in order to determine their ability to adapt to 20%. saltwater. During spring, both immature and sexually precocious parr became silvery and showed progressive development of downstream-directed movements. In early June the fish exhibited good hypoosmoregulatory ability in 20%. saltwater and swimming was predominantly downstream. During late June and early July there was a marked reversal in swimming behaviour, accompanied by a dramatic change in saltwater adaptation. The fish moved mainly upstream and showed decreasing ability to meet the seawater challenge test. This was accompanied by a loss of silvery coloration. The annual cycle of swimming behaviour and seawater adaptation is discussed in relation to the appearance of a smolt-window, i.e., a critical interval for smolt migration.     

Mariculture of kurosoi,Sebastes schlegeli

Synopsis The technology of collecting developing larvae from female kurosoiSebastes schlegeli, and raising the larvae to juveniles (100 mm total length (TL)) to be released into the oopen sea, is presented. Gravid females 40–46 cm TL were captured in May–June 1977–1980 and held in the laboratory until parturition. Fecundity of fish in this size range was 100 000–184 000. Larvae were sequentially fed rotifers,Artemia nauplii, and young sand lance,Ammodytes personatus, until reaching 25 mm; this required 35 days and yielded a survival rate of 50%. Thereafter, the fish were reared in separate size groups to avoid cannibalism. Minced or chopped sand lance and commercial food were provided until the final size of 100 mm was attained. The growth of juvenile kurosoi from 25 to 100 mm required 85 days, with a survival rate of 90%. The effect of released cultured fish on the local stock is being determined from information on the recapture of tagged fish.     

Reduced performance of native infauna following recruitment to a habitat-forming invasive marine alga

Despite well-documented negative impacts of invasive species on native biota, evidence for the facilitation of native organisms, particularly by habitat-forming invasive species, is increasing. However, most of these studies are conducted at the population or community level, and we know little about the individual fitness consequences of recruitment to habitat-forming invasive species and, consequently, whether recruitment to these habitats is adaptive. We determined the consequences of recruitment to the invasive green alga Caulerpa taxifolia on the native soft-sediment bivalve Anadara trapezia and nearby unvegetated sediment. Initially, we documented the growth and survivorship of A. trapezia following a natural recruitment event, to which recruitment to C. taxifolia was very high. After 12 months, few clams remained in either habitat, and those that remained showed little growth. Experimental manipulations of recruits demonstrated that all performance measures (survivorship, growth and condition) were significantly reduced in C. taxifolia sediments compared to unvegetated sediments. Exploration of potential mechanisms responsible for the reduced performance in C. taxifolia sediments showed that water flow and water column dissolved oxygen (DO) were significantly reduced under the canopy of C. taxifolia and that sediment anoxia was significantly higher and sediment sulphides greater in C. taxifolia sediments. However, phytoplankton abundance (an indicator of food supply) was significantly higher in C. taxifolia sediments than in unvegetated ones. Our results demonstrate that recruitment of native species to habitat-forming invasive species can reduce growth, condition and survivorship and that studies conducted at the community level may lead to erroneous conclusions about the impacts of invaders and should include studies on life-history traits, particularly juveniles.     

池塘养殖环境下滇池金线鲃仔稚鱼的食性转化与生长

2008年3月—2009年3月,把35 000尾滇池金线鲃(Sinocyclocheilus grahami)仔稚鱼分别饲养于3个池塘进行对比饲养研究。密度分别是：P1为208尾/m3;P2为167尾/m3;P3为41尾/m3。饲养期间采用相同的管理措施。每天数据收集采用：在仔鱼孵化后的5～16 d的每天8:00和18:00从每个育苗池中捞取5～8尾仔鱼进行测量分析。仔鱼开口30ｄ后,每月从培育池各捞取15尾,测量全长和体重。研究发现,滇池金线鲃仔鱼的开口时间为孵化后的5ｄ,混合营养期3～5 d,这与初孵的滇池金线鲃仔鱼的全长和卵黄囊较大有关。在容易造成仔鱼大量死亡的混合营养期,通过采用浆状物—轮虫—人工混合饲料的方式,大幅度提高了滇池金线鲃仔稚鱼的存活率,孵化一年后的滇池金线鲃稚鱼存活率可达82.7%。经过一周年的饲养,滇池金线鲃稚鱼的体重由(0.027±0.01) g（0.003~1.22）增长到(8.83±0.54) g（3.7~16.7）,月均增重为0.73 g;全长由(15.8±0.30) mm（11.5~20.0）增长到(91.6±1.67)mm（75.0~16.0）,全长月均增长6.32 mm。滇池金线鲃稚鱼全年全长的增长呈线性相关,y=9.82+7.05 month（R2=0.989 1）;全年体重的增长呈指数关系,y=0.0158 month2.54（R2=0.993 9）。     

Morphology of Hydrozetes confervae () and H. parisiensis (Acari: Oribatida: Hydrozetidae), and keys to European species of Hydrozetes Berlese, 1902

Hydrozetes confervae [Schrank, F.P., 1781. Enumeratio insectorum Austriae indigenorum. Augustae Vindeliciorum, 1-552] and Hydrozetes parisiensis [Grandjean, F., 1948. Sur les Hydrozetes (Acariens) de l’Europe occidentale. Bull. Mus. Nat. Hist. nat., Paris, ser. 2(20), 328-335] are common European species of the aquatic oribatid mite family Hydrozetidae, but their external morphology is incompletely known. We describe and illustrate their larvae for the first time, and the nymphs of both species are redescribed and illustrated. Juveniles of the two species differ mainly by the position of gastronotal seta lm in relation to the opisthonotal gland opening (gla) and by the number of extremely long posterior hysterosomal setae in nymphs. In H. confervae seta lm inserts anteromedial to gla, but posterior to gla in H. parisiensis; nymphs of H. confervae have three pairs of long hysterosomal setae, while H. parisiensis has a larger, but variable number. Separate identification keys for the larvae, nymphs and adults of all known European species of Hydrozetes Berlese, 1902, are presented.