Analysis of occurrence patterns and biological factors of cetaceans based on long‐term and fine‐scale data from platforms of opportunity: Madeira Island as a case study          下载免费PDF全文

Filipe Alves  Rita Ferreira  Miguel Fernandes  Zofia Halicka  Luís Dias  Ana Dinis 《Marine Ecology》2018,39(2)

Management and conservation issues are addressed through the identification of areas of particular importance, which requires the acquisition of baseline information on species distribution and dynamics. These types of data are particularly difficult to obtain at high resolution for large marine vertebrates like cetaceans, given that dedicated surveys are complex and logistically expensive. This study uses daily presence–absence sighting data of cetaceans collected year‐round from whale‐watching boats to support the theory that fine‐scale data obtained from platforms of opportunity can provide valuable information on species occurrence and group dynamics. Data from 7,551 (daily) sightings comprising 22 species were collected from 3,527 surveyed days over 11 years (mean of 321 days per year, SD = 17) in the pelagic environment of Madeira Island. Cetaceans were observed on 92% of the surveyed days, and a mean of 15.4 (SD = 1.5), 8.2 (SD = 2.0) and 2.1 (SD = 1.2) species were recorded per year, month, and day, respectively. There were significant differences in the number of species per month (p < .001), with the highest diversity recorded in June. At least nine species, comprising 96% of all sightings, were found to use the Madeiran waters on a regular basis, such as the Atlantic spotted dolphin (Stenella frontalis), the short‐beaked common dolphin (Delphinus delphis), the bottlenose dolphin (Tursiops truncatus), and others featured in the Red List of the International Union for Conservation of Nature as Endangered, Vulnerable, and Data Deficient. In addition, 10 species were found to use the Madeiran waters for travelling, feeding, resting, socializing and calving, which suggests that the southern and southeastern waters of Madeira Island constitute an area of interest for cetaceans. This study characterizes the cetaceans’ community structure (occurrence, aggregation sizes, behaviours, proportion of calves, and inter‐specific relationships) of a poorly studied region, providing important information for managers. Finally, the advantages and limitations of using fine‐scale data from a type of platform of opportunity that is increasing along coastlines globally are discussed.  相似文献   

On the feasibility of studying the exospheres of Earth-like exoplanets by Lyman-<Emphasis Type="Italic">α</Emphasis> monitoring     

Ana I. Gómez de Castro  Leire Beitia-Antero  Sabina Ustamujic 《Experimental Astronomy》2018,45(2):147-163

Observations of the Earth’s exosphere have unveiled an extended envelope of hydrogen reaching further than 10 Earth radii composed of atoms orbiting around the Earth. This large envelope increases significantly the opacity of the Earth to Lyman α (Lyα) photons coming from the Sun, to the point of making feasible the detection of the Earth’s transit signature from 1.35 pc if pointing with an 8 meter primary mirror space telescope through a clean line of sight (N _H <?10¹⁷ cm^??2), as we show. In this work, we evaluate the potential detectability of Earth analogs orbiting around nearby M-type stars by monitoring the variability of the Lyα flux variability. We show that, in spite of the interstellar, heliospheric and astrospheric absorption, the transit signature in M5 V type stars would be detectable with a dedicated Lyα flux monitor implemented in a 4–8 m class space telescope. Such monitoring programs would enable measuring the robustness of planetary atmospheres under heavy space weather conditions like those produced by M-type stars. A 2-m class telescope, such as the World Space Observatory, would suffice to detect an Earth-like planet orbiting around Proxima Centauri, if there was such a planet or nearby M5 type stars.  相似文献   

Reproductive output in a Mediterranean population of the homosclerophorid Corticium candelabrum (Porifera, Demospongiae), with notes on the ultrastructure and behavior of the larva   总被引：1，自引：0，他引：1  

Manuel Maldonado  & Ana Riesgo 《Marine Ecology》2008,29(2):298-316

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Assessment of coastal management options by means of multilayered ecosystem models     

Ana M. Nobre  João G. Ferreira  João P. Nunes  Xiaojun Yan  Suzanne Bricker  Richard Corner  Steve Groom  Haifeng Gu  Anthony J.S. Hawkins  Rory Hutson  Dongzhao Lan  João D. Lencart e Silva  Philip Pascoe  Trevor Telfer  Xuelei Zhang  Mingyuan Zhu 《Estuarine, Coastal and Shelf Science》2010

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of the main forcing functions, such as catchment loading and aquaculture activities. This approach was developed as a tool for sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed in conjunction with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay were predicted to exceed the thresholds for poor quality defined by Chinese seawater quality legislation. For all scenarios there is still a Moderate High to High nutrient loading from the catchment, so further reductions might be enacted, together with additional decreases in fish cage culture. The model predicts that overall, shellfish production decreases by 10%–28% using any of these development scenarios, principally because shellfish growth is being sustained by the substances to be reduced for improvement of water quality. The model outcomes indicate that this may be counteracted by zoning of shellfish aquaculture at the ecosystem level in order to optimize trade-offs between productivity and environmental effects. The present case study exemplifies the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and may be particularly useful for the application of coastal management regulation, for instance in the implementation of the European Marine Strategy Framework Directive.  相似文献   

A description of chloride cell and kidney tubule alterations in the flatfish Solea senegalensis exposed to moderately contaminated sediments from the Sado estuary (Portugal)     

Pedro M. Costa  Sandra Caeiro  Mrio S. Diniz  Jorge Lobo  Marta Martins  Ana M. Ferreira  Miguel Caetano  Carlos Vale  T. ngel DelValls  M. Helena Costa 《Journal of Sea Research》2010,64(4):465-472

The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level (TEL) and the Probable Effects Level (PEL). The Sediment Quality Guideline Quotient indices (SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic balance, contributing for the high mortality levels observed. The results suggest that sediment-bound organic contaminants such as PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls) may be very toxic to the analyzed organs, especially the kidney, even when present in low-risk concentrations.  相似文献   

Feeding habits of Solea senegalensis in earthen ponds in Sado estuary     

Maria Ana Castelo Branco  Marco A. Arruda  Sofia Gamito   《Journal of Sea Research》2010,64(4):446-450

The senegale sole, Solea senegalensis Kaup, 1858, is a commercially valuable fish and it is beginning to be cultured in a semi-intensive way in fish farms in southern European countries. The present study was initiated to investigate the diet of S. senegalensis under semi-extensive conditions. The feeding habits of sole were studied in two earthen ponds of a fish farm in the Sado estuary. In one earthen pond, artificial fish ration was given. S. senegalensis feeds on few prey items, its diet is mainly composed of insect larvae (Chironomus salinarus) and polychaeta (Hediste diversicolor). The diet composition of this species suggests feeding specialization, by consuming mainly annelids and insect larvae and by avoiding other items, extremely abundant in the environment, such as gastropods. In the water reservoir where ration was given, some fish consumed simultaneously benthic organism together with ration. However, benthic organisms seem to be the most important component of S. senegalensis diet.  相似文献   

Seasonal variations in lipid composition of the hydrothermal vent mussel Bathymodiolus azoricus from the Menez Gwen vent field     

Ana Colaço  Catarina Prieto  Ana Martins  Miguel Figueiredo  Virginie Lafon  Margarida Monteiro  Narcisa M. Bandarra 《Marine environmental research》2009,67(3):146-152

Specimens of the hydrothermal mussel Bathymodiolus azoricus collected in Menez Gwen hydrothermal vent field (NE Atlantic) during 2002–2003 were examined for feeding patterns variations through three seasons. The fatty acid profile and lipid classes of the mussels were studied, together with the MODIS/AQUA-derived near-surface chlorophyll a to test the hypothesis that surface productivity might be related to the feeding patterns of this species. The lipid levels showed pronounced seasonal fluctuations with the highest values occurring in January and August. Seasonal variations in lipid classes and fatty acid composition of neutral and polar lipids in the mussels are presented. Differences in the fatty acid profile of lipid classes in different seasons suggest that the higher energy requirements in summer and winter were supplied by bacterial biomarkers ω7 MUFA (monounsaturated fatty acids), whereas ω6 PUFA (polyunsaturated fatty acids) and NMI (non-methylene-interrupted) fatty acids predominated during the spring. The MODIS/AQUA data show marked seasonal variability and an anomalous peak during January of 2003, although this cannot be directly linked to lipid composition variation.  相似文献   

In situ experimental study of reed leaf decomposition along a full salinity gradient     

Victor Quintino  Franca Sangiorgio  Fernando Ricardo  Renato Mamede  Adília Pires  Rosa Freitas  Ana Maria Rodrigues  Alberto Basset 《Estuarine, Coastal and Shelf Science》2009

An experimental study on Phragmites australis leaf litter decomposition was conducted in the estuarine environment, Ria de Aveiro, Western Portugal, using the leaf-bag technique, with fine- (1 mm) and coarse-mesh (5 mm) bags. The leaf bags were placed in the field sites at day 0, covering a complete salinity gradient, and replicates were collected over time, at days 3 (leaching), 7, 15, 30 and 60. The biomass loss through the leaching phase, about 20% of the initial leaf mass, was independent of both the salinity and the bag mesh size. The biomass decay pattern along the salinity gradient varied through time and presented strong similarities between the two mesh sizes, with the remaining biomass always lower in the 5 mm mesh-size bags. At days 7 and 15, the lowest remaining biomass was observed at the head of the estuary, the preferential distribution area of P. australis. At day 30, the remaining biomass was higher in the marine area and diminished under a direct relationship with salinity, reaching the lowest value in the freshwater environment, with values ranging from 66% to 44% of the initial weight in 5 mm bags, and from 79% to 51% in 1 mm bags. The largest heterogeneity in the remaining biomass among the study areas positioned along the salinity gradient was found close to days 30 (5 mm) and 40 (1 mm). The overall results indicate that the relationship between leaf decay rate and salinity depends on the decay time considered (k₁₅, k₃₀ or k₆₀) and, for the later stages (k₆₀), also on the leaf-bag mesh size. This implies that the use of leaf litter decay rates as a functional indicator in transitional waters will need to take into consideration the factor location in the salinity gradient and leaf litter stage at which the decay rate is determined. The differences between the decay rates with the mesh size acted mainly at the level of the absolute k value and not at the level of the pattern along the salinity gradient. Even so, the data obtained at the mouth of the estuary, in the area closest to a fully marine environment, indicated that after the initial biomass loss through leaching, P. australis decayed either very slowly, in the 5 mm, or not at all, in the 1 mm mesh bags.  相似文献   

Diopatra neapolitana and Diopatra marocensis from the Portuguese coast: Morphological and genetic comparison     

Ana Maria Rodrigues  Adília PiresSónia Mendo  Victor Quintino 《Estuarine, Coastal and Shelf Science》2009

This paper reports the presence of Diopatra marocensis in European waters, for which Diopatra neapolitana was the only species recognized until recently. Both species coexist in transitional waters, where D. marocensis may be mistaken for young specimens of D. neapolitana. The population of D. marocensis studied in the coastal shelf can be traced back to 1997 and is increasing in density, apparently benefiting from a local anthropogenic organic enrichment source.  相似文献   

Seasonal variations of shelf circulation in Hidaka Bay,Hokkaido, Japan,with an interpretation of the migration route of juvenile walleye pollock     

Ana Luisa Rosa  Yutaka Isoda  Naoto Kobayashi 《Journal of Oceanography》2009,65(5):615-626

The outer shelf of Funka Bay, located at the bay head of Hidaka Bay, is a recognised main winter spawning ground for walleye pollock (Theragra chalcogramma), whose newly hatched juveniles migrate eastward along the Hidaka shelf to the nursery ground located in the Doto area. To examine the seasonal change of the coastal current along this migration route, four current moorings were deployed along the shelf in Hidaka Bay from April, 2004 to June, 2006. Since these mooring sites were close to the coast, the circulation was estimated after removal of the wind-driven component. It was found that the winter coastal flow, forced by a north-westerly monsoon wind, is clockwise along the Hidaka shelf. However, this flow is weak due to the superimposition of the opposite Coastal Oyashio flow trapped on the shelf. In summer, a bifurcation of the coastal current occurs along the north-eastern Hidaka shelf with a south-eastward flow, associated with the Tsugaru Gyre, and a north-westward flow, consisting of a branch from this gyre. Our results provide a new understanding of the migration of juvenile walleye pollock: (1) very slow transport of juveniles along the Hidaka shelf from winter to spring, and (2) selection of earlier spawning survivors due to the bifurcated flow in early summer.  相似文献