Headwater–river gradient: trait-based approaches show functional dissimilarities among tropical fish assemblages

2018 ◽  
Vol 69 (4) ◽  
pp. 574 ◽  
Author(s):  
Rodrigo Assis de Carvalho ◽  
Francisco Leonardo Tejerina-Garro

Traditionally, species richness and composition of freshwater communities are expected to change according to the structural variation from headwaters to river mouth. In the present study, we hypothesised that fish functional traits will respond to this gradient, leading to functional dissimilarities between fish assemblages of headwaters and those of rivers. We addressed the following questions: (1) which functional traits are present in fish assemblages of each habitat type; (2) which environmental factors determine the occurrence of fish functional traits; and (3) how functional traits are related to each environmental variable? Our findings showed dissimilarities between fish assemblages of headwaters and those of rivers, mainly driven by channel depth, channel width, water temperature, water turbidity and concentration of dissolved oxygen, whereas altitude, water temperature and pH were mainly correlated with variation within each habitat type. These results suggested that not only do the physical variables proposed in classical theory of the river-continuum concept follow the upstream–downstream gradient in structuring the functional organisation of fish assemblages, but that also physicochemical variables, such as turbidity and concentration of dissolved oxygen, display this trend in tropical river systems. Moreover, our results have given a first perspective on what kind of fish species and fish functional traits to expect in each habitat type and, consequently, along the headwater–river mouth gradient.

2013 ◽  
Vol 11 (2) ◽  
pp. 413-424 ◽  
Author(s):  
Ana Cristina Petry ◽  
Fabiane Abujanra ◽  
Luiz Carlos Gomes ◽  
Horacio Ferreira Julio Jr. ◽  
Angelo Antonio Agostinho

The effects of the duration of the floods on abiotic variables and attributes of species tolerant and intolerant to hypoxia (STH and SIH respectively) were evaluated in rivers and lakes of the upper Paraná River. Fish were sampled once a year, in six sampling stations, during the high water period from 2000 to 2003. There were overall reductions in dissolved oxygen levels and increases in transparency of water in lakes in years of moderate floods. The duration of floods influenced species differentially based on their tolerance to hypoxia: in moderate floods, richness of STH increased and numerical abundance and biomass of SIH reduced significantly. Opposite relationships were detected between dissolved oxygen and the attributes of STH and SIH. Dissolved oxygen was the best predictor of variability of STH and SIH in years of moderate floods, whereas water transparency predicted significant amounts of STH in years of short floods. Being positively affected by dissolved oxygen reductions, STH seem to take advantages in persisting in seasonally harsh lentic habitats. The incorporation of abiotic data as well the differential tolerance of species to hypoxia would improve further investigations of the effects of interannual variations in the flood pulse on tropical fish assemblages


Author(s):  
Okan Külköylüoğlu ◽  
Mehmet Yavuzatmaca ◽  
Derya Akdemir ◽  
Ebru Çelen ◽  
Nurhayat Dalkıran

The relationship between ecological characteristic of freshwater ostracods and their habitat preferences has been a critical issue for understanding of both current and past aquatic conditions. To evaluate this idea, 121 water bodies with 11 different habitat types were randomly sampled in the province of Kütahya. Water quality measurements indicated high to low (Ca2+ > Mg2+ > Na+) cations and relatively low (SO42− > Cl− > F−) anion concentrations with Ca2+ being the dominant ion. Sixteen of 23 species were new reports for the area. Alpha diversity (H′ = 3.64) was found relatively high. Four most abundant species with ca. 93% of similarities contributed highest alpha values in warm to cooler (lower than 25 °C), alkaline (pH 8.22), and fresh to slightly brackish waters. Heterocypris salina and Ilyocypris bradyi also revealed the highest tolerances for electrical conductivity. Based on habitat type, species were clustered into three main groups (I–III). Canonical Correspondence Analyses explained about 57.4% of correlation between species and environmental variables. Redox potential, pH, water temperature and electrical conductivity were found to be the most effective factors on species occurrences while habitat type and dissolved oxygen were not effective. Total number of species showed strong negative and positive relationships with water temperature and dissolved oxygen, respectively. Results clearly showed that cosmopolitan species exhibited relatively wide tolerance ranges to different environmental variables. Accordingly, having wide tolerance ranges seems to provide advantages to cosmopolitan species, increasing their survival chances in a variety of habitats.


2021 ◽  
Author(s):  
Festus P. Nashima ◽  
Nadine A. Strydom ◽  
Stephen J. Lamberth

Abstract A continuous gradient of physical and biological processes exists within a river system from headwaters to mouth, according to the River Continuum Concept. In this study, the River Continuum Concept was used to compare patterns in fish assemblages and diversity trends to Remane predictions. The findings show that species diversity is low near the estuary's mouth and increases upstream. While the presence of several marine and estuarine species increased species diversity upstream in the river due to the dominance of freshwater fishes, it decreased downstream due to the presence of several marine and estuarine species. These patterns are consistent with the biogeographical trend of decreasing species richness along the South African coast from east to west. Based on the findings of this study, the River Continuum Concept ignores plasticity, which is evident in species that use transitional waters. As a result, the concept is insufficiently valid for the Orange River Estuarine Continuum, and a new concept known as the “River-Estuarine Continuum” has been proposed.


2019 ◽  
Vol 22 ◽  
pp. 177-203
Author(s):  
Olexandr V. Zhukov ◽  
Dmytro L. Bondarev ◽  
Yuliia I. Yermak ◽  
Marina P. Fedushko

The effect of the temperature on the spawining phenology of the fish assemblages and the role of the exogenious and endogenious factors in temporal niche overlaping of fish assemblages were investigated in different water body types of the Dnipro River basin within the “Dnipro-Orilskiy" Nature Reserve (Ukraine in the years 1997-2018. The period of spawning (beginning and end) of the Blicca bjoerkna, Carassius gibelio, Scardinius erythrophthalmus, Abramis brama, Perca fluviatilis, Rutilus rutilus, and Esox lucius was estimated. Community niche overlap was estimated by calculating the pairwise Pianka index. The temperature was discused as an exogenous factor effecting on the fishes spawn timing. From 1998 to 2018 the average temperature in the study area continued to rise. The annual course of the temperature takes the sinusoidal waveform, which can be described by a fourth-degree polynomial. The residuals of the corresponding polynomial trend are specific for each year. The regular components of the residuals variation were revealed by dbMEM-variables. Fishes spawning occurred within the narrow water temperature ranges, which are specific for each fish species. There are statistically significant differences between ponds in water temperatures at which the spawning start occurred. The water temperature at which the spawning start occurred is linearly dependent on the time of the spawning start. There were temporal overlaps between spawning of the different species. The deviation of the Pianka mean niche overlap indexes from random alternatives does not depend on the habitat type. The decreasing trend of the Pianka mean niche overlap indexes was observed during the study period. There is no statistically significant correlation between the average annual air temperature and the level of the niche overlap. The degree of niche overlapping depends on broad-, medium-, and fine-scale temperature patterns.


2013 ◽  
Vol 1 (1) ◽  
pp. 26
Author(s):  
Irma Pulukadan ◽  
Rene Ch Keppel ◽  
Grevo S Gerung

Alga is a marine resource of potential to fisheries and marine sector. It has an important economic value to promote the economy in Indonesia. Nowdays, algae have been used as a relatively high value fisheries commodity since it has been used for food, industrial, pharmaceutical and cosmetic raw materials. This important potential needs to be supported with understanding of its biology and ecology, so that its utilization could increase the livelihood of the coastal villagers. This study was aimed at inventorying and identifying the members of genus Caulerpa found in North Minahasa Regency waters and studying some biological and ecological aspects of the algae in the area. Resuls showed that there were 7 species recorded, Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata,C. lentillifera and C. peltata. Ecologically, the environmental parameters, such as water temperature, salinity, pH, dissolved oxygen, turbidity, were in tolerable ranges for algal growth. Bottom substrate supported the growth of genus Caulerpa as well© Saat ini alga dijadikan sebagai komoditas hasil perikanan dengan nilai ekonomis yang relatif tinggi karena manfaatnya sebagai bahan makanan serta bahan baku industri, farmasi, dan kosmetik. Potensi yang cukup penting ini harus ditunjang dengan ilmu pengetahuan tentang biologi dan ekologi dari alga laut, sehingga pemanfaatannya dapat meningkatkan taraf hidup masyarakat pesisir. Penelitian tentang kajian bioekologi alga makro genus Caulerpa di perairan Minahasa Utara ini dilaksanakan dan diharapkan dapat memberikan informasi ilmiah tentang bioekologi alga makro genus Caulerpa, sehingga dapat dimanfaatkan untuk pengembangan pemanfaatan bagi kepentingan masyarakat pesisir khususnya dan industri alga makro umumnya. Penelitian ini bertujuan untuk menginventarisasi dan mengidentifikasi alga makro genus Caulerpa di perairan Kabupaten Minahasa Utara, dan mengkaji aspek bioekologinya. Hasil penelitian menunjukkan bahwa ditemukan 7 spesies, yaitu Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata, C. lentillifera dan C. peltata. Parameter lingkungan seperti suhu, salinitas, pH, oksigen terlarut, tingkat kecerahan air berada pada kisaran yang dapat ditolerir untuk pertumbuhan alga makro, sedangkan substrat juga mendukung pertumbuhan alga makro ini©


Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1980
Author(s):  
Bushra Tasnim ◽  
Jalil A. Jamily ◽  
Xing Fang ◽  
Yangen Zhou ◽  
Joel S. Hayworth

In shallow lakes, water quality is mostly affected by weather conditions and some ecological processes which vary throughout the day. To understand and model diurnal-nocturnal variations, a deterministic, one-dimensional hourly lake water quality model MINLAKE2018 was modified from daily MINLAKE2012, and applied to five shallow lakes in Minnesota to simulate water temperature and dissolved oxygen (DO) over multiple years. A maximum diurnal water temperature variation of 11.40 °C and DO variation of 5.63 mg/L were simulated. The root-mean-square errors (RMSEs) of simulated hourly surface temperatures in five lakes range from 1.19 to 1.95 °C when compared with hourly data over 4–8 years. The RMSEs of temperature and DO simulations from MINLAKE2018 decreased by 17.3% and 18.2%, respectively, and Nash-Sutcliffe efficiency increased by 10.3% and 66.7%, respectively; indicating the hourly model performs better in comparison to daily MINLAKE2012. The hourly model uses variable hourly wind speeds to determine the turbulent diffusion coefficient in the epilimnion and produces more hours of temperature and DO stratification including stratification that lasted several hours on some of the days. The hourly model includes direct solar radiation heating to the bottom sediment that decreases magnitude of heat flux from or to the sediment.


2012 ◽  
Vol 72 (1) ◽  
pp. 121-130 ◽  
Author(s):  
II César ◽  
SM Martín ◽  
A Rumi ◽  
M Tassara

The Island of Martin Garcia is located in the Upper Río de la Plata, to the south of mouth the Uruguay River. The aim of the present study was to analyse the biodiversity of the island freshwater mollusks and their relationships to environmental variables. Twelve sampling sites were selected, five were along the littoral section of the island and seven were Inland ponds. Seven major environmental variables were measured: water and air temperature, percentage of oxygen saturation, dissolved oxygen, electrical conductivity, total dissolved solids and pH. Twenty-seven mollusk species were found, Antillorbis nordestensis, Biomphalaria tenagophila tenagophila , B. t. guaibensis, B. straminea, B. peregrina, Drepanotrema kermatoides, D. cimex, D. depressissimum, Chilina fluminea, C. rushii, C. megastoma, Uncancylus concentricus, Hebetancylus moricandi, Stenophysa marmorata, Heleobia piscium, H. parchappii, Potamolithus agapetus, P. buschii, P. lapidum, Pomacea canaliculata, P. megastoma, Asolene platae, Corbicula fluminea, Eupera platensis, Pisidium sterkianum, P. taraguyense and Limnoperna fortunei. UPGMA clustering of species based on their occurrence in different ecological conditions revealed two main species groups. The Canonical Correspondence Analysis suggests that the species distribution is related to the physico-chemical condition of water. Axis two of the ordination diagram displayed the approximately 95.6% of the correlation between species and environmental variables. Dissolved oxygen, conductivity, water temperature and pH showed the highest fluctuations during the sampling period. The species richness (S) showed relationships mainly with water temperature and conductivity. The biodiversity of the gastropods and bivalves from Martín García Island amounts to up to 26 species. Among the Gastropoda, the Planorbidae family made the most sizeable contribution. The Lithogliphidae P. agapetus (26.28%) and P. buschii (9.50%) showed the highest relative frequencies of occurrence within the littoral environments, while the Planorbidae D. cimex (23.83%) and D. kermatoides (11.59%) likewise did so in the inland ponds.


2003 ◽  
Vol 47 (12) ◽  
pp. 293-300 ◽  
Author(s):  
J. Veenstra ◽  
S. Nolen ◽  
J. Carroll ◽  
C. Ruiz

A 3-year study was conducted by the U.S. Army Corps of Engineers assessing water quality related impacts of aquaculture of 250,000 channel catfish (Ictalurus punctatus) in floating net pens in the Rock Creek Arm of Lake Texoma, Oklahoma/Texas. Five large nylon nets suspended from a floating framework of galvanized metal anchored in open water 100 m offshore made up the net pens with fish stocking densities varying from 88 to 219 fish/m3. Water quality sampling was conducted biweekly from April to September and monthly from October to March at three locations. On all sampling dates field measurements of water temperature, pH, dissolved oxygen, and conductivity were recorded at 1 m depth intervals and water samples were collected at a depth of 0.5 m and near the bottom of the water column at each site. Sample analyses included: total alkalinity, total hardness, turbidity, chloride, sulfate, orthophosphate, total phosphorus, nitrate-N, nitrite-N, total Kjeldahl nitrogen, total organic carbon, dissolved organic carbon, biochemical oxygen demand, and chlorophyll a. The results showed statistically significant decreases in water temperature and dissolved oxygen and significant increases in field conductivity in surface waters near the net pens relative to other sampling sites. The most dramatic water quality effect observed during the study was decrease in dissolved oxygen levels near the net pens following lake turnover in the second year.


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