Books by Julian D Reynolds
Ireland's Rivers, 2020
IRELAND’S RIVERS: ABSTRACT
Rivers are said to be the veins, and streams the capillaries, that car... more IRELAND’S RIVERS: ABSTRACT
Rivers are said to be the veins, and streams the capillaries, that carry freshwater, the scarce lifeblood of the Earth. However, freshwaters are experiencing species extinction at a rate faster than any other ecosystem, and human activities are threatening our survival through overexploiting and degrading water quality. Rivers have been channelled, buried underground, diverted and polluted; some so over-abstracted that their waters no longer reach the sea. With abundant rainfall, Irish rivers are less damaged than many of those in other countries, but most have water quality problems that can impact the quality of our lives and economic activities, as shortages of safe water supplies have demonstrated.
This timely book aims to raise awareness of Ireland’s fantastic and often undervalued river resource, and the importance of changing our behaviour and policies to ensure that we keep it in a healthy condition for its sustainable benefits, as well as protection of its biodiversity. This book captures the expertise of 37 Irish freshwater experts to provide an up-to-date account on the evolution of Ireland’s rivers and their flow characteristics, biodiversity and how humans have depended on, used and abused our rivers through time.
Irish rivers include types that are rare elsewhere in Europe and support a wide range of aquatic organisms and processes. The 19 chapters focus on their hydrology and their animal and plant life, including fish, crayfish, pearl mussels and aquatic birds and mammals, describing their importance and the threats to their survival such as pollution and loss of habitat. There are case studies of characteristic but contrasting Irish rivers, the Avonmore, Burrishoole, Araglin and the mighty Shannon, and information on invasive aquatic species. Water quality and river management are underlying themes. Ireland’s Rivers concludes with some suggestions for ways that individuals, households, communities and policy makers can help protect the health of our rivers and their water and wildlife.
Invasive Species and Human Health, ed. Giuseppi Mazza and Elena Tricarico, 2018
Inland waters are subject to more widespread biotic invasions than terrestrial ecosystems. During... more Inland waters are subject to more widespread biotic invasions than terrestrial ecosystems. During the last century, 756 aquatic species were introduced in Europe, frequently carrying new parasites for native fauna and humans. The consequences of such invasions are the loss of the invaders’ original parasites, the introduction of new parasites, or new intermediate hosts or vectors for existing parasites. Many parasites are water-borne and need aquatic species to complete their transmission cycles. The list of 100 of the World’s Worst Invasive Alien Species (Lowe et al., 2000) does not take into account human health problems, so a risk assessment of the consequences of invasive freshwater alien species requires more attention.
Here we review the direct and indirect impacts of invasive freshwater alien species on human health. Direct impacts include the injuries or allergies and new contaminants (bacteria, toxins), and their role as intermediate hosts to human parasites. Indirect impacts include the effects of the chemicals needed to control these aliens, changes to ecosystem services making the invaded area less suitable for recreational human use and damage to cultivation/ aquaculture affecting human well-being in developing countries. A clear management response is urgently needed to halt their spread and reduce or minimize the risk of human and wildlife disease.
ASPECTS OF THE ECOLOGY OF TWO SPECIES OF CENOCORIXA (CORIXIDAE: HEMIPTERA) IN ALLOPATRY AND SYMPA... more ASPECTS OF THE ECOLOGY OF TWO SPECIES OF CENOCORIXA (CORIXIDAE: HEMIPTERA) IN ALLOPATRY AND SYMPATRY.
Julian D. Reynolds. PhD Thesis, Zoology Department, UBC. 1974
ABSTRACT
Facets of the biology of the sibling species Cenocorixa bifida and C. expleta (Corixidae) were compared in different habitats, constituting both sympatric and allopatric populations. The study aimed to identify reasons for the differing distribution of the two species. In particular, it sought to (a) explain why and how the species coexisted over part of their range in lakes of moderate salinity, and (b) deduce why C. expleta is absent from the more freshwater lakes. The thesis is divided into six sections. An introduction, reviewing competition theory and summarising the problem, is followed by studies on the environments investigated, in Chapter II. Chapter III discusses distribution, abundance and breeding pattern of the corixid species encountered, to obtain data relevant to certain indirect measures of competition, and Chapters IV and V describe feeding experiments and serological gut analyses of field-collected corixids. The feeding experiments aimed to obtain one measure of the fundamental niche, while the gut enalyses were carried out fer a measure of the realised niche. The final section discusses the findings in terms of potential species interaction. The study area comprised six lakes on Becher's Prairie, in the Chilcotin area of B.C., and another near Kamloops; all lakes were similar in general morphology. Although temperature patterns were similar between lakes, they varied considerably in conductivity. Temperatures and conductivity data corroborate earlier findings, suggesting that the studied years were not atypical. Oxygen levels and phytoplankton primary production were generally higher in the more freshwater lakes, but the contribution of aquatic macrophytes and benthic algae there was not measured. Phytoplankon production was restrained. Plankters were abundant in all lakes, especially inshore, but the levels fluctuated most in the three freshwater lakes, being very low there before mid-June. Diaptomid copepods and fairy shrimps were confined to the higher salinity lakes, while chaoborids and amphipods were restricted to the three freshwater lakes; other invertebrates were widely distributed. Both biomass and diversity of organisms were highest in the freshwater lakes, but they were by no means low in the saline lakes studied. The data suggest that there was an abundance of food in all lakes at all times. C. bifida bred in all lakes investigated, although excluded apparently through increasing salinity from lake LB 2 after spring. C. expleta bred sympatrically with C. bifida in waters of over 6000 umhos cm-1 conductivity, whereas Cymatia americana, Hesperocorixa laevigata, Callicorixa audeni and Sicjara sp. bred only in the three most freshwater lakes. C. expleta produced three generations a year in the highest salinities (LB 2 and Barnes Lakes) and two in other high salinities. C. bifida produced two generations a year in the higher salinities, but like all the other corixids, in the three most freshwater lakes often produced only one generation a year. Corixids showed no definite trends of different abundance with alkalinity, and the two species of Cenocorixa did not show depressed population levels in sympatry. Further, the phenology was essentially contemporary in sympatry. C. expleta when allopatric occurred in both marginal and mid-lake areas, whereas C. bifida when allopatric was more confined to the littoral areas. In both species, habitat preferences of instars varied with season, but in general the largest individuals of each species preferred the most complex environments. Overall, C. expleta in sympatry was relatively commanest over deeper waters and over plain mud or silt, whereas C. bifida preferred rocks, logs and reeds. However, the segregation was not marked. Both C. bifida and C. expleta took a wide variety of preys offered in experiments. C. expleta adults accepted more of the preys offered than did C. bifida. Juveniles showed less marked species differences than did adults, and accepted prey more often than them. Both species accepted both live and dead organisms. Juveniles of both species preferred dead prey to live; however, only for C. expleta was this trend significant overall. When offered live or dead mixed plankton, C. bifida took chiefly ceriodaphniids, whereas C. expleta took both diaptomids and ceriodaphniids in the proportions offered. In other choice situations, both species fed more often on chironomids than daphniids, taking zygopterans least. However, unsuccessful attacks were far more frequent on daphniids than on the benthic and littoral organisms. In summary, the experimental feeding results suggest that the fundamental niches of the two species of Cenocorixa are similar, but not identical. Guts of field-collected corixids were analysed by serological techniques using 10 active antisera. Mcst reactions indicated a clearly carnivorous habit, less than 1% being positive for algae. Results suggest that foods eaten varied dynamically between instars, lakes and seasons. In C. bifida daphniids and zygopterans were more frequently recorded in guts from the sympatric lakes than from the freshwater lakes. Ephemeropterans and amphipods were identified chiefly from summer-collected corixids, and were chiefly restricted to the freshwater lakes, paralleling their distribution. However, some reactions were also seen in guts from these lakes with diaptomid antiserum, perhaps a reaction to other copepod species. In C. expleta most positive results were seen for daphniids in spring and fall corixid samples. More male than female C. exjaleta took ephemeropterans, and more male than female C. bifida took zygopterans. Specific differences between saline and freshwater lakes seemed to relate to prey distribution, but in Lake LB 2 C. exgleta took significantly more diaptomids in fall than in summer. In sympatry, most juveniles of both species took an increasingly diverse diet with increasing instar size, although the preferred order chironomids, then zygopterans, ephemeropterans and diaptomids, remained relatively constant. Second instar C. expleta reached a plateau level of feeding intensity only reached by third instar C. bifida ; this seems related to instar size. In larger instars, C. bifida showed more serological reactions with most foodstuffs than e. expleta. Overall, C. expleta showed more positive reactions than C. bifida with chironomids and daphniids, but less with diaptomids and zygopterans. In sympatry, C. bifida fed more on daphniids and ephemeropterans than in allopatry, which tends to contradict ideas of competition for food. The serological data suggest that the realised niche with respect to feeding is not markedly more restricted than the fundamental niche. Other corixid species had similarly carnivorous diets, C. audeni showing more reactions for amphipods and chironomids than H. laevigata , but less for chaoborids, suggesting more benthic orientation for the former. In field-collected corixids, red guts usually contained diaptomids, while brown guts reacted with a variety of antisera. In several brown and olive guts there was no serological reaction, indicating that the antisera did not cover the total dietary range. Occasional guts were bright blue-green, suggesting cyanophyte material. Despite, a wide geographical overlap between the species, C. bifida and C. expleta possess somewhat different osmotic and ionic regulatory capacities, and show slightly different habitat and food preferences. Therefore they cannot be considered as true ecological homologues, and hence competition need not necessarily result in exclusion of one or other. With regard to habitat, some of the differences observed may be related to variation in the environments between lakes studied, but other differences show the species not to be identical. C. expleta seems to have a rather wider fundamental niche in terms of habitat than C. bifida, but neither show marked restriction in sympatry. The serological feeding results suggest that in sympatry, each species took different proportions of the same foodstuffs. The realised niches appear somewhat restricted from the fundamental niche data obtained from feeding experiments. C. expleta seemed somewhat more specialised in feeding than C. bifida, thus fulfilling the requirements cof an included niche species; again a point usually considered to permit coexistence. However, diet and habitat preferences of species and instars varied with season and lake, suggesting that pooling data obscures much of the real variation. In general, the evidence shows that the two species of Cenocorixa are not exact ecological homologues, and competition between them in sympatry was not evident. The reason for the absence of C. expleta from the more freshwater lakes, to which it appears physiologically suited, still remains obscure.
URI: http://hdl.handle.net/2429/19532
Ireland’s Freshwaters, by Julian D. Reynolds
Limnology is well served by a number of internation... more Ireland’s Freshwaters, by Julian D. Reynolds
Limnology is well served by a number of international texts, but these reflect in the main the large continental land-masses. Although processes and community structures in Irish lakes and streams are the same as those encountered elsewhere, an outlying island will always be subject to different factors and influences.
In this short account you will find descriptions of the rock structure of Ireland, which is largely Palaeozoic, and of its geomorphology – a rather flat centre surrounded by an intermittent ring of mountains. These impose special conditions: lakes and catchments may be large in the centre, smaller at the periphery. In former times ice-sheets irregularly eroded the landscape and dumped transported materials, resulting in extensive, often shallow lake basins. The oceanic climate has encouraged the luxuriant growth of aquatic vegetation leading to the accumulation of large peat deposits. Today, the high rainfall and westerly winds ensure rapid flushing of many lakes, and stratification is rare. Karstified lowland limestone beds have permitted underground drainage, which spills over during periods of high flow into temporary surface lakes of ‘turloughs’.
The main sections of this book contain descriptions of the larger lakes and of other wetlands of particularly Irish interest, biogeographical considerations of the fauna and flora, and human impacts on Irish aquatic systems. Each section is necessarily brief and selective, but it is hoped that it may serve as an introduction to further reading through a general bibliography at the end of each chapter, and selected text references (indicated by numbers). The short text is supplemented by appendices providing information on former contributors to limnology in Ireland and on the current research activities of many institutions. There is a brief annotated gazetteer to Irish lakes, rivers and wetlands. Finally, there is a detailed index to topics and species mentioned in the text.
Integrating research into freshwater biodiversity and the role of keystone species, we present fr... more Integrating research into freshwater biodiversity and the role of keystone species, we present freshwater crayfish as representatives of human-exacerbated threats to biodiversity and conservation. We use examples from these and other large decapods to explore how communities function and are controlled, alongside the implications of human demands and conflicts over limited resources.
Three key topics are the present situation of crayfish in world freshwater ecosystems, the application of science to conservation management, and knowledge transfer for successful crayfish management, thus protecting ecosystem quality in the future.
The first Flora for County Limerick, with accounts for over 1100 native and alien flowering plant... more The first Flora for County Limerick, with accounts for over 1100 native and alien flowering plants, ferns, fern-allies and conifers growing in the wild from the Shannon Estuary to the Galty Mountains. It gives their frequency, distribution and habitats in the county, with first and historical records. Introductory chapters include a history of botanical recording in Limerick, a description of the varied terrin, accounts of the main Limerick habitats with their characteristic species, and an analysis of the overall flora. The Flora is the result of some thirty years of fieldwork and research by botanist Sylvia Reynolds, author of 'A Catalogue of alien plants in Ireland' (2002), latterly assisted by freshwater ecologist Julian Reynolds
Freshwater crayfish articles by Julian D Reynolds
Aquatic Conservation: Marine and Freshwater Ecosystems, 2020
Diversity, 2019
Invasive alien species are widespread in freshwater systems compared to terrestrial ecosystems. A... more Invasive alien species are widespread in freshwater systems compared to terrestrial ecosystems. Among crustaceans, crayfish in particular have been widely introduced and are considered a major threat to freshwater ecosystem functioning. New emerging techniques for detecting and controlling invasive crayfish and protecting endangered native species are; thus, now highly desirable and several are under evaluation. Important innovations have been developed in recent years for detection of both invasive and native crayfish, mainly through eDNA, which allows for the detection of the target species even at low abundance levels and when not directly observable. Forecasting models have also moved towards the creation of realistic invasion scenarios, allowing effective management plans to be developed in advance of invasions. The importance of monitoring the spread and impacts of crayfish and pathogens in developing national data and research networks is emphasised; here "citizen science" can also play a role. Emerging techniques are still being considered in the field of invasive crayfish control. Although for decades the main traditional techniques to manage invasive crayfish were solely based on trapping, since 2010 biological, biocidal, autocidal controls and sexual attractants, monosex populations, RNA interference, the sterile male release technique and oral delivery have all also been investigated for crayfish control. In this review, ongoing methodologies applied to the detection and management of invasive crayfish are discussed, highlighting their benefits and limitations.
" Integrating research into freshwater biodiversity and the role of keystone spe... more " Integrating research into freshwater biodiversity and the role of keystone species, this fascinating book presents freshwater crayfish as representatives of human-exacerbated threats to biodiversity and conservation. It uses examples from these and other large ...
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Books by Julian D Reynolds
Rivers are said to be the veins, and streams the capillaries, that carry freshwater, the scarce lifeblood of the Earth. However, freshwaters are experiencing species extinction at a rate faster than any other ecosystem, and human activities are threatening our survival through overexploiting and degrading water quality. Rivers have been channelled, buried underground, diverted and polluted; some so over-abstracted that their waters no longer reach the sea. With abundant rainfall, Irish rivers are less damaged than many of those in other countries, but most have water quality problems that can impact the quality of our lives and economic activities, as shortages of safe water supplies have demonstrated.
This timely book aims to raise awareness of Ireland’s fantastic and often undervalued river resource, and the importance of changing our behaviour and policies to ensure that we keep it in a healthy condition for its sustainable benefits, as well as protection of its biodiversity. This book captures the expertise of 37 Irish freshwater experts to provide an up-to-date account on the evolution of Ireland’s rivers and their flow characteristics, biodiversity and how humans have depended on, used and abused our rivers through time.
Irish rivers include types that are rare elsewhere in Europe and support a wide range of aquatic organisms and processes. The 19 chapters focus on their hydrology and their animal and plant life, including fish, crayfish, pearl mussels and aquatic birds and mammals, describing their importance and the threats to their survival such as pollution and loss of habitat. There are case studies of characteristic but contrasting Irish rivers, the Avonmore, Burrishoole, Araglin and the mighty Shannon, and information on invasive aquatic species. Water quality and river management are underlying themes. Ireland’s Rivers concludes with some suggestions for ways that individuals, households, communities and policy makers can help protect the health of our rivers and their water and wildlife.
Here we review the direct and indirect impacts of invasive freshwater alien species on human health. Direct impacts include the injuries or allergies and new contaminants (bacteria, toxins), and their role as intermediate hosts to human parasites. Indirect impacts include the effects of the chemicals needed to control these aliens, changes to ecosystem services making the invaded area less suitable for recreational human use and damage to cultivation/ aquaculture affecting human well-being in developing countries. A clear management response is urgently needed to halt their spread and reduce or minimize the risk of human and wildlife disease.
Julian D. Reynolds. PhD Thesis, Zoology Department, UBC. 1974
ABSTRACT
Facets of the biology of the sibling species Cenocorixa bifida and C. expleta (Corixidae) were compared in different habitats, constituting both sympatric and allopatric populations. The study aimed to identify reasons for the differing distribution of the two species. In particular, it sought to (a) explain why and how the species coexisted over part of their range in lakes of moderate salinity, and (b) deduce why C. expleta is absent from the more freshwater lakes. The thesis is divided into six sections. An introduction, reviewing competition theory and summarising the problem, is followed by studies on the environments investigated, in Chapter II. Chapter III discusses distribution, abundance and breeding pattern of the corixid species encountered, to obtain data relevant to certain indirect measures of competition, and Chapters IV and V describe feeding experiments and serological gut analyses of field-collected corixids. The feeding experiments aimed to obtain one measure of the fundamental niche, while the gut enalyses were carried out fer a measure of the realised niche. The final section discusses the findings in terms of potential species interaction. The study area comprised six lakes on Becher's Prairie, in the Chilcotin area of B.C., and another near Kamloops; all lakes were similar in general morphology. Although temperature patterns were similar between lakes, they varied considerably in conductivity. Temperatures and conductivity data corroborate earlier findings, suggesting that the studied years were not atypical. Oxygen levels and phytoplankton primary production were generally higher in the more freshwater lakes, but the contribution of aquatic macrophytes and benthic algae there was not measured. Phytoplankon production was restrained. Plankters were abundant in all lakes, especially inshore, but the levels fluctuated most in the three freshwater lakes, being very low there before mid-June. Diaptomid copepods and fairy shrimps were confined to the higher salinity lakes, while chaoborids and amphipods were restricted to the three freshwater lakes; other invertebrates were widely distributed. Both biomass and diversity of organisms were highest in the freshwater lakes, but they were by no means low in the saline lakes studied. The data suggest that there was an abundance of food in all lakes at all times. C. bifida bred in all lakes investigated, although excluded apparently through increasing salinity from lake LB 2 after spring. C. expleta bred sympatrically with C. bifida in waters of over 6000 umhos cm-1 conductivity, whereas Cymatia americana, Hesperocorixa laevigata, Callicorixa audeni and Sicjara sp. bred only in the three most freshwater lakes. C. expleta produced three generations a year in the highest salinities (LB 2 and Barnes Lakes) and two in other high salinities. C. bifida produced two generations a year in the higher salinities, but like all the other corixids, in the three most freshwater lakes often produced only one generation a year. Corixids showed no definite trends of different abundance with alkalinity, and the two species of Cenocorixa did not show depressed population levels in sympatry. Further, the phenology was essentially contemporary in sympatry. C. expleta when allopatric occurred in both marginal and mid-lake areas, whereas C. bifida when allopatric was more confined to the littoral areas. In both species, habitat preferences of instars varied with season, but in general the largest individuals of each species preferred the most complex environments. Overall, C. expleta in sympatry was relatively commanest over deeper waters and over plain mud or silt, whereas C. bifida preferred rocks, logs and reeds. However, the segregation was not marked. Both C. bifida and C. expleta took a wide variety of preys offered in experiments. C. expleta adults accepted more of the preys offered than did C. bifida. Juveniles showed less marked species differences than did adults, and accepted prey more often than them. Both species accepted both live and dead organisms. Juveniles of both species preferred dead prey to live; however, only for C. expleta was this trend significant overall. When offered live or dead mixed plankton, C. bifida took chiefly ceriodaphniids, whereas C. expleta took both diaptomids and ceriodaphniids in the proportions offered. In other choice situations, both species fed more often on chironomids than daphniids, taking zygopterans least. However, unsuccessful attacks were far more frequent on daphniids than on the benthic and littoral organisms. In summary, the experimental feeding results suggest that the fundamental niches of the two species of Cenocorixa are similar, but not identical. Guts of field-collected corixids were analysed by serological techniques using 10 active antisera. Mcst reactions indicated a clearly carnivorous habit, less than 1% being positive for algae. Results suggest that foods eaten varied dynamically between instars, lakes and seasons. In C. bifida daphniids and zygopterans were more frequently recorded in guts from the sympatric lakes than from the freshwater lakes. Ephemeropterans and amphipods were identified chiefly from summer-collected corixids, and were chiefly restricted to the freshwater lakes, paralleling their distribution. However, some reactions were also seen in guts from these lakes with diaptomid antiserum, perhaps a reaction to other copepod species. In C. expleta most positive results were seen for daphniids in spring and fall corixid samples. More male than female C. exjaleta took ephemeropterans, and more male than female C. bifida took zygopterans. Specific differences between saline and freshwater lakes seemed to relate to prey distribution, but in Lake LB 2 C. exgleta took significantly more diaptomids in fall than in summer. In sympatry, most juveniles of both species took an increasingly diverse diet with increasing instar size, although the preferred order chironomids, then zygopterans, ephemeropterans and diaptomids, remained relatively constant. Second instar C. expleta reached a plateau level of feeding intensity only reached by third instar C. bifida ; this seems related to instar size. In larger instars, C. bifida showed more serological reactions with most foodstuffs than e. expleta. Overall, C. expleta showed more positive reactions than C. bifida with chironomids and daphniids, but less with diaptomids and zygopterans. In sympatry, C. bifida fed more on daphniids and ephemeropterans than in allopatry, which tends to contradict ideas of competition for food. The serological data suggest that the realised niche with respect to feeding is not markedly more restricted than the fundamental niche. Other corixid species had similarly carnivorous diets, C. audeni showing more reactions for amphipods and chironomids than H. laevigata , but less for chaoborids, suggesting more benthic orientation for the former. In field-collected corixids, red guts usually contained diaptomids, while brown guts reacted with a variety of antisera. In several brown and olive guts there was no serological reaction, indicating that the antisera did not cover the total dietary range. Occasional guts were bright blue-green, suggesting cyanophyte material. Despite, a wide geographical overlap between the species, C. bifida and C. expleta possess somewhat different osmotic and ionic regulatory capacities, and show slightly different habitat and food preferences. Therefore they cannot be considered as true ecological homologues, and hence competition need not necessarily result in exclusion of one or other. With regard to habitat, some of the differences observed may be related to variation in the environments between lakes studied, but other differences show the species not to be identical. C. expleta seems to have a rather wider fundamental niche in terms of habitat than C. bifida, but neither show marked restriction in sympatry. The serological feeding results suggest that in sympatry, each species took different proportions of the same foodstuffs. The realised niches appear somewhat restricted from the fundamental niche data obtained from feeding experiments. C. expleta seemed somewhat more specialised in feeding than C. bifida, thus fulfilling the requirements cof an included niche species; again a point usually considered to permit coexistence. However, diet and habitat preferences of species and instars varied with season and lake, suggesting that pooling data obscures much of the real variation. In general, the evidence shows that the two species of Cenocorixa are not exact ecological homologues, and competition between them in sympatry was not evident. The reason for the absence of C. expleta from the more freshwater lakes, to which it appears physiologically suited, still remains obscure.
URI: http://hdl.handle.net/2429/19532
Limnology is well served by a number of international texts, but these reflect in the main the large continental land-masses. Although processes and community structures in Irish lakes and streams are the same as those encountered elsewhere, an outlying island will always be subject to different factors and influences.
In this short account you will find descriptions of the rock structure of Ireland, which is largely Palaeozoic, and of its geomorphology – a rather flat centre surrounded by an intermittent ring of mountains. These impose special conditions: lakes and catchments may be large in the centre, smaller at the periphery. In former times ice-sheets irregularly eroded the landscape and dumped transported materials, resulting in extensive, often shallow lake basins. The oceanic climate has encouraged the luxuriant growth of aquatic vegetation leading to the accumulation of large peat deposits. Today, the high rainfall and westerly winds ensure rapid flushing of many lakes, and stratification is rare. Karstified lowland limestone beds have permitted underground drainage, which spills over during periods of high flow into temporary surface lakes of ‘turloughs’.
The main sections of this book contain descriptions of the larger lakes and of other wetlands of particularly Irish interest, biogeographical considerations of the fauna and flora, and human impacts on Irish aquatic systems. Each section is necessarily brief and selective, but it is hoped that it may serve as an introduction to further reading through a general bibliography at the end of each chapter, and selected text references (indicated by numbers). The short text is supplemented by appendices providing information on former contributors to limnology in Ireland and on the current research activities of many institutions. There is a brief annotated gazetteer to Irish lakes, rivers and wetlands. Finally, there is a detailed index to topics and species mentioned in the text.
Three key topics are the present situation of crayfish in world freshwater ecosystems, the application of science to conservation management, and knowledge transfer for successful crayfish management, thus protecting ecosystem quality in the future.
Freshwater crayfish articles by Julian D Reynolds
Rivers are said to be the veins, and streams the capillaries, that carry freshwater, the scarce lifeblood of the Earth. However, freshwaters are experiencing species extinction at a rate faster than any other ecosystem, and human activities are threatening our survival through overexploiting and degrading water quality. Rivers have been channelled, buried underground, diverted and polluted; some so over-abstracted that their waters no longer reach the sea. With abundant rainfall, Irish rivers are less damaged than many of those in other countries, but most have water quality problems that can impact the quality of our lives and economic activities, as shortages of safe water supplies have demonstrated.
This timely book aims to raise awareness of Ireland’s fantastic and often undervalued river resource, and the importance of changing our behaviour and policies to ensure that we keep it in a healthy condition for its sustainable benefits, as well as protection of its biodiversity. This book captures the expertise of 37 Irish freshwater experts to provide an up-to-date account on the evolution of Ireland’s rivers and their flow characteristics, biodiversity and how humans have depended on, used and abused our rivers through time.
Irish rivers include types that are rare elsewhere in Europe and support a wide range of aquatic organisms and processes. The 19 chapters focus on their hydrology and their animal and plant life, including fish, crayfish, pearl mussels and aquatic birds and mammals, describing their importance and the threats to their survival such as pollution and loss of habitat. There are case studies of characteristic but contrasting Irish rivers, the Avonmore, Burrishoole, Araglin and the mighty Shannon, and information on invasive aquatic species. Water quality and river management are underlying themes. Ireland’s Rivers concludes with some suggestions for ways that individuals, households, communities and policy makers can help protect the health of our rivers and their water and wildlife.
Here we review the direct and indirect impacts of invasive freshwater alien species on human health. Direct impacts include the injuries or allergies and new contaminants (bacteria, toxins), and their role as intermediate hosts to human parasites. Indirect impacts include the effects of the chemicals needed to control these aliens, changes to ecosystem services making the invaded area less suitable for recreational human use and damage to cultivation/ aquaculture affecting human well-being in developing countries. A clear management response is urgently needed to halt their spread and reduce or minimize the risk of human and wildlife disease.
Julian D. Reynolds. PhD Thesis, Zoology Department, UBC. 1974
ABSTRACT
Facets of the biology of the sibling species Cenocorixa bifida and C. expleta (Corixidae) were compared in different habitats, constituting both sympatric and allopatric populations. The study aimed to identify reasons for the differing distribution of the two species. In particular, it sought to (a) explain why and how the species coexisted over part of their range in lakes of moderate salinity, and (b) deduce why C. expleta is absent from the more freshwater lakes. The thesis is divided into six sections. An introduction, reviewing competition theory and summarising the problem, is followed by studies on the environments investigated, in Chapter II. Chapter III discusses distribution, abundance and breeding pattern of the corixid species encountered, to obtain data relevant to certain indirect measures of competition, and Chapters IV and V describe feeding experiments and serological gut analyses of field-collected corixids. The feeding experiments aimed to obtain one measure of the fundamental niche, while the gut enalyses were carried out fer a measure of the realised niche. The final section discusses the findings in terms of potential species interaction. The study area comprised six lakes on Becher's Prairie, in the Chilcotin area of B.C., and another near Kamloops; all lakes were similar in general morphology. Although temperature patterns were similar between lakes, they varied considerably in conductivity. Temperatures and conductivity data corroborate earlier findings, suggesting that the studied years were not atypical. Oxygen levels and phytoplankton primary production were generally higher in the more freshwater lakes, but the contribution of aquatic macrophytes and benthic algae there was not measured. Phytoplankon production was restrained. Plankters were abundant in all lakes, especially inshore, but the levels fluctuated most in the three freshwater lakes, being very low there before mid-June. Diaptomid copepods and fairy shrimps were confined to the higher salinity lakes, while chaoborids and amphipods were restricted to the three freshwater lakes; other invertebrates were widely distributed. Both biomass and diversity of organisms were highest in the freshwater lakes, but they were by no means low in the saline lakes studied. The data suggest that there was an abundance of food in all lakes at all times. C. bifida bred in all lakes investigated, although excluded apparently through increasing salinity from lake LB 2 after spring. C. expleta bred sympatrically with C. bifida in waters of over 6000 umhos cm-1 conductivity, whereas Cymatia americana, Hesperocorixa laevigata, Callicorixa audeni and Sicjara sp. bred only in the three most freshwater lakes. C. expleta produced three generations a year in the highest salinities (LB 2 and Barnes Lakes) and two in other high salinities. C. bifida produced two generations a year in the higher salinities, but like all the other corixids, in the three most freshwater lakes often produced only one generation a year. Corixids showed no definite trends of different abundance with alkalinity, and the two species of Cenocorixa did not show depressed population levels in sympatry. Further, the phenology was essentially contemporary in sympatry. C. expleta when allopatric occurred in both marginal and mid-lake areas, whereas C. bifida when allopatric was more confined to the littoral areas. In both species, habitat preferences of instars varied with season, but in general the largest individuals of each species preferred the most complex environments. Overall, C. expleta in sympatry was relatively commanest over deeper waters and over plain mud or silt, whereas C. bifida preferred rocks, logs and reeds. However, the segregation was not marked. Both C. bifida and C. expleta took a wide variety of preys offered in experiments. C. expleta adults accepted more of the preys offered than did C. bifida. Juveniles showed less marked species differences than did adults, and accepted prey more often than them. Both species accepted both live and dead organisms. Juveniles of both species preferred dead prey to live; however, only for C. expleta was this trend significant overall. When offered live or dead mixed plankton, C. bifida took chiefly ceriodaphniids, whereas C. expleta took both diaptomids and ceriodaphniids in the proportions offered. In other choice situations, both species fed more often on chironomids than daphniids, taking zygopterans least. However, unsuccessful attacks were far more frequent on daphniids than on the benthic and littoral organisms. In summary, the experimental feeding results suggest that the fundamental niches of the two species of Cenocorixa are similar, but not identical. Guts of field-collected corixids were analysed by serological techniques using 10 active antisera. Mcst reactions indicated a clearly carnivorous habit, less than 1% being positive for algae. Results suggest that foods eaten varied dynamically between instars, lakes and seasons. In C. bifida daphniids and zygopterans were more frequently recorded in guts from the sympatric lakes than from the freshwater lakes. Ephemeropterans and amphipods were identified chiefly from summer-collected corixids, and were chiefly restricted to the freshwater lakes, paralleling their distribution. However, some reactions were also seen in guts from these lakes with diaptomid antiserum, perhaps a reaction to other copepod species. In C. expleta most positive results were seen for daphniids in spring and fall corixid samples. More male than female C. exjaleta took ephemeropterans, and more male than female C. bifida took zygopterans. Specific differences between saline and freshwater lakes seemed to relate to prey distribution, but in Lake LB 2 C. exgleta took significantly more diaptomids in fall than in summer. In sympatry, most juveniles of both species took an increasingly diverse diet with increasing instar size, although the preferred order chironomids, then zygopterans, ephemeropterans and diaptomids, remained relatively constant. Second instar C. expleta reached a plateau level of feeding intensity only reached by third instar C. bifida ; this seems related to instar size. In larger instars, C. bifida showed more serological reactions with most foodstuffs than e. expleta. Overall, C. expleta showed more positive reactions than C. bifida with chironomids and daphniids, but less with diaptomids and zygopterans. In sympatry, C. bifida fed more on daphniids and ephemeropterans than in allopatry, which tends to contradict ideas of competition for food. The serological data suggest that the realised niche with respect to feeding is not markedly more restricted than the fundamental niche. Other corixid species had similarly carnivorous diets, C. audeni showing more reactions for amphipods and chironomids than H. laevigata , but less for chaoborids, suggesting more benthic orientation for the former. In field-collected corixids, red guts usually contained diaptomids, while brown guts reacted with a variety of antisera. In several brown and olive guts there was no serological reaction, indicating that the antisera did not cover the total dietary range. Occasional guts were bright blue-green, suggesting cyanophyte material. Despite, a wide geographical overlap between the species, C. bifida and C. expleta possess somewhat different osmotic and ionic regulatory capacities, and show slightly different habitat and food preferences. Therefore they cannot be considered as true ecological homologues, and hence competition need not necessarily result in exclusion of one or other. With regard to habitat, some of the differences observed may be related to variation in the environments between lakes studied, but other differences show the species not to be identical. C. expleta seems to have a rather wider fundamental niche in terms of habitat than C. bifida, but neither show marked restriction in sympatry. The serological feeding results suggest that in sympatry, each species took different proportions of the same foodstuffs. The realised niches appear somewhat restricted from the fundamental niche data obtained from feeding experiments. C. expleta seemed somewhat more specialised in feeding than C. bifida, thus fulfilling the requirements cof an included niche species; again a point usually considered to permit coexistence. However, diet and habitat preferences of species and instars varied with season and lake, suggesting that pooling data obscures much of the real variation. In general, the evidence shows that the two species of Cenocorixa are not exact ecological homologues, and competition between them in sympatry was not evident. The reason for the absence of C. expleta from the more freshwater lakes, to which it appears physiologically suited, still remains obscure.
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Limnology is well served by a number of international texts, but these reflect in the main the large continental land-masses. Although processes and community structures in Irish lakes and streams are the same as those encountered elsewhere, an outlying island will always be subject to different factors and influences.
In this short account you will find descriptions of the rock structure of Ireland, which is largely Palaeozoic, and of its geomorphology – a rather flat centre surrounded by an intermittent ring of mountains. These impose special conditions: lakes and catchments may be large in the centre, smaller at the periphery. In former times ice-sheets irregularly eroded the landscape and dumped transported materials, resulting in extensive, often shallow lake basins. The oceanic climate has encouraged the luxuriant growth of aquatic vegetation leading to the accumulation of large peat deposits. Today, the high rainfall and westerly winds ensure rapid flushing of many lakes, and stratification is rare. Karstified lowland limestone beds have permitted underground drainage, which spills over during periods of high flow into temporary surface lakes of ‘turloughs’.
The main sections of this book contain descriptions of the larger lakes and of other wetlands of particularly Irish interest, biogeographical considerations of the fauna and flora, and human impacts on Irish aquatic systems. Each section is necessarily brief and selective, but it is hoped that it may serve as an introduction to further reading through a general bibliography at the end of each chapter, and selected text references (indicated by numbers). The short text is supplemented by appendices providing information on former contributors to limnology in Ireland and on the current research activities of many institutions. There is a brief annotated gazetteer to Irish lakes, rivers and wetlands. Finally, there is a detailed index to topics and species mentioned in the text.
Three key topics are the present situation of crayfish in world freshwater ecosystems, the application of science to conservation management, and knowledge transfer for successful crayfish management, thus protecting ecosystem quality in the future.
For a decade from 1885, Sir Stephen de Vere of Curragh Chase and Foynes Island, County Limerick, translated most of the Odes of Horace, assisted by his poet brother Aubrey de Vere and sometimes with inputs from other Limerick and Clare landowners. Existing translations were ordered by post, and printers and publishers dealt with from a remote location. Stephen’s unpublished journals detail the interactions between the brothers, here exemplified by 19 selected odes, with full texts and notes on publication. Their published translations were admired and read into the 1900s.
So tourists don't need to get manic -
There'll be no torrid heat,
Frequent rain is a treat,
And westerly winds, so don't panic.