Changes In Fish Diversity Research Articles

An assessment of demersal fisheries by trawling in less than 50 m of water off Egypt’s Mediterranean coast

Trawl fishing is identified as one of the most significant factors that could affect the diversity of demersal fish groups but not for all depth strata. Since the increased exploitation of Non-Indigenous Species (NIS) has caused the trawl fishing grounds to shift towards shallower seas where their biomass density is maximum, this study aimed to assess demersal fisheries by bottom trawls in the Mediterranean water off Egypt at depths less than 50 m. In this study, data from eight bottom-trawl hauls were used to describe the diversity of the demersal fish catch. The hauls varied in their species composition and both in the number and the weight of individuals. The length frequency distribution of the most occurred species was studied. A total of 87 species were identified in the catch, out of which 32 were recognized as NIS. The percentages of most of the NIS decreased from the east to the west of the surveyed area. There are always changes in fish diversity because of increasing fishing efforts on demersal fish communities, but not for all depth strata, therefore, a monitoring program has to be designed for better assessment of fisheries resources in the Mediterranean water off Egypt.

Temporal variations of the multifaceted biodiversity and assembly mechanisms in lake fish assemblages

AbstractUnderstanding long‐term changes in fish diversity and community assembly rules is crucial for freshwater conservation. Growing evidence indicates that studying functional and phylogenetic diversity beyond purely taxonomic considerations can provide different but complementary information on community assembly. Here, the taxonomic, functional, and phylogenetic β‐diversity of fish communities, as well as the community assembly mechanisms, were explored in five impounded lakes of the China's South‐to‐North Water Diversion Project (SNWDP) from the 1980s to the 2010s. We found that (1) there was an obvious trend of species homogenization in the five impounded lakes, but the long‐term transformations of different dimensional β‐diversity were divergent; (2) water quality and land use variables have greater impacts on multidimensional β‐diversity; and (3) community assembly process in taxonomic and functional dimensions were dominated by random process in both periods, while shifting from limiting similarity to habitat filtering in the phylogenetic dimension. These results highlight that functional and phylogenetic diversity are important additional ecological indices for assessing the patterns of fish diversity in lakes.

Geology, climate, and hydrochemistry shape the spatial patterns of multiple diversity facets and functional traits of fishes

AbstractIn a large river with significant environmental variations in space (i.e., microhabitat) or over time (i.e., seasonality and/or long‐term trend), discovering the spatial changes in fish diversity, distributions, and functional traits would provide an important foundation for the understanding of ecosystem structure and function. In the Pearl River in China, three datasets as fish distribution, species functional traits, and environmental variables were constructed and sorted to (1) test the relationships between and congruence of taxonomic diversity, functional diversity, and phylogenetic diversity by a randomisation procedure, (2) map the spatial pattern of diversity and the correlation to environmental variables by maximal information coefficient, and (3) determine the fish traits tendency under environmental changes by the fourth‐corner method. The Pearl River possesses the highest fish richness among all the rivers in China, with 438 freshwater fish species including 119 cave species. At basin scale, phylogenetic diversity showed faster change than functional diversity, suggesting a little divergence of functional traits despite high phenotypic or genetic diversity across species, as parallel evolution. However, at a small scale, when only considering cave fishes, the variation rate of species traits was faster than that of species increase, as evolutionary radiation in a variety of microhabitats. For all three aspects of diversity, random permutation tests confirmed that congruence values in each grid cell were significantly different from the random expectations. Besides widely accepted variables such as altitude, precipitation, and slope concerned with fish biogeography, hydrochemical variables showed influential impacts on the morphological and growth traits of fishes in the Pearl River characterised by the dominance of the karst habitat.

Tracking Changes in Fish Diversity in the South-Eastern Adriatic Sea (Albania) Based on Local Ecological Knowledge

Abstract Evidence from the last two centuries has identified changes in the biodiversity of the Mediterranean basin triggered by the arrival of new species. Compared to the central and northern areas, the southern part of the Adriatic Sea, specifically the Albanian coast, has been less studied. The aim of this study is to evaluate the prevalence of new/non-native fish species on the north Albanian coast in order to provide the first data on their presence. Data collection was carried out from March to August 2019 using LEK (Local Ecological Knowledge) protocol in five different locations along the northern part of the Albanian coast. The research followed a predefined methodology previously successfully applied in different countries of the Mediterranean basin by using a semi-structured questionnaire. During this study, 9 new and non-native species were recognized by the fishers, while only 5 of them have shown an evident abundance increase based on their respective catches in recent years. Results suggest that some of the analyzed species, such as blue crab Callinectes sapidus and bluefish Pomatomus saltatrix, represent important members of the fish fauna in north Albania coastal waters (including the lagoons). Future studies regarding the assessment of their impact and management strategies are highly recommended.

Increasing fish diversity of Chicago's waterways

Descriptions of shifts in biodiversity across time are desired for urban freshwater systems to better study ecosystem change and causal mechanisms. I document changes in fish diversity within the Chicago Area Waterways across 35 years using a battery of diversity metrics calculated on both abundance and biomass data. Has diversity of Chicago's waterways changed over 35 years and if so, do different diversity metrics exhibit different trends or breakpoints in trends? Diversity of the fish assemblage increased across the three decades of study. Breakpoint analysis suggested that trends across the timeseries were nonlinear. Changes in dominant species influenced behavior of less traditional metrics, whereas Margalef's Richness, Shannon-Weiner, and Gini-Simpson appeared more robust. Increases in richness and taxonomic diversity combined with decreases in species dominance suggest an ecosystem of increasing quality. The fish community of the Chicago Area Waterway System is more diverse both in abundance as well as biomass (i.e., energy flows) in the late 2010's than it was in the late 1980's. Although external factors related to wastewater treatment increased water quality and likely led to these assemblage-level changes breakpoint analysis did not allow verification of causal mechanisms.

Changes in ecosystem functions generated by fish populations after the introduction of a non-native predator (Cichla kelberi) (Perciformes: Cichlidae)

Abstract The introduction of non-native predators is a matter of great concern, but their impacts on ecosystem functions remain poorly understood. We investigated how changes in fish diversity following the invasion of Cichla kelberi affected ecosystem functions generated by fish populations. Fish assemblages were sampled in macrophyte patches in a Neotropical impoundment over a 5-year period, before and after the introduction of the predator. We assigned seven ecosystem functions (26 trait-states) to each fish species, and examined how these functions behaved after the invasion. We collected 577 fish belonging to 25 species. Species richness, fish biomass and main species declined significantly over periods. The biomass of ecosystem functions changed significantly over time, and most trait-states declined. Few trait-states were lost, but all functions had at least one trait-state reduced by more than 85%. A null model analysis showed that changes in functions were not driven by species identities, while species richness correlated positively with total biomass and with most functions, suggesting that the loss of taxa and biomass drove observed changes in ecosystem functions. Our study provided evidence that community disassembly associated with the invasion of C. kelberi translated to the decline of several ecosystem functions, affecting energy mobilization and transference.

Changes in fish diversity and assemblage during comprehensive restoration of the Suzhou River in Shanghai

Changes in fish diversity and assemblage during comprehensive restoration of the Suzhou River in Shanghai

Seasonal changes in fish diversity, density, biomass, and assemblage alongside environmental variables in the Yangtze River Estuary.

The present study used multivariate techniques, to analyze the fish species diversity and distribution patterns in order to determine the possible role of environmental parameters as drivers of fish community structure and composition in the Yangtze River Estuary (YRE). This analysis was conducted using data obtained in the YRE from February 2012 to December 2014. Analysis of the catch data showed that species composition, total density, and total biomass varied significantly between stations and seasons. Thirty-eight species belonging to 18 families were collected. Sciaenidae was the most dominant family accounting for 40.8% of total captured specimens. In descending order, Collichthys lucidus, Cynoglossus gracilis, Chaeturichthys stigmatias, and Lophiogobius ocellicauda dominated catches in the YRE. These four species constituted 64.2% of the total catches and showed average dissimilarities of 74.19% between stations and 81.3% between months. The highest number of fish specimens captured was recorded in August 2012 while the highest species richness was observed in December 2013. The mean fish density and biomass for the YRE was 0.35 individuals/m2 and 2.5g/m2, respectively. The mean density and biomass for the most important and dominant species changed significantly between stations and seasons. Canonical correspondence analysis indicated that salinity and chlorophyll-a were the key variables that structured the fish assemblage in the YRE. High total species density and biomass were recorded in high saline stations (North Branch) of the YRE. This study confirms that most species captured in the YRE needs estuarine conditions to complete their growth and development. Hence, the findings in this study are important to understanding and developing suitable conservation plans for the management of fish resources in the YRE.

How intensive agricultural practices and flow regulation are threatening fish spawning habitats and their connectivity in the St. Lawrence River floodplain, Canada

Hydrological and land use changes for human purposes, have resulted in the increased fragmentation of river landscapes and the loss of aquatic habitats, leading to profound changes in fish diversity and productivity. In the fluvial Lake Saint-Pierre (St. Lawrence River, Canada), we studied how agricultural practices and water-flow regulation have impacted the area and connectivity of spawning habitats of northern pike (Esox lucius). Northern pike spawning and nursery habitats were modelled over a 49-year period (1965–2013) to estimate effective spawning area under four contrasting hydrological conditions. Simulations coupled with land cover analyses revealed that natural flow conditions historically favourable for fish reproduction (high and stable water flows) have been lost due to human activities. The highest potential for reproduction and habitat connectivity have been lost due to (1) intensive agriculture and ploughing of natural vegetation in the upper floodplain that overlaps suitable spawning areas for northern pike, and (2) flow regulation that has lowered and shortened spring floods and dried spawning grounds more frequently. To restore the St. Lawrence River functions, we propose to reconvert the portion of the floodplains that is vital to fish, but is currently used by intensive agriculture, into natural wetlands or perennial crops and to restore a more natural flow regime by extending the duration of floods between spawning and nursery periods. The highest priority for habitat restoration should target the most effective and recurrent spawning habitats, ditch and stream networks, and connected managed wetlands.

Community reassembly after river regulation: rapid loss of fish diversity and the emergence of a new state

Hydroelectric expansion has affected the functioning of most tropical rivers in the world. However, community reassembly in Neotropical impoundments remains poorly understood, because long-term studies are incipient. In this context, we evaluated temporal changes in fish diversity before and after the construction of Peixe Angical Dam, Upper Tocantins River, Amazon Basin. Specifically, we investigated changes in taxonomic (richness, abundance and species composition) and functional diversity (trait richness and composition) over a period of a decade. Fish assemblages were sampled at five sites along the river, between 2004 and 2014 (before and after river regulation). As predicted, taxonomic and trait richness declined in the impoundment, and the composition shifted over the years, with increasing dissimilarity between sites. We also observed significant changes in species abundance and trait composition. However, changes were abrupt and a novel community state emerged after the fifth year of the impoundment. After this period, richness and abundance tended to stabilize at low levels, with different species/trait composition when compared to the pre-damming period. Our results indicate that major changes in community structure occurred during the first years of the impoundment, with relevant losses in taxonomic and functional diversity, along with a rapid change towards a new state.

SPATIO-TEMPORAL VARIATION OF THE ICHTHYOFAUNA IN THE ESTUARY FROM MANAMO CHANNEL, ORINOCO RIVER DELTA, VENEZUELA

<p>The delta of Orinoco River constitutes a long estuarine extension of a great importance to fisheries at Venezuela, because, it is an indispensable area for reproduction, feeding and growing of several fish species, most of them with a commercial application. The purpose of this research was to identify and analyze the changes in fish diversity and the structural dynamic of the community at four zones of channel Manamo, during dry and rainy season. Samples were taken on March and May for dry period and July and August for rainy season. A total of 48 species were identified, grouped into 24 families and 42 genera. The diversity was higher in Bajo del Medio during the dry season (2.58 bits/ind), decreasing to 1.66 bits/ind in el Pajar (rains). The PERMANOVAS analyzes showed statistical differences in the composition of species with respect to the climate season (psed-F = 0.0365, <em>p</em> <0.05), but not between the sampling stations (psed-F 0.6668; <em>p</em> < 0.05). The results indicated that the fish fauna of the region is composed of elements characteristic of an estuary, being the climate seasons the most important factors for the evaluated group and this reflects the seasonal nature of this community.</p>

Temporal changes in fish diversity in lotic and lentic environments along a reservoir cascade

Abstract Long‐term modifications in hydrological conditions due to river damming result in varied effects on fish diversity, which can be stronger in a reservoir cascade. Therefore, we assessed changes in fish diversity over a 28‐year period, in a series of reservoirs along the Araguari River Basin, a Neotropical drainage in Brazil, in both lentic environments (reservoirs) and the lotic stretches between them. We used linear mixed models to assess long‐term changes in fish diversity. Diversity was measured as α diversity (fish species richness) and β diversity (Jaccard's and Raup–Crick's dissimilarity index). Beta diversity was then partitioned into turnover (species replacement) and nestedness (species loss). To understand fish species replacement along the cascade, we modelled turnover with four covariates: age, richness of native and non‐native fish species, and longitudinal position of sampling site along the cascade. The reduction of total richness and the increase in non‐native richness were related to reservoir age. These effects were similar in both lotic and lentic environments, with no significant difference between them. We also observed a decrease in native fish richness over time, with a slight tendency for lentic environments to lose more species than lotic environments. Dissimilarity in fish assemblage increased over time and β Raup–Crick results corroborated those derived from β Jaccard, yielding similar significant temporal trends. Changes in fish species composition occurred predominantly due to turnover, compared to nestedness. We observed a greater species loss in reservoirs, suggesting that the transformation from a lotic environment into a lentic had greater impact on fish assemblages than the flow regulation of the lotic stretches downstream of the dams. Our results suggest that species replacement can be explained mainly by the increase of non‐native fish richness, followed by the longitudinal position along the cascade in an upstream–downstream direction, and reservoir age. This study reveals that, even after 2 decades of monitoring, we still observe important changes in fish assemblages, demonstrating the importance of long‐term monitoring to assess biodiversity. Our findings reinforce the importance of long‐term fish monitoring schemes for the investigation of the effects of non‐native fish species on native fish assemblages.

The Response of Fish Diversity in a Highly Modified Large River System to Multiple Anthropogenic Stressors

AbstractLarge riverine landscapes are among the most productive ecosystems on earth, and the most affected by humans. Few studies explicitly explore the effects of, or responses to, multiple stressors in highly modified large river systems. Changes in fish assemblages in response to multiple anthropogenic stressors were explored from a 60‐year data set for the Illinois River (Illinois, USA). Despite a legacy of stressors, the highly modified Illinois River responded to additional multiple stressors, especially four distinct stressor phases, which included two policies to improve water quality and bigheaded carp invasion. The response in fish diversity (Shannon H′) was complex in terms of the number of thresholds in the pattern of fish diversity, the rate and direction of change between thresholds, and the variance of response at two spatial scales and two ecological levels of organization. Overall, nine response trajectories were observed. Changes in fish diversity in the Illinois River since 1959 do not conform to current ecosystem response models. Without long‐term and broad‐scale data, elucidating complex responses in large river ecosystems is unlikely. Expanding the spatial and temporal scale of investigation in modified large rivers will increase our ability to understand how these ecosystems respond to multiple stressors.

Changes in fish diversity and community structure in the central and southern Yellow Sea from 2003 to 2015

The central and southern Yellow Sea is an important overwintering ground for many fish species in the Bohai Sea and Yellow Sea. For better understanding the status of the fish community after years of heavy exploitation, variations in fish community structure and diversity were analyzed using data from bottom trawls during 2003–2015. Five fish assemblage indices all showed fluctuations without clear trends from 2003 to 2015, yet there were strong positive and significant correlations ( P 0.05); there were also no significant differences between the slope of the size-spectra and fishing effort. The catch per unit effort and mean individual weight analyses of the whole fish assemblage both showed a significantly decreasing trend over time. Overall, the results showed that the fish community structure in the central and southern Yellow Sea was relatively stable from 2003 to 2015 and the study could be used as a reference for supporting ecosystem-based fishery management.

Selecting Piscivorous Bird Species for Monitoring Environmental Change in the Banc d'Arguin, Mauritania

This study aims to select piscivorous bird species to be used as indicators to monitor changes in fish diversity at the Banc d'Arguin, Mauritania. Such species should have a high diet diversity, low dietary overlap and data should be easy to collect. We compared the diets of five colony nesting bird species at the Banc d'Arguin: the Slender-billed Gull Chroicocephalus genei, Caspian Tern Hydroprognecaspia and Royal Tern Thalasseus maximus albididorsalis, which are part of an ongoing monitoring program, and the White-breasted Cormorant Phalacrocorax carbo lucidus and Mauritanian Spoonbill Platalea leucorodiabalsaci as potential new additions. All species considerably differed in prey species composition, prey species diversity and prey size. Diet overlap indices varied between 0.05 and 0.69 with the highest overlap values between Mauritanian Spoonbill and Slender-billed Gull. There are major differences between the species in ecological and behavioural mechanisms promoting diet segregation, such as foraging habitat use, foraging ranges and prey-catching techniques. We conclude that the species investigated serve our monitoring goal well. Practical recommendations for the implementation of a monitoring program are given.

Changes in Fish Diversity and Fisheries in Ziway-Shala Basin: The Case of Lake Ziway, Ethiopia

Lake Ziway is an economically important lake in the country. However, the physico-chemical parameters of the lake seem to be threatened by anthropogenic and climatic factors, which in turn affect biotic factors as reflected in fish catch. A study was made to assess the status and trends of fish diversity and fishery during October 2012 to September 2014 in Lake Ziway. Ten fish species were identified with low species diversity for the lake (H′ value of 1.67). The composition of the fishes has undergone some changes as compared to the last few decades.

English

There is evidence that ammonia, hydrogen sulphide and dissolved oxygen are implicated in fish kills occurring on the Lake Malawi shores of Karonga town. Exposure to fish is influenced by strong winds while water temperature differences cause upwelling and fish mortalities in surface waters. The vulnerability of fish in Karonga town to physico-chemical factors was computed from secondary sources data obtained in 2000 to 2016 regarding lethal and sub-lethal limits; this has helped to broaden our understanding of aquatic risk factors in this area. Equilibria relationships of ammonia (NH3 + H2O = NH4+ + OH-; K = 10-4.74; 2.70-4.28 µg.L-1 at depth of 100 to 200 m) and hydrogen sulphide (H2S = HS- + H+; K= 10-7.01; 54.9-82.5 mg.L-1 at a depth of 0-150 m) are imputed to have been implicated in the cause of a spate of fish kills.  Uranium fallout might also be implicated but further analysis on actual exposure is needed to confirm this. Inferences of fish vulnerability have been drawn from studies done elsewhere on similar freshwater fish but under controlled conditions. While fish catches temporarily improved in 2007-2008 and 2010-2011, changes in fish diversity have been consistent, such as the disappearance of Ntchila (Labeo mesops), decline of Chambo (Oreochromis species) and the dominance of sardine type Usipa (Engraulicyprus sardella). Therefore, other sources of risks are over-fishing and climate change; the latter is evidenced by warming of the deep water columns, reduced dissolved oxygen and declining Lake Malawi water levels. The significance of fish by-catch recorded as ‘others’ indicates that a high number of fish species remain scientifically undescribed, hence the need for further taxonomic studies. Fish catches as per caput fish supply for Karonga District (19.5-38 kg) are above the current national average of 4.0 go 5.8 kg. Since fish provides Karonga communities with affordable animal protein, it significantly contributes to food security for the town. More than 5,500 people depend directly on fishing, representing 10% of the population of Karonga. Fisheries are a driver to rural commercialization for businesses of up to 22,000 people; hence, it is critical to people’s livelihoods and incomes at the local level. Therefore, this study confirms what has commonly been observed for Karaonga town; that fish as a nutrition and income source should be factored into studies dealing with risks to livelihoods of Karonga town communities; even where this might require indirect methods of assessment. Key words: Fish catches, Karonga town, Lake Malawi, fish diversity, per caput fish supply, thermodynamic concentrations (H2S/HS-; NH3/NH4+).

Determinants of changes in fish diversity and composition in floodplain lakes in two basins in the Pantanal wetlands, Brazil

The aim of this study was to investigate the effects of physical characteristics on fish assemblages. To this end, we studied 42 lakes distributed in two river basins of the Brazilian Pantanal: the Negro River basins in the South Pantanal and the Cuiaba River basins in the North Pantanal. We hypothesized that fish diversity and composition change significantly between these basins in response to physical differences and landscape structure (the geographical position of the basins). The alternative hypothesis was that local assemblages are distributed randomly between the two basins because of a regional homogenizing factor in the system. Our analysis suggests that the physical characteristics (lake area, depth and distance from the river margin) and the effect of geographical position of the basin were the main factors determining the organization of fish assemblages in these basins. This would indicate that regional fish diversity is not uniform over large areas of these Pantanal floodplains, but that communities close to each other are more similar than those that are further apart. Although there was a small variation between the lakes, this was not sufficient to affect the communities of both basins, either in composition or in diversity. Our study also supports the hypothesis that fish assemblages in the littoral zone of the Cuiaba River are richer and more diverse than assemblages in the corresponding area of the Negro River and that these differences are related to landscape characteristics. Hence, our results strongly suggest that area lake, depth, position of the basin, and smaller contribution of distance from the river margin are the key factor determining fish assemblage structure in floodplain lakes in the Cuiaba River and Negro River basins.

珠江东塔产卵场鳙繁殖的生态水文需求

PDF HTML阅读 XML下载 导出引用 引用提醒 珠江东塔产卵场鳙繁殖的生态水文需求 DOI: 10.5846/stxb201501290244 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金青年项目（31400354）；农业部公益性行业专项（201303048）；省自然科学重大项目（2013GXNSFEA053003） Analysis of the ecohydrological demands of bighead carp breeding in the Dongta spawning grounds of the Pearl River, via cross-wavelet analysis Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:鳙（Aristichthys nobilis（Richardson）），我国著名的四大家鱼之一，是一种重要的大型淡水经济鱼类。然而近年来由于各种原因，我国鳙种群数量急剧下降。依据2006-2013年珠江中下游长时间序列仔鱼数据和日平均流量数据，分析了研究水域鳙的繁殖生态，包括仔鱼出现的时间分布特征和早期资源周年变化规律，同时采用交互小波光谱分析方法（cross wavelet analysis），分析了径流量与鳙仔鱼多度的关系。发现珠江水系鳙早期资源发生主要在5至8月，2006-2011年早期补充资源量逐渐减少，2012-2013年间呈明显著增加；鳙早期资源年度出现的时间呈缩减趋势，其中最大繁殖量出现的时间逐年提前。交互小波光谱分析结果表明：径流量的改变与鳙仔鱼的多度显著正相关，当径流量大于5×103m3/s，且持续2d以上，是珠江水系鳙大量繁殖的基础，将对受梯级水坝控制的鳙产卵场的繁殖生态水文保障具有指导意义。 Abstract:Bighead carp, Aristichthys nobilis (Cyprinidae, Hypophthalmichthys), is one of the four big traditional domestic carp species (along with black carp, grass carp, and silver carp). It is a large fish of high commercial importance because of its palatability and popularity with Chinese consumers. The size of the bighead carp population in China has decreased significantly in recent years, because of various environmental stressors and habitat losses due to dam construction, pollution, and overfishing. In this study, we investigated the ecology of bighead carp breeding in the Pearl River, which is a large subtropical river and the longest river in southern China. This study was based on a dataset generated by sampling at a fixed station (23° 2' 40" N, 112° 27' 5" E) every 2 d, from 2006 to 2013. The earliest bighead carp larvae were captured on April 13, 2008, and the latest were found on October 7, 2006. The breeding season primarily lasted from May to August and accounted for 99% of all annual spawning. The total number of larvae found decreased gradually from 2006 to 2011, and then increased significantly in 2011. The date of the earliest recorded spawning did not change over the years, but the date of the latest spawning day occurred earlier each year, indicating that the length of the spawning period (interval between the first and last spawning days of the year) has decreased over time. Our results also show that peak spawning occurs earlier each year. We used cross-wavelet analysis with phase angle and coherency parameters to analyze the relationship between the abundance of bighead carp larvae and the local hydrological conditions. Simulation studies have shown that the spectral signature produced by the cross-wavelet method is a useful approach to developing an objective and quantitative understanding of how river discharge affects the population size of bighead carp larvae. Discharge was positively correlated with the abundance of bighead carp larvae, though larval occurrence always lagged behind discharge. That is, water discharge acted as a trigger for the spawning of bighead carp. Simulation studies have shown that an increase in water discharge >5×103 m3/s and lasting at least 2 d is a prerequisite for the bloom spawning of bighead carp in the Pearl River. This study was undertaken as part of a long-term investigation of the Pearl River's wild fisheries resources, and our results will help guide their protection and management. The wavelet approach is a particularly promising method of analyzing ecological data such as the relationship between hydrological conditions and fish larva occurrence. Our results will help pave the way for the quantitative analysis of the impact of the environment on an organism. We propose that frequency and scale domain methods, in the form of wavelet transforms, can serve as useful probes during preliminary investigations of fisheries data, in order to elucidate the mechanisms underlying changes in fish diversity and abundance. We conclude with a discussion about the role wavelet analysis could play in appropriately guiding flexible probabilistic models linking fisheries with environmental covariates. 参考文献 相似文献 引证文献

Predicting fish species richness and assemblages with climatic, geographic and morphometric factors: A broad-scale study in Chinese lakes

The present study was designed to investigate the relative importance of climatic (temperature and precipitation), geographic (altitude) and morphometric (lake area) factors in predicting fish species richness and assemblages in Chinese lakes at a large spatial scale. Two recursive partitioning tree-based approaches: Classification and Regression Trees (CARTs) and Multivariate Regression Trees (MRTs) were employed to generate predictive models respectively. Six fish assemblages were thus defined from the MRT model. The results indicated that lake altitude was the main determinant for predicting fish assemblages in Chinese lakes (30.43%), followed by precipitation of the driest month (10.47%), temperature annual range (3.62%) and annual mean temperature (3.15%). Validated CART model implied that precipitation of driest month, maximum temperature of warmest month and lake area were the main predictors in determining fish species richness patterns. Overall, our results indicated that the altitudinal extent and range of climatic variation was sufficient to overshadow the area effect in predicting fish species richness and assemblages in Chinese lakes. At the macroecological scale, the effect of temperature and precipitation on fish richness and assemblages also suggests future changes in fish diversity as a consequence of climate change.