支持西印度洋地区海洋和海岸带资源可持续管理的海洋研究

西印度洋(WIO)地区以其迷人的海岸带、丰富的海洋生物多样性以及富饶的海洋和海岸带资源而著称.但是地处WIO地区的许多国家像肯尼亚、莫桑比克、索马里、南非、坦桑尼亚、科摩罗、马达加斯加、毛里求斯、留尼旺、塞舌尔等却极度贫困,特别是近二三十年以来,该地区的环境退化现象以及自然资源和生物多样性的下降越来越明显.     

Climate change/variability implications on hydroelectricity generation in the Zambezi River Basin

The study has analysed the effects of various factors on hydroelectric power generation potential to include climate change/variability, water demand, and installation of proposed hydroelectric power schemes in the Zambezi River Basin. An assessment of historical (1970–2000) power potential in relation to climate change/variability at existing hydro electric power schemes(Cahora Bassa, Kariba, Kafue Gorge and Itezhi-Tezhi) in the Zambezi River Basin was conducted. The correlation of hydroelectric power potential with climate change/variability aimed at observing the link and extent of influence of the latter on the former was investigated. In order to predict the future outlook of hydro electric power potential, General Circulation Models (GCM) were used to generate projected precipitation. The monthly simulated precipitation was extracted from the GCM for every sub basin and used to compute future precipitation. Further, future water demand in the sub basins of the Zambezi River Basin were estimated based on the respective population growth rate in each sub basin. Subsequently, water balance model, with projected precipitation and water demand input was used to determine projected run-offs of sub basins of the Zambezi River Basin. .Based on the projected run-offs of sub basins, reservoir storage capacities at existing hydro electric power schemes were estimated. The baseline assessment revealed a strong relationship between hydroelectric power potential and climate change/variability. The study also revealed that the main climate and other risks associated with current and future hydro electric power generation include projected dry years, floods and increasing water demand. The results indicate that the hydroelectric power potential has a tendency towards gradual reduction in its potential in all existing and proposed hydroelectric power schemes owing to climate change and increasing water demand.     

Modelling the Karenia mikimotoi bloom that occurred in the western English Channel during summer 2003

Observations from space and in situ from the R.V. Corystes 8/03 Cruise show that a massive Karenia mikimotoi bloom occured during summer 2003 in the western English Channel. Due to exceptional climatoligical conditions that occured in June 2003, the installation of a very strong thermocline enhanced the development of a massive bloom over 1 million cells l⁻¹ in the Central English Channel. This paper presents the application of a mathematical model of this species, previously developed in for the Bay of Biscay, into a general 3D model of the primary production of the English Channel and southern Bight of the North Sea. Allelopathic interactions exerted by K. mikimotoi on other phytoplankton species and the role of agitation in the mortality of this species are taken into account. The model includes the dynamics of the bloom and consequently reproduces with good agreement the geographical distribution of the K. mikimotoi bloom both surface and subsurface. The model suggests that the apparent transport of the bloom towards the French coasts as inferred from the satellite observation was not due to advection but was only caused by the establishment of suitable conditions. The sensivity of the K. mikimotoi distribution to boundary conditions, initialization and the role of turbulence is discussed.     

Combined use of pheromone trails and visual landmarks by the common garden ant Lasius niger

This study investigated the relative importance of pheromone trails and visual landmarks on the ability of Lasius niger foragers to relocate a previously used food source. Colonies formed foraging trails to a 1-M sucrose feeder. Sections of this trail were then presented back to the same colony after variable time intervals. Individual outgoing foragers were observed to determine if they walked for 15 cm in the direction of the feeder or not. On newly established pheromone trails formed by 500 ant passages, 77% of the foragers walked in the correct direction vs 31% for control foragers (no trail pheromone). Pheromone trails decayed to the control levels in 20–24 h. Trails formed with fewer ant passages (125 or 30) decayed quicker. The use of visual landmarks was investigated by using trails with outgoing foragers from the colony that established the trail, either in the same room or in a different room, with different visual landmarks, to that used during trail establishment. Approximately 20% more ants walked in the correct direction in the same room vs the different room. This difference decreased to around 10% 2 h after trail establishment, indicating that the ants in the different room were learning the new visual cues to navigate by. Our results show that visual landmarks and pheromone trails are approximately equally useful in initially guiding L. niger foragers to food locations and that these two information sources have a complementary function.     

Molecular phylogenies help resolve taxonomic confusion with Asian <Emphasis Type="Italic">Crassostrea</Emphasis> oyster species

Identification of oyster species is still largely based on phenotypic characters that are highly plastic. Prompted by the proposed introduction of the Asian oyster species Crassostrea ariakensis into the Chesapeake Bay region of the U.S.A., this study uses molecular genetic information to understand the taxonomic framework surrounding C. ariakensis and to confidently distinguish among various sympatric oyster species. Putative samples of C. ariakensis and other species of cupped oysters from across Asia were collected and phylogenetic analyses were conducted on DNA sequences of both nuclear (ITS-1) and mitochondrial (COI) regions. Trees generated based on the two independent molecular datasets were highly congruent, and indicate that many oysters collected for this study as C. ariakensis were originally misidentified. Results also indicate that C. ariakensis, C. hongkongensis and C. nippona are distinct, but closely related species. There is strong support in both analyses for a close relationship between C. gigas and C. sikamea, as well as between C. belcheri and C. gryphoides, and between C. iredalei and C. madrasensis. The parsimony analyses based on these DNA markers, however, did not provide evidence to support C. angulata as a distinct species from C. gigas. Overall, the results emphasize the need for rigorous species identification, and additional extensive and intensive sampling to more accurately determine relationships among Crassostrea species, define their geographic distributions, and establish existing sympatry patterns.     

Inter-year differences in survival of Atlantic puffins Fratercula arctica are not associated with winter distribution

Miniature geolocator loggers (Global Location Sensing, GLS) that provide daily locations of birds have revolutionised the study of winter ecology and migration patterns of seabirds. A long-term study of ringing recoveries and analyses of heavy metals and pollutants in tissues of Atlantic puffins Fratercula arctica from the Isle of May, south-east Scotland, suggested that this population wintered mainly within the North Sea. However, deployment of GLS devices over the 2007/2008 winter showed that many breeding birds made major excursions into the east Atlantic. This winter was the second of two when survival was extremely low (survival in 2006/2007 and 2007/2008 was 0.696 and 0.695, respectively, compared to the average of 0.922 over the period 1984/1985–2005/2006). These low rates of survival suggested that the unexpected use of the Atlantic might have been associated with unusually poor conditions in the North Sea as indicated by very low breeding success in 2007. Survival rate returned to previous levels in 2008/2009 providing the opportunity to test whether higher survival was associated with birds remaining in the North Sea, or whether movements into the Atlantic are a feature of this population unrelated to survival. Accordingly, geolocators were deployed over the 2009/2010 winter when adult survival was subsequently established to be high (0.913). We found greater support for the hypothesis that winter distribution is not associated with survival. Thus, 8 (40 %) of 20 individuals followed in 2009/2010 went into the Atlantic, a rate not significantly different from 11 (58 %) of the 19 followed in the 2007/2008 winter. Indeed, birds actually spent longer in the Atlantic and used a wider variety of areas in 2009/2010, although the time spent away from the colony was significantly shorter than in 2007/2008. Since our data were from individuals that survived, remaining in or moving out of the North Sea can both be successful strategies during winters when the population as a whole shows either high or low survival rates. Unfortunately, we do not know where birds that died had gone, and hence, the relative survival of birds that did or did not move into the Atlantic. Determining the link between survival and wintering area for any seabird remains a formidable challenge and will have to await the development of technologies that can determine both where and when birds die.     

Fresh, stockpiled, and composted beef cattle feedlot manure: nutrient levels and mass balance estimates in Alberta and Manitoba

The fate of manure nutrients in beef cattle (Bos taurus) feedlots is influenced by handling treatment, yet few data are available in western Canada comparing traditional practices (fresh handling, stockpiling) with newer ones (composting). This study examined the influence of handling treatment (fresh, stockpiled, or composted) on nutrient levels and mass balance estimates of feedlot manure at Lethbridge, Alberta, and Brandon, Manitoba. Total carbon (TC) concentration of compost (161 kg Mg(-1)) was lower (P < 0.001) than stockpiled (248 kg Mg(-1)), which was in turn lower (P < 0.001) than fresh manure (314 kg Mg(-1)). Total nitrogen (TN) concentration was not affected by handling treatment while total phosphorus (TP) concentration increased with composting at Lethbridge. The percent inorganic nitrogen (PIN) was lower (P < 0.01) for compost (5.1%) than both fresh (24.7%) and stockpiled (28.9%) manure. Composting led to higher (P < 0.05) dry matter (DM) losses (39.8%) compared to stockpiling (22.5%) and higher (P < 0.05) total mass (water + DM) losses (65.6 vs. 35.2%). Carbon (C) losses were higher (P < 0.01) with composting (66.9% of initial) than with stockpiling (37.5%), as were nitrogen (N) losses (46.3 vs. 22.5%, P < 0.05). Composting allowed transport of two times as much P as fresh manure and 1.4 times as much P as stockpiled manure (P < 0.001) on an "as is" basis. Our study looked at one aspect of manure management (i.e., handling treatment effects on nutrient concentrations and mass balance estimates) and, as such, should be viewed as one component in the larger context of a life cycle assessment.     

Physico-chemical characterization of grease interceptors with and without biological product addition

Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line blockages leading to sanitary sewer overflows (SSOs). However, there have been very few long-term assessments of the physico-chemical characteristics of full-scale grease interceptors (GIs), the first "line of defense" against FOG buildup in sewer lines. In this study, we assessed the physico-chemical characteristics of two full-scale GIs (at a restaurant and a retirement community kitchen) over a one-year period. Statistically significant differences between bioaugmented and untreated cycles were detected for several chemical and physical properties. The treated cycles had lower BOD and COD at the grease interceptor outlet. While the combined data for all treated cycles did not show lower FOG concentrations in the GI outlet compared to the combined data for all untreated cycles, comparison of specific individual treated and untreated cycles show a positive effect due to the addition of product.     

Polynomial response of 2,4-D mineralization to temperature in soils at varying soil moisture contents, slope positions and depths

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is a widely used broadleaf control agent in cereal production systems. Although 2,4-D soil-residual activity (half-lives) are typically less than 10 days, this herbicide also has as a short-term leaching potential due to its relatively weak retention by soil constituents. Herbicide residual effects and leaching are influenced by environmental variables such as soil moisture and temperature. The objective of this study was to determine impacts of these environmental variables on the magnitude and extent of 2,4-D mineralization in a cultivated undulating Manitoba prairie landscape. Microcosm incubation experiments were utilized to assess 2,4-D half-lives and total mineralization using a 4 × 4 × 3 × 2 factorial design (with soil temperature at 4 levels: 5, 10, 20 and 40°C; soil moisture at 4 levels: 60, 85, 110, 135 % of field capacity; slope position at 3 levels: upper-, mid- and lower-slopes; and soil depth at 2 levels: 0-5 cm and 5-15 cm). Half-lives (t(?)) varied from 3 days to 51 days with the total 2,4-D mineralization (M(T)) ranging from 5.8 to 50.9 %. The four-way interaction (temperature × moisture × slope × depth) significantly (p < 0.001) influenced both t(?) and M(T). Second-order polynomial equations best described the relations of temperature with t(?) and M(T) as was expected from a biological system. However, the interaction and variability of t(?) and M(T) among different temperatures, soil moistures, slope positions, and soil depth combinations indicates that the complex nature of these interacting factors should be considered when applying 2,4-D in agricultural fields and in utilizing these parameters in pesticide fate models.