Symbiont presence and identity influence life history strategies of a temperate sea anemone

Along the North American Pacific coast, the common intertidal sea anemone Anthopleura elegantissima engages in facultative, flexible symbioses with Symbiodinium muscatinei (a dinoflagellate) and Elliptochloris marina (a chloro- phyte). Determining how symbiotic state affects host fitness is essential to understanding the ecological significance of engaging in such flexible relationships with diverse symbionts. Fitness consequences of hosting S. muscatinei, E. marina or negligible numbers of either symbiont (aposymbiosis) were investigated by measuring growth, cloning by fission and gonad development after 8.5 – 11 months of sustained exposure to high, moderate or low irradiance under seasonal environmental conditions. Both symbiotic state and irradiance affected host fitness, leading to divergent life-history strategies. Moderate and high irradiances led to a greater level of gonad development in individuals hosting E. marina, while high irradiance and high summer temperature promoted cloning in individuals hosting S. muscatinei and reduced fitness of aposymbiotic anemones. Associating with S. muscatinei may contribute to the success of A. elegantissima as a spatial competitor on the high shore: (i) by offsetting the costs of living under high temperature and irradiance conditions, and (ii) by promoting a high fission rate and clonal expansion. Our results suggest that basic life-history characteristics of a clonal cnidarian can be affected by the identity of the endosymbionts it hosts

Inorganic Nutrient Fluxes in Anemone-dominated Tide Pools

Physical and chemical characteristics of seawater in two natural tide pools on Rosario Beach, Fidalgo Island, Washington, were compared during midday low tides in July 1991. One pool contained a mixed assemblage of macroalgae (40% cover) and invertebrates (50% cover). The second pool was dominated (75% cover) by the sea anemone Anthopleura elegantissima (Brandt, 1835), which contains symbiotic algae (zooxanthellae). Temperature, salinity, dissolved oxygen, and pH levels increased in both pools with irradiance and length of emersion. The resident organisms caused changes in the inorganic nutrient levels of the tide-pool seawater. Anthopleura elegantissima released substantial amounts of ammonium; NH4 + in the anemone-dominated pool increased by 33% whereas NH4 + declined in the mixed assemblage pool by an average of 28%. Nitrate and nitrite declined in both pools, whereas phosphate remained constant during the 6-hr sampling periods. NH4 + release by A. elegantissima was confirmed in studies of artificial tide pools, where NH4 + levels increased by an average of 71% over an 8-hr period. Release of ammonium by A. elegantissima under natural conditions in the field provides a contrast to nutrient fluxes observed for tropical symbiotic associations

DISPERSAL OF ZOOXANTHELLAE ON CORAL REEFS BY PREDATORS ON CNIDARIANS

Volume: 167Start Page: 159End Page: 16

Phylogenetic Placement of "Zoochlorellae" (Chlorophyta), Algal Symbiont of the Temperate Sea Anemone Anthopleura elegantissima

Volume: 207Start Page: 87End Page: 9

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially