Molecular Phylogenetics of Mole Crabs (Hippidae : Emerita)

Mole crabs of the genus Emerita (Family Hippidae) inhabit many of the temperate and tropical sandy beaches of the world. The nine described species of this genus are rarely sympatric, and most are endemic to broad biogeographic regions. The phylogenetic relationships among the species have not yet been investigated. Based on presumed morphological synapomorphics, it has been suggested that the species inhabiting the New World constitute a monophyletic group, as do the species inhabiting the Old World, The relationships within the New World species were previously studied using sequence data from Cytochrome Oxidase I and 16S rRNA mitochondrial genes; the results strongly suggested that one of the species, Emerita analoga, was very divergent from the other taxa examined. This observation prompted uncertainty about monophyly of the New World species. The goal of the present study was to elucidate the relationships among the species within the genus Emerita. Partial sequences for the mitochondrial COI and 16S rRNA genes for all nine species of the genus (and several outgroups) were examined. Phylogenetic analyses suggest that E. analoga is closer to the Old World taxa than to the other New World species; thus the New World Emerita species do not constitute a monophyletic group.

Different Early Post-Settlement Strategies Between American Lobsters Homarus Americanus and Rock Crabs Cancer Irroratus in the Gulf of Maine

The abundance of many invertebrates with planktonic larval stages can be determined shortly after they reach the benthos. In this study, we quantified patterns of abundance and habitat utilization of early benthic phases of the American lobster Homarus americanus and the rock crab Cancer irroratus. These 2 decapods are among the most common and abundant macroinvertebrates in coastal zones of the Gulf of Maine, with similar densities of larger individuals. Settlement and early postsettlement survival indicate that lobsters are highly substrate-specific early in life, settling predominantly in cobble beds. Crabs appear to be less selective, setting both in cobble and sand. Cumulative settlement of crabs, inferred from weekly censuses over the summer, was an order of magnitude greater than that of lobsters over the same time period. However, only crabs showed significant postsettlement losses. Although the identity of specific predators is unknown, predator exclusion experiments and placement of vacant uninhabited nursery habitat suggested that post-settlement mortality rather than emigration was responsible for these losses. The selective habitat-seeking behavior and lower post-settlement mortality of lobsters is consistent with their lower fecundity and later onset of reproductive maturity. The patterns observed for crabs, however, suggest a different strategy which is more in accordance with their higher fecundity and earlier onset of maturity. It is possible that lower fecundity but greater per-egg investment, along with strict habitat selection at settlement and lower post-settlement mortality, allows adult lobster populations to equal adult populations of crabs. This occurs despite crabs being more fecund and less habitat-selective settlers but sustaining higher postsettlement mortality.

Modeling Responses of Diatom Productivity and Biogenic Silica Export to Iron Enrichment in the Equatorial Pacific Ocean

Using a three-dimensional physical-biogeochemical model, we have investigated the modeled responses of diatom productivity and biogenic silica export to iron enrichment in the equatorial Pacific, and compared the model simulation with in situ (IronEx II) iron fertilization results. In the eastern equatorial Pacific, an area of 540,000 km(2) was enhanced with iron by changing the photosynthetic efficiency and silicate and nitrogen uptake kinetics of phytoplankton in the model for a period of 20 days. The vertically integrated Chl a and primary production increased by about threefold 5 days after the start of the experiment, similar to that observed in the IronEx II experiment. Diatoms contribute to the initial increase of the total phytoplankton biomass, but decrease sharply after 10 days because of mesozooplankton grazing. The modeled surface nutrients (silicate and nitrate) and TCO(2) anomaly fields, obtained from the difference between the "iron addition'' and "ambient'' (without iron) concentrations, also agreed well with the IronEx II observations. The enriched patch is tracked with an inert tracer similar to the SF6 used in the IronEx II. The modeled depth-time distribution of sinking biogenic silica (BSi) indicates that it would take more than 30 days after iron injection to detect any significant BSi export out of the euphotic zone. Sensitivity studies were performed to establish the importance of fertilized patch size, duration of fertilization, and the role of mesozooplankton grazing. A larger size of the iron patch tends to produce a broader extent and longer-lasting phytoplankton blooms. Longer duration prolongs phytoplankton growth, but higher zooplankton grazing pressure prevents significant phytoplankton biomass accumulation. With the same treatment of iron fertilization in the model, lowering mesozooplankton grazing rate generates much stronger diatom bloom, but it is terminated by Si(OH)(4) limitation after the initial rapid increase. Increasing mesozooplankton grazing rate, the diatom increase due to iron addition stays at minimum level, but small phytoplankton tend to increase. The numerical model experiments demonstrate the value of ecosystem modeling for evaluating the detailed interaction between biogeochemical cycle and iron fertilization in the equatorial Pacific.

Decadal Variability in the Northeast Pacific in a Physical-Ecosystem Model: Role of Mixed Layer Depth and Trophic Interactions

A basin-wide interdecadal change in both the physical state and the ecology of the North Pacific occurred near the end of 1976. Here we use a physical-ecosystem model to examine whether changes in the physical environment associated with the 1976-1977 transition influenced the lower trophic levels of the food web and if so by what means. The physical component is an ocean general circulation model, while the biological component contains 10 compartments: two phytoplankton, two zooplankton, two detritus pools, nitrate, ammonium, silicate, and carbon dioxide. The model is forced with observed atmospheric fields during 1960-1999. During spring, there is a similar to 40% reduction in plankton biomass in all four plankton groups during 1977-1988 relative to 1970-1976 in the central Gulf of Alaska (GOA). The epoch difference in plankton appears to be controlled by the mixed layer depth. Enhanced Ekman pumping after 1976 caused the halocline to shoal, and thus the mixed layer depth, which extends to the top of the halocline in late winter, did not penetrate as deep in the central GOA. As a result, more phytoplankton remained in the euphotic zone, and phytoplankton biomass began to increase earlier in the year after the 1976 transition. Zooplankton biomass also increased, but then grazing pressure led to a strong decrease in phytoplankton by April followed by a drop in zooplankton by May: Essentially, the mean seasonal cycle of plankton biomass was shifted earlier in the year. As the seasonal cycle progressed, the difference in plankton concentrations between epochs reversed sign again, leading to slightly greater zooplankton biomass during summer in the later epoch.

Kelp Forest Ecosystems: Biodiversity, Stability, Resilience and Future

Kelp forests are phyletically diverse, structurally complex and highly productive components of cold-water rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40-60degrees latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2-3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The largescale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

Size-Fractionated Nitrogen Uptake Measurements in the Equatorial Pacific and Confirmation of the Low Si-High-Nitrate Low-Chlorophyll Condition

The equatorial Pacific Ocean is the largest natural source of CO(2) to the atmosphere, and it significantly impacts the global carbon cycle. Much of the large flux of upwelled CO(2) to the atmosphere is due to incomplete use of the available nitrate (NO(3)) and low net productivity. This high-nutrient low-chlorophyll (HNLC) condition of the equatorial upwelling zone (EUZ) has been interpreted from modeling efforts to be due to low levels of silicate ( Si( OH) 4) that limit the new production of diatoms. These ideas were incorporated into an ecosystem model, CoSINE. This model predicted production by the larger phytoplankton and the picoplankton and effects on air-sea CO(2) fluxes in the Pacific Ocean. However, there were no size-fractionated rates available for verification. Here we report the first size-fractionated new and regenerated production rates (obtained with (15)N - NO(3) and (15)N - NH(4) incubations) for the EUZ with the objective of validating the conceptual basis and functioning of the CoSINE model. Specifically, the larger phytoplankton ( with cell diameters > 5 mu m) had greater rates of new production and higher f-ratios (i.e., the proportion of NO(3) to the sum of NO(3) and NH(4) uptake) than the picoplankton that had high rates of NH(4) uptake and low f-ratios. The way that the larger primary producers are regulated in the EUZ is discussed using a continuous chemostat approach. This combines control of Si(OH)(4) production by supply rate (bottom-up) and control of growth rate ( or dilution) by grazing ( top-down control).

Characteristics and comprehensiveness of adult HIV care and treatment programmes in Asia-Pacific, sub-Saharan Africa and the Americas: results of a site assessment conducted by the International epidemiologic Databases to Evaluate AIDS (IeDEA) Collaboration

INTRODUCTION HIV care and treatment programmes worldwide are transforming as they push to deliver universal access to essential prevention, care and treatment services to persons living with HIV and their communities. The characteristics and capacity of these HIV programmes affect patient outcomes and quality of care. Despite the importance of ensuring optimal outcomes, few studies have addressed the capacity of HIV programmes to deliver comprehensive care. We sought to describe such capacity in HIV programmes in seven regions worldwide. METHODS Staff from 128 sites in 41 countries participating in the International epidemiologic Databases to Evaluate AIDS completed a site survey from 2009 to 2010, including sites in the Asia-Pacific region (n=20), Latin America and the Caribbean (n=7), North America (n=7), Central Africa (n=12), East Africa (n=51), Southern Africa (n=16) and West Africa (n=15). We computed a measure of the comprehensiveness of care based on seven World Health Organization-recommended essential HIV services. RESULTS Most sites reported serving urban (61%; region range (rr): 33-100%) and both adult and paediatric populations (77%; rr: 29-96%). Only 45% of HIV clinics that reported treating children had paediatricians on staff. As for the seven essential services, survey respondents reported that CD4+ cell count testing was available to all but one site, while tuberculosis (TB) screening and community outreach services were available in 80 and 72%, respectively. The remaining four essential services - nutritional support (82%), combination antiretroviral therapy adherence support (88%), prevention of mother-to-child transmission (PMTCT) (94%) and other prevention and clinical management services (97%) - were uniformly available. Approximately half (46%) of sites reported offering all seven services. Newer sites and sites in settings with low rankings on the UN Human Development Index (HDI), especially those in the President's Emergency Plan for AIDS Relief focus countries, tended to offer a more comprehensive array of essential services. HIV care programme characteristics and comprehensiveness varied according to the number of years the site had been in operation and the HDI of the site setting, with more recently established clinics in low-HDI settings reporting a more comprehensive array of available services. Survey respondents frequently identified contact tracing of patients, patient outreach, nutritional counselling, onsite viral load testing, universal TB screening and the provision of isoniazid preventive therapy as unavailable services. CONCLUSIONS This study serves as a baseline for on-going monitoring of the evolution of care delivery over time and lays the groundwork for evaluating HIV treatment outcomes in relation to site capacity for comprehensive care.

Glacial–interglacial temperature change in the tropical West Pacific: A comparison of stalagmite-based paleo-thermometers

In the tropics, geochemical records from stalagmites have so far mainly been used to qualitatively reconstruct changes in precipitation, but several new methods to reconstruct past temperatures from stalagmite material have emerged recently: i) liquide vapor homogenization of fluid inclusion water ii) noble gas concentrations in fluid inclusion water, iii) the partitioning of oxygen isotopes between fluid inclusion water and calcite, and iv) the abundance of the 13C18O16O(‘clumped’) isotopologue in calcite. We present, for the first time, a direct comparison of these four paleo-thermometers by applying them to a fossil stalagmite covering nearly two glaciale interglacial cycles (Marine Isotope Stages (MIS) 12 e 9) and to two modern stalagmites, all from northern Borneo. The temperature estimates from the different methods agree in most cases within errors for both the old and recent samples; reconstructed formation temperatures of the recent samples match within 2-sigma errors with measured cave temperatures. However, slight but systematic deviations are observed between noble gas and liquide vapor homogenization temperatures. Whereas the temperature sensitivity of fluid inclusion d18O and clumped isotopes is currently debated, we find that the calibration of Tremaine et al. (2011) for fluid inclusion d18O and a synthetic calcite-based clumped isotope calibration (Ziegler et al., in prep.) yield temperature estimates consistent with the other methods. All methods (with the potential exception of clumped isotopes) show excellent agreement on the amplitude of glaciale interglacial temperature change, indicating temperature shifts of 4-5 C°. This amplitude is similar to the amplitude of Mg/Ca-based regional sea surface temperature records, when correcting for sea level driven changes in cave elevation. Our reconstruction of tropical temperature evolution over the time period from 440 to 320 thousand years ago (ka) adds support to the view that climate sensitivity to varying greenhouse forcing is substantial also in the deep tropics.

Intensification of tropical Pacific biological productivity due to volcanic eruptions

Major volcanic eruptions generate widespread ocean cooling, which reduces upper ocean stratification. This effect has the potential to increase nutrient delivery into the euphotic zone and boost biological productivity. Using externally forced last millennium simulations of three climate/Earth System models (Model for Interdisciplinary Research On Climate (MIROC), Community Earth System Model (CESM), and LOch-Vecode-Ecbilt-CLio-agIsm Model (LOVECLIM)), we test the hypothesis that large volcanic eruptions intensify nutrient-driven export production. It is found that strong volcanic radiative forcing enhances the likelihood of eastern Pacific El Niño-like warming in CESM and LOVECLIM. This leads to an initial reduction of nutrients and export production in the eastern equatorial Pacific. However, this initial response reverses after about 3 years in association with La Niña cooling. The resulting delayed enhancement of biological production resembles the multiyear response in MIROC. The model simulations show that volcanic impacts on tropical Pacific dynamics and biogeochemistry persist for several years, thus providing a new source for potential multiyear ecosystem predictability.