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The anemone–anemonefish association is the quintessential symbol of a symbiotic mutualism from the Indo-Pacific waters. Both historical field documentation and extant scientific research advocate that these interactions are fundamental at the level of nutrient exchanges and evolutionary driving forces (natural selection) to facilitate this mutualism. Through the use of ¹⁵N and ¹³C stable isotope tracers, complementary laboratory- and field-based experiments were implemented in the Philippines to investigate the possibility of nutrient transmission from the host anemone, Heteractis crispa and/or endosymbiotic zooxanthellae, to two species of exosymbiotic anemonefishes (Amphiprion clarkii and A. perideraion). Mass spectrometry analyses suggest that ¹⁵N and ¹³C concentrations were significantly higher in tissues of the anemonefishes (intestines, liver, gills, and gonads), anemone host, and zooxanthellae compared with controls. We interpret the presence of ¹⁵N and ¹³C in the anemonefish tissues as direct empirical evidence for the transmission of nitrogen and/or carbon from host anemone and endosymbiotic zooxanthellae to resident anemonefish. These “translocations” and resultant recycling of elements within this classical tripartite relationship highlight the fundamental role of nutrient dynamics in this synergistic symbiosis.

The relationship between anemones and anemonefishes is an oft-cited and endearing example of a mutualistic symbiosis. Current research on mutualistic symbioses suggests these relationships are more commonplace and have greater importance at the ecosystem level on nutrient dynamics and evolutionary processes than previously thought. Using stable isotopes ¹⁵N and ¹³C, both field and laboratory experiments were designed to investigate whether nutrient transfer from two species of resident anemonefishes (Amphiprion perideraion and A. clarkii) to host anemones (Heteractis crispa) occurs. Mass spectroscopy indicated that both ¹⁵N and ¹³C were significantly elevated in the tissues of anemonefishes and in both host anemone and zooxanthellae fractions. These experiments provide the first direct empirical evidence of nitrogen and carbon transfer from resident anemonefishes to host anemones and endosymbiotic zooxanthellae. Such transfer of elements within this intriguing tripartite association underscores the central role that nutrient dynamics contributes to the evolutionary processes of these marine symbioses.

The sea anemone Anthopleura elegantissima hosts two phylogenetically different symbiotic microalgae, a dinoflagellate Symbiodinium (zooxanthellae, ZX) and a chlorophyte (zoochlorellae, ZC). The photosynthetic productivity (P), respiration (R), and contribution of algal carbon translocated to the host (CZAR) in response to a year's seasonal ambient changes of natural light and temperature are documented for both ZX- and ZC-bearing anemones. Light and temperature both affect photosynthesis, respiration, and CZAR, as well as various algal parameters; while there are evident seasonal differences, for the most part the relative effects on P, R, and CZAR by the two environmental variables cannot be determined. Net photosynthesis (Pn) of both ZX and ZC was significantly higher during spring and summer. During these seasons, the Pn of ZX was always greater than that of ZC. Regardless of algal symbiont, anemone respiration (R) was significantly higher during the spring and summer. The annual net carbon fixation rate of anemones with ZX and ZC was 325 and 276 mg C anemone-1 year-1, respectively, which translates to annual net community productivity rates of 92 and 60 g C m-1 year-1 for anemones with ZX or ZC, respectively. CZAR did not show a clear relationship with season; however the CZAR for ZX was always significantly greater than for ZC. Lower ZX growth rates, coupled with higher photosynthetic rates and higher CZAR estimates, compared to ZC, suggest that if A. elegantissima is simply carbon limited, ZX-bearing anemones should be the dominant symbiont in the field. However ZC-bearing anemones persist in low light and reduced temperature microhabitats, therefore more than the translocation of carbon from ZC must be involved. Given that global climate change will increase water temperatures, the potential for latitudinal range shifts of both ZC and ZX (S. californium and muscatinei) might be used as biological indicators of thermal shifts in the littoral zone of the Pacific Northwest. [PUBLICATION ABSTRACT]

Movement rate, oxygen consumption, and respiratory tree ammonium concentration were measured in situ in the holothurians Pearsonothuria graeffei and Holothuria edulis in the Agan-an Marine Reserve, Sibulan, Philippines (9 degrees 20'30 N, 123 degrees 18'31 E). Measurements were made both day and night for both species during April-July 2005. P. graeffei had significantly higher movement rate during the day than at night (1.14 and 0.27 m h-1, respectively; three-way ANOVA, P < 0.05) while H. edulis had higher movement rate at night compared to the day (0.83 and 0.07 m h-1, respectively), spending the daylight hours sheltering under coral. More than 80% of H. edulis had movement rate of zero during the day. Oxygen consumption of P. graeffei was significantly higher during the day than at night (1.61 and 0.83 mcmol O2 g-1 h-1, respectively; two-way ANCOVA, P < 0.05), but the reduction at night was not as pronounced as the reduction in movement. H. edulis had a 75% reduction in oxygen consumption during the day compared to night (0.51 and 1.96 mcmol O2 g-1 h-1, respectively), matching this species' reduced movement rates during the day. Ammonium concentration in water withdrawn from the respiratory trees of P. graeffei during the day (12.0 mcM) was three times higher than in respiratory tree water sampled at night (4.3 mcM) and 15 times higher than ambient seawater (0.8 mcM; three-way ANOVA, P < 0.05). Ammonium concentration in the respiratory tree water of H. edulis was six times higher at night (14.6 mcM) than during the day (2.2 mcM) and 16 times higher than that of ambient seawater (0.9 mcM). Even though H. edulis and P. graeffei are found within the same coral reef environment, they may affect different substrates and reef organisms due to their different habitats and distinct but opposite diel cycles. [PUBLICATION ABSTRACT]

We investigated several aspects of the larval biology of the anemone Anthopleura elegantissima, which harbors algal symbionts from two different taxa, and the non-symbiotic A. artemisia. From a 7-year study, we report variable spawning and fertilization success of A. elegantissima in the laboratory. We examined the dynamics of symbiosis onset in larvae of A. elegantissima. Zoochlorellae, freshly isolated from an adult host, were taken up and retained during the larval feeding process, as has been described previously for zooxanthellae. In addition, larvae infected with zooxanthellae remained more highly infected in high-light conditions, compared to larvae with zoochlorellae, which remained more highly infected in low-light conditions. These results parallel the differential distribution of the algal types observed in adult anemones in the field and their differential tolerances to light and temperature. We report on numerous failed attempts to induce settlement and metamorphosis of larvae of A. elegantissima, using a variety of substrates and chemical inducers. We also describe a novel change in morphology of some older planulae, in which large bulges, resembling tentacles, develop around the mouth. Finally, we provide the first description of planulae of A. artemisia and report on attempts to infect this non-symbiotic species with zooxanthellae and zoochlorellae.

The association between the symbiont Symbiodinium microadriaticum (zooxanthellae) and its host jellyfish, Cassiopea xamachana, was investigated as a function of jellyfish size and season. Symbiont cell diameter and volume were higher during January than September. Although zooxanthella-specific chlorophyll was independent of jellyfish size, both chlorophyll a and c were higher during January. Regardless of season, algal density and jellyfish size were inversely related. The diel mitotic index (MI) of zooxanthellae was phased, with a peak of 0.25% occurring between 09:00 and 12:00 h. September photosynthetic rates were always higher than January rates and reflected the seasonal light and temperature regimes at the latitude of the Florida Keys (USA). Photosynthesis, when normalized to either zooxanthella density or protein, displayed an inverse relationship with jellyfish size. Medusan respiration rates also showed an inverse relationship with jellyfish size, with September metabolism being higher than that of January. The carbon budgets calculated for these medusae indicate that the carbon photosynthetically fixed by the zooxanthellae, and subsequently translocated to the host, is capable of satisfying about 169% of the host's metabolic demand (CZAR) and is independent of both jellyfish size and season. These seasonally influenced physiological effects underscore the necessity for seasonal examinations of algal-cnidarian symbioses in order to understand the photophysiology of the association on an annual basis.

Effects of erythropoietin on left ventricular hypertrophy in adults with severe chronic renal failure and hemoglobin <10 g/dL. Left ventricular hypertrophy (LVH) frequently complicates chronic renal insufficiency. Anemia is also common in these patients and may contribute to LVH. We conducted an open-label interventional trial to evaluate the effect of recombinant erythropoietin (rhEPO) on left ventricular mass index (LVMI) in anemic patients with renal insufficiency. Adults with creatinine clearance 10 to 30mL /min (nondiabetics) or 20 to 40mL /min (diabetics) were recruited, and rhEPO was given to those with anemia (hemoglobin level <10 g/dL). Baseline and 6-month LVMI and LVH (LVMI >130 g/m2 in men and >100 g/m2 in women), hemoglobin levels, creatinine clearance, blood pressure, medications, and medical history were obtained. Forty anemic and 61 nonanemic control subjects were enrolled. Overall, the prevalence of LVH was 68.3% (95% CI 58.3-77.2), and entry hemoglobin level was the only significant predictor of baseline LVH (adjusted OR 0.69 per g/dL increase in hemoglobin, 95% CI 0.50-0.94). After 6 months, LVMI decreased in anemic patients receiving rhEPO (142 ± 56 vs. 157 ± 56 g/m2) (P = 0.007), with an increase in hemoglobin (11.3 ± 1.9 vs. 9.1 ± 0.7 g/dL) (P = 0.001). There were no changes in LVMI or hemoglobin level among controls. After adjusting for confounders and change in hemoglobin, receipt of rhEPO was associated with a significant reduction in LVMI (P = 0.01). Treatment with rhEPO was not independently associated with significant changes in blood pressure or renal function. LVH is a common finding in chronic renal insufficiency and is associated with lower hemoglobin levels. Treatment with rhEPO may decrease LVH in patients with severe renal insufficiency and anemia.

This field study tested the relevance of the hypothesis that perceived competence mediates the effects of participation in risk recreation or sports on self-esteem. A theoretical and operational distinction was made between general and specific perceived competence. To test the hypothesis, 95 rock climbers were interviewed before the day's climb and 64 after the day's climb; in addition, 23 members of a climbing club were asked to fill out the Rosenberg Self-Esteem Scale. The general perceived competence was not significantly influenced by the day's climb, nor did it contribute significantly to self-esteem. Similarly, the number of climbing trips per year and number of years of climbing experience failed to increase self-esteem. Instead, it was the perceived competence with a specific climbing occasion that increased self-esteem significantly. If generalizeable, the results suggest that to increase self-esteem, sports and recreation programs should be so planned that they facilitate the acquisition of new skills or advancement to a higher level of skill in a familiar activity.