Long‐term habitat loss in a lightly‐disturbed population of the Indo‐Pacific humpback dolphin,Sousa chinensis

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Environmental models for predicting habitat of the Indo‐Pacific humpback dolphins in Fujian,China

1. The coast of Fujian Province is a key area for the Indo‐Pacific humpback dolphin (Sousa chinensis), but the characteristics of their preferred habitats are poorly defined.
2. The species distribution model, MaxEnt, was used to predict suitable habitat distributions of humpback dolphins in Fujian, China. The model indicated that the distance to the coastline (63.5% contribution), chlorophyll‐a levels (20.2%) and the bathymetry (15.6%) were important predictors of humpback dolphin habitats.
3. The model predicted 2,043.96 km² of highly suitable habitat that was concentrated in five areas. Four are known to be within the area of the current distribution of humpback dolphins; Putian was identified as a new area with suitable habitat, however, it is unclear if dolphins are present.
4. The predicted locations of suitable humpback dolphin habitats provided in this study should be the focus of future research and nature reserve designs.

     

Indo‐Pacific humpback dolphins (Sousa chinensis) in the Moyang River Estuary: The western part of the world's largest population of humpback dolphins

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Habitat configuration for an obligate shallow‐water delphinid: The Indo‐Pacific humpback dolphin,Sousa chinensis,in the Beibu Gulf (Gulf of Tonkin)

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Social structure in a critically endangered Indo‐Pacific humpback dolphin (Sousa chinensis) population

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Food risk trade‐off in the Indo‐Pacific humpback dolphin: An exploratory case study

1. Based on optimal foraging theory, animals are expected to maximize foraging benefits whilst minimizing risks. Despite risking being subjected to anthropogenic impacts such as water contamination, marine traffic, and underwater noise, estuaries have been identified as the preferred habitat of the Indo‐Pacific humpback dolphin (Sousa chinensis, IPHD). However, it remains unclear why this vulnerable species favours such risky habitats.
2. Here, an exploratory case study in Zhanjiang estuary, China, was conducted to test the hypothesis that IPHDs select estuarine habitats as a trade‐off that maximizes foraging opportunities whilst minimizing the risk of mortality.
3. The results showed that IPHDs accept greater mortality risks for higher food rewards but select habitats with lower risks when food rewards are similar between two locations.
4. Although this type of information is important for underpinning models for individual dolphins, its principal role is to show environmental protection agencies why IPHDs favour estuaries despite the increased mortality risks.
5. Habitat conservation plans should carefully consider prey stocks, possibly through the presence of marine protected areas near estuaries, as local overfishing may lead vulnerable cetacean populations to take greater risks.

     

Habitat protection actions for the Indo‐Pacific humpback dolphin: Baseline gaps,scopes, and resolutions for the Taiwanese subspecies

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Conservation hotspots of biodiversity and endemism for Indo‐Pacific coral reef fishes

• 1. Distribution patterns of 3919 species of Indo‐Pacific reef fishes were analysed using GIS mapping software for the purpose of conservation prioritization of extraordinary high concentrations (‘hotspots’) of diversity and endemism.
• 2. Megadiversity countries with more than 1000 coral reef species include Indonesia, Australia, Philippines, Papua New Guinea, Malaysia, Japan, Taiwan, Solomon Islands, Palau, Vanuatu, Fiji, New Caledonia, and the Federated States of Micronesia.
• 3. The richest area for reef fishes is the renowned Coral Triangle, which includes eastern Indonesia, Sabah (Malaysia), Philippines, Papua New Guinea, and the Solomon Islands. The highest concentration of species within this region extends from south‐eastern Indonesia to the central Philippines.
• 4. Occupying only 3% of the surface area of the tropical Indo‐west and central Pacific, the heart of the Coral Triangle contains 52% of its total species.
• 5. The top‐ranked areas based on percentage of endemism are Easter Island, Baja California, Hawaiian Islands, Galapagos Islands, Red Sea, Clipperton Island, Marquesas, Isla del Coco, Mascarene Islands, and Oman.
• 6. The highest concentration of endemics per unit area occurs at remote south‐eastern Polynesian and eastern Pacific islands including Clipperton, Isla del Coco, Easter, Rapa, and the Pitcairn Group.

Copyright © 2007 John Wiley & Sons, Ltd.     

Conservation management of common dolphins: Lessons learned from the North-East Atlantic

1. The short-beaked common dolphin is one of the most numerous cetacean species in the North-East Atlantic and plays a key functional role within the ecosystem as a top predator. However, in 2013, its conservation status for the European Marine Atlantic, under Article 17 of the Habitats Directive, was assessed as ‘Unfavourable-Inadequate’. Of key concern for this species is fishery bycatch, with pollution also being an issue. There are, however, major knowledge gaps concerning the extent of the effects of such pressures on the species.
2. Implementation of national observer bycatch programmes and bycatch mitigation measures under EC Regulation 812/2004 has been important. The responsibility for this is currently being transferred to the EU fisheries Data Collection Framework and Technical Measures Framework, the potential advantages and disadvantages of which are discussed. Collection of data and samples through national stranding schemes in some countries has enabled assessments of life-history parameters, dietary requirements, and the effects of stressors such as pollutants.
3. Nevertheless, in order to improve the conservation status of the North-East Atlantic population, a number of key actions are still required. These include the implementation of a species action plan, finalization of a management framework procedure for bycatch, and coordination between member states of monitoring programmes. It is important that there is monitoring of the state of the common dolphin population in the North-East Atlantic management unit through regular surveys spanning the range of the management unit, as well as continued assessment of the independent and interactive effects of multiple stressors. Above all, conservation status would be improved through application and enforcement of existing legislation in European waters.
4. This paper provides a summary of the current state of our knowledge of common dolphins in the North-East Atlantic along with recommendations for conservation management that may also be relevant to the species in the Mediterranean Sea.

     

Explaining spatial variability in stream habitats using both natural and management‐influenced landscape predictors

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Salinity and geomorphology drive long‐term changes to local and regional fish assemblage attributes in the lower Pecos River,Texas

River systems throughout arid regions worldwide have been heavily impacted by human activities, resulting in long‐term ecological consequences. The lower Pecos River in the Trans‐Pecos region of Texas is no exception, having undergone anthropogenic changes that include decreased flow, elevated salinity, species loss and species invasion. We compared historical and contemporary fish assemblage attributes from the Pecos River at local (site‐specific) and regional (Trans‐Pecos region) scales across a 24‐year time period. Fish assemblage data were collected in October 1987 and 2011, by seining at 15 sites spanning 430 km of the river in Texas. Additionally, we examined contemporary environmental conditions to determine species–environment relationships. We found that fish assemblages were significantly different between time periods, likely due to increased salinisation in the upper half of the study region. Decreased species richness, species replacement and increases in euryhaline species were documented in the upstream sites. Freshwater springs lower the salinity and maintain flows in the downstream reach, allowing for maintenance of the native fish fauna. Careful management of regional aquifers, irrigation practices and petroleum waste water will be necessary for protecting biodiversity and environmental flows in the lower Pecos River.     

Using object‐based image analysis with multi‐temporal aerial imagery and LiDAR to detect change in temperate intertidal habitats

1. Intertidal habitat maps are needed at both fine and coarse scales to monitor change and inform conservation and management, but current methods of field survey and expert interpretation of aerial imagery can be time‐consuming and subjective. Object‐based image analysis (OBIA) of remote sensing data is increasingly employed for producing habitat or land cover maps. Users create automated workflows to segment imagery, creating ecologically meaningful objects, which are then classified based on their spectral or geometric properties, relationships to other objects and contextual data.
2. This study evaluates the change‐detection capability of OBIA in the intertidal environment by developing and comparing two OBIA methods for quantifying change in extent and distribution of habitats from freely available multi‐temporal aerial imagery and LiDAR data. Despite considerable variability in the data, pre‐ and post‐classification change detection methods had sufficient accuracy (mean overall accuracy from 70.5 to 82.6%) to monitor deviation from a background level of natural environmental fluctuation.
3. This insight into spatial and temporal patterns of natural cyclical change and their detectability by OBIA could inform use of remote sensing for regular, rapid coastal assessment, providing an alert system to direct survey resources to areas of ecologically relevant change.

     

Role of large‐ and fine‐scale variables in predicting catch rates of larval Pacific lamprey in the Willamette Basin,Oregon

Pacific lamprey Entosphenus tridentatus is an anadromous fish native to the Pacific Northwest of the USA. That has declined substantially over the last 40 years. Effective conservation of this species will require an understanding of the habitat requirements for each life history stage. Because its life cycle contains extended freshwater rearing (3–8 years), the larval stage may be a critical factor limiting abundance of Pacific lamprey. The objective of our study was to estimate the influence of barriers and habitat characteristics on the catch‐per‐unit‐effort (CPUE) of larval Pacific lamprey in the Willamette River Basin, Oregon, USA. We sampled lampreys at multiple locations in wadeable streams throughout the basin in 2011–13 and used an information theoretic approach to examine the relative influence of fine‐ and large‐scale predictors of CPUE. Pacific lamprey was observed across the basin, but its relative abundance appeared to be limited by the presence of natural and artificial barriers in some sub‐basins. Lower velocity habitats such as off‐channel areas and pools contained higher densities of larval lamprey; mean Pacific lamprey CPUE in off‐channel habitats was 4 and 32 times greater than in pools and riffles respectively. Restoration and conservation strategies that improve fish passage, enhance natural hydrologic and depositional processes and increase habitat heterogeneity will likely benefit larval Pacific lamprey.     

Changes in habitat use patterns by bottlenose dolphins over a 10‐year period render static management boundaries ineffective

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Springs in time: fish fauna and habitat changes in springs over a 20‐year interval

• 1. Despite the range of threats to springs and the number of spring‐endemic species, studies of temporal changes in the fauna of springs have rarely been reported. Changes in the fish of 22 Oklahoma (USA) springs were compared among surveys in 1981, 1982, and 2001.
• 2. Twenty‐year assemblage differences were correlated with physical alteration of specific springs and stocking of native fish, which was made possible by past habitat changes that produced pools. Physical alteration of springs is a major ongoing threat to Oklahoma springs.
• 3. Variation in spring fish assemblages among the three surveys was apparently affected by fish movement in and out of springs, and the greater rain‐induced connectivity between springs and streams during one year.
• 4. Although flow reduction is a commonly cited threat to springs, there was little evidence of flow reduction impacts in this study because Oklahoma springs may have been affected prior to 1981 and high‐flow springs, which most often contain fish, were in areas with low groundwater water use.

Copyright © 2008 John Wiley & Sons, Ltd.     

Long‐term changes in the fish assemblage of the Laja River,Guanajuato, central Mexico

• 1. The structure and composition of fish communities in rivers of central Mexico have been altered as a result of water over‐exploitation, habitat fragmentation, introduction of exotic species, and pollution. However, the specific pattern and degree of change are poorly documented.
• 2. Long‐term information from the Laja River (Guanajuato, Mexico) in the Lerma River basin was used to explore trends in fish species richness and community composition (species origin, trophic niche, tolerance, and preferred habitat) from the 1960s to the present in both river and reservoir sites.
• 3. Declines in native, sensitive, benthic native and carnivore species ranging from 11% to 30% per decade, and increases in the number of tolerant and exotic species by 9–20% per decade, are documented. Repeated measures ANOVA and sign tests revealed significant declines in the number of benthic, native, carnivore and sensitive species. Species richness, number of exotics, tolerant species and omnivore species did not change statistically, though statistical power was low. Some important changes occurred in these variables, such as the expansion and establishment of exotics such as Xiphophorus variatus and Micropterus salmoides, which pose a serious potential threat to native species.
• 4. The changes in fish community composition for the Laja portray how the fish communities in other rivers in central Mexico, for which long‐term data do not exist, have changed or could change if environmental deterioration continues.

Copyright © 2006 John Wiley & Sons, Ltd.     

北太平洋小型中上层鱼类资源对气候–海洋变化的响应研究进展

小型中上层鱼类是北太平洋海域重要的渔业资源,具有生命周期短、生长速度快、高集群性等特点,其资源年间波动显著,且受气候-海洋变化的影响。本文围绕秋刀鱼（Coloabis saira）、鲣（Katsuwonus pelamis）、鲐（Scomber japonicus）、鳀（Engraulis japonious）、竹䇲鱼（Trachurus japonicus）、沙丁鱼（Sardinops sagax）6种主要的小型中上层鱼类,回顾了厄尔尼诺-南方涛动（El Niño/La Niña-southern oscillation,ENSO）、太平洋年代际振荡（the Pacific decadal oscillation,PDO）、黑潮-亲潮（Kuroshio-Oyashio,KR-OY）等关键气候-海洋指数的特点及对鱼类栖息地环境和资源变动的影响。概括了气候-海洋变化对小型中上层鱼类的洄游分布和资源丰度的直接影响过程,以及对亲体繁殖产卵、仔稚体成活率和资源量波动间接的滞后影响过程。建议：（1）在多种气候-海洋指数基础上添加种群动态过程、捕捞方式系数、自然死亡率等参数构建生物量动态模型,揭示气候-海洋变化对渔业资源量的影响过程;（2）结合北太平洋涛动（North Pacific oscillation,NPO）、北极涛动（Arctic oscillation,AO）、北太平洋环流振荡（North Pacific gyre oscillation,NPGO）等其他北太平洋主要气候,基于物理海洋模型及空间耦合水动力学模型研究大尺度海流、中尺度涡旋对小型中上层鱼类影响。     

Predictive modelling of mesophotic habitats in the north‐western Gulf of Mexico

1. Effective management of marine resources requires an understanding of the spatial distribution of biologically important communities.
2. The north‐western Gulf of Mexico contains diverse marine ecosystems at a large range of depths and geographic settings. To better understand the distribution of these marine habitats across large geographic areas under consideration for marine sanctuary status, presence‐only predictive modelling was used.
3. Results confirmed that local geographic characteristics can accurately predict the probability of occurrence for marine habitat types, and include a novel technique for assigning a single, most likely habitat in areas where multiple habitats are predicted.
4. The highest resolution bathymetric data (10 m) available for the region was used to develop raster layers that represent characteristics that have been shown to influence species occurrence in other settings.
5. A georeferenced historical photo record collected via remotely operated vehicle was classified according to six commonly found mesophotic habitats across the 18 reefs and banks under consideration for Flower Garden Banks National Marine Sanctuary boundary expansion.
6. Using maximum entropy modelling, the influence of local geographic characteristics on the presence of these habitats was measured and a spatial probability distribution was developed for each habitat type across the study area.

     

Estimating size‐specific brook trout abundance in continuously sampled headwater streams using Bayesian mixed models with zero inflation and overdispersion

Abstract – We examined habitat factors related to reach‐scale brook trout Salvelinus fontinalis counts of four size classes in two headwater stream networks within two contrasting summers in Connecticut, USA. Two study stream networks (7.7 and 4.4 km) were surveyed in a spatially continuous manner in their entirety, and a set of Bayesian generalised linear mixed models was compared. Trout abundance was best described by a zero‐inflated overdispersed Poisson model. The effect of habitat covariates was not always consistent among size classes and years. There were nonlinear relationships between trout counts and stream temperature in both years. Colder reaches harboured higher trout counts in the warmer summer of 2008, but this pattern was not observed in the cooler and very wet summer of 2009. Amount of pool habitat was nearly consistently important across size classes and years, and counts of the largest size class were correlated positively with maximum depth and negatively with stream gradient. Spatial mapping of trout distributions showed that reaches with high trout counts may differ among size classes, particularly between the smallest and largest size classes, suggesting that movement may allow the largest trout to exploit spatially patchy habitats in these small headwaters.     

Conservation of newt guilds in an agricultural landscape of Belgium: the importance of aquatic and terrestrial habitats

• 1. Amphibians are declining worldwide in response to local and global pressures. Pond‐breeding species are particularly vulnerable to environmental change because they rely on two components of the landscape: aquatic and terrestrial habitats. Agricultural practices are changing rapidly at world and local scales. As a consequence, farm ponds and their surrounding terrestrial landscapes will probably be affected.
• 2. This study investigated the main habitat determinants for the occurrence of four species of newts (genus Triturus) inhabiting the Pays de Herve, a rural area in Belgium. Newt occurrence was determined for 258 ponds and the effect of habitat on distribution determinants was evaluated using generalized linear models.
• 3. Newts were found in 42% of the ponds. Contrary to expectations, the distribution of newts was not positively associated with a high density of ponds. However, a low occurrence of newts and the low water depth of many ponds suggest a low quality of habitats. Proximity to forest, deep water, and an absence of fish in ponds are factors that significantly favour newts, but terrestrial habitat requirements vary among species.
• 4. These results indicate the necessity of maintaining both forest and meadow patches in close proximity to ponds inhabited by newts, and of controlling fish introduction in those ponds. These findings stress the importance of conservation and management of terrestrial and aquatic habitats for maintaining amphibian diversity.

Copyright © 2007 John Wiley & Sons, Ltd.