Spatial patterns of sub-tidal seagrasses and their tissue nutrients in the Torres Strait,northern Australia: Implications for management     

James K. Sheppard  Alex B. Carter  Len J. McKenzie  C. Roland Pitcher  Robert G. Coles 《Continental Shelf Research》2008

The distribution and nutritional profiles of sub-tidal seagrasses from the Torres Strait were surveyed and mapped across an area of 31,000 km². Benthic sediment composition, water depth, seagrass species type and nutrients were sampled at 168 points selected in a stratified representative pattern. Eleven species of seagrass were present at 56 (33.3%) of the sample points. Halophila spinulosa, Halophila ovalis, Cymodocea serrulata and Syringodium isoetifolium were the most common species and these were nutrient profiled. Sub-tidal seagrass distribution (and associated seagrass nutrient concentrations) was generally confined to northern-central and south-western regions of the survey area (<longitude 142.60), where mean water depth was relatively shallow (approximately 13 m below MSL) and where sediments were comprised primarily muddy sand to gravelly sand. Seagrass nitrogen and starch content, the most important nutrients for marine herbivores, were significantly correlated with species and with the plant component (above or below ground). For all seagrass species, the above-ground component (shoots and leaves) possessed greater nitrogen concentrations than the below-ground component (roots and rhizomes), which possessed greater starch concentrations. S. isoetifolium had the highest total nitrogen concentrations (1.40±0.05% DW). However, it also had higher fibre concentrations (38.2±0.68% DW) relative to the other four species. H. ovalis possessed the highest starch concentrations (2.76±0.12% DW) and highest digestibility (83.24±0.66% DW) as well as the lowest fibre (27.2±0.66% DW). The high relative abundance (found at 55% of the sites that had seagrass) and nutrient quality characteristics of H. ovalis make it an important source of energy to marine herbivores that forage sub-tidally in the Torres Strait. There were two regions in Torres Strait (north-central and south-western) where sub-tidal seagrass meadows were prevalent and of relatively higher nutritional value. This spatial and nutritional information can be used by local agencies to manage and to protect the ecological, economic and cultural values of the sub-tidal seagrass ecosystems and associated fisheries of the Torres Strait.  相似文献   

Productivity,carbon assimilation and intra-annual change in tropical reef platform seagrass communities of the Torres Strait,north-eastern Australia     

Michael A. Rasheed  Kara R. Dew  Len J. McKenzie  Robert G. Coles  Simon P. Kerville  Stuart J. Campbell 《Continental Shelf Research》2008

Detailed data on seagrass distribution, abundance, growth rates and community structure information were collected at Orman Reefs in March 2004 to estimate the above-ground productivity and carbon assimilated by seagrass meadows. Seagrass meadows were re-examined in November 2004 for comparison at the seasonal extremes of seagrass abundance. Ten seagrass species were identified in the meadows on Orman Reefs. Extensive seagrass coverage was found in March (18,700 ha) and November (21,600 ha), with seagrass covering the majority of the intertidal reef-top areas and a large proportion of the subtidal areas examined. There were marked differences in seagrass above-ground biomass, distribution and species composition between the two surveys. Major changes between March and November included a substantial decline in biomass for intertidal meadows and an expansion in area of subtidal meadows. Changes were most likely a result of greater tidal exposure of intertidal meadows prior to November leading to desiccation and temperature-related stress.  相似文献   

Harvest patterns and effort dynamics of indigenous and non-indigenous commercial sectors of the eastern Torres Strait reef line fishery     

Ashley J. Williams  Aaron C. Ballagh  Gavin A. Begg  Cameron D. Murchie  Leanne M. Currey 《Continental Shelf Research》2008

The reef line fishery (RLF) in eastern Torres Strait (ETS) is unique in that it has both a commercial indigenous sector and a commercial non-indigenous sector. Recently, concerns have been expressed by all stakeholders about the long-term sustainability of the fishery. These concerns have been exacerbated by the lack of detailed catch and effort information from both sectors, which has precluded any formal assessment of the fishery. In this paper, we characterise the harvest patterns and effort dynamics of the indigenous and non-indigenous commercial sectors of the ETS RLF using a range of data sources including commercial logbooks, community freezer records, voluntary logbooks and observer surveys. We demonstrate that bycatch is a significant component of the catch for both sectors and identify substantial differences in harvest patterns and effort dynamics between the sectors. Differences between sectors were observed in species composition and spatial and temporal patterns in catch, effort and catch per unit effort. These results highlight the inherent variation in catch and effort dynamics between the two commercial sectors of the ETS RLF and provide valuable information for the development of future assessments and appropriate management strategies for the fishery. The more reliable estimates of harvest patterns and effort dynamics for both sectors obtained from observer surveys will also assist in resolving issues relating to allocation of reef fish resources in Torres Strait.  相似文献   

Temporal variability in the life history and reproductive biology of female dugongs in Torres Strait: The likely role of sea grass dieback     

Helene Marsh  Donna Kwan 《Continental Shelf Research》2008

The extensive sea grass meadows in Torres Strait enable it to be a globally important habitat for the dugong, Dugong dugon, a marine mammal of cultural and dietary significance to Torres Strait Islanders and the basis for the substantial island-based fishery in the Torres Strait Protected Zone. Torres Strait sea grass communities are subjected to episodic diebacks which are now believed to be largely natural events. Information on dugong life history was obtained from specimens obtained from female dugongs as they were butchered for food by Indigenous hunters at two major dugong hunting communities in Torres Strait: Daru (9.04°S, 143.21°E) in 1978–1982 (a time of sea grass dieback and recovery) and Mabuiag Island (9.95°S, 142.15°E) in 1997–1999 (when sea grasses were abundant). Dugongs sampled in 1997–1999 had their first calf at younger ages (minimum of 6 cf. 10 years), and more frequently (interbirth interval based on all possible pregnancies 2.6±0.4 (S.E.) yr cf. 5.8±1.0 yr) than the dugongs sampled in 1978–1982. Pregnancy rates increased monotonically during 1978–1982, coincident with sea grass recovery. The age distribution of the female dugongs collected in 1997–1999 also suggested a low birth rate between 1973 and 1983 and/or or a high level of mortality for animals born during this period. These results add to the evidence from other regions that the life history and reproductive rate of female dugongs are adversely affected by sea grass loss, the effect of which cannot be separated from a possible density-dependent response to changes in dugong population size. Many green turtles in Torres Strait were also in poor body condition coincident with the 1970s sea grass dieback. The impacts of future sea grass diebacks need to be anticipated when management options for the traditional Torres Strait fisheries for dugongs and green turtles are evaluated.  相似文献   

Modelling the Gibraltar Strait/Western Alboran Sea ecohydrodynamics     

Nikolaos Skliris  Jean-Marie Beckers 《Ocean Dynamics》2009,59(3):489-508

The ecohydrodynamics of the Gibraltar Strait and the Western Alboran Sea is investigated using a 3-D, two-way nested, coupled hydrodynamic/plankton ecosystem model, exploiting the MEDATLAS climatological database. A high-resolution model (~1 km) of the Gibraltar/Western Alboran region embedded within a coarse-resolution model of the West Mediterranean (~5 km) is implemented. The model seasonal climatology of the 3-D circulation and the flow characteristics at the Gibraltar Strait and the Alboran Sea are discussed, and their impact on the plankton ecosystem evolution is explored. An important ecohydrodynamic feature produced by the model is a permanent upwelling zone in the northwestern part of the Alboran Sea in agreement with observations. Model results show that both horizontal and vertical current intensity of the Atlantic Jet increases progressively at the strait to obtain maximum values in the northeastern Mediterranean entrance, inducing an upward displacement of the nitracline. The nutrient-rich water transport through the strait along with the generation of cyclonic vorticity in the northwestern Alboran Sea result in the accumulation of nutrients there and thus induce a permanent fertilisation of this area.  相似文献   

大型海底、海岸和沙漠沙丘的形态和迁移特征   总被引：3，自引：0，他引：3       下载免费PDF全文

高抒 《地学前缘》2009,16(6):13-22

海底、海岸和沙漠沙丘的迁移与其波高、波长等形态参数有关。对一些代表性大型沙丘的分析表明,海底、海岸和沙漠沙丘的形态特征存在着较大的差异,在相同波长条件下,海底沙丘波高最小,海岸沙丘波高次之,沙漠沙丘波高最大。其原因主要是流体厚度的差异,其次是物质供给条件的不同:浅海地区的水深限制了沙丘向上生长,而陆地气流厚度较大,给沙丘的向上生长提供了较大的空间;沙漠环境的沉积物供给远大于海岸环境,因而导致沙丘高度的差异。沙丘形态参数经常偏离统计的波长 波高曲线,数值实验结果显示,这与推移质输运率有关。推移质输运率的沿程变化可以使形态参数系统性地偏离波长 波高曲线;推移质输运率的沿程突变可使沙丘迁移受阻,造成沉积物的垂向堆积,形成超高的沙丘。由于大型沙丘的迁移特征受控于推移质输运率和沙丘高度,因此可以通过波高设计来计算迁移距离 历时曲线,进而控制沙丘迁移动态。文中给出了一个获取迁移距离 历时曲线的算例。设计波高可通过人工篱笆、隔挡墙、沟渠、表面护层等措施而实现。  相似文献   

Holocene reef growth in Torres Strait     

C. D. Woodroffe  D. M. Kennedy  D. Hopley  C. E. Rasmussen  S. G. Smithers 《Marine Geology》2000,170(3-4):331-346

The platform and fringing reefs of Torres Strait are morphologically similar to reefs of the northern Great Barrier Reef to the south, except that several are elongated in the direction of the strong tidal currents between the Coral Sea and the Gulf of Carpentaria. Surface and subsurface investigations and radiocarbon dating on Yam, Warraber and Hammond Islands reveal that the initiation and mode of Holocene reef growth reflect antecedent topography and sea-level history. On the granitic Yam Island, fringing reefs have established in some places over a Pleistocene limestone at about 6 m depth around 7000 years BP. Emergent Holocene microatolls of Porites sp. indicate that the reefs have prograded seawards while sea level has fallen gradually from at least 0.8 m above present about 5800 years BP. On the Warraber Island reef platform drilling near the centre indicated a Pleistocene limestone foundation at a depth of about 6 m over which reefs established around 6700 years BP. Reef growth lagged behind that on Yam Island. Microatolls on the mature reef flat indicate that the reef reached sea level around 5300 years BP when the sea was around 0.8–1.0 m above present. On the reef flat on the western side of Hammond Island bedrock was encountered at 7–8 m depth, overlain by terrigenous mud. A progradational reef sequence of only 1–2 m thickness has built seaward over these muds, as sea level has fallen over the past 5800 years. Reef-flat progradation on these reefs is interpreted to have occurred by a series of stepwise buildouts marked by lines of microatolls parallel to the reef crest, marking individual coalescing coral heads. Detrital infill has occurred between these. This pattern of reef progradation is consistent with the radiocarbon dating results from these reefs, and with seismic investigations on the Torres Reefs.  相似文献   

近岸海域光合色素的生物标志作用研究Ⅰ.台湾海峡特征光合色素的分布及其对浮游植物类群结构的指示     

王海黎  洪华生 《海洋学报》2000,22(3):94-102

１引言 由于高效液相色谱法（ＨＰＬＣ）的建立,利用光合色素,尤其是类胡萝卜素作为区分浮游植物类群的指示物,成为更方便和有效的化学分类法［１,２］．原因是色素能够很好地进行定量,可涵盖浮游植物的全部粒级范围;而且,适用于大批量样品的分析,甚至可实现现场的船上测定．海洋浮游植物光合色素的研究,比较多地集中在开放大洋,多为利用类胡萝卜素表征浮游植物的类群结构［３－５］;或以光合色素及其降解产物作为浮游植物参与的生物地球化学过程的生物标志物［６－８］．相比较而言,在近岸、陆架海域开展的此类研究较少,且多…  相似文献   

近岸海域光合色素的生物标志作用研究：Ⅰ.台湾海峡特征光合色素的分？…   总被引：4，自引：1，他引：3  

王海黎  洪华生 《海洋学报》2000,22(3):94-102

  相似文献   

台湾海峡1997年夏季和1998年冬季两航次颗粒有机碳研究   总被引：8，自引：0，他引：8  

刘占飞  彭兴跃  徐立  洪华生 《台湾海峡》2000,19(1):95-101

1997～1998年台湾海峡两个航次的数据表明,颗粒有机碳(POC)的平均含量为0．120±0．009mg/dm3,表层POC浓度在夏季和冬季分别存在几个高值区。POC在随深度变化的剖面分布图中,最大值出现在10m层,底层水明显受再悬浮影响,这一剖面的变化规律普遍存在于整个海区及不同季节。夏季POC的深度变化幅度要显著大于冬季,这与垂直混合作用有关。POC与Chl－a相关性较差,暗示以Chl－a估算浮游植物的不确定性及POC产生及来源的复杂性。  相似文献