Eastern boundary systems support major fisheries of species whose early stages depend on upwelling production. However, upwelling can be highly variable at the regional scale, leading to complex patterns of feeding, growth, and survival for taxa that are broadly distributed in space and time. The northern California Current (NCC) is characterized by latitudinal variability in the seasonality and intensity of coastal upwelling. We examined the diet and larval growth of a dominant myctophid (Stenobrachius leucopsarus) in the context of their prey and predators in distinct NCC upwelling regimes. Larvae exhibited significant differences in diet and growth, with greater seasonal than latitudinal variability. In winter, during reduced upwelling, growth was substantially slower, guts less full, and diets dominated by copepod nauplii. During summer upwelling, faster-growing larvae had guts that were more full from feeding on calanoid copepods and relying less heavily on lower trophic level prey. Yet, our findings revealed a dome-shaped relationship with the fastest growth occurring at moderate upwelling intensity. High zooplanktivorous predation pressure led to above average growth, which may indicate the selective loss of slower-growing larvae. Our results suggest that species whose spatio-temporal distributions encompass multiple regional upwelling regimes experience unique feeding and predation environments throughout their range with implications for larval survivorship.
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null (Ed.)Suspension feeders, including ascidians (Phylum Chordata, Class Ascidiacea), experience a dilute prey field composed of extremely small particles. The filtration apparatus of ascidians is based on a mucous-mesh that is continuously secreted and ingested. The rate and metabolic cost of this mesh secretion has not been quantified to date. We used video boroscopy to quantify the mucous-mesh production rate of the solitary ascidian Herdmania momus under different food and temperature treatments. H. momus individuals with an average (±95% CI) biomass of 30.7 ± 1.1 mg and a branchial sac area of 10.3 ± 1.2 cm 2 produced an average of 276 ± 33.5 cm 2 of mucous-mesh h -1 , corresponding to a median turnover rate of 625 ± 82 mesh d -1 . Since the mean mesh mass was 2.44 ± 0.58 mg, this production rate corresponds to roughly 50 ± 8 times the individual’s biomass per day. Food concentration had no detectable effect on mesh production rate, whereas a temperature difference of ~9°C (20 vs. 29°C) moderately increased mesh production by 30-50%. The current study reveals that the feeding process of H. momus involves a high expenditure on mucous-mesh synthesis that, combined with low food availability, may limit its growth in oligotrophic waters and under changing climate regimes.more » « less
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Despite its delicate morphology, the lobate ctenophore Mnemiopsis leidyi thrives in coastal ecosystems as an influential zooplankton predator. Coastal ecosystems are often characterized as energetic systems with high levels of natural turbulence in the water column. To understand how natural wind-driven turbulence affects the feeding ecology of M. leidyi, we used a combination of approaches to quantify how naturally and laboratory generated turbulence affects the behavior, feeding processes and feeding impact of M. leidyi. Experiments using laboratory generated turbulence demonstrated that turbulence can reduce M. leidyi feeding rates on copepods and Artemia nauplii by > 50%. However, detailed feeding data from the field, collected during highly variable surface conditions, showed that wind-driven turbulence did not affect the feeding rates or prey selection of M. leidyi. Additional laboratory experiments and field observations suggest that the feeding process of M. leidyi is resilient to wind-driven turbulence because M. leidyi shows a behavioral response to turbulence by moving deeper in the water column. Seeking refuge in deeper waters enables M. leidyi to maintain high feeding rates even under high turbulence conditions generated by wind driven mixing. As a result, M. leidyi exerted a consistently high predatory impact on prey populations during highly variable and often energetic wind-driven mixing conditions. This resilience adds to our understanding of how M. leidyi can thrive in a wide spectrum of environments around the world. The limits to this resilience also set boundaries to its range expansion into novel areas.more » « less
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Abstract Background Little is known about the adequacy of nutrient intakes and the overall diet quality of Indigenous Australian pregnant women. The aim of this cross‐sectional study was to assess nutrient sufficiency and diet quality, as measured using the Australian Recommended Food Score (
ARFS ), in pregnant women from theGomeroi gaaynggal cohort (n = 58).Methods Maternal dietary intake during pregnancy was assessed using the Australian Eating Survey Food Frequency Questionnaire, which was self‐administered in the third trimester. Diet quality was determined using the
ARFS . Food group servings and nutrient intakes were compared to the Australian Guide to Health Eating (AGHE ) and Australian Nutrient Reference Values (NRV s). The current analysis examined the adequacy of usual intakes from food sources only, excluding supplements.Results None of the women met all
AGHE daily food group serving recommendations. The highest alignment rates were for dairy (33%), meat/alternatives (31%) and vegetables (29.3%). Almost 93% of participants exceeded the recommended intake of energy‐dense, nutrient‐poor foods and percentage energy from saturated fat was high (15%). Of the five key nutrients for optimal reproductive health (folate, iron, calcium, zinc and fibre), the nutrients with the highest percentage of pregnant women achieving theNRV s were zinc (77.6%) and folate (68.9%), whereas iron was the lowest. Only one person achieved allNRV s (folate, iron, calcium, zinc and fibre) important in pregnancy. The medianARFS was 28 points (maximum of 73).Conclusions Although the small cohort limits the generalisability of the findings of the present study, the data obtained indicate that the diets of these Indigenous pregnant women are inadequate. Therefore, strategies aiming to optimise nutrient intakes of Indigenous pregnant women are needed urgently.
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