Experimental Change of the Orientation of Two Populations of Talitrus saltator (Crustacea Amphipoda Talitridae) from Cap Bon (North‐Eastern Tunisia)

The orientation of sandhopper populations is adapted to the direction of the shoreline of the sandy beaches where they live; this behaviour was shown to be inherited in some Mediterranean populations. The question was open whether this behaviour could be adaptively modified in case of changing shoreline or passive transfer to a new differently oriented shoreline. The Cap Bon beaches in north‐eastern Tunisia are particularly interesting because they belong to two different Mediterranean Basins, the central and the eastern one, and their supra‐tidal populations do not come together. This work verified the effect of experimental change of the shoreline direction in two populations of Talitrus saltator from Cap Bon (north‐eastern Tunisia) through a displacement experiment. We transferred samples of T. saltator from two different localities (Korba and Ratiba) from their original beach to the familiar one and tested their solar and landscape orientation on the new beach that had an almost opposite direction with respect to the previous one. The comparisons of the results on the home beach and the new one confirmed the use of the solar compass in both populations, as well as the importance of landscape view and optical local sky factor in adjusting the escape direction. In both populations, an increase of scatter was observed on the new beach, especially when individuals could see the landscape. Also, a clear behavioural difference between the two populations was recorded, being Ratiba population not significantly oriented to the shoreline when tested on the unfamiliar beach, while Korba population maintained its home direction also on the new beach.     

From castaways to throwaways: marine litter in the Pitcairn Islands

Pollution of the oceans by garbage is a serious problem. Worldwide, as many as 8 million items of garbage may enter the seas on a daily basis. These items may survive some time, drifting in the oceans and give rise to other environmental problems such as causing hazards to wildlife (through ingestion and entanglement) before being washed ashore. Surveys of beaches on Ducie and Oeno Atolls in the Pitcairn Islands were compared with a similar survey on a beach in S.W. Ireland. The three beaches were similar in the density and major categories of garbage to be found, but differed in subtle ways. For example the Pacific beaches had a greater proportion of bottles and buoys, whereas the Irish beach had a greater proportion of sweet wrappers and polythene bags. Although these remote islands may be thousands of miles from industrial centres their beaches are apparently as dirty as those in Europe.     

Ectothiorhodospira marismortui sp. nov., an obligately anaerobic,moderately halophilic purple sulfur bacterium from a hypersaline sulfur spring on the shore of the Dead Sea

A novel type of purple sulfur bacterium was isolated from a hypersaline sulfur spring on the shore of the Dead Sea. The cells of the isolate are irregularly rod-shaped or curved, and motile by means of a tuft of polar flagella. The photosynthetic system, containing bacteriochlorophyll a and carotenoids of the spirilloxanthin series, is located on stacks of lamellar membranes in the cell cytoplasm. The organism can grow either photoautotrophically with sulfide as electron donor, which is oxidized via extracellular sulfur to sulfate, or photoheterotrophically, using acetate, succinate, fumarate, malate or pyruvate as carbon sources. The bacterium is obligately anaerobic, and requires a source of reduced sulfur for growth. The isolate is moderately halophilic, and grows optimally at NaCl concentrations between 3 and 8%, temperatures between 30 and 45°C, and neutral pH. 16S ribosomal RNA oligonucleotide cataloging suggests a close relationship to purple sulfur bacteria of the genus Ectothiorhodospira. As the isolate differs greatly from the described members of the genus Ectothiorhodospira, we describe the isolate as a new species, and propose the name Ectothiorhodospira marismortui sp. nov.     

Talitrid orientation as bioindicator of shoreline stability: Protected headland-bays versus exposed extended beaches

The behaviour of talitrids, being a local adaptation to beaches, is known to be related to environmental stability. The use of behavioural responses of resident populations as bioindicator of shoreline stability has been tested under various conditions, including after soft and hard engineering actions to stabilise eroded beaches. Port structures likely have impact on sediment longshore transportation and shoreline stability. The question was whether talitrid orientation behaviour could be proposed as bioindicator of impacts also for sandy bays of limited extension and highly used for recreation, such as those in the vicinity of touristic port structures. Orientation experiments were carried out on a set of sandy beaches of different extension and morphology, each of them in the vicinity of a touristic port, across the Mediterranean coasts. The protocol included field orientation tests of populations of talitrids, then analysed in terms of orientation precision seawards (considering sun compass orientation as the most locally adapted behavioural mechanism) in different seasons (before and after the touristic season) and times of day. The populations from more protected (either naturally or artificially) headland-bays showed a higher precision of orientation with respect to the shoreline direction than those from extended beaches, more subject to changes in longshore sedimentary transport as consequence of natural and human activities. The distance from the port and touristic pressure had no influence on talitrid orientation. An important stabilising factor for the sandy beach ecosystems, including talitrid populations and their behavioural adaptation, appeared to be the presence of seagrass banquette. The behavioural data point out that biotic information proceeding from local animal populations linked to beach sediments may complement sedimentology data and allow scaling the impacts occurring on a developed coastline. This becomes particularly relevant when considering interdisciplinary approaches to monitoring strategies.     

Comparing methods used in estimating biodiversity on sandy beaches: Pitfall vs. quadrat sampling

We compared the two most commonly used sampling methods, pitfall trapping and quadrat sieving, to study community diversity and talitrid abundance on sandy beaches. They are both widely used methods, however they are related to different behaviors: surface activity (pitfall traps) and burrowing in the substrate (quadrat sieving). To detect bias intrinsically generated by the use of different sampling methods, we applied both methods on a set of five beaches in New South Wales, Australia. The set included non-contiguous beaches, exposed and sheltered, more or less affected by recreational use. The results indicated a high fluctuation in biodiversity features. However, the most human-frequented beaches were grouped together by Multi Dimensional Scaling, and substrate-modifiers talitrid amphipods (sand-hoppers), played a major role in this scaling. The analysis of similarities (ANOSIM) indicated the roles of exposure and human recreational use in shaping the community, while the methods (quadrats vs. traps) resulted in higher fluctuation within samples than between, and informative outliers. Generalized Linear Models developed to estimate the probability of capture of talitrids by sampling method pointed to a higher probability to capture both sand-hoppers and beach-hoppers with the quadrat method. We finally suggest: (1) the comparative use of both sampling methods whenever possible, to capture multiple information and avoid bias in biodiversity estimates; and (2) an ad-hoc strategy when dealing with target populations. In particular, attention should be paid when targeting co-occurring talitrid species characterized by different ecology and behavioral traits: sand-hoppers (substrate modifiers) appeared to be more sensitive than beach-hoppers (non-substrate modifiers) to the impacts considered. In terms of biodiversity assessment the methods were equal, but for talitrid sampling quadrat sieving was more efficient.     

红菜薹游离小孢子培养与植株再生

以5个红菜薹(Brassica compestris ssp．chinensis var．pupurea Hort．)基因型为试材,探讨了基因型和活性炭对产胚量的影响。结果表明：产胚量最高的是基因型8902,达到42个／皿,最少的为零;加适量活性炭可以使产胚量提高近3倍。同时,对胚状体进一步再生成苗因素也进行了研究：在培养基中添加1．2％的琼脂浓度再生率最高,达到50．1％;4℃下处理10d可使再生成苗率从45％提高到65％;随胚状体年龄的延长,其再生成株率明显降低,最适的胚龄是20-24d;而培养基B5和MS对小孢子再生率的影响不大。     

Water purification using sand

Slow sand filters are used to purify drinking water. Each filter consists of a large tank containing a bed of sand through which water passes at typical rates of 0.1–0.3 m h^–1. Water is cleaned by physico–chemical and biological processes occurring at the air–water interface, within the bulk water, over the surface of the sand, and within the bed of sand. The processes found in sand filters replicate many of those found in natural sand banks and sandy beaches.     

紫水鸡非繁殖期日节律与时间分配

2011年1月至11月使用瞬时扫描法及焦点动物取样法对云南省大理市洱源县西湖湿地(26°00′~26°01′N,100°02′~100°03′E,平均海拔1 970 m)的紫水鸡(Porphyrio porphyrio)行为进行了观察,将行为定义为取食、寻食、休息、修饰、警戒、位移和其他共7类,扫描时将取食和寻食合并为觅食,分析非繁殖期的日节律和时间分配特点。觅食高峰出现在早晨和傍晚,低谷在秋季为下午14:30时(占所有行为类型56.56%)、冬季12:30时(55.61%)、春季11:00时(55.80%)。休息高峰秋季出现在12:30时(26.79%),冬季一日内呈上升趋势,春季呈双峰型,低谷在13:30时(14.64%)。从时间分配来看,寻食、取食、修饰等行为在不同季节间存在显著差异,寻食时间从高至低依次为冬季、春季、秋季,分别占总活动时间的19.87%、9.36%、3.03%;取食时间则相反,依次为秋季(72.54%)、春季(56.78%)及冬季(44.59%);与新西兰Pukepuke Lagoon种群相比,西湖湿地紫水鸡种群在秋季大量取食,在冬季增加寻食和休息时间,以应对高原湿地的温度和食物变化。修饰行为在繁殖期前(春季)最多(15.84%),繁殖期后(秋季)减少(11.10%)。以上结果说明,为适应气候、食物等条件的年周期变化,紫水鸡行为策略在不同时期和地点具有可塑性,这可能是该物种在滇西北地区得以繁衍及扩散的原因之一。     

High genetic diversity in the blue-listed British Columbia population of the purple martin maintained by multiple sources of immigrants

To assess genetic diversity in the blue-listed purple martin (Progne subis) population in British Columbia, we analysed mitochondrial control region sequences of 93 individuals from British Columbia and 121 individuals collected from seven localities of the western and eastern North American subspecies P. s. arboricola and P. s. subis, respectively. Of the 47 haplotypes we detected, 34 were found exclusively in western populations, and 12 were found only in eastern populations. The most common eastern haplotype (25) was also found in three nestlings in British Columbia and one in Washington. Another British Columbia nestling had a haplotype (35) that differed by a C to T transition from haplotype 25. Coalescent analysis indicated that these five nestlings are probably descendents of recent immigrants dispersing from east to the west, because populations were estimated to have diverged about 200,000–400,000 ybp, making ancestral polymorphism a less likely explanation. Maximum likelihood estimates of gene flow among all populations detected asymmetrical gene flow into British Columbia not only of rare migrants from the eastern subspecies in Alberta but also a substantial number of migrants from the adjacent Washington population, and progressively lower numbers from Oregon in an isolation-by distance pattern. The influx of migrants from different populations is consistent with the migrant-pool model of recolonization which has maintained high genetic diversity in the small recovering population in British Columbia. Thus, the risk to this population is not from genetic erosion or inbreeding following a severe population crash, but from demographic stochasticity and extinction in small populations.