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19 Research products, page 1 of 2

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  • Open Access English
    Authors: 
    Gunn, Jeffrey David;

    By the late eighteenth century, the ever-increasing British need for local labour in West Africa based on malarial, climatic, and manpower concerns led to a willingness of the British and Kru to experiment with free wage labour contracts. The Krus familiarity with European trade on the Kru Coast (modern Liberia) from at least the sixteenth century played a fundamental role in their decision to expand their wage earning opportunities under contract with the British. The establishment of Freetown in 1792 enabled the Kru to engage in systematized work for British merchants, ship captains, and British naval officers. Kru workers increased their migration to Freetown establishing what appears to be their first permanent labouring community beyond their homeland on the Kru Coast. Their community in Freetown known as Kroo Town (later Krutown) ensured their regular employment on board British commercial ships and Royal Navy vessels circumnavigating the Atlantic and beyond. In the process, the Kru established a network of Krutowns and community settlements in many Atlantic ports including Fernando Po, Ascension Island, and the Cape of Good Hope, and in the British Caribbean in British Guiana and Trinidad. This dissertation structures the fragmented history of Kru workers into a coherent framework. In this study, I argue that the migration of Kru workers in the Atlantic, and even to the Indian and Pacific Oceans, represents a movement of free wage labour that transformed the Kru Coast into a homeland that nurtured diasporas and staffed a vast network of workplaces. As the Kru formed permanent and transient working communities, they underwent several phases of social, political, and economic innovation, which ultimately overcame a decline in employment in their homeland on the Kru Coast by the end of the nineteenth century by increasing employment in their diaspora. At a time when slavery was widespread and the slave trade was subjected to the abolition campaign of the British Navy, Kru workers were free with an expertise in manning seaborne craft. The Kru thereby stand out as an anomaly in the history of Atlantic trade when compared with the much larger diasporas of enslaved Africans.

  • Open Access
    Authors: 
    Paul, Michael;
    Publisher: DEU

    On the occasion of the 70th founding anniversary of China’s national navy, a big naval parade with more than 30 Chinese ships sailed off the coast of Qingdao. A few days later, on 29 April 2019, the "Joint Sea 2019" Russian-Chinese bilateral naval exercise began. In numbers, China’s navy now has the world’s biggest fleet - also thanks to decades of Russian naval armament. From Beijing's point of view, however, the Chi­nese armed forces have a serious shortcoming: a lack of operational experience. Here, too, Moscow fills some gaps. Since the first joint manoeuvre in 2005, cooperation has increased at many levels. Sino-Russian sea manoeuvres now also serve as a menacing signal of support for China’s claims in the South China Sea or in the Sino-Japanese disputes in the East China Sea. Moscow and Beijing use the joint naval exercises to set geopolitical signals. Despite all historic mistrust, Sino-Russian cooperation seems to rest on a relatively stable foundation of partnership. But maritime cooperation and coordinated partnership must not lead to an alliance. (Autorenreferat)

  • Open Access English
    Authors: 
    Gold Quiros, Taylor Rene;

    Mercury (Hg) is known to bioaccumulate over time in freshwater fish and biomagnify up freshwater food webs, so top predatory fish have the highest Hg body burden. Within Texas, Hg studies in freshwater fish have primarily focused on the northern half of the state and south Texas is relatively understudied. This study investigated the concentration of Hg in muscle tissue from 41 trophically diverse species (n = 1,772) in relation to body length and trophic position at five sites on the Guadalupe River in South Central Texas using a direct mercury analyzer and stable isotope analysis (δ13C, δ15N). The majority of fishes showed a positive relationship between body length and Hg concentration, indicating that Hg was bioaccumulating over time. Striped mullet was the only species that displayed an inverse relationship suggesting growth dilution is occurring. Mercury concentrations were higher in top predators including longnose gar, flathead catfish, and striped bass, and lower in moderate and low trophic level fishes, including Mexican tetra, threadfin shad, and suckermouth catfish. Within the five sites examined, the average Hg concentration in each species was higher in reservoir sites than riverine sites. There was a positive relationship (p < 0.05) between δ15N and Hg concentration at 4 of the 5 sites, indicating that Hg biomagnification is occurring at these sites. The biomagnification factor differed between sites, however it was not positively correlated with food chain length. Among species, the estimated trophic level was the strongest predictor of Hg concentration and within species, total length was the strongest predictor of Hg concentration. These findings provide valuable insight into bioaccumulation and biomagnification of Hg in a relatively understudied freshwater system in South Central Texas. Four species (flathead catfish, white bass, striped bass and longnose gar) had at least one individual that exceeded the Texas Department of State Health Services (TDSHS) human health criterion for Hg (0.7 µg/g wet weight), with at least one species at Canyon Lake, Lake Dunlap, and Victoria exceeding the guideline. Based on this data, the current Hg advisory for Canyon Lake needs to be reevaluated and Victoria and Lake Dunlap may need to have Hg advisories issued.

  • Open Access English
    Authors: 
    Gates, Anna Y.;

    Heavy rainfall events have been associated with outbreaks of many waterborne diseases including salmonellosis. Salmonellosis is caused by members of the genus Salmonella that can enter water systems through sewage contamination, runoff after heavy rainfalls, or flow-through channels through manure fields after heavy rains or flooding. Currently, salmonellae are not closely monitored in regards to water quality. In this study, Hypostomus plecostomus, an invasive, algae consuming fish, was sampled from the San Marcos River (San Marcos, TX), the intestines analyzed for the presence of salmonellae by quantitative real-time polymerase chain reaction (qPCR) after semi-selective enrichment, and results related to precipitation and other ecological factors affecting the river area. Salmonellae were detected in the intestines of H. plecostomus in 40-100% of the fish following most precipitation events, but were not consistently detected in environmental samples (i.e. water and sediments). Other ecological factors affecting the river do not appear to play a significant role in the prevalence of salmonellae in the intestines of H. plecostomus, other than turbidity. This leads us to believe that H. plecostomus is ingesting salmonellae through their food sources and that the amount of salmonellae present in those food sources may be increasing after large rainfall events, but may not be dependent on these events. Further studies included characterization of Salmonella isolates from positive samples by repetitive polymerase chain reaction (rep-PCR). Unique isolates were then serotyped using Multi-locus Sequence Typing (MLST). Several sampled H. plecostomus were observed to be infected by multiple serotypes of Salmonella, whereas other positive fish were observed to be infected by one serotype only. Some serotypes were observed to be common across multiple sampling dates, which leads us to believe that there may be a common environmental serotype residing in the intestines of infected H. plecostomus. Furthermore, detection of multiple serotypes in the intestines of H. plecostomus was an unexpected observation.

  • Open Access English
    Authors: 
    Maguire, Heather Fiona;

    Commercial shipping is a vital part of Canadas economy, moving goods through an intricate network of waterways, lakes, rivers and ports. It is also an industry that is undergoing a remarkable transformation, as new (at least to the industry) digital technologies are taking hold in the wheelhouses and engine rooms of these freighters and tankers. Coupled with the emergence of the digital ship, sailors now have access to a broad array of mobile information and communication technologies, including cellphones, and satellite-based internet access. In light of this, this thesis considers the experiences of sailors who grapple with these changes, to explore how mobile ICTs challenge, complicate, enhance, and otherwise transform their lives. This thesis draws on ethnographic research conducted over a month-long, 4,000 nautical mile journey on an articulated tug and barge that transports liquid asphalt and other black oil products through the Great Lakes-St. Lawrence Seaway system. Drawing upon media studies, science and technology studies, and mobilities studies, I seek to understand the physical, representational, and virtual worlds of sailors as an assemblage of devices, people, movements, geographies and histories. To do so, three interconnected narratives emerge. The first is a story of connectivity, as sailors manage the home-work divide. The second story is about the sociotechnical power of mobile ICTs, as expertise and autonomy are being eroded by the use of digital devices. The third story is perhaps in response to mobile ICTs, a story about how, even with all of these digital and automation technologies now permeating the fabric of sailors everyday lives, they still, first and foremost, rely on their embodied knowledge to do their jobs. I argue that while the virtual and the representational worlds of the sailor are important, the physical world still holds sway.

  • Open Access English
    Authors: 
    Codd-Downey, Robert Frank;

    This work examines the problem of solving SLAM in aquatic environments using an unmanned surface vessel under conditions that restrict global knowledge of the robot's pose. These conditions refer specifically to the absence of a global positioning system to estimate position, a poor vehicle motion model, and absence of magnetic field to estimate absolute heading. These conditions are present in terrestrial environments where GPS satellite reception is occluded by surrounding structures and magnetic inference affects compass measurements. Similar conditions are anticipated in extra-terrestrial environments such as on Titan which lacks the infrastructure necessary for traditional positioning sensors and the unstable magnetic core renders compasses useless. This work develops a solution to the SLAM problem that utilizes shore features coupled with information about the depth of the water column. The approach is validated experimentally using an autonomous surface vehicle utilizing omnidirectional video and SONAR, results are compared to GPS ground truth.

  • Open Access English
    Authors: 
    Farah, Qasim Hersi;

    Since January 1991, Somalia has been a war-torn society without law and order machinery. After a decade of chaos, in January 2001, an interim government formed in Djibouti was brought to Mogadishu, albeit it failed to function. Two similar others followed; one in 2004 and the other in 2007. In 2012, a federal government was elected by 275 members of parliament, but it is yet to govern most of the countrys regions. Consequently, over 25 years, there has been sociopolitical and economic instability which jeopardised Somalias environment and security (land and marine). Now, who are the actors of socio-political and economic instability, and can marine sustainability be achieved in the absence of stability? This doctoral study identifies, defines, examines and analyzes each of the state and non-state actors/networks operating in Somalia, at the international, regional, national, provincial, and local levels. I investigated who are they and what are their backgrounds/origins? What are their objectives and strategies? What are their capacities and economic status? What are their motives and manoeuvres? and what are their internal and external relationships? I categorised each one of them based on these scales: instability, potential stability or stability. I adopted a multi-dimensional approach which aims at tackling both marine environmental degradation and insecurity in the Somali basin, while establishing a community-based policy as a milestone for the formulation of a national/provincial policy. The study finds out that the competing multifaceted and multipurpose (economic, political or social gains) networks deliberately or inadvertently destroy the countrys environment and contribute to instability. Yet, in the countrys post-conflict situation, environmental traditional-based policy and socio-legal systems can be practiced at the grassroots level. I then proposed the roles to be played by individuals, local communities, provincials, and national, as well as regional, and international communities in the implementation of this bottom-up approach policy. While showing the relationship between environmental sustainability and sociopolitical stability, I argue that marine problems are borderless and as such, need global attention. I shed light on how war-torn states and post-conflict countries can establish vital means of environmental sustainability by applying community-based policy, implemented through self-help programs.

  • Open Access English
    Authors: 
    Chen, Miranda;

    As global air temperatures rise and precipitation events fluctuate as a result of climate change, environmental conditions for many freshwater fish are expected to change. Fish are particularly sensitive to climate change as their distributions and contaminant loads are influenced by water temperatures. My study focuses on two main objectives: (1) how the distributions of cisco (Coregonus artedii) may be altered by future climate change and (2) the role of climate and industrial emissions on fish mercury trends in Ontario. Data were obtained from multiple government and open sources. Future cisco occurrence models demonstrated a decline of 7-47% by 2070. Trend analysis and models of mercury levels in sport fish revealed increasing rates (0.2-0.4 ug/g/decade) within recent years, particularly influenced by changes in local climate. This period of rapid environmental change demands further investigation, to better inform fisheries management decisions and consumption advisories at various spatial and temporal scales.

  • Open Access English
    Authors: 
    Phillips, Melissa B.;

    Occurrence and types of microplastics in the digestive system of freshwater fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments. Recent studies report increasing amounts of microplastics in marine systems and in the gut tracts of marine fishes. To date, only one study has reported percent occurrence of microplastics (12%) in the digestive system of freshwater fishes. Purposes of this study were to quantify occurrences and types of microplastics ingested by fishes within the western freshwater drainages of the Gulf Mexico and an estuary of the Gulf of Mexico. My study objectives were (1) to enumerate and identify microplastics from fishes taken from 10 sites and nine freshwater drainages of Texas and harbor, bay, and gulf sites within or near the Laguna Madre of southeast Texas, (2) to compare percent occurrence of microplastics among habitat and trophic guilds of fishes, and (3) to compare percent occurrence of microplastics between urbanized and non-urbanized streams and thus test the hypothesis that fishes from urbanized streams will have greater percent occurrence of microplastics than fishes from non-urbanized streams. Among 535 fishes examined in this study, percent occurrence of microplastics was 8% in freshwater fishes and 10% in marine fishes. Plastic types included polyester, polystyrene, polypropylene, acrylate, and nylon. Percent occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one urbanized streams (Neches River; 29%). Percent occurrence by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar. Percent occurrences of microplastics reported herein are similar for freshwater fishes and towards the lower end of the range of microplastic ingestion in marine fishes (range: 8 - 33%). Occurrences of microplastics in the fishes pose several environmental concerns. For fish health, microplastics absorb toxins and can be passed through the digestive system, into the circulatory system, and accumulate in tissue. Long-term effects are unknown for the fish or the effects on human consumers.

  • Open Access English
    Authors: 
    Vaughn, Christopher R.;

    Water quantity management in Texas and elsewhere is currently managed under the theory of the Natural Flow Paradigm, which states that sound ecological riverine environments are dependent upon the dynamic character of flow. Water quantity recommendations and standards prescribe a multi-tier flow regime, consisting of subsistence, base, and high-flow pulses, with magnitudes of each based on long-term averages of site-specific hydrographs. The next step in water quantity management is to validate that the recommended flow regimes are sufficient to maintain a sound ecological environment, although validation methodologies are rarely incorporated into water quantity management plans. Purposes of this study were to develop methodologies for validating flow recommendation and standards that are transferable and replicable and to quantify the value of flow tiers relating to organic drift. Objectives of this study were to assess drift biomass of coarse particulate matter (CPM) and drift rates of macroinvertebrates and larval fishes related to flow tiers (i.e., subsistence, base, two per season high flow pulse, one per season high flow pulse, and one per year high flow pulse) across four sites and two rivers (i.e., San Antonio and Guadalupe rivers). A priori predictions were that CPM, macroinvertebrates, and larval fishes were in greater biomass or densities at higher levels of flow tiers, though at some point flows would be sufficiently high and induce a washout effect. Findings were generally inconsistent with the predications. Biomass of CPM did not differ among flows ranging from subsisted to two per season high flow pulse events, and densities of macroinvertebrate did not differ among flows ranging between base and one per season events. However, densities of fluvial specialist Neoperla (Order Plecoptera) were positively correlated with flow as a continuous variable rather than a categorical variable. Densities of larval fishes were greatest at subsistence, base, and two per season high flow pulses and decreased at 1 per season flow pulses. It is uncertain if a washout effect occurred or if survival of larval fishes was decreased at a higher flow pulses. With a validation methodology in place, replications from other sites and river basins can be added to the existing model to improve statistical power and inference, along with other flow-dependent variables, in order to fully assess the value of multi-tier flow regimes.

Advanced search in Research products
Research products
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Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
The following results are related to European Marine Science. Are you interested to view more results? Visit OpenAIRE - Explore.
19 Research products, page 1 of 2
  • Open Access English
    Authors: 
    Gunn, Jeffrey David;

    By the late eighteenth century, the ever-increasing British need for local labour in West Africa based on malarial, climatic, and manpower concerns led to a willingness of the British and Kru to experiment with free wage labour contracts. The Krus familiarity with European trade on the Kru Coast (modern Liberia) from at least the sixteenth century played a fundamental role in their decision to expand their wage earning opportunities under contract with the British. The establishment of Freetown in 1792 enabled the Kru to engage in systematized work for British merchants, ship captains, and British naval officers. Kru workers increased their migration to Freetown establishing what appears to be their first permanent labouring community beyond their homeland on the Kru Coast. Their community in Freetown known as Kroo Town (later Krutown) ensured their regular employment on board British commercial ships and Royal Navy vessels circumnavigating the Atlantic and beyond. In the process, the Kru established a network of Krutowns and community settlements in many Atlantic ports including Fernando Po, Ascension Island, and the Cape of Good Hope, and in the British Caribbean in British Guiana and Trinidad. This dissertation structures the fragmented history of Kru workers into a coherent framework. In this study, I argue that the migration of Kru workers in the Atlantic, and even to the Indian and Pacific Oceans, represents a movement of free wage labour that transformed the Kru Coast into a homeland that nurtured diasporas and staffed a vast network of workplaces. As the Kru formed permanent and transient working communities, they underwent several phases of social, political, and economic innovation, which ultimately overcame a decline in employment in their homeland on the Kru Coast by the end of the nineteenth century by increasing employment in their diaspora. At a time when slavery was widespread and the slave trade was subjected to the abolition campaign of the British Navy, Kru workers were free with an expertise in manning seaborne craft. The Kru thereby stand out as an anomaly in the history of Atlantic trade when compared with the much larger diasporas of enslaved Africans.

  • Open Access
    Authors: 
    Paul, Michael;
    Publisher: DEU

    On the occasion of the 70th founding anniversary of China’s national navy, a big naval parade with more than 30 Chinese ships sailed off the coast of Qingdao. A few days later, on 29 April 2019, the "Joint Sea 2019" Russian-Chinese bilateral naval exercise began. In numbers, China’s navy now has the world’s biggest fleet - also thanks to decades of Russian naval armament. From Beijing's point of view, however, the Chi­nese armed forces have a serious shortcoming: a lack of operational experience. Here, too, Moscow fills some gaps. Since the first joint manoeuvre in 2005, cooperation has increased at many levels. Sino-Russian sea manoeuvres now also serve as a menacing signal of support for China’s claims in the South China Sea or in the Sino-Japanese disputes in the East China Sea. Moscow and Beijing use the joint naval exercises to set geopolitical signals. Despite all historic mistrust, Sino-Russian cooperation seems to rest on a relatively stable foundation of partnership. But maritime cooperation and coordinated partnership must not lead to an alliance. (Autorenreferat)

  • Open Access English
    Authors: 
    Gold Quiros, Taylor Rene;

    Mercury (Hg) is known to bioaccumulate over time in freshwater fish and biomagnify up freshwater food webs, so top predatory fish have the highest Hg body burden. Within Texas, Hg studies in freshwater fish have primarily focused on the northern half of the state and south Texas is relatively understudied. This study investigated the concentration of Hg in muscle tissue from 41 trophically diverse species (n = 1,772) in relation to body length and trophic position at five sites on the Guadalupe River in South Central Texas using a direct mercury analyzer and stable isotope analysis (δ13C, δ15N). The majority of fishes showed a positive relationship between body length and Hg concentration, indicating that Hg was bioaccumulating over time. Striped mullet was the only species that displayed an inverse relationship suggesting growth dilution is occurring. Mercury concentrations were higher in top predators including longnose gar, flathead catfish, and striped bass, and lower in moderate and low trophic level fishes, including Mexican tetra, threadfin shad, and suckermouth catfish. Within the five sites examined, the average Hg concentration in each species was higher in reservoir sites than riverine sites. There was a positive relationship (p < 0.05) between δ15N and Hg concentration at 4 of the 5 sites, indicating that Hg biomagnification is occurring at these sites. The biomagnification factor differed between sites, however it was not positively correlated with food chain length. Among species, the estimated trophic level was the strongest predictor of Hg concentration and within species, total length was the strongest predictor of Hg concentration. These findings provide valuable insight into bioaccumulation and biomagnification of Hg in a relatively understudied freshwater system in South Central Texas. Four species (flathead catfish, white bass, striped bass and longnose gar) had at least one individual that exceeded the Texas Department of State Health Services (TDSHS) human health criterion for Hg (0.7 µg/g wet weight), with at least one species at Canyon Lake, Lake Dunlap, and Victoria exceeding the guideline. Based on this data, the current Hg advisory for Canyon Lake needs to be reevaluated and Victoria and Lake Dunlap may need to have Hg advisories issued.

  • Open Access English
    Authors: 
    Gates, Anna Y.;

    Heavy rainfall events have been associated with outbreaks of many waterborne diseases including salmonellosis. Salmonellosis is caused by members of the genus Salmonella that can enter water systems through sewage contamination, runoff after heavy rainfalls, or flow-through channels through manure fields after heavy rains or flooding. Currently, salmonellae are not closely monitored in regards to water quality. In this study, Hypostomus plecostomus, an invasive, algae consuming fish, was sampled from the San Marcos River (San Marcos, TX), the intestines analyzed for the presence of salmonellae by quantitative real-time polymerase chain reaction (qPCR) after semi-selective enrichment, and results related to precipitation and other ecological factors affecting the river area. Salmonellae were detected in the intestines of H. plecostomus in 40-100% of the fish following most precipitation events, but were not consistently detected in environmental samples (i.e. water and sediments). Other ecological factors affecting the river do not appear to play a significant role in the prevalence of salmonellae in the intestines of H. plecostomus, other than turbidity. This leads us to believe that H. plecostomus is ingesting salmonellae through their food sources and that the amount of salmonellae present in those food sources may be increasing after large rainfall events, but may not be dependent on these events. Further studies included characterization of Salmonella isolates from positive samples by repetitive polymerase chain reaction (rep-PCR). Unique isolates were then serotyped using Multi-locus Sequence Typing (MLST). Several sampled H. plecostomus were observed to be infected by multiple serotypes of Salmonella, whereas other positive fish were observed to be infected by one serotype only. Some serotypes were observed to be common across multiple sampling dates, which leads us to believe that there may be a common environmental serotype residing in the intestines of infected H. plecostomus. Furthermore, detection of multiple serotypes in the intestines of H. plecostomus was an unexpected observation.

  • Open Access English
    Authors: 
    Maguire, Heather Fiona;

    Commercial shipping is a vital part of Canadas economy, moving goods through an intricate network of waterways, lakes, rivers and ports. It is also an industry that is undergoing a remarkable transformation, as new (at least to the industry) digital technologies are taking hold in the wheelhouses and engine rooms of these freighters and tankers. Coupled with the emergence of the digital ship, sailors now have access to a broad array of mobile information and communication technologies, including cellphones, and satellite-based internet access. In light of this, this thesis considers the experiences of sailors who grapple with these changes, to explore how mobile ICTs challenge, complicate, enhance, and otherwise transform their lives. This thesis draws on ethnographic research conducted over a month-long, 4,000 nautical mile journey on an articulated tug and barge that transports liquid asphalt and other black oil products through the Great Lakes-St. Lawrence Seaway system. Drawing upon media studies, science and technology studies, and mobilities studies, I seek to understand the physical, representational, and virtual worlds of sailors as an assemblage of devices, people, movements, geographies and histories. To do so, three interconnected narratives emerge. The first is a story of connectivity, as sailors manage the home-work divide. The second story is about the sociotechnical power of mobile ICTs, as expertise and autonomy are being eroded by the use of digital devices. The third story is perhaps in response to mobile ICTs, a story about how, even with all of these digital and automation technologies now permeating the fabric of sailors everyday lives, they still, first and foremost, rely on their embodied knowledge to do their jobs. I argue that while the virtual and the representational worlds of the sailor are important, the physical world still holds sway.

  • Open Access English
    Authors: 
    Codd-Downey, Robert Frank;

    This work examines the problem of solving SLAM in aquatic environments using an unmanned surface vessel under conditions that restrict global knowledge of the robot's pose. These conditions refer specifically to the absence of a global positioning system to estimate position, a poor vehicle motion model, and absence of magnetic field to estimate absolute heading. These conditions are present in terrestrial environments where GPS satellite reception is occluded by surrounding structures and magnetic inference affects compass measurements. Similar conditions are anticipated in extra-terrestrial environments such as on Titan which lacks the infrastructure necessary for traditional positioning sensors and the unstable magnetic core renders compasses useless. This work develops a solution to the SLAM problem that utilizes shore features coupled with information about the depth of the water column. The approach is validated experimentally using an autonomous surface vehicle utilizing omnidirectional video and SONAR, results are compared to GPS ground truth.

  • Open Access English
    Authors: 
    Farah, Qasim Hersi;

    Since January 1991, Somalia has been a war-torn society without law and order machinery. After a decade of chaos, in January 2001, an interim government formed in Djibouti was brought to Mogadishu, albeit it failed to function. Two similar others followed; one in 2004 and the other in 2007. In 2012, a federal government was elected by 275 members of parliament, but it is yet to govern most of the countrys regions. Consequently, over 25 years, there has been sociopolitical and economic instability which jeopardised Somalias environment and security (land and marine). Now, who are the actors of socio-political and economic instability, and can marine sustainability be achieved in the absence of stability? This doctoral study identifies, defines, examines and analyzes each of the state and non-state actors/networks operating in Somalia, at the international, regional, national, provincial, and local levels. I investigated who are they and what are their backgrounds/origins? What are their objectives and strategies? What are their capacities and economic status? What are their motives and manoeuvres? and what are their internal and external relationships? I categorised each one of them based on these scales: instability, potential stability or stability. I adopted a multi-dimensional approach which aims at tackling both marine environmental degradation and insecurity in the Somali basin, while establishing a community-based policy as a milestone for the formulation of a national/provincial policy. The study finds out that the competing multifaceted and multipurpose (economic, political or social gains) networks deliberately or inadvertently destroy the countrys environment and contribute to instability. Yet, in the countrys post-conflict situation, environmental traditional-based policy and socio-legal systems can be practiced at the grassroots level. I then proposed the roles to be played by individuals, local communities, provincials, and national, as well as regional, and international communities in the implementation of this bottom-up approach policy. While showing the relationship between environmental sustainability and sociopolitical stability, I argue that marine problems are borderless and as such, need global attention. I shed light on how war-torn states and post-conflict countries can establish vital means of environmental sustainability by applying community-based policy, implemented through self-help programs.

  • Open Access English
    Authors: 
    Chen, Miranda;

    As global air temperatures rise and precipitation events fluctuate as a result of climate change, environmental conditions for many freshwater fish are expected to change. Fish are particularly sensitive to climate change as their distributions and contaminant loads are influenced by water temperatures. My study focuses on two main objectives: (1) how the distributions of cisco (Coregonus artedii) may be altered by future climate change and (2) the role of climate and industrial emissions on fish mercury trends in Ontario. Data were obtained from multiple government and open sources. Future cisco occurrence models demonstrated a decline of 7-47% by 2070. Trend analysis and models of mercury levels in sport fish revealed increasing rates (0.2-0.4 ug/g/decade) within recent years, particularly influenced by changes in local climate. This period of rapid environmental change demands further investigation, to better inform fisheries management decisions and consumption advisories at various spatial and temporal scales.

  • Open Access English
    Authors: 
    Phillips, Melissa B.;

    Occurrence and types of microplastics in the digestive system of freshwater fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments. Recent studies report increasing amounts of microplastics in marine systems and in the gut tracts of marine fishes. To date, only one study has reported percent occurrence of microplastics (12%) in the digestive system of freshwater fishes. Purposes of this study were to quantify occurrences and types of microplastics ingested by fishes within the western freshwater drainages of the Gulf Mexico and an estuary of the Gulf of Mexico. My study objectives were (1) to enumerate and identify microplastics from fishes taken from 10 sites and nine freshwater drainages of Texas and harbor, bay, and gulf sites within or near the Laguna Madre of southeast Texas, (2) to compare percent occurrence of microplastics among habitat and trophic guilds of fishes, and (3) to compare percent occurrence of microplastics between urbanized and non-urbanized streams and thus test the hypothesis that fishes from urbanized streams will have greater percent occurrence of microplastics than fishes from non-urbanized streams. Among 535 fishes examined in this study, percent occurrence of microplastics was 8% in freshwater fishes and 10% in marine fishes. Plastic types included polyester, polystyrene, polypropylene, acrylate, and nylon. Percent occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one urbanized streams (Neches River; 29%). Percent occurrence by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar. Percent occurrences of microplastics reported herein are similar for freshwater fishes and towards the lower end of the range of microplastic ingestion in marine fishes (range: 8 - 33%). Occurrences of microplastics in the fishes pose several environmental concerns. For fish health, microplastics absorb toxins and can be passed through the digestive system, into the circulatory system, and accumulate in tissue. Long-term effects are unknown for the fish or the effects on human consumers.

  • Open Access English
    Authors: 
    Vaughn, Christopher R.;

    Water quantity management in Texas and elsewhere is currently managed under the theory of the Natural Flow Paradigm, which states that sound ecological riverine environments are dependent upon the dynamic character of flow. Water quantity recommendations and standards prescribe a multi-tier flow regime, consisting of subsistence, base, and high-flow pulses, with magnitudes of each based on long-term averages of site-specific hydrographs. The next step in water quantity management is to validate that the recommended flow regimes are sufficient to maintain a sound ecological environment, although validation methodologies are rarely incorporated into water quantity management plans. Purposes of this study were to develop methodologies for validating flow recommendation and standards that are transferable and replicable and to quantify the value of flow tiers relating to organic drift. Objectives of this study were to assess drift biomass of coarse particulate matter (CPM) and drift rates of macroinvertebrates and larval fishes related to flow tiers (i.e., subsistence, base, two per season high flow pulse, one per season high flow pulse, and one per year high flow pulse) across four sites and two rivers (i.e., San Antonio and Guadalupe rivers). A priori predictions were that CPM, macroinvertebrates, and larval fishes were in greater biomass or densities at higher levels of flow tiers, though at some point flows would be sufficiently high and induce a washout effect. Findings were generally inconsistent with the predications. Biomass of CPM did not differ among flows ranging from subsisted to two per season high flow pulse events, and densities of macroinvertebrate did not differ among flows ranging between base and one per season events. However, densities of fluvial specialist Neoperla (Order Plecoptera) were positively correlated with flow as a continuous variable rather than a categorical variable. Densities of larval fishes were greatest at subsistence, base, and two per season high flow pulses and decreased at 1 per season flow pulses. It is uncertain if a washout effect occurred or if survival of larval fishes was decreased at a higher flow pulses. With a validation methodology in place, replications from other sites and river basins can be added to the existing model to improve statistical power and inference, along with other flow-dependent variables, in order to fully assess the value of multi-tier flow regimes.