Temporal variations in the diet of pearly razorfish Xyrichtys novacula (Osteichthyes: Labridae)

The diet of pearly razorfish Xyrichtys novacula, caught monthly along the shores of the Island of Lampedusa, appeared to be mainly composed of crustaceans, followed by colonial ascidians, molluscs and polychaetes. Among prey, sand dwellers and phanerogam‐associated species were recorded. In winter months, the diet was characterized by a small number of prey items, dominated by colonial ascidians, while in spring and summer a wider prey array was recorded. Dietary indices show that X. novacula do not strictly exploit benthic prey but also pelagic organisms, such as copepods. This feeding behaviour reached its peak in March and October, when the abundance of primary consumers was at its highest after phytoplankton blooms. Furthermore, X. novacula caught prey organisms according to their availability and seasonal patterns during their life cycles, irrespective of fish size.     

OPEN-BOAT WHALING ON THE STRAITS OF GIBRALTAR GROUND AND ADJACENT WATERS

Logbooks ( n = 317) from whaling expeditions made in the North Atlantic during the 19th century were examined to investigate activity in the Gibraltar Straits grounds. At least forty expeditions of whaling vessels from European and American ports visited the area. In all cases the main target was the sperm whale, but pilot whales, dolphins, sea turtles, and even a blue whale were also taken. Whaling effort concentrated on the Atlantic side of the Straits; only two expeditions ventured into the Mediterranean Sea, obtaining negligible catches. The whaling season extended during spring and summer and peaked in June–July. This seasonality appeared not to be governed by changes in whale density but by the trade winds necessary to sail southward or westward to cross the Atlantic. Searching effort continued while trying out, but the rate of sighting cetaceans was about half that of searching periods. However, the rate of sighting or capturing a sperm whale remained unchanged during processing, probably because the gregarious habits of the species produced clumping of catches. For every whale secured, 1.31 whales were struck. After correcting for struck but lost whales and for "gammed" vessels, the minimum number of removals of sperm whales during 1862–1889 is estimated at 237.     

Growth variation in larval Makaira nigricans

The Atlantic blue marlin Makaira nigricans larvae were collected from Exuma Sound, Bahamas and the Straits of Florida over three summers (2000–2002). Sagittal otoliths were extracted and read under light microscopy to determine relationships between standard length ( L _S) and age for larvae from each year and location. Otolith growth trajectories were significantly different between locations: after the first 5–6 days of life, larvae from Exuma Sound grew significantly faster than larvae from the Straits of Florida. Exponential regression coefficients were similar among years for Exuma Sound larvae (mean instantaneous growth rate, G _L = 0·125), but differed between years for larvae from the Straits of Florida ( G _L = 0·086–0·089). Differences in larval growth rates between locations resulted in a 4–6 mm difference in L _S by day 15 of larval life. These differences in growth appeared to be unrelated to mean ambient water temperatures, and may have been caused by location‐specific differences in prey composition or availability. Alternatively, population‐specific differences in maternal condition may have contributed to these differences in early larval growth.     

Long‐term temporal and spatial trends in eutrophication status of the Baltic Sea

Much of the Baltic Sea is currently classified as ‘affected by eutrophication’. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50–100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long‐term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112‐year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid‐1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long‐term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large‐scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem‐based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.     

Reproductive phenology,growth and primary production of Phyllariopsis purpurascens (Phyllariaceae,Phaeophyta) from the Straits of Gibraltar

Two populations of Phyllariopsis purpurascens from the Straits of Gibraltar area were investigated during 1990 and 1991. This area has very strong currents (～2·5 m s^-1 at spring tide). The first sporophytes (less than 0·5 cm in length) were observed in April; they disappeared after the first storm period in October. The estimated number of spores produced in an unilocular sporangium was 64. The fertility period started in May and continued until October, but the maximum sorus surface area (27%) was reached in September. The maximum sporangial density was 1476±236 mm^-2. The slow development of fertility and its correlation with the seasonal increase in temperature suggest that sporangial development is controlled by temperature and not by photoperiod. The drag effect produced by the strong currents (at spring tides and storm periods) is sufficient to break adult plants (with 0·01 m² in surface intercepting the current). At the beginning of the sporophytic production cycle (210 days), the meristematic zone produces more tissue for blade growth than for stipe growth. Holdfast growth occurs in the first 3 months. The mortality was 90% for sporophytes 0–10 cm in length, and decreased to ～50% in adult plants. One cohort in the cycle has been identified. The net primary production (calculated by the graphic model of Allen) was 0·04 g dry weight m^-2·day^-1 from April to October (210 days). The production is among the lowest values estimated for seaweeds.     

Spatial and temporal variability of the benthic assemblages associated to the holdfasts of the kelp <Emphasis Type="Italic">Macrocystis pyrifera</Emphasis> in the Straits of Magellan,Chile

Macrocystis pyrifera (L.) C. Agardh is a characteristic macroalga in the Magellan region covering almost 30% of the shallow coastal waters. The focus of this study was to analyse the spatial and seasonal patterns in macrofauna communities associated to the holdfasts of Macrocystis pyrifera at two study sites in the Straits of Magellan, South Chile. In total, 114 species from 10 major taxa were isolated from the holdfasts. MDS clearly separated the holdfast fauna collected in different seasons, with autumn and winter collections being richer in terms of species richness and abundance as compared to the spring and summer situation. MDS also clearly separated the holdfast associated faunas of the two study sites, Bahía Laredo and Fuerte Bulnes. The community structure and species composition of the associated macro-invertebrates and vertebrates appeared rather heterogeneous, probably due to the extremely heterogeneous environmental conditions along the entire coastline of the Subantarctic Magellan region.     

海峡西岸经济区景观格局10年变化及驱动力

海峡西岸经济区是在国家区域发展战略引领下的我国未来发展的重点区域之一,分析其景观格局的变化有利于促进经济区的可持续发展。基于2000、2005、2010年的土地覆被分类数据,采用空间分析、主成分分析、景观指数分析的方法,研究海峡西岸经济区景观格局特征及其变化的驱动力。研究结果表明,由于城市用地面积的扩张,导致耕地、湿地、草地的面积下降,其中面积减少最多的为耕地,10年间减少了约14.0%,与此同时建设用地面积增长了38.6%。除建设用地外,各类景观的最大斑块指数(LPI)值均降低,建设用地的LPI值由0.1增至0.4,成为除林地外的优势景观。耕地的景观形状指数(LSI)由325.1下降到315.9,而其他各类景观的LSI值为上升趋势。林地的平均斑块面积(AREA_MN)急剧增加,由560.6增长到787.6,其他各类型景观AREA_MN值变化甚微。选取经济因素和政策因素分析海峡西岸经济区景观变化的驱动因子,结果表明,海峡西岸经济区景观格局的变化是两个因素共同作用的结果。海峡西岸经济区未来的经济发展需要与该区域耕地缩减的情况相平衡。     

台湾海峡晚更新世人类肱骨化石

产自台湾海峡海底的人类右肱骨石化程度高; 个体大而粗壮 ,三角肌粗隆发育 ,骨干上下两半段不在同一纵轴上 ,形成 6 5°的夹角 ,这些显示不同于新石器时代和现代人的原始性状 ,其演化水平和日本的港川人及欧洲的克罗马农人相当。与人化石一同捞出的哺乳动物化石有古菱齿象、野马、最后鬣狗、达氏四不像鹿等 ,表明其时代为晚更新世晚期。     

Straits in the Russian Arctic

The issues surrounding the regimes of international straits, noninternational straits, and ice-covered areas are analyzed for the purpose of looking at Russian practices in its Arctic straits. It is concluded that the Russian practice exceeds that permitted to states bordering straits under the traditional regime for straits. Nevertheless, viewing the U.S. practice as a coastal state, as well as the coastal state practice of Canada, substantial similarities are found with the Russian practice. Conflicting claims and practices result in a confused Arctic legal regime. An international conference is recommended to discuss and perhaps settle the issues.