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1.
确定自然海岸特征是海岸修复中的重要内容,但是在开发后弃管的无居民海岛却面临缺少历史资料参考的困难。在大连普兰店湾中部前大连岛的研究证明,依据历史影像和现存海岸地质地貌情况可以分析确定原自然海岸位置及性质。1972年KH 卫星影像表明当时的前大连岛仍然保持自然海岸形态,海岸位置在2020年海岸后 方的岛屿陆域内部。结合2020年海岸地质考察结果可以进一步确定1972年的前大连岛东部、西部分布海蚀崖形式的基岩海岸,南部、北部则分布砾石质海岸。1972—2020年,前大连岛自然海岸全部变化为人工海岸,海岸长度也从约2.38 km 增加至约3.12 km。  相似文献   

2.
The second mid-summer survey of surface-nesting seabirds at the Prince Edward Island group (Marion and Prince Edward islands) was conducted during December 2008, seven years after the initial mid-summer survey. Wandering albatrosses Diomedea exulans may have decreased slightly at Prince Edward Island, mirroring a decrease of roughly 2% per year at Marion Island from 1998 to 2005, a decline that has since reversed. Numbers of grey-headed albatrosses Thalassarche chrysostoma on Marion Island have remained stable, whereas the population on Prince Edward Island decreased by 20% from 2001 to 2008 (3% per year). The estimate of Indian yellow-nosed albatrosses T. carteri at Prince Edward Island was similar in 2001 and 2008. Counts of both sooty albatrosses Phoebetria spp. were substantially higher at Prince Edward Island in 2008, possibly as a result of better coverage compared to 2001. Dark-mantled sooty albatrosses P. fusca on Marion Island have decreased by almost 2% per year since 1996, continuing a negative trend from the early 1980s, whereas light-mantled sooty albatrosses P. palpebrata have increased by almost 6% per year at Marion Island since 1996. Counts of both giant petrels increased at Prince Edward Island (northern Macronectes halli by 44%; southern M. giganteus by 28%), whereas their numbers have remained stable at Marion Island. Current best estimates for annual breeding populations (pairs) at the two islands are 3 650 wandering albatrosses, 9 500 grey-headed albatrosses, 7 000 Indian yellow-nosed albatrosses, 2 900 dark-mantled sooty albatrosses, 800 light-mantled sooty albatrosses, 750 northern giant petrels and 2 800 southern giant petrels, confirming the global importance of the Prince Edward Islands for these seven species. Apart from the dark-mantled sooty albatross, their populations are reasonably healthy despite fishing mortality.  相似文献   

3.
The genetic structure of a population of the Japanese turban shell, Turbo (Batillus) cornutus at Sata-Misaki Point, on the southern coast of Kyushu Island, was determined on the basis of nucleotide sequences of mitochondrial DNA and compared with that of a population of the western coast of Kyushu Island. The significant genetic differentiation between these two populations suggests that the courses of the warm currents along the coast of the Kyushu Island have been relatively stable after the divergence between the two genetically distant groups of the Japanese turban shell, which was estimated to have occurred during some period in Pleistocene.  相似文献   

4.
Pre-metamorphic leptocephali of Pisodonophis sangjuensis (n = 91, 10.4?90.2 mm in total length, TL) were collected in the East China Sea for the first time. Pre-metamorphic leptocephali of P. sangjuensis, which were identified using mitochondrial DNA cytochrome c oxidase subunit I gene (mtDNA COI), are characterized by various combinations of morphological characters: 8 moderate to pronounced gut loops with the kidney terminating on the 6-7th loops; and 8 subcutaneous pigment patches on the tail just ventral to the notochord. Pisodonophis sangjuensis leptocephali were more numerously collected offshore than inshore around Jeju Island. The smallest leptocephali (< 15.0 mm TL) were collected from the south far from Jeju Island, and the largest leptocephali (> 100.0 mm TL) were collected from around Jeju Island and the southern coast of Korea. Our findings indicate that P. sangjuensis spawns offshore south of Jeju Island that is an area associated with high water temperature, and then the hatched leptocephali are transported to Jeju Island or the southern coast of Korea by the Tsushima Warm Current.  相似文献   

5.
Four species of penguin breed regularly at South Africa's Prince Edward Islands: king penguin Aptenodytes patagonicus, gentoo penguin Pygoscelis papua, macaroni penguin Eudyptes chrysolophus and southern rockhopper penguin E. chrysocome. In December 2008, it was estimated that some 65 000 pairs of king penguins were incubating eggs at Marion Island, the larger of the two islands in the group, and 2 000 pairs at Prince Edward Island. At Marion Island from 1987 to 2008, there was no long-term trend in numbers of king penguin chicks that survived to the end of the winter period, but there was considerable fluctuation in chick production in the 1990s. It was roughly estimated that on average 88% of king penguin chicks survived the winter period (from April to September/October). Numbers of gentoo penguins at Marion Island decreased from more than 1 300 pairs in the mid-1990s to fewer than 800 pairs in 2003, and then increased to almost 1 100 pairs in 2008 as breeding success improved. Between 1994/1995 and 2008/2009, numbers of macaroni and southern rockhopper penguins at Marion Island decreased by about 30% and 70% respectively. In 2008/2009, some 290 000 pairs of macaroni penguins bred at this island, mostly in two large colonies where there was a progressive decrease in the density of nests. At both these colonies, decreases in numbers breeding followed outbreaks of disease. Inadequate breeding success has influenced the decreases of macaroni and rockhopper penguins. In 2008/2009, some 42 000 pairs of southern rockhopper penguins bred at Marion Island and 12 000 pairs of macaroni penguins and 38 000 pairs of southern rockhopper penguins at Prince Edward Island.  相似文献   

6.
The narrow-barred Spanish mackerel Scomberomorus commerson is one of the most important linefish species caught in KwaZulu-Natal and southern Mozambique waters, forming the basis of important commercial, artisanal and recreational fisheries. A total of 439 S. commerson were sampled along the east coast of southern Africa (KwaZulu-Natal, South Africa, and southern Mozambique) between April 2011 and March 2012. Retrospective length-at-age data observed from whole otoliths were used to compare and describe sex-specific growth. Growth rates obtained from otolith-derived data were compared with those estimated from 29 tag-recaptured fish. Overall, ages ranged from 0.48 to 14.6 years for females and 0.4 to 13.57 years for males. Otolith readings yielded an average percent error of 11.21%, lower than recorded in a previous study from the region. Marginal zone analysis provided strong evidence that one translucent and one opaque growth zone were laid down annually. Schnute growth-function parameters indicated significant differences in growth between sexes. Females approached their mean asymptotic length at a faster rate, and grew to a greater mean length-at-age, relative to males. Growth in both sexes was rapid, achieving 67.46 cm FL (females) and 65.4 cm FL (males) in their first year of life. Growth rates obtained from tag-recaptured S. commerson indicated slower growth for smaller/younger fish up until 70 cm FL after which growth was very similar to that observed from otolith-derived data. The results of this study provide accurate, validated life-history parameters for king mackerel that are important for the assessment of stock status in the region.  相似文献   

7.
White sharks Carcharodon carcharias aggregate at specific times of the year at localities along the South African coast. At Mossel Bay, on the southern Cape coast, four sites were sampled (Seal Island, Hartenbos, Kleinbrak and Grootbrak) to investigate spatial and seasonal patterns in relative abundance and life-history composition. These are known aggregation sites within the bay, each having particular physical and/or biological characteristics. Sightings-per-unit-effort data were collected from February to December 2008–2010. Sighting rates demonstrated significant seasonal and interannual variation at the four sites. The highest mean sighting rate was recorded at Seal Island and the lowest at Hartenbos, which might be a consequence of differences in prey availability. The greatest interannual variability was recorded at Kleinbrak, followed by Seal Island, with little variability at Grootbrak and Hartenbos. White sharks appeared to concentrate at Grootbrak and Kleinbrak in summer and autumn, at Seal Island in winter, and at Hartenbos and Seal Island in spring. All life-history stages were present year-round but their occurrence was influenced significantly by season (p < 0.05), although not site. Few adults (325–424 cm total length) were seen, with the highest frequency being in spring, whereas that of young-of-the-year (≤174 cm) was in autumn. Juveniles (175–324 cm) constituted 78% of the animals sighted, indicating that Mossel Bay is an important aggregation site for this life-history stage.  相似文献   

8.
Two species of spiny lobsters (marine crayfish) inhabit New Zealand waters: Jasus edwardsii (Hutton, 1875), and J verreauxi (H. Milne Edwards, 1851). J edwardsii, the more common species, is present along most rocky coastlines in New Zealand, but is more abundant in the south‐west of the South Island and at the Chatham Islands. The species apparently reaches its northern limit of distribution at the Three Kings Islands (34°S) and its southern limit at the Auckland Islands (51°S).

J. verreauxi, the less common species, is almost solely restricted in New Zealand waters to the north‐east coast of the North Island. It is uncommon in the west and the south of the North Island, and is rare in the South Island. J. verreauxi apparently reaches its northern limit of distribution at the Kermadec Islands (31°S), and its southern limit near Bluff (47°S) in the South Island.  相似文献   

9.
利用 ISSR 分子标记技术对采自浙江省南麂岛和渔山列岛的4株不同形状野生坛紫菜(Porphyra haitanensis)进行了遗传多样性分析.从33条引物中筛选出11条可扩增出清晰条带的引物,在4株坛紫菜中共扩增出62条 DNA 带,其中多态性条带比例达88.71%.遗传距离分析表明4株坛紫菜之间的遗传距离范围是0.3226~0.6129,聚类分析结果表明渔山列岛坛紫菜遗传距离最近,而南麂岛的两株坛紫菜则距离相对较远.该研究说明浙江附近岛屿的野生坛紫菜遗传多样性丰富  相似文献   

10.
对古氏非螺(Afer cumingii (Reeve,1844))的齿舌形态以及线粒体CO1和16S rRNA基因序列进行了分析,并以犬齿螺科种类为外群,采用邻接法(NJ)和最大简约法(MP)构建了系统发育树。结果表明,古氏非螺的齿舌具有典型的蛾螺科种类特征;古氏非螺在系统树上与蛾螺科种类聚在一起,而不与犬齿螺科种类聚类。齿舌形态和线粒体基因分析的结果都表明古氏非螺属于蛾螺科,进一步证实了将非螺属修订到蛾螺科的结论。  相似文献   

11.
By measuring the maximum water level of the traces attained by the Japan Sea Tsunami on 26 May 1983, we obtained the distribution along the west coast of the northeast Japan. The level reaches a maximum at the coast eastward of the epicenter and decreases with the relationship 8.6e –0.017x (m) with distancex (km) measured from the coast nearest to the epicenter. A small increase of levels was observed at coasts to the south of the tsunami source having distance larger than 200 km. With the aid of tide gauge records we revealed an excitation of edge wave which brought about the small increase of levels at the southern coast. In comparison with the decrease with distance obtained on the coasts of the main islands of Japan, some noticeable peaks were observed at several small islands. It is suggested that the reason why a short period component is predominant for the initial wave motion of tsunami is that the source region has depth of 3, 000 meters. The feature of wave period is discussed in comparison with that of the 1964 Niigata Tsunami.  相似文献   

12.
Cape fur seals Arctocephalus pusillus pusillus were estimated to kill some 6 000 Cape gannet Morus capensis fledglings around Malgas Island in the 2000/01 breeding season, 11 000 in 2003/04 and 10 000 in 2005/06. This amounted to about 29%, 83% and 57% of the overall production of fledglings at the island in these breeding seasons respectively. Preliminary modelling suggests this predation is not sustainable. There was a 25% reduction in the size of the colony, the second largest of only six extant Cape gannet colonies, between 2001/02 and 2005/06. There has been a large increase in predation by Cape fur seals on seabirds around southern African islands since the mid-1980s, coincidental with both an increase in the seal population, altered management of the islands and an altered distribution of prey for gannets and seals. At Malgas Island, most gannet fledglings were killed between 10:00 and 18:00, the period when most are in the water around the island, from mid-January to mid-March, the main fledging period. The Cape gannet is classified as Vulnerable.  相似文献   

13.
Numerical simulation on diurnal and semidiurnal tidal currents is made for the eastern and southern parts of the East China Sea bounded by the Tsushima, islands of Kyushu and Ryukyu in the east and extending to the central Taiwan Strait in the south. The numerical computation shows that the rapid variation in the seabed topography near the Okinawa Trough may cause computational instability and this instability can be removed by setting a suitable lateral eddy viscosity. The computed results are in good agreement with the observations and indicate that the tidal currents in the greater part of the area studied rotate clockwise. An M2 current-amphidromic point exists in the southern part of the Korea Strait and another one appears in the west of Okinawa with less certainty. K1 and M2 cotidal charts based on the observed and computed tidal currents in the sea and the observed tides on the coast are also given.  相似文献   

14.
用沿岸上升流指数分析中国东南沿岸风生上升流的特征   总被引:2,自引:0,他引:2  
苗馨  胡建宇 《海洋通报》2011,30(3):258-265
对1968年1月到2007年12月中国东南沿海(17°N~30°N,109°E~123°E)上升流指数月平均数据进行分析,结论如下:(1)风生沿岸上升流主要在4-8月间发生于海南岛东部、雷州半岛东部、汕头以北至浙江沿岸.(2)风生沿岸上升流的强度具有时空分布变化特征,其中海南岛东部沿岸上升流最强,浙江沿岸其次;整个中国...  相似文献   

15.
The comparative limnology of some New Zealand lakes   总被引:1,自引:1,他引:0  
The morphometry, environmental conditions, and some physical and chemical data are given for twenty‐four New Zealand lakes: seven are in the southern part of the South Island, the others, excluding Lakes Waikaremoana and Waikareiti, are in the “thermal region” of the central North Island. These lakes form two separate groups and include the largest and deepest lakes in both islands.

The lakes in which stratification was established were found to belong to the class known as warm monomictic Two lakes, Rotorua and Rotoehu, were found to be homothermous throughout the year. Open water surface temperatures did not exceed 23°c in the North Island lakes or 19°c in the South Island, and minimum temperatures recorded were 7°c in the northern lakes and 5°c in the southern. In deep lakes the range of temperature was much less: Wakutipu had a range of 16–8.85°c.

The disappearance level of a Secchi disc varied from 18 m (Lake Taupo) to 0.8 m (Lake Rotongaio). The transparency of the water in the glacial and volcanic lakes was comparable to that of similar lakes in other parts of the world.

It was found that total ions, measured by the ion‐exchange resins reached high concentrations in lakes fed by thermal waters: Rotomahana 14.32m.e./l. By contrast Tikitapu, a seepage lake, had the low concentration of. 0.28m.e./l, and Wakatipu, a glacial fed lake, a concentration of O.58m.e./1. The pH range was 8.1–5.8, the lowest value being in Tikitapu, a volcanic lake. Slightly lower pH values were recorded in the bottom waters of lakes when stratified. Lakes were usually supersaturated with oxygen at the surface, and only a few small lakes showed a hypolimnial deficiency. Silica and phosphate were found in high concentrations in some thermal lakes but nitrogen in the forms measured, was found to be low.  相似文献   

16.
Sawfishes are coastally distributed rays that grow to very large sizes. All five species are assessed as Endangered or Critically Endangered as a result of population declines caused mainly by entanglements in fishing gear and by habitat degradation. Three species occur in the western Indian Ocean, but their populations are believed to have declined drastically in many areas and little is known about their presence in Tanzania. Fisher interviews were conducted to provide an overview of the status of sawfishes in Tanzania and to highlight where conservation actions should be focused to conserve sawfishes nationally. In total, 386 interviews were conducted: 296 at 31 villages in four regions on Tanzania’s mainland, and 90 interviews at 12 villages in four regions of Pemba Island. Less than half (46%) of the fishers were familiar with sawfishes and could identify one from a photograph. A precipitous decline in sawfish abundance in Tanzania could be inferred from the age-related decline in local knowledge of their existence; all fishers aged between 70 and 80 years were familiar with sawfishes, whereas only 10% of fishers younger than age 20 had ever heard of them. A total of 29 sawfish records were compiled, comprising 16 rostra and 14 catches that occurred between 2002 and 2014 (one record included both a catch and a rostrum). All rostra examined were from the largetooth sawfish Pristis pristis. Since 2002, the sawfish catches occurred in three locations, all on the mainland coast: in the southern Mtwara region, in the vicinity of the Rufiji Delta, and at Bagamoyo on the Zanzibar Channel. Interview data and rostra evidence suggest that the Rufiji Delta may be a largetooth sawfish nursery area, and confirmation of this should be a priority.  相似文献   

17.
Multi‐specific synchronous spawning has never been documented for East Africa, but coral spawn‐slicks are observed annually around Vamizi Island, Northern Mozambique. We monitored gamete development in Acropora species from July 2012 to October 2013 and from August to September 2014 to describe patterns of reproductive seasonality and synchrony within and amongst species of Acropora. Gamete maturation was highly synchronized within and amongst Acropora species and culminated in multi‐specific spawning events lasting 1–3 nights in each year of the study, in late August or September. In 2013 and 2014, 50% or more of the colonies of over 50% of the species sampled prior to the spawning events had mature gametes. In all years, 91–99% colonies sampled after the spawning events had no visible gametes. The percentage of colonies with mature gametes was up to 100% for some species. In other species, the absence of mature gametes throughout the study period indicates that they might not spawn in certain years. The analysis of a 8‐year record of observations of spawn‐slicks showed that spawning generally occurred once a year for a few consecutive days between September and December, during periods of rising sea surface temperature and low wind speed and rainfall. This study is the first to quantitatively document coral reproduction in Mozambique and multi‐specific synchronous spawning off the coast of Africa. These findings contrast with the asynchronous breeding reported for Kenyan reefs and support the absence of breakdown in coral reproductive synchrony towards low latitudes.  相似文献   

18.
Notolabrus fucicola Richardson, a large common labrid inhabiting shallow waters around New Zealand and southern Australia, were collected monthly (December 1996‐February 1998) around Kaikoura on the east coast of the South Island, New Zealand. Their diet, temporal variation in prey and gut fullness, and ontogenetic differences were examined. N. fucicola is a generalist predator, the major prey items being bivalves, amphipods, and crabs, which varied temporally in their diet. There were size specific changes in their diet. Small fish (100–180 mm) ate mostly amphipods and isopods, whereas larger fish (> 180 mm) ate mainly bivalves, crabs, and gastropods. There was a temporal variation in gut fullness but no significant difference between sexes.  相似文献   

19.
Breeding numbers of Laridae and other surface-nesting seabirds have been monitored at sub-Antarctic Marion Island since 1996/1997 and counts of breeding birds were made at nearby Prince Edward Island in December 2001 and December 2008. Four species are regular breeders at the islands: Subantarctic skua Catharacta antarctica, kelp gull Larus dominicanus, Antarctic tern Sterna vittata and Kerguelen tern S. virgata. The latter three species currently each have populations of below 150 breeding pairs at the islands. Kelp gull numbers appear to be relatively stable though they may have decreased since the 1980s. Kerguelen tern numbers decreased and then recovered at Marion Island, but numbers of the species have declined at Prince Edward Island and it maintains a tenuous foothold there. The small Antarctic tern population appears to be stable.  相似文献   

20.
Hydroclathrus clathratus (C. Agardh) Howe (Phacophyta: Punctariales) is recorded from two harbours on the Northland east coast, North Island, New Zealand. The possibility of its being a recently introduced species is discussed.  相似文献   

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