Nematopsis N. Sp. (Sporozoa: Gregarinia) in Perna canaliculus (note)     

J. B. Jones 《新西兰海洋与淡水研究杂志》2013,47(4):567-568

Spores of a new species of Nematopsis have been found in the green‐lipped mussel Perna canaliculus Gmelin. This is the first record of a sporozoan parasite of a New Zealand shellfish.  相似文献   

Protecting window‐size female American lobster,Homarus americanus,to increase egg production     

Robert MacMillan  Michel Comeau  Manon Mallet 《新西兰海洋与淡水研究杂志》2013,47(1):525-536

A new conservation measure aimed at protecting the larger broodstock (females with a carapace length between 115 and 129 mm, i.e., window‐size females, WSF) to enhance egg production was implemented in 2003 for the American lobster (Homarus americanus) fishery in the southern Gulf of St. Lawrence, Canada. To assess the effectiveness of this new measure, a tagging project was carried out between 2004 and 2007 in the Hillsborough Bay area with the collaboration of local harvesters. Based on a single mark‐recapture Petersen model, the estimated catch rates of WSF not carrying eggs under the abdomen in the study area varied between 40% and 53%. The catch‐per‐unit‐effort (animals per 100 traps) of both berried (egg‐bearing) and non‐berried WSF increased from 0.2 to 0.8 and 1.0 to 1.6, respectively, between 2004 and 2007. Based on the estimated number of non‐berried WSF in the population observed during the spring fishery between 2004 and 2007, the potential total egg production for WSF was estimated at 1.1 billion in the study area. From this total, 515 million eggs would have been produced by WSF directly protected by the conservation measure, i.e., females that would have been harvested if not for the new regulation. Finally, the contribution of berried WSF to the annual egg production in the study area increased from 4% to 23% between 2003 and 2007 based on the at‐sea sampling programme and the fecundity curve. WSF that represented 10% of the total berried female population in 2007 contributed 23% of the annual egg production. Hence, the protection of WSF seems to be an effective conservation measure to increase egg production based on the catch‐per‐unit‐effort and egg production.  相似文献   

Characterization of the cyp19a1a gene froma BAC sequence in half-smooth tongue sole (Cynoglossus semilaevis) and analysis of its conservation among teleosts     

SHAO Changwei  LIU Geng  LIU Shanshan  LIU Changlin  CHEN Songlin 《海洋学报(英文版)》2013,32(8):35-43

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Impact of minimum legal size increases on egg‐per‐recruit production,size structure,and ovigerous females in the American lobster (Homarus americanus) population off the Magdalen Islands (Quebec,Canada): A case study     

Louise Gendron 《新西兰海洋与淡水研究杂志》2013,47(3):661-674

In the mid 1990s, American lobster (Homarus americanus) from Canadian waters was considered overfished based on estimated levels of egg‐per‐recruit production (EPR). In 1997, the Department of Fisheries Oceans responded by adopting a goal of doubling the level of EPR from its 1996 level. In the Magdalen Islands (Quebec), results from a simulation model indicated that doubling EPR could be reached by increasing the minimum legal size (MLS) from 76 mm to 83 mm carapace length. This was done at a pace of 1 mm per year from 1997 to 2003. Following the increase of MLS, the size structure, mean size, and the abundance of ovigerous females improved significantly in the catches. However, levels of fishing effort are still very high. This could cause undesirable effects such as altering sex ratios and size structure of males, which could lead to sperm limitation, and reducing the contribution of multiple spawners to egg production, which could become an issue if egg quality is important. Consideration of these issues leads to the recommendation of a multidimensional approach to lobster conservation.  相似文献   

Endemic new cyclostome bryozoans from Spirits Bay,a New Zealand marine‐biodiversity “hotspot”     

Paul D. Taylor  Dennis P. Gordon 《新西兰海洋与淡水研究杂志》2013,47(3):653-669

Two notable species of erect cyclostome bryozoans from a nearshore benthic fauna off Spirits Bay, northernmost New Zealand, are described here for the first time. The first, Spiritopora perplexa gen. et sp. nov., is an endemic cerioporine‐grade genus which is abundant in this area. Colonies are characterised by an unusual combination of fixed‐and free‐walled skeletal morphologies: autozooids forming the extensive encrusting colony bases are normally fixed‐walled, whereas those forming the short, bifoliate erect branches are usually free‐walled. The highly distinctive morphology of S. perplexa, very different from any other fossil or Recent cyclostome, together with its success in overgrowing competitors for space, makes its restricted geographical distribution puzzling and highlights the importance of conservation in this area now closed to trawling, Danish seining, and commercial scallop dredging. The second species, Calvetia osheai sp. nov., is less common, and has small, tree‐like colonies. It is the third species assigned to this distinctive cancellate genus, previously known only from Recent of Tierra del Fuego and the Eocene of Antarctica.  相似文献   

Comparative salinity tolerances of four siphonariid limpets in relation to habitat restriction of the rare and endangered Siphonaria compressa     

《African Journal of Marine Science》2013,35(3):311-318

The salinity tolerances of four South African species of limpet in the genus Siphonaria were experimentally tested, in the context that one of them, S. compressa, is South Africa's most endangered marine mollusc and is restricted to two lagoonal localities that normally experience little variation in salinity. Its habitat is additionally restricted in that it occurs only on the eelgrass Zostera capensis. The other three species, S. capensis, S. concinna and S. serrata, are abundant and widespread on temperate rocky shores. We hypothesised that S. compressa would have limited tolerance to low salinities, contributing to its absence from otherwise suitable estuaries that experience regular fluctuations of salinity. The percentage survival of the limpets was recorded in salinities ranging from 2 to 35 over that period. Both salinity and species significantly affected the survival of the limpets over the 96 hours. Survival was highest in salinities close to those of normal seawater, and greatly reduced in the hypo saline waters. S. compressa had the lowest salinity tolerance of the four species, its time-to-50% mortality in hyposaline waters being significantly less than that for the other three species, which differed in a manner that could be correlated with their zonation patterns. Restriction to eelgrass, coupled with low salinity tolerance, probably explains why S. compressa is found at only two localities, both of which normally experience salinities close to that of seawater. Even there, mass mortalities of S. compressa have been recorded in association with die-backs of eelgrass after abnormal freshwater flooding or sedimentation—further emphasising the vulnerability of S. compressa to extinction.  相似文献   

Unravelling population structure of black musselcracker Cymatoceps nasutus: evidence for multiple populations in South African coastal waters     

《African Journal of Marine Science》2013,35(4):493-503

Genetic studies on South African marine fishes have shown that many species exist as single, well-mixed stocks throughout their core distribution. The black musselcracker or poenskop Cymatoceps nasutus is a slow-growing, late-maturing and long-lived sparid (Perciformes: Sparidae) that is endemic to South African coastal waters. Conventional tagging studies suggest that it is resident, with limited connectivity between different regions along the coast. Mitochondrial and nuclear DNA were used to investigate the genetic structure of C. nasutus along the South African coastline and showed evidence of at least two populations. Samples collected from the Tsitsikamma Marine Protected Area on the South Coast to KwaZulu-Natal on the East Coast showed no significant population structure over much of the distribution. Gene flow for C. nasutus within this region is not limited by geographic distance and appears to be unaffected by various oceanographic barriers and biogeographical boundaries. Samples from the Western Cape to the west of Tsitsikamma, however, showed moderate to substantial differentiation for both markers, which may be influenced by a temperature barrier – a coldwater ridge – along the South Coast. These data provide the first genetic assessment of this South African sparid, and suggest that a two-stock management strategy would be appropriate for the species.  相似文献   

Assessing the suitability of commercial fisheries data for local-scale marine spatial planning in South Africa     

《African Journal of Marine Science》2013,35(4):467-480

This study integrates fisheries logbook data with observer and vessel monitoring system (VMS) data in order to assess the accuracy of reported data and to develop high-resolution spatial data suitable for use in local-scale marine spatial planning analyses. Spatial assessments were conducted on five nearshore commercial fisheries to provide baseline information to inform spatial management and conservation planning in Algoa Bay, South Africa. Clear spatial patterns in the distribution of fishing effort were apparent for the linefishery, chokka-squid and inshore demersal trawl sectors. Observer and VMS data confirmed the broad spatial distribution of resource-use patterns of logbook data. Combining these data sources allowed higher-resolution spatial indices of fishing effort to be developed, which are suitable for systematic spatial planning on a local scale and can be used for future spatial management and conservation.  相似文献   

The obligation to heal when the market hurts - national regulation of the electricity sector and local industrial impacts     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(1):12-21

The article offers an institutional-comparative approach to a discussion about national regulation and its local consequences. The industrial regulations formulated after Norwegian independence in 1905 allowed public control of transactions concerning rights to Norwegian waterfalls. Efforts to restructure energy-intensive industry have often encountered local demands for the maintenance of local production. Due to the regulations, companies were forced to negotiate with the state and later also with local authorities. Deregulation of the electricity sector in the early 1990s facilitated a radical restructuring as companies stopped using electricity in local production and instead exported it from the region where it was generated. However, companies are still obliged to make different kinds of compensation to the host locality. The article presents cases of single company towns in Telemark and Nordland counties in Norway.  相似文献   

基于多智能体模拟的旅游地保护行为决策     

傅丽华  谢炳庚  李晓青  朱东国  胡贤辉 《地理研究》2012,31(3):555-564

运用基于复杂适应性系统理论支持下的ABM建模方法,以历史文化名镇湘西里耶镇为研究对象,构建多智能体构成的保护行为执行主体系统。以系统行为偏好和行为影响分析为切入点,分析古镇旅游开发过程中各智能体的保护行为特征,从微观层面研究各智能体的保护行为变化对系统行为决策的影响,并依据行为动态模拟结果推导反映系统协调和优化的古镇保...  相似文献