Phylogeography of competing sexual and parthenogenetic forms of a freshwater flatworm: patterns and explanations

Background: Models of the maintenance of sex predict that one reproductive strategy, sexual or parthenogenetic, should outcompete the other. Distribution patterns may reflect the outcome of this competition as well as the effect of chance and historical events. We review the distribution data of sexual and parthenogenetic biotypes of the planarian Schmidtea polychroa. Results: S. polychroa lives in allopatry or sympatry across Europe except for Central and North-Western Europe, where sexual individuals have never been reported. A phylogenetic relationship between 36 populations based on a 385 bp fragment of the mitochondrial cytochrome oxidase I gene revealed that haplotypes were often similar over large geographic distances. In North Italian lakes, however, diversity was extreme, with sequence differences of up to 5% within the same lake in both sexuals and parthenogens. Mixed populations showed "endemic" parthenogenetic lineages that presumably originated from coexisting sexuals, and distantly related ones that probably result from colonization by parthenogens independent from sexuals. Conclusions: Parthenogens originated repeatedly from sexuals, mainly in Italy, but the same may apply to other Mediterranean regions (Spain, Greece). The degree of divergence between populations suggests that S. polychroa survived the ice ages in separate ice-free areas in Central, Eastern and Southern Europe and re-colonised Europe after the retreat of the major glaciers. Combining these results with those based on nuclear markers, the data suggest that repeated hybridisation between sexuals and parthenogenetic lineages in mixed populations maintains high levels of genetic diversity in parthenogens. This can explain why parthenogens persist in populations that were originally sexual. Exclusive parthenogenesis in central and western populations suggests better colonisation capacity, possibly because of inbreeding costs as well

Freshwater biodiversity and conservation in mediterranean climate streams of Chile.

In Chile, mediterranean climate conditions only occur in the Central Zone (ChMZ). Despite its small area, this mediterranean climate region (med-region) has been recognised as a hotspot for biodiversity. However, in contrast to the rivers of other med-regions, the rivers in the ChMZ have been studied infrequently, and knowledge of their freshwater biodiversity is scarce and fragmented. We gathered information on the freshwater biodiversity of ChMZ, and present a review of the current knowledge of the principal floral and faunal groups. Existing knowledge indicates that the ChMZ has high levels of endemism, with many primitive species being of Gondwanan origin. Although detailed information is available on most floral groups, most faunal groups remain poorly known. In addition, numerous rivers in the ChMZ remain completely unexplored. Taxonomic specialists are scarce, and the information available on freshwater biodiversity has resulted from studies with objectives that did not directly address biodiversity issues. Research funding in this med-region has a strong applied character and is not focused on the knowledge of natural systems and their biodiversity. Species conservation policies are urgently required in this highly diverse med-region, which is also the most severely impacted and most populated region of the country.

Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems

Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers.

Invasive species and habitat degradation in Iberian streams: an analysis of their role in freshwater fish diversity loss

Mediterranean endemic freshwater fish are among the most threatened biota in the world. Distinguishing the role of different extinction drivers and their potential interactions is crucial for achieving conservation goals. While some authors argue that invasive species are a main driver of native species declines, others see their proliferation as a co-occurring process to biodiversity loss driven by habitat degradation. It is difficult to discern between the two potential causes given that few invaded ecosystems are free from habitat degradation, and that both factors may interact in different ways. Here we analyze the relative importance of habitat degradation and invasive species in the decline of native fish assemblages in the Guadiana River basin (southwestern Iberian Peninsula) using an information theoretic approach to evaluate interaction pathways between invasive species and habitat degradation (structural equation modeling, SEM). We also tested the possible changes in the functional relationships between invasive and native species, measured as the per capita effect of invasive species, using ANCOVA. We found that the abundance of invasive species was the best single predictor of natives’ decline and had the highest Akaike weight among the set of predictor variables examined. Habitat degradation neither played an active role nor influenced the per capita effect of invasive species on natives. Our analyses indicated that downstream reaches and areas close to reservoirs had the most invaded fish assemblages, independently of their habitat degradation status. The proliferation of invasive species poses a strong threat to the persistence of native assemblages in highly fluctuating environments. Therefore, conservation efforts to reduce native freshwater fish diversity loss in Mediterranean rivers should focus on mitigating the effect of invasive species and preventing future invasions

Homogenization Dynamics and Introduction Routes of Invasive Freshwater Fish in the Iberian Peninsula

Nonnative invasive species are one of the main global threats to biodiversity. The understanding of the traits characterizing successful invaders and invasion-prone ecosystems is increasing, but our predictive ability is still limited. Quantitative information on biotic homogenization and particularly its temporal dynamics is even scarcer. We used freshwater fish distribution data in the Iberian Peninsula in four periods (before human intervention, 1991, 1995, and 2001) to assess the temporal dynamics of biotic homogenization among river basins. The percentage of introduced species among fish faunas has increased in recent times (from 41.8% in 1991 to 52.5% in 2001), leading to a clear increase in the similarity of community composition among basins. The mean Jaccard's index increase (a measure of biotic homogenization) from the pristine situation to the present (17.1%) was similar to that for Californian fish but higher than for other studies. However, biotic homogenization was found to be a temporally dynamic process, with finer temporal grain analyses detecting transient stages of biotic differentiation. Introduced species assemblages were spatially structured along a latitudinal gradient in the Iberian Peninsula, with species related to sport fishing being characteristic of northern basins. Although the comparison of fish distributions in the Iberian Peninsula and France showed significant and generalized biotic homogenization, nonnative assemblages of northeastern Iberian basins were more similar to those of France than to those of the rest of the Iberian Peninsula, indicating a main introduction route. Species introduced to the Iberian Peninsula tended to be mainly piscivores or widely introduced species that previously had been introduced to France. Our results indicate that the simultaneous analysis of the spatial distribution of introduced assemblages (excluding native species that reflect other biogeographical patterns) and their specific traits can be an effective tool to detect introduction and invasion routes and to predict future invaders from donor regions

Ultimobranchial gland of freshwater catfish, Heteropneustes fossilis, in response to calcitonin administration

The absence o!!f a hypocalcemic effect of calcitonin (CT) in fishes has been suggested due to exceedingly high plasma levels of CT; the fish may be saturated with respect of circulating CT and therefore unable to respond to exogenously administered CT. Earlier it has been suggested that a hypocalcemic action of injected CT may be obscured by changes in the release of endogenous CT and other calcium regulating hormones. In this study we have used artificial freshwater, calcium-deficient freshwater and calcium-rich freshwater and injected the fish with CT. The aim behind selecting these media were (i) in calcium-deficient medium there would be reduced circulating levels of CT, (ii) in calcium-rich medium there would be diminished secretion of prolactin (this hormone is hypercalcemic in fish), and (iii) by keeping the fish in calcium-rich medium we can test the antihypercalcemic action of CT. Moreover, the present study would reveal the changes in the ultimobranchial gland (UBG) after keeping the fish in all the above three media and/or injecting the fish with CT. Freshwater catfish, Heteropneustes fossilis, were administered intraperitoneally daily with vehicle or 0.5 U/100g body wt of salmon calcitonin (CT) and kept in artificial freshwater, calcium-rich freshwater and calcium-deficient freshwater for 10 days. Blood samples were collected on 1, 3, 5, and 10 days following the treatment and analyzed for serum calcium levels. The ultimobranchial gland (UBG) was also fixed for histological studies on these intervals. In artificial freshwater there was no change in the serum calcium levels of calcitonin-injected fish. The ultimobranchial gland of calcitonin-injected fish exhibited a progressive decrease in the nuclear volume from day 5 onwards. On day 10 vacuolization in the gland was also noticed. In vehicle-injected fish (control) kept in calcium-rich freshwater hypercalcemia has been noticed which persists till the end of the experiment. In calcitonin-treated fish maintained in calcium-rich freshwater there is no change in serum calcium level as compared to vehicle-injected fish. In vehicle-injected fish the UBG depicts decreased staining response and increased nuclear volume at day 5. On day 10 the nuclear volume is further increased and few degenerating cells have been noticed. Calcitonin fails to induce any histological change in the UBG as compared to control. In vehicle-injected fish kept in calcium-deficient freshwater the serum calcium levels decrease from day 1 to day 3. The levels exhibit hypercalcemia on day 10. CT treatment to the fish kept in calcium-deficient freshwater evokes a decrease in the calcium levels on day 1 and day 3. A significant hypercalcemia has been noticed on day 5 and day 10. In vehicle-injected fish kept in calcium-deficient freshwater the UBG reveals a decreased staining response on day 10. In CT-injected fish maintained in calcium-deficient freshwater the UBG depicts an increased nuclear volume and few exhausted cells on day 10. It can be concluded that CT can provoke hypocalcemia only when the fish is kept in medium which reduces the circulating levels of this hormone. The UBG of the fish kept in different calcemic media responded in a manner to indicate that it produces hypocalcemic factor - CT.

Parasites of the freshwater fish trade in Brazil: science metric study

This paper presents a science metric study of parasites of fish farming in Brazil, including a significant review of the literature. The methodology used was based on researching articles in three different databases, carried out ​on May 2012: ISI (Institute for Scientific Information), SciELO (Scientific Electronic Library Online), and Google Academic. The number of articles on fish parasites is mounting (currently over 110), having much increased since 1995. However, the quantity is still low compared with the amount of papers on parasites of fish from natural environments. In Brazil, the farmed fish that have been studied the most are pacu, tilapia and tambaqui. Monogeneans represent the most prevalent group, followed by protozoa and crustaceans. The regions most researched were the southeast and south, making up 84% of the total literature. The main issue addressed in articles was pathology, followed by treatment and record. In conclusion, the treatment of parasitic diseases of farmed fish in Brazil is still incipient, highlighting the importance and usefulness of management practices to prevent the occurrence of health problems.

Vitamin D3-induced calcemic and phosphatemic responses in the freshwater mud eel Amphipnous cuchia maintained in different calcium environments

Vitamin D3 (100 ng 100 g body weight-l day-l) was administered intraperitoneally (ip) to the freshwater mud eel Amphipnous cuchia kept in artificial freshwater, calcium-free freshwater, low-calcium freshwater (0.2 mmol/l CaCl2) or calcium-rich freshwater (13.4 mmol/l CaCl2) for 15 days. Analyses of serum calcium and phosphate levels were performed on days 1, 3, 5, 10 and 15 after the beginning of the experiment (six eels from each group at each interval). Administration of vitamin D3 elevated the serum calcium [maximum elevation occurred at day 10 in artificial freshwater (vehicle: 10.55 ± 0.298, vitamin D: 13.90 ± 0.324), low-calcium freshwater (vehicle: 11.17 ± 0.220, vitamin D: 12.98 ± 0.297) and calcium-rich freshwater (vehicle: 11.24 ± 0.373, vitamin D: 14.24 ± 0.208) whereas it occurred at day 5 (vehicle: 8.42 ± 0.253, vitamin D: 11.07 ± 0.328) in calcium-free freshwater] and phosphate levels [maximum elevation at day 15 in artificial freshwater (vehicle: 4.39 ± 0.105, vitamin D: 5.37 ± 0.121), calcium-free freshwater (vehicle: 4.25 ± 0.193, vitamin D: 5.12 ± 0.181), low-calcium freshwater (vehicle: 3.93 ± 0.199, vitamin D: 5.28 ± 0.164) and calcium-rich freshwater (vehicle: 3.77 ± 0.125, vitamin D: 5.46 ± 0.151)] of the fish maintained in the above mentioned environmental media, but the responses were more pronounced in the fish kept in calcium-rich media

Annual changes in serum calcium and inorganic phosphate levels and correlation with gonadal status of a freshwater murrel, Channa punctatus (Bloch)

Adult Channa punctatus murrels of both sexes (60-80 g) were collected locally from Ramgarh Lake during the second week of every month (10 individuals of each sex/month) throughout the year. Blood samples were collected and analyzed for serum calcium and phosphate levels by the methods of Trinder (1960) and Fiske and Subbarow (1925), respectively. Gonads were fixed to judge the state of maturation of the fish. Males exhibited no change in serum calcium levels throughout the year in correlation with testicular maturation. However, serum phosphate levels exhibited a rise in correlation with the increased gonadosomatic index. Females showed marked seasonal changes in serum calcium and phosphate levels which were associated with ovarian maturation (vitellogenesis).

Investigating the potential of thecamoebians (testate amoebae) as bio-indicators of impact of oil sands mining operations on freshwater environments in Northeastern Alberta, Canada

Thecamoebian (testate amoeba) species diversity and assemblages in reclamation wetlands and lakes in northeastern Alberta respond to chemical and physical parameters associated with oil sands extraction. Ecosystems more impacted by OSPM (oil sands process-affected material) contain sparse, low-diversity populations dominated by centropyxid taxa and Arcella vulgaris. More abundant and diverse thecamoebian populations rich in difflugiid species characterize environments with lower OSPM concentrations. These shelled protists respond quickly to environmental change, allowing year-to-year variations in OSPM impact to be recorded. Their fossil record thus provides corporations with interests in the Athabasca Oil Sands with a potential means of measuring the progression of highlyimpacted aquatic environments to more natural wetlands. Development of this metric required investigation of controls on their fossil assemblage (e.g. seasonal variability, fossilization potential) and their biogeographic distribution, not only in the constructed lakes and wetlands on the oil sands leases, but also in natural environments across Alberta.

Freshwater dinoflagellates as proxies of cultural eutrophication: a case study from Crawford Lake, Ontario

Crawford Lake, Ontario, provides an ideal natural laboratory to study the response of freshwater dinoflagellates to cultural eutrophication. The anoxic bottom waters that result from meromixis in this small (2.4 ha) but deep (24 m) lake preserve varved sediments that host an exceptional fossil record. These annual layers provide dates for human activity (agriculture and land disturbance) around the lake over the last millennium by both Iroquoian village farmers (ca. A.D. 1268-1486) and Canadian farmers beginning ~A.D. 1883. The well established separate intervals of human activity around Crawford Lake, together with an abundance of available data from other fossil groups, allow us to further investigate the potential use of the cyst of freshwater dinoflagellates in studies of eutrophication. Cyst morphotypes observed have been assigned as Peridinium willei Huitfeldt-Kaas, Peridinium wisconsinense Eddy and Peridinium volzii Lemmermann and Parvodinium inconspicuum (Lemmermann) Carty. The latter two cyst-theca relationships were determined by culturing and by the exceptional preservation of thecae of P. inconspicuum in varves deposited at times of anthropogenic reductions in dissolved oxygen.

Haematological Studies on the Freshwater Mussel - Lamellidens Marginalis ( Lamark, 1819 )

School of Environmental Studies, Cochin University of Science and Technology

Biochemical and Storage Characteristics of Myofibrillar Protein ( Surimi ) from Freshwater Major Carps

School of Industrial Fisheries, Cochin University of Science and Technology

Optimization of Process Parameters for the Extraction of Gelatin from the Skin of Freshwater Fish and the Evaluation of Physical anal Chemical Characteristics

Faculty of Marine Sciences,Cochin University of Science and Technology

Apptication of Biofloc Technology (BFI) in Ihe nunery rearing and farming of giant freshwater prawn, Macrobrachillm rosenbergii (de Man)

This thesis Entitled Application of Biofloc technology (BFT) In the Nursery Rearing and Farming of Giant Freshwater Prawn,Macrobrachium Rosenbergii(De Man). Aquaculture, rearing plants and animals under controlled conditions is growing with an annual growth rate of 8.3% in the period 1970-2008 (FAO, 2010). This trend of growth is essential for the supply of protein-rich food for ever increasing world population. But growth and development of aquaculture should be in sustainable manner, preferably without jeopardizing the aquatic environment.In the present study, the application of BFT in the nursery rearing and farming ofgiant freshwater prawn, M. rosenbergii, is attempted. The result of the study is organised into eight chapters. In the first chapter, the subject is adequately introduced. Various types of aquaculture practices followed, development and status of Indian aquaculture, present status of freshwater pravm culture, BF T and its use for the sustainable aquaculture systems, theory of BFT based aquaculture practices, hypothesis, objective and outline of the thesis are described. An extensive review of literature on studies carried out so far on biofloc based aquaculture are given in chapter 2. The third chapter deals with the application of BFT in the primary nursery phase of freshwater prawn. Several workers suggested the need for an intermediate nursery phase in the culture system of freshwater prawn for the successful production. Thirty day experiment was conducted to study the effect of BFT on the water quality, and animal welfare under the various stocking densities. The study concluded that stocking finfishes in biofloc-based monoculture system of freshwater prawns has the potential of increasing total yield. Prawns having a higher commercial value than finfishes besides ensuring economic sustainability. Results showed that prawn yield and survival was better in catla dominated tanks. Based on the results of the study, it is recommended to incorporate 25% rohu and 75% catla in the biofloc-based culture system of giant freshwater prawns. The results of the present study also recommend to stock relatively larger catla for biofloc-based culture system. Fish production was also higher in the 100% catla tank. When catla was added in higher percentages it should ensured that the hiding objects in the culture ponds shall be used in order to reduce the chance of cannibalism among prawns. rohu and catla equally have the ability to harvest the biofloc, catla consumes the planktonic contributes in the floc whereas rohu grazed on the bacterial consortium suspended in the water column. In Chapter 8, recommendations and future research perspectives in the field of biofloc based aquaculture is presented.