Coral recruitment and early benthic community development on several materials used in the construction of artificial reefs and breakwaters

Artificial reefs are increasingly being promoted as a means to mitigate impacts from human activities in coastal urban areas. Coastal defense structures such as breakwaters are becoming recognized as large-scale artificial reefs that support abundant and diverse marine communities and play important roles in coastal ecology and management. However, there is limited understanding of how substrate materials used to construct artificial reefs or breakwaters can influence the development of habitat-forming benthic organisms. To assess the influence of substrata on coral recruitment and overall benthic community development, we deployed standard-size tiles of materials used in the construction of breakwaters and artificial reefs (concrete, gabbro, granite, and sandstone), along with terra-cotta for comparative purposes, at two breakwaters (DDD, PRT) and two natural reef sites (NR1, NR2) in Dubai, United Arab Emirates, for one year. Kruskal-Wallis ANOVA with post-hoc Mann-Whitney U-tests were used to examine differences in coral recruitment among sites and materials. Coral recruitment was highest at the DDD (4.9 ± 0.5 recruits 100 cm^− 2), while recruitment was low and did not differ among other sites (PRT: 0.1 ± 0.04, NR1:0.3 ± 0.1, NR2: 0.1 ± 0.03 recruits 100 cm^− 2). There were significant differences in coral recruitment among materials at DDD, where gabbro had higher recruit densities than concrete and sandstone; sandstone also contained less coral recruits than terra-cotta. Variability associated with low coral recruit densities precluded significant differences among materials at other sites. Overall benthic community structure differed more as a result of differences among sites than among substrate materials. Higher community dissimilarity was observed among sites than among material in SIMPER analysis, and significant differences were only observed among sites in ANOSIM. Univariate comparison of the benthos correlated with community differences in NMS ordination also showed significant differences among sites but not material. Overall, these results indicate that site-specific differences in recruitment patterns are more important in determining early benthic community structure and coral recruitment than are differences among substrate material. However, where coral recruitment is high, these results suggest that gabbro should be used preferentially over concrete or sandstone where it is feasible, but that granite may be a suitable alternative where it is the dominant stone. Coral recruitment on terra-cotta was comparable to all materials but sandstone, supporting its continued use in recruitment studies. These results also indicate that using stone amenable to coral recruitment is unlikely to influence the wider benthic community.     

A multi-lake comparison of epilithic diatom communities on natural and artificial substrates

In a multi-season, multi-lake study of epilithic diatom communities, glass slide artificial substrate samplers provided poor representation of communities on natural substrates. Percent similarities between the two communities averaged only 37 over the course of the study. Overall, natural substrates exhibited greater species richness than artificial samplers, particularly during the summer, although this difference was slight. Patterns of selection and inhibition by artificial substrates of individual diatom species varied by both season and lake. Members of the genus Cymbella, particularly C. microcephala, appeared to be the most consistently inhibited, while Achnanthes minutissima was often selected for. In spite of the great differences between the two substrate types, replicability of artificial substrates was very high, and could prove to be a more important quality in monitoring applications than accurate representation of the natural community.     

Effects of age and altrenogest treatment on conceptus development and secretion of LH, progesterone and eCG in early-pregnant mares

The treatment of early pregnant mares with a history of repeated early embryonic loss with the progestin altrenogest has become routine; however no controlled studies on the efficiency of altrenogest to prevent embryonic losses are available so far. In the present study, we have investigated effects of altrenogest treatment in mares on conceptus development and the secretion of LH, progesterone, and eCG until day 100 of pregnancy. In addition, differences related to age of mares were assessed. Mares were treated with altrenogest (0.044 mg/kg per os once daily) or sunflower oil (10 ml per os once daily) from day 6 to day 100 after ovulation. Blood samples for analysis of LH, progesterone, and eCG were collected. The size of the embryonic vesicle and embryo/fetus was determined by ultrasound. No difference in the per cycle pregnancy rate between altrenogest-treated (75%) and sunflower oil-treated mares (74%) was detected (n.s.). A significant effect of age but not of altrenogest treatment on mean diameter of the embryonic vesicle was found between days 12 and 22 of pregnancy (e.g. day 15: control, 4-8 years: 22.9 ± 1.0 mm, >8 years: 22.0 ± 1.7 mm, altrenogest, 4-8 years: 26.1 ± 2.0 mm, >8 years: 20.4 ± 1.0 mm, P < 0.05). A significant effect of age and treatment on size of the embryo proper between days 30 and 45 was detected (P < 0.05). In the control group but not in the altrenogest group, size of the embryo proper respective fetus was negatively correlated with age of the mares (day 30: r = −0.834, P < 0.05; day 35: r = −0.506, P < 0.05). Plasma concentrations of LH and progesterone were neither effected by age nor by treatment of mares, but significant effects of age and altrenogest treatment on eCG concentrations between days 40 and 130 were detected (P < 0.05). The present study demonstrates for the first time a positive influence of altrenogest-treatment on a retarded development of the embryo respective fetus around the beginning of placentation in mares older than 8 years.     

Community structure of stony and soft corals on vertical unplanned artificial reefs in Eilat (Red Sea): comparison to natural reefs

In many reef ecosystems, artificial reefs (AR) have become permanent additions to the area, sustaining well-developed benthic communities. Long-term studies on the development of AR coral communities are scarce, and comparisons with their natural surroundings are limited. The present study describes the stony and soft coral community structure of unplanned vertical AR in Eilat (Red Sea) that have progressed beyond the initial successional phases, and compares these to the adjacent natural reefs (NR). Coral communities were characterized using belt transects, conducted on 34- and 14-year-old unplanned AR, and on two proximate NR. Stony corals were the major component in the NR, while soft corals, mainly Nephtheidae, accounted for up to 90% of the total living coverage in the AR. This was attributed to physical and biological features associated with the ARs vertical orientation, which was absent in the NR, and to the life history traits of these soft corals. Community differences between the two AR were related to structural stability and age. The results suggest that AR may increase local heterogeneity and space availability by adding novel habitats, increasing production and elevating species diversity in the surroundings.Communicated by Biological Editor H.R. Lasker     

Trichomonas vaginalis: Dependence of resistance among different mouse strains upon the non-H-2 gene haplotype,sex, and age of recipient hosts

The genetic control of resistance or susceptibility to Trichomonas vaginalis infection has been studied in mice of various strains infected by different routes. $\text{BALB}\text{c}$ and $\text{DBA}\text{2}$ female mice appear to be highly susceptible to intraperitoneal, subcutaneous, or intravaginal infection by T. vaginalis. By contrast, female mice on A background are resistant to T. vaginalis infection via any route. $\text{C}\text{57}\text{BL}\text{6}$ and C3H female mice display intermediate levels of resistance following intraperitoneal or subcutaneous inoculum, whereas they display high levels of resistance to intravaginal infection. On the other hand, susceptibility or resistance to T. vaginalis infection appears to be influenced by the host sex, since males inoculated subcutaneously display much higher levels of resistance than females of the same strain. Lastly, the age of the host seems to play an important role in determining the course of infection. Susceptibility to T. vaginalis decreases with age, being maximal at 3–4 weeks and minimal at 40–42 weeks. All together these results suggest that resistance or susceptibility to T. vaginalis infection is regulated by genes mapping outside the major histocompatibility complex (H-2 in the mouse), whose activity is modulated by the anatomic site first coming into contact with the protozoon, the sex, and the age of the recipient host.     

Assessment of pollution impact on aquatic microbial communities based on DNA hybridization and protozoan identification: preliminary method development and comparison

Common methods of assessing the biological impact of point source discharge involve a census of organisms above and below the discharge. The identification and enumeration of organisms necessary for this approach can be time consuming and costly. When microbial communities are used, identification and enumeration are often impossible because the majority of species are identifiable only when cultured and most native species cannot be cultured. As such, little is known about the response of nonculturable aquatic microbial communities to anthropogenic changes. We isolated aquatic microbial DNA from colonized artificial substrates in two streams receiving industrial waste. DNA was isolated from the microbial communities upstream and downstream of the discharges and the similarity of these communities were compared by DNA-DNA hybridization. These novel estimates of impact were compared to more conventional estimates based on a component of the microbial communities that could be readily identified, the protozoans. Protozoan species were identified and similarity between upstream and downstream stations was assessed using Jaccard's similarity index.In the Roanoke River, protozoan species richness was significantly lower at the downstream station. Both Jaccard's coefficients and DNA hybridizations indicated that upstream communities were more similar to each other than with the downstream site. However, these differences were not significant. Estimates of community similarity from Jaccard's coefficients and DNA hybridizations were not correlated. In Peak Creek, protozoan species richness was significantly lower at the downstream station. Jaccard's coefficients and DNA hybridizations were not significantly higher within upstream stations than between upstream and downstream stations. The two similarity measures were not correlated. Problems in this preliminary study included small sample sizes and highly variable background on hybridization membranes resulting from the use of nonradioactive DNA probe label and detection methods. Alternative approaches using radioisotopes or COT curves may be more viable means of making molecular methods a useful tool in impact assessment.     

Plant virtues are in the eyes of the beholders: A comparison of known palm uses among indigenous and folk communities of Southwestern Amazonia

Despite its central importance to tropical forest conservation, the understanding of patterns in traditional resource use still is incipient. To address this deficiency, we compared known palm uses among two indigenous (Yawanawd and Kaxinawá) and two folk (rubber tapper and ribeirinho) communities in Southwestern Amazonia (Acre, Brazil). We conducted one-hundred-and -forty semi-structured “checklist” interviews about palm uses with male and female adults in the four communities. The knowledge of each community about the uses of the 17 palm species common to all communities was compared by testing for significant differences in the mean number of uses cited per informant and by calculating the Jaccard similarity index of known uses of palm species among the four communities. The following three hypotheses were confirmed: 1) the use of palms differs according to the cultural preferences of each community; 2) indigenous communities know significantly more about palm uses than folk communities; and 3) part of the indigenous knowledge was acquired through contact with Amazonian folk communities.     

不同食料植物对棉古毒蛾生长发育和繁殖的影响

在恒温(28±1)℃、恒湿(80±5)%RH条件下,研究了莲雾、芒果、荔枝、龙眼、毛叶枣、木菠萝等6种食料植物对棉古毒蛾的生长发育和繁殖的影响。结果表明,棉古毒蛾能在这6种食料植物上完成其世代循环。其发育历期、雌蛹重、存活率、成虫繁殖力和寿命等,在6种寄主植物间均存在显著差异,其中莲雾和芒果是最适宜的寄主植物,荔枝和龙眼是不适宜的寄主植物。     

A comparative study on the anatomy and development of different shapes of domatia in Cinnamomum camphora (Lauraceae)

BACKGROUND AND AIMS: Domatia are small organs usually found in the axils of major veins on the underside of leaves and, although they have received wide attention from ecologists, few detailed reports exist on their anatomy or development. This study is focused on the domatia of Cinnamomum camphora (Lauraceae) and is the first comparative study on the anatomy and development of the different shapes of domatia within a single plant. METHODS: Four types of domatia in C. camphora leaves were observed on paraffin sections under a microscope. KEY RESULTS: The domatia consisted of six histological parts: the upper epidermis, the upper mesophyll tissue, spongy tissue, the lower mesophyll tissue, the tissue filling the rim opening, and the lower epidermis. They differed from the non-domatial lamina mainly in the cell structure of the upper and lower mesophyll tissue and the rim tissue. Differences in domatium shapes were mainly associated with differences in the structure of the upper mesophyll and in the number and size of the rim tissue cells. Differences in the development of domatium types were observed in terms of initiation timing, differentiation of the upper mesophyll cells and degree of rim tissue development. CONCLUSIONS: In domatia, active anticlinal division in the lower mesophyll cells, as compared with the upper mesophyll cells, was coordinated with dynamic growth of rim tissue cells and resulted in cavity formation. The anatomical or developmental differences among the four types of domatia were related to the positions of the domatia within a leaf. In terms of the ecological implications, the major anatomical difference between the domatia used by herbivorous and carnivorous mites was in the development of the rim tissue.     

A comparison of the development and metabolic activity of mycorrhizas formed by arbuscular mycorrhizal fungi from different genera on two tropical forage legumes

 Two glasshouse experiments were done to assess the development and metabolic activity of mycorrhizas formed by isolates of arbuscular mycorrhizal fungi (AMF) from three different genera, Acaulospora, Gigaspora and Glomus on either Pueraria phaseoloides L. or Desmodium ovalifolium L. plants. The second of the two experiments included three levels of a localised phosphate source in the pots. Alkaline phosphatase (ALP), stained histochemically in the intra-radical mycelium (IRM) of AMF over sequential harvests, did not provide a direct marker for the efficiency of AMF in mobilising phosphorus (P) for plant growth and development. The ability of the extra-radical mycelium (ERM) to scavenge a localised phosphate source, determined by its extraction from buried 35-μm mesh pouches, was dependent on the species of AMF tested. This work indicates that AMF from different genera have unique patterns of mycelial development when forming mycorrhizas with tropical hosts in the presence of a localised phosphate source. AMF also appear to have different mechanisms for the control of P transfer, within the mycelium, to the host. The significance of the architecture of the ERM is discussed as well as the localisation of ALP in the IRM in determining the efficiency of AMF in terms of P accumulation in planta and subsequent growth of plants. Accepted: 19 August 1998     

Culture dependent and independent analyses of 16S rRNA and ATP citrate lyase genes: a comparison of microbial communities from different black smoker chimneys on the Mid-Atlantic Ridge

The bacterial and archaeal communities of three deep-sea hydrothermal vent systems located on the Mid-Atlantic Ridge (MAR; Rainbow, Logatchev and Broken Spur) were investigated using an integrated culture-dependent and independent approach. Comparative molecular phylogenetic analyses, using the 16S rRNA gene and the deduced amino acid sequences of the alpha and beta subunits of the ATP citrate lyase encoding genes were carried out on natural microbial communities, on an enrichment culture obtained from the Broken Spur chimney, and on novel chemolithoautotrophic bacteria and reference strains originally isolated from several different deep-sea vents. Our data showed that the three MAR hydrothermal vent chimneys investigated in this study host very different microbial assemblages. The microbial community of the Rainbow chimney was dominated by thermophilic, autotrophic, hydrogen-oxidizing, sulfur- and nitrate-reducing Epsilonproteobacteria related to the genus Caminibacter. The detection of sequences related to sulfur-reducing bacteria and archaea (Archaeoglobus) indicated that thermophilic sulfate reduction might also be occurring at this site. The Logatchev bacterial community included several sequences related to mesophilic sulfur-oxidizing bacteria, while the archaeal component of this chimney was dominated by sequences related to the ANME-2 lineage, suggesting that anaerobic oxidation of methane may be occurring at this site. Comparative analyses of the ATP citrate lyase encoding genes from natural microbial communities suggested that Epsilonproteobacteria were the dominant primary producers using the reverse TCA cycle (rTCA) at Rainbow, while Aquificales of the genera Desulfurobacterium and Persephonella were prevalent in the Broken Spur chimney.     

Host plant and latitude-related diapause variation in Rhagoletis pomonella: a test for multifaceted life history adaptation on different stages of diapause development

Variation in the overwintering pupal diapause of Rhagoletis pomonella appears to adapt sympatric populations of the fly to seasonal differences in the fruiting times of their host plants, generating ecological reproductive isolation. Here, we investigate what aspects of diapause development are differentially affected (1) by comparing the propensities of apple vs. hawthorn-infesting host races of R. pomonella to forgo an initially deep diapause and directly develop into adults, and (2) by determining the chronological order that R. pomonella races and sibling species break diapause and eclose when reared under standardized environmental conditions. The results imply that factors affecting initial diapause depth (and/or differential mortality during the prewintering period) and those determining the timing of diapause termination or rates of post-diapause development are both under differential selection and are to some degree genetically uncoupled in flies. The modular nature of diapause life history adaptation in Rhagoletis suggests that phenology may involve multiple genetic changes and represent a stronger ecological barrier separating phytophagous specialists than is generally appreciated.     

A comparison of the effects of auxin on cluster root initiation and development in Grevillea robusta Cunn. ex R. Br. (Proteaceae) and in the genus Lupinus (Leguminosae)

The effect of NAA (naphthaleneacetic acid) on the development of cluster roots in members of the Proteaceae and Leguminosae was investigated. The exogenous addition of NAA led to initiation of cluster roots in phosphate conditions normally inhibitory for their development, but initiation took place within the limits of the cluster pattern under –P conditions. There was no change in spacing within the cluster root nor between cluster roots in Grevillea robusta Cunn. ex R. Br. or in rootlet length or cluster root length. In Lupinus albus L., change in rootlet length and cluster root length was noted at 10^-10 and 10¹² M NAA. In L. albus, the length of time that roots were exposed to NAA does not appear to be important, with similar levels of cluster root initiation after 48 h and 7 days. Cluster root production in G. robusta differed from that in L. albus in terms of the concentration of NAA needed to induce initiation, and in the effects of extremely low levels of NAA on rootlet numbers and lengths. L. arboreus L. does not produce cluster roots under –P conditions. Furthermore, neither L. arboreus L., L. angustifolius L., L. luteus L. nor L. mutabilis L. were induced to produce cluster roots under –P conditions, nor under +P conditions in the presence of exogenous NAA. Thus, exogenous NAA only leads to the induction of cluster roots, at levels of P normally inhibitive of their development, in species of Lupinus that produce them under –P conditions. Auxin-induced cluster roots develop within the same constraints as those developing under –P conditions. NAA does not induce cluster roots in species of Lupinus that do not produce them under –P conditions.     

Effects of development and altered gravity conditions on cytochrome oxidase activity in a vestibular nucleus of the larval teleost brain: A quantitative electronmicroscopical study

The mitochondrial enzyme, cytochrome oxidase, was localized cytochemically in the nucleus magnocellularis, a primary relay nucleus of vestibular information within the area octavolateralis in the fish brain. Larvae of the cichlid fish Oreochromis mossambicus were analyzed at different developmental stages (4, 10, and 35 days posthatching) and after long-term exposure (8 days) to increased gravity (2–4 g). Quantification of highly reactive, moderately reactive, and nonreactive mitochondria reveals differences in the cytochrome oxidase activity of various cellular structures, for example, perikarya of neurons, presynaptic terminals, and myelinated and nonmyelinated cell profiles. Cytochrome oxidase activity in the mitochondria of neuronal perikarya increases during development which parallels the differentiation of the area octavolateralis. This possibly reflects the increasing energy demand during maturation and innervation of the magnocellular nucleus. Hyper-g-exposure of the larvae for 8 days (centrifuge) caused a further augmentation of cytochrome oxidase activity in the perikarya within the nucleus magnocellularis. This may reflect an increased oxidative metabolism resulting from the need for compensation of altered inputs from gravity-sensitive epithelia in the inner ear. Another possibility is that acceleration within a centrifuge causes physiological stress for the animals and, therefore, influences the cytochrome oxidase activity in neurons. © 1993 John Wiley & Sons, Inc.