Seasonal cycles of phytoplankton in relation to the hydrography of Monterey Bay

Annual cycles of relative abundance are described for phytoplankton species collected from Monterey Bay, California, from July 1974 to June 1976, and the population dynamics related to the annual hydrographic cycle. Neritic diatom species dominated the population during the Upwelling and Oceanic periods, with dinoflagellate species becoming numerically more important during the Davidson period. Recurrent species groups identified using Fager's regroup analysis revealed the presence of a large neritic group of overwhelming numerical importance. This group is composed of indigenous species and is present in the bay during most of the year. Conspicuous changes in the phytoplankton population occurred predominantly among species within this group. During the Davidson period, the advection of southern waters into the bay may temporarily displace the endemic species with dinoflagellates becoming numerically more important. A red tide bloom of Gonyaulax polyedra occurred during this period in 1974, which dominated the phytoplankton population for a period of six weeks. The population dynamics of two hydrographically different stations were compared. A station located over the deep waters of the submarine canyon exhibited much lower phytoplankton standing stocks than a station located over the shelf area in the south of the bay, but seasonal changes in relative abundance and species composition were similar. Physical and chemical differences observed between the two stations appear to be the result of the presence of more recently upwelled water in the canyon area, and higher biological utilization in the south of the bay. A close correlation of species diversity with the depth of the mixed layer was observed, with diversity rising with the shoaling of the thermocline. It is suggested that this may reflect the introduction of new species from below the thermocline into the mixed layer as a result of upwelling activity. It is also suggested that this may be an artifact due to sampling problems associated with internal waves. (Document contains 100 pages.)

Seasonal, horizontal, and vertical distribution of phytoplankton chlorophyll a in the Northeast U.S. Continental Shelf Ecosystem

The broad scale features in the horizontal, vertical, and seasonal distribution of phytoplankton chlorophyll a on the northeast U.S. continental shelf are described based on 57,088 measurements made during 78 oceanographic surveys from 1977 through 1988. Highest mean water column chlorophyll concentration (Chlw,) is usually observed in nearshore areas adjacent to the mouths of the estuaries in the Middle Atlantic Bight (MAB), over the shallow water on Georges Bank, and a small area sampled along the southeast edge of Nantucket Shoals. Lowest Chlw «0.125 ug l-1) is usually restricted to the most seaward stations sampled along the shelf-break and the central deep waters in the Gulf of Maine. There is at least a twofold seasonal variation in phytoplankton biomass in all areas, with highest phytoplankton concentrations (m3) and highest integrated standing stocks (m2) occurring during the winter-spring (WS) bloom, and the lowest during summer, when vertical density stratification is maximal. In most regions, a secondary phytoplankton biomass pulse is evident during convective destratification in fall, usually in October. Fall bloom in some areas of Georges Bank approaches the magnitude of the WS-bloom, but Georges Bank and Middle Atlantic Bight fall blooms are clearly subordinate to WS-blooms. Measurements of chlorophyll in two size-fractions of the phytoplankton, netplankton (>20 um) and nanoplankton «20 um), revealed that the smaller nanoplankton are responsible for most of the phytoplankton biomass on the northeast U.S. shelf. Netplankton tend to be more abundant in nearshore areas of the MAB and shallow water on Georges Bank, where chlorophyll a is usually high; nanoplankton dominate deeper water at the shelf-break and deep water in the Gulf of Maine, where Chlw is usually low. As a general rule, the percent of phytoplankton in the netplankton size-fraction increases with increasing depth below surface and decreases proceeding offshore. There are distinct seasonal and regional patterns in the vertical distribution of chlorophyll a and percent netplankton, as revealed in composite vertical profiles of chlorophyll a constructed for 11 layers of the water column. Subsurface chlorophyll a maxima are ubiquitous during summer in stratified water. Chlorophyll a in the subsurface maximum layer is generally 2-8 times the concentration in the overlying and underlying water and approaches 50 to 75% of the levels observed in surface water during WS-bloom. The distribution of the ratio of the subsurface maximum chlorophyll a to surface chlorophyll a (SSR) during summer parallels the shelfwide pattern for stability, indexed as the difference in density (sigma-t) between 40 m and surface (stability 40. The weakest stability and lowest SSR's are found in shallow tidally-mixed water on Georges Bank; the greatest stability and highest SSR's (8-12:1) are along the mid and outer MAB shelf, over the winter residual water known as the "cold band." On Georges Bank, the distribution of SSR and the stability40 are roughly congruent with the pattern for maximum surface tidal current velocity, with values above 50 cms-1 defining SSR's less than 2:1 and the well-mixed area. Physical factors (bathymetry, vertical mixing by strong tidal currents, and seasonal and regional differences in the intensity and duration of vertical stratification) appear to explain much of the variability in phytoplankton chlorophyll a throughout this ecosystem. (PDF file contains 126 pages.)

Optical Remote Sensing of Coastal Habitats, Moss Landing, California, 9-11 January, 2006: workshop proceedings

The Alliance for Coastal Technologies (ACT) Workshop on Optical Remote Sensing of Coastal Habitats was convened January 9-11, 2006 at Moss Landing Marine Laboratories in Moss Landing, California, sponsored by the ACT West Coast regional partnership comprised of the Moss Landing Marine Laboratories (MLML) and the Monterey Bay Aquarium Research Institute (MBARI). The "Optical Remote Sensing of Coastal Habitats" (ORS) Workshop completes ACT'S Remote Sensing Technology series by building upon the success of ACT'S West Coast Regional Partner Workshop "Acoustic Remote Sensing Technologies for Coastal Imaging and Resource Assessment" (ACT 04-07). Drs. Paul Bissett of the Florida Environmental Research Institute (FERI) and Scott McClean of Satlantic, Inc. were the ORS workshop co-chairs. Invited participants were selected to provide a uniform representation of the academic researchers, private sector product developers, and existing and potential data product users from the resource management community to enable development of broad consensus opinions on the role of ORS technologies in coastal resource assessment and management. The workshop was organized to examine the current state of multi- and hyper-spectral imaging technologies with the intent to assess the current limits on their routine application for habitat classification and resource monitoring of coastal watersheds, nearshore shallow water environments, and adjacent optically deep waters. Breakout discussions focused on the capabilities, advantages ,and limitations of the different technologies (e.g., spectral & spatial resolution), as well as practical issues related to instrument and platform availability, reliability, hardware, software, and technical skill levels required to exploit the data products generated by these instruments. Specifically, the participants were charged to address the following: (1) Identify the types of ORS data products currently used for coastal resource assessment and how they can assist coastal managers in fulfilling their regulatory and management responsibilities; (2) Identify barriers and challenges to the application of ORS technologies in management and research activities; (3) Recommend a series of community actions to overcome identified barriers and challenges. Plenary presentations by Drs. Curtiss 0. Davis (Oregon State University) and Stephan Lataille (ITRES Research, Ltd.) provided background summaries on the varieties of ORS technologies available, deployment platform options, and tradeoffs for application of ORS data products with specific applications to the assessment of coastal zone water quality and habitat characterization. Dr. Jim Aiken (CASIX) described how multiscale ground-truth measurements were essential for developing robust assessment of modeled biogeochemical interpretations derived from optically based earth observation data sets. While continuing improvements in sensor spectral resolution, signal to noise and dynamic range coupled with sensor-integrated GPS, improved processing algorithms for georectification, and atmospheric correction have made ORS data products invaluable synoptic tools for oceanographic research, their adoption as management tools has lagged. Seth Blitch (Apalachicola National Estuarine Research Reserve) described the obvious needs for, yet substantial challenges hindering the adoption of advanced spectroscopic imaging data products to supplement the current dominance of digital ortho-quad imagery by the resource management community, especially when they impinge on regulatory issues. (pdf contains 32 pages)

Hypoxic and low pH water in the nearshore marine environments of Monterey Bay, California: characterizing a decade of oxygen and pH, and drivers of variability.

A decade-long time series recorded in southern Monterey Bay, California demonstrates that the shallow, near-shore environment (17 m depth) is regularly inundated with pulses of cold, hypoxic and low pH water. During these episodes, oxygen can drop to biologically threatening levels, and pH levels were lower than expected. Weekly water chemistry monitoring revealed that the saturation state of aragonite (the more soluble form of calcium carbonate) was often below saturation and had a moderate positive relationship with pH, however, analytical and human error could be high. Pulses of hypoxia and low pH water with the greatest intensity arise at the onset of the spring upwelling season, and fluctuations are strongly semidurnal (tidal) and diurnal. Arrival of cold, hypoxic water on the inner shelf typically occurs 3 days after the arrival of a strong upwelling event and appears to be driven by upwelling modulated by internal tidal fluctuations. I found no relationship between the timing of low-oxygen events and the diel solar cycle nor with terrestrial nutrient input. These observations are consistent with advection of hypoxic water from the deep, offshore environment where water masses experience a general decline of temperature, oxygen and pH with depth, and inconsistent with biochemical forcing. Comparisons with concurrent temperature and oxygen time series taken ~20 km away at the head of the Monterey Canyon show similar patterns but even more intense hypoxic events due to stronger semidiurnal forcing there. Analysis of the durations of exposure to low oxygen levels establishes a framework for assessing the ecological relevance of these events. Increasing oceanic hypoxia and acidification of both surface and deep waters may increase the number, intensity, duration and spatial extent of future intrusions along the Pacific coast. Evaluation of the resiliency of nearshore ecosystems such as kelp forests, rocky reefs and sandy habitats, will require consideration of these events.

A influência da deposição atmosférica da poeira mineral da Patagônia na biomassa fitoplanctônica do setor Atlântico do Oceano Austral

O Oceano Austral é a região oceânica de maior extensão em que os macronutrientes necessários à produção primária permanecem em níveis elevados por todo ano. Essa condição é conhecida como High Nutrient Low Clorophyll (HNLC) e é determinada, em grande parte, pela relativa escassez de micronutrientes, particularmente o ferro. Diversos experimentos comprovaram que a entrada de ferro neste sistema intensifica a produção biológica, aumentando a fixação do carbono e, eventualmente, sua exportação para águas profundas. Este fenômeno recebeu muita atenção nos últimos 20 anos devido a sua possível influencia no clima, via ciclo do carbono. A relação inversa entre concentração de CO2 na atmosfera e o fluxo de poeira mineral observados em registros glaciais da Antártica Central sugere que a deposição atmosférica pode ser uma importante via para o aporte de micronutrientes. Porém, a contribuição da deposição de poeira mineral para a produção primária nesta região permanece para ser demonstrada e seu possível papel no sistema climático ainda não é conclusivo. No caso do setor Atlântico do Oceano Austral, que recebe influência da Patagônia, os baixos fluxos modernos de poeira mineral e a baixa solubilidade do ferro associado à estrutura dos alumíniossilicato levam muitos autores a postular que fontes oceânicas de micronutrientes sejam mais determinantes. Faltam, no entanto, evidências experimentais. Neste trabalho, abordamos o estudo da fertilização do setor Atlântico do Oceano Austral pela poeira da Patagônia utilizando duas ferramentas: (1) o sensoriamento remoto orbital de aerossóis minerais e clorofila-a em escala interanual; e (2) um experimento de fertilização, com poeira da Patagônia, realizado na Passagem de Drake, considerando fluxos estimados para a era moderna e para o último glacial. Após doze dias de bioensaio, os tratamentos de adição de poeira mostraram a elevação da clorofila-a e da abundância de células em níveis acima dos controles. Níveis intermediários e maiores de adição não diferiram entre si na intensidade de resposta biológica, separando-se apenas da menor adição. Esses resultados indicam que a poeira da Patagônia, mesmo nos fluxos atuais, é capaz de prover os micronutrientes escassos na coluna dágua, com potencial para deflagrar aumentos significativos de biomassa. Através da análise por sensoriamento remoto, identificamos uma região de alta correlação entre poeira e clorofila-a, que está localizada entre a Frente Subtropical e a Frente Polar, se estendendo da Argentina ao sul da África. Esta região difere das águas ao sul da Frente Polar pela menor profundidade da camada de mistura, menor concentração de silicatos, baixa biomassa de diatomáceas e, estima-se, maior estresse fisiológico devido à escassez de ferro e menor aporte oceânico deste nutriente. Em conjunto, essas características parecem criar condições que tornam a resposta biológica mais sensível à deposição de poeira mineral. Estes resultados lançam nova luz sobre o controle atual da produção primária na região e sobre a hipótese da regulação climática pelo fitoplâncton no Oceano Austral, mediado pela deposição de poeira da Patagônia.

Season- and depth-dependent variability of a demersal fish assemblage in a large fjord estuary (Puget Sound, Washington)

Fjord estuaries are common along the northeast Pacific coastline, but little information is available on fish assemblage structure and its spatiotemporal variability. Here, we examined changes in diversity metrics, species biomasses, and biomass spectra (the distribution of biomass across body size classes) over three seasons (fall, winter, summer) and at multiple depths (20 to 160 m) in Puget Sound, Washington, a deep and highly urbanized fjord estuary on the U.S. west coast. Our results indicate that this fish assemblage is dominated by cartilaginous species (spotted ratfish [Hydrolagus colliei] and spiny dogfish [Squalus acanthias]) and therefore differs fundamentally from fish assemblages found in shallower estuaries in the northeast Pacific. Diversity was greatest in shallow waters (<40 m), where the assemblage was composed primarily of flatfishes and sculpins, and lowest in deep waters (>80 m) that are more common in Puget Sound and that are dominated by spotted ratf ish and seasonally (fall and summer) by spiny dogfish. Strong depth-dependent variation in the demersal fish assemblage may be a general feature of deep fjord estuaries and indicates pronounced spatial variability in the food web. Future comparisons with less impacted fjords may offer insight into whether cartilaginous species naturally dominate these systems or only do so under conditions related to human-caused ecosystem degradation. Information on species distributions is critical for marine spatial planning and for modeling energy flows in coastal food webs. The data presented here will aid these endeavors and highlight areas for future research in this important yet understudied system.

Estudo teórico e experimental da velocidade do som em sistemas contendo hidrocarbonetos

A descoberta de reservatórios de petróleo na camada do pré-sal abriu novas perspectivas para a economia brasileira. A grandes profundidades, com elevado teor de CO2 e submetidos a altas pressões e temperaturas, a exploração de petróleo das camadas de pré-sal constitui um considerável desafio tecnológico. Neste contexto, o conhecimento dos coeficientes de compressibilidade são fundamentais para o estudo do comportamento termodinâmico e escoamento dos fluidos destes campos de produção. Com este objetivo, foram determinadas experimentalmente nesta dissertação a massa específica e a velocidade do som de sistemas envolvendo quatro hidrocarbonetos puros: n-decano, n-hexadecano, decalina e tetralina, assim como para sistemas multicompostos envolvendo estes hidrocarbonetos e para uma amostra de condensado de petróleo. Os resultados obtidos permitiram o cálculo dos coeficientes de compressibilidade isentrópica, isotérmica e isentálpica. É apresentada uma avaliação sobre a capacidade de se correlacionar dados experimentais de velocidade do som aos dados calculados pelas equações de estado de Peng-Robinson e Lee-Kesler com regras de mistura: (i) Spencer e Danner e (ii) Lee-Kesler

Klima-aldaketaren eraginak euskal kostaldeko mendebaldeko sakonera handiko begetazio azpimarealean

[eus] Euskal kostaldeko mareazpiko begetazioak aldaketa esanguratsuak jasan ditu azken hiru hamarkadetan. Aurretik egindako ikerketek jakinarazi dute aldaketa horiek klima-aldaketak eragindakoak direla. Ikerketa honen helburua inpaktu horri buruzko informazio gehiago lortzea da. Horretarako, sakonera handiko uretako fitobentosaren osaerari eta ugaritasunari buruzko balioespena egin da. 2014. urteko udan 7 trantsektu ezarri ziren, Kobaroneko muturretik Muskizeko muturreraino. Trantsektu horiek aurretik ikertuak izan ziren 1982 eta 2007 urteetan, eta laginketa suntsitzailea egin zen. Analisi estatistikoek aldaketa esanguratsuak erakusten dituzte sakoneko (9-11m) komunitateetan azken 32 urteetan. Uraren tenperaturaren emendioa eta eguzki-erradiazio altuagoa detektatutako aldaketen erantzuleak izan daitezke neurri batean. Pterosiphonia complanata espezie esziafiloaren gainbeherak eta Cystoseira baccata eta Aphanocladia stichidiosa espezieen ugaritzeak hipotesi hori azaltzen dute. Espero genuenaren kontra, Gelidium corneum espeziea, sakontasun gutxiko uretan gainbehera bortitza jasaten ari dena, ez da 9 metrotik beherako sakonerara lekualdatu. Hala ere, ezin da ziurtatu egungo ingurumeneko baldintzak optimoak ez direnik G. corneum espeziearen garapenerako 9-11 metroko sakoneretan. Migrazio bertikal hori ez gertatzearen arrazoi onargarriena C. baccata- rekiko lehiakortasuna dela dirudi. Bestalde, C. baccata hiru dimentsiotako habitatak eratzeko gai den tamaina handiko alga bat da, espezie askorentzat babesleku gisa diharduena. Ondorioz, haren hedapenak G. corneum-ek sakonera txikiagoetan betetzen zuen funtzioa ordezka lezake neurri batean.

Halocinese e tectônica de rafts na bacia emersa de Benguela (Angola): dados de campo, modelagem física e restauração estrutural

Este trabalho foi feito com dados de campo da Bacia de Benguela, na costa sul de Angola. Nesta área aflora uma plataforma carbonática de idade albiana, análoga às formações produtoras de petróleo de mesma idade na Bacia de Campos. Duas unidades principais compõem a seção albiana na área: uma unidade inferior caracterizada por carbonatos de águas rasas com intercalações de conglomerados e arenitos na base, totalizando 300 m de espessura total, e uma unidade superior formada por sedimentos carbonáticos de águas mais profundas com espessura de 100 m. Esta seção se apresenta em dois domínios estruturais. O norte é caracterizado por uma plataforma de cerca de 5 km de largura, 35 km de comprimento na direção NE e que se encontra próxima ao embasamento. No domínio sul, essa plataforma se apresenta em fragmentos de menos de 10 km de comprimento por até 5 km de largura, alguns deles afastados do embasamento. Dado que há evaporitos sob essa plataforma, fez-se este trabalho com o objetivo de se avaliar a influência da tectônica salífera na estruturação das rochas albianas. A utilização de imagens de satélite de domínio público permitiu a extrapolação dos dados pontuais e a construção de perfis topográficos que possibilitaram a montagem das seções geológicas. Os dados de campo indicam que a estruturação na parte norte, onde há menos sal, é influenciada pelas estruturas locais do embasamento. Já na parte sul, onde a espessura de sal é maior, a deformação é descolada das estruturas do embasamento. Foi feita uma seção geológica em cada domínio e a restauração dessas duas seções mostrou que a unidade albiana na parte sul sofreu uma distensão de 1,25 (125%) e a de norte se distendeu em 1,05 (105%). Essa diferença foi causada por uma maior espessura original de sal na parte sul, que fez com que a cobertura albiana se distendesse mais em consequência da fluência do sal mergulho abaixo, em resposta ao basculamento da bacia em direção a offshore. A intensidade da deformação na parte sul foi tal que os blocos falhados perderam os contatos entre si, formando rafts. Este efeito foi reproduzido em modelos físicos, indicando que a variação na espessura original de sal tem grande influência na estruturação das rochas que o cobrem. As variações de espessura de sal são controladas por zonas de transferência do embasamento e estas mesmas estruturas controlam os limites dos blocos que sofrem soerguimento diferencial no Cenozoico.

Diferenciação genética do golfinho-de-dentes-rugosos, Steno bredanensis (Cuvier in Lesson, 1828) (Cetartiodactyla: Delphinidae): taxonomia molecular e estrutura populacional

O gênero Steno pertence à Ordem Cetartiodactyla, Família Delphinidae, e compreende apenas uma espécie: o golfinho-de-dentes-rugosos, Steno bredanensis. O golfinho-de-dentes-rugosos é encontrado nos Oceanos Atlântico, Pacífico e Índico, em águas profundas tropicais, subtropicais e temperadas quentes. Entretanto, em algumas localidades como as regiões Sudeste e Sul do Brasil, esta espécie é conhecida por apresentar hábitos costeiros, o que a torna suscetível a ameaças antropogênicas como a degradação do hábitat, as capturas acidentais e diversos tipos de poluição. Conhecer a magnitude destes impactos e o grau de diferenciação genética das populações usando marcadores moleculares são aspectos importantes para a conservação da espécie. Os marcadores moleculares são segmentos específicos de DNA que podem ou não fazer parte de um gene e que apresentam grau de polimorfismo adequado para responder questões sobre as relações genéticas de indivíduos, populações ou diferentes espécies. O DNA mitocondrial é um dos marcadores moleculares mais utilizados em estudos sobre estrutura populacional, sistemática e filogenia de cetáceos. Estudos genéticos têm mostrado que várias espécies de delfinídeos apresentam estrutura populacional genética, entre e dentro das bacias oceânicas. No presente estudo foi investigada a diferenciação genética do golfinho-de-dentes-rugosos usando sequências da região controle mitocondrial de várias localidades em todo o mundo (Oceano Pacífico Centro-Sul: N=59; Pacífico Tropical Leste: N= 4; Pacífico Noroeste: N=1; Oceano Índico: N=1; Atlântico - Caribe: N=3; Atlântico Sudoeste: N=44; N total = 112). Análises preliminares indicaram grande diferenciação genética entre os Oceanos Atlântico e Pacífico/Índico (distância p = 0,031), que foram posteriormente investigadas utilizando sequências do citocromo b e mitogenomas completos. As análises filogenéticas de Neighbor-Joining e Bayesianas não foram conclusivas sobre a existência de especiação críptica em Steno. No entanto, a grande diferenciação entre as bacias oceânicas merece uma análise mais aprofundada, utilizando outros marcadores genéticos (por ex., sequências nucleares) bem como dados morfológicos. Não obstante, as análises AMOVA e FST par-a-par revelaram forte diferenciação populacional, não só entre os oceanos Atlântico e Pacífico, mas também no Atlântico, onde foram detectadas três populações: Caribe, região Sudeste e região Sul do Brasil. As populações detectadas no Atlântico Sudoeste devem ser aceitas como Unidades de Manejo (Management Units, MU) e dados demográficos básicos precisam ser levantados para essas MU, a fim de possibilitar uma melhor avaliação dos impactos antrópicos sobre elas. Este estudo fornece a primeira perspectiva sobre a diferenciação genética mundial de S. bredanensis.

The occurrence of yellowfin tuna (Thunnus albacares) at Espiritu Santo Seamount in the Gulf of Mexico) at Espiritu Santo Seamount in the Gulf of Mexico

Pelagic fishes are not evenly dispersed in the oceans, but aggregate at distinct locations in this vast and open environment. Nomadic species such as mackerels, tunas, and sharks form assemblages at seamounts (Klimley and Butler, 1988; Fontenau, 1991). Fishermen have recognized this behavior and have placed moorings with surface buoys in deep waters to provide artificial landmarks, around which fish concentrate and are more easily captured. These fish aggregating devices (termed FADs) are common in the tropical oceans (see review, Holland, 1996). In a sense, it may only be the larger size that separates a seamount from a man-made FAD.

Avaliaçāo preliminar dos recursos de camarāo de profundidade em Moçambique

Although it is known enough of the biology of shallow+ waters shrimps, knowledge of the deep-waters shrimp is still limited. This is due to the fact that: these resources are relatively new and the study of deep waters species is more difficult and expensive. Some biological informations on the main species of shrimp in depth of Mozambique have been collected during investigation cruises (Sports et al., Pacule, 1987) and through sampling carried out on board commercial vessels (DDR fleet) between 1983 and 1986.

Changes in phytoplankton communities and primary production

Lake Victoria is the second largest lake in the world (69000km2) by surface area, but it is the shallowest (69m maximum depth) of the African Great Lakes. It is situated across the equator at an altitude of 1240m and lies in a shallow basin between two uplifted ridges of the eastern and western rift valleys (Beadle 1974). Despite their tropical locations, African lakes exhibit considerable seasonality related to the alteration of warm, wet and cool, dry seasons and the accompanying changes in lucustrine stratification and mixing (Tailing, 1965; 1966; Melack 1979; Hecky& Fee 1981; Hecky& Kling,1981; 1987; Bootsma 1993; Mugidde 1992; 1993). Phytoplankton productivity, biomass and species composition change seasonally in response to variations in light environment and nutrient availability which accompany changes in mixed layer depth and erosion or stabilization of the metalimnion / hypolimnion (Spigel & Coulter 1996; Hecky et al., 1991; Tailing 1987). Over longer, millennial time scales, the phytoplankton communities of the African Great Lakes have responded to variability in the EastAfrican climate (Johnson 1996; Haberyan& Hecky, 1986) which also alters the same ecological factors (Kilham et al., 1986). Recently, over the last few decades, changes in external and or internal factors in Lake Victoria and its basin have had a profound inlluence on the planktic community of this lake (Hecky, 1993; Lipiatou et al., 1996). The lake has experienced 2-10x increases in chlorophyll and 2x increase in primary productivity since Tailing's observations in the early 1960s (Mugidde 1992, 1993). In addition to observed changes in the lake nutrient chemistry (Hecky & Mungoma, 1990; Hecky & Bugenyi 1992; Hecky 1993; Bootsma & Hecky 1993), the deep waters previouslyoxygenated to the sediment surface through most of the year are now regularly anoxic(Hecky et al., 1994).

Issues of HIV/AIDS/ health among the fisher communities of Lake Albert and Kyoga

The fisheries resources of Lakes Albert and Kyoga present a high potential for economic growth, food, employment and foreign earnings. However, livelihoods appear to be compromised with the emergence and rapid spread of HIV/AIDS in the fisher communities of L. Albert and Kyoga. HIV/AIDS is considered a silent epidemic that is unique, posing a great challenge to the fisheries managers, health service providers, development planners and the resource users themselves. Fishers have high HIV prevalence, as well as AIDS-related illnesses and mortality rates. The high HIV prevalence rates among the fishing communities in Uganda is between 10-40% compared to the national rates which lie between 6% and 7%. This indicates that the national programmes have not adequately addressed the plight of the fishing communities of Lakes Albert, and Kyoga and the consequences have been devastating. Men and women living in fishing villages across the world have been found to be between five and ten times more vulnerable to the disease than other communities (Tarzan et al 2005, FAO, 2007). The present prevalence rates among the fishing communities stands at 10 to 40 % (LVFO, 2008). Meanwhile the same fishing communities are the essential labour for the Lakes’ fishery industry which is thriving nationally and internationally. That resource potentially can alleviate poverty and the HIV/AIDS threat. Fishing communities are the hidden victims of the disease, mixing patterns with the general population could act as a reservoir of infection that could spill over into the general population to drive the epidemic. On L. Albert, a quarter of the fisher folk were HIV-positive by 1992 compared to 4% in a nearby Agricultural village. Since then, there have been no targeted studies to address or monitor the prevalence rates eight years later, yet the multiplicity factor is high. HIV/AIDS can be linked to unsustainable fisheries, as the labour force available would not go to deep waters to fish, instead would fish in the shallow waters as a coping mechanism. A further effect is the loss to National and local economies and reduced nutritional security for the wider population. HIV/AIDS remains a significant challenge that has created a mosaic of complexity in the fishery sector. This needs to be addressed. It is, therefore, paramount that a comprehensive study was under taken to address this pandemic and the phenomenon of HIV/AIDS based on the study objectives. 1. To determine the trend in HIV/AIDS infection among fishing communities and the factors affecting it 2. To assess the impacts of HIV/AIDS on fish production and the implications for fisheries management.

Benthic foraminifera and bottom water evolution in the middle-southern Okinawa Trough during the last 18 ka

A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed based on the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS(14)C dating, and the previous results achieved in the southern Okinawa Trough. The result shows that the benthic fauna was dominated by Bulimina aculeata (d'Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta (Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua (Brady), Pullenia bulloides (d'Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides (d'Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glacial period after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivity estimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those of the post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from the southern to the central Okinawa Trough during the glaciation-deglaciation, which could be caused by the discrepancy of the terrigenous nutrients supply. High abundances of E exigua, an indicator of pulsed organic matter input, after 9.2 cal. ka. BP may indicate that the intensity of seasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than in the south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glacial period is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glaciation has no evident influence on the deep-water of the middle-southern Okinawa Trough. Additionally, the variations in agglutinated benthic foraminiferal abundance and other carbonate dissolution proxies indicate that carbonate dissolution gradually increased since the last 18 ka in the Okinawa Trough and rapidly enhanced at 9.2 cal. ka BP. The modern shallow carbonate lysocline could form at 3 cal. ka BP.