Departures from isotropy: the kinematics of a larval snail in response to food

Author Posting. © Company of Biologists, 2020. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 224(2), (2020): jeb.239178, https://doi.org/10.1242/jeb.239178.The swimming behavior of invertebrate larvae can affect their dispersal, survival and settlement in the ocean. Modeling this behavior accurately poses unique challenges as behavior is controlled by both physiology and environmental cues. Some larvae use cilia to both swim and create feeding currents, resulting in potential trade-offs between the two functions. Food availability is naturally patchy and often occurs in shallow horizontal layers in the ocean. Also, larval swimming motions generally differ in the horizontal and vertical directions. In order to investigate behavioral response to food by ciliated larvae, we measured their behavioral anisotropy by quantifying deviations from a model based on isotropic diffusion. We hypothesized that larvae would increase horizontal swimming and decrease vertical swimming after encountering food, which could lead to aggregation at food layers. We considered Crepidula fornicata larvae, which are specifically of interest as they exhibit unsteady and variable swimming behaviors that are difficult to categorize. We tracked the larvae in still water with and without food, with a portion of the larvae starved beforehand. On average, larvae in the presence of food were observed higher in the water column, with higher swimming speeds and higher horizontal swimming velocities when compared with larvae without food. Starved larvae also exhibited higher vertical velocities in food, suggesting no aggregation behavior. Although most treatments showed strong anisotropy in larval behavior, we found that starved larvae without food exhibited approximately isotropic kinematics, indicating that behavioral anisotropy can vary with environmental history and conditions to enhance foraging success or mitigate food-poor environments.M.H.D. and K.S.M.-K. were supported by postdoctoral scholarships from Woods Hole Oceanographic Institution, and B.T. was supported by a WHOI Summer Student Fellowship. This work was also supported by National Science Foundation grant OCE-0850419

Five Year Follow Up of Extremely Low Gestational Age Infants after Timely or Delayed Administration of Routine Vaccinations

This study is aimed at detecting the rate of untimely immunization in a large cohort of extremely low gestational age neonates (ELGANs) of the German Neonatal Network (GNN) and at addressing risk factors for delayed vaccination and associated long-term consequences. We performed an observational study of the GNN between 1st January 2010 and 31st December 2019. The immunization status for the hexavalent and pneumococcal immunization was evaluated in n = 8401 preterm infants <29 weeks of gestation. Univariate analysis and logistic/linear regression models were used to identify risk factors for vaccination delay and outcomes at a 5-year follow-up. In our cohort n = 824 (9.8%) ELGANs did not receive a timely first immunization with the hexavalent and pneumococcal vaccine. Risk factors for delayed vaccination were SGA status (18.1% vs. 13.5%; OR 1.3; 95% CI: 1.1–1.7), impaired growth and surrogates for complicated clinical courses (i.e., need for inotropes, necrotizing enterocolitis). At 5 years of age, timely immunized children had a lower risk of bronchitis (episodes within last year: 27.3% vs. 37.7%; OR 0.60, 95% CI: 0.42–0.86) but spirometry measures were unaffected. In conclusion, a significant proportion of ELGANs are untimely immunized, specifically those with increased vulnerability, even though they might particularly benefit from the immune-promoting effects of a timely vaccination

Transitioning to Country Ownership of HIV Programs in Rwanda

Agnes Binagwaho and colleagues describe how Rwanda achieved country ownership of its HIV programs

Recruit abundance on a long-term experiment (1999-2017) in the LTER observatory HAUSGARTEN

These data represent the results of a long-term colonization experiment at the Long-Term Ecological Research observatory HAUSGARTEN. Recruitment panels were constructed from plastic and brick and deployed attached to a metal frame in 1999 at the station HG-IV (Arctic Ocean, 79 N, 04 E, 2500 m depth). The experiment was recovered in 2017. Following recovery, all invertebrates and foraminiferans on the panels were counted using a dissecting microscope on board R/V Polarstern and then saved in 95% ethanol. Species were identified by reference to published literature and taxonomic experts. Species richness was low compared to surrounding hard-bottom communities, indicating that Arctic benthic communities may take decades to develop

Megabenthic standing stocks and organic carbon demand in a warming Arctic

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mazurkiewicz, M., Meyer-Kaiser, K., Sweetman, A. K., Renaud, P. E., & Wlodarska-Kowalczuk, M. Megabenthic standing stocks and organic carbon demand in a warming Arctic. Progress in Oceanography, 196, (2021): 102616, https://doi.org/10.1016/j.pocean.2021.102616.Benthic megafauna (organisms large enough to be visible on seabed photographs) are regarded as important for carbon cycling in benthic habitats. They are a food source for many predators like fish and marine mammals and may stimulate carbon mineralization in sediment by bioturbation. However, few studies address these basic characteristics of megabenthos quantitatively. This study quantifies the spatial variability in standing stock (biomass) and functioning (secondary production, respiration and carbon demand) of benthic megafauna in fjords and on the continental shelf of Svalbard. Organisms were measured from sea bottom images to assess their biomass using length-weight relationships and volumetric methods, then respiration and production were estimated with empirical artificial neural network models. Significantly higher standing stock, secondary production, respiration, and carbon demand were found in fjords categorized as ‘cold’ (as defined by water temperature, prevailing water masses and ice-cover) than in the ‘warm’ ones. Cold fjords were dominated by Echinodermata, while in warm fjords Crustacea prevailed. All megafaunal community parameters were negatively correlated with bottom temperature. It was not possible to assess specific direct impacts of temperature, and indirect effects may be more relevant to our findings. These include temperature-driven changes in primary production, ice cover and ice-algae production or predation pressure from carnivores expanding their ranges northward. The progression of climate warming may affect megafaunal communities by reducing their biomass, production, and carbon demand and have profound effects on ecosystem functioning.Financing was provided by the University Centre in Svalbard and Akvaplan-niva (to PER), by the National Science Centre grant number UMO-2016/23/B/NZ8/02410 (AbeFun), and statutory funds of the Institute of Oceanology, Polish Academy of Sciences (to MWK)

Larval dispersal and recruitment of benthic invertebrates in the Arctic Ocean

Larval dispersal is a fundamental process responsible for colonization and connectivity of benthic invertebrate populations. It is difficult to study larval dispersal in polar environments because weather and climate conditions restrict sample collection to certain seasons. In this study, we leveraged oceanographic moorings as long-term scientific platforms for collecting larvae and recruits of benthic invertebrate species in the Fram Strait and along the continental slope north of Svalbard in 2017–2021. Larval traps and fouling panels were deployed at various depths on 15 moorings at 8 locations, and additional specimens of biofouling were obtained opportunistically from moored instruments. Our results showed a significant difference in species composition between samples collected in Atlantic Water in the West Spitsbergen Current (WSC) and samples collected in Arctic Water near the seafloor and in the East Greenland Current (EGC) in the western part of the Fram Strait. There was also a stark difference between Atlantic Water species in the Fram Strait and on the north Svalbard slope. Most specimens collected in the WSC belonged to species with long-duration planktotrophic larvae, such as the ubiquitous bivalve Hiatella arctica, the bryozoan Alcyonidium mamillatum, and two nudibranchs. Samplers exposed primarily to Arctic water at their given depth and location were dominated by hydrozoans. We observed medusae budding off of the hydroids Stegopoma plicatile and Rhizoragium roseum. Our study demonstrates that the WSC is an important vector for larval dispersal into the central Arctic Ocean. Integration of biological samplers on oceanographic moorings holds great promise for monitoring efforts as climate change progresses, especially in environments where research is challenging and seasonally limited, such as the Arctic. 1. Introduction For benthic invertebrates, especially those with sessile adult stages (e.g., sponges, anemones), larval dispersal is the primary mechanism of dispersal to new habitats (Pechenik, 1999). The patterns and mechanisms of larval dispersal are difficult to study in the Arctic Ocean, where weather and climate conditions restrict sample collection to summer months. As a result, larval dispersal and the subsequent processes of settlement and recruitment in benthic invertebrates are poorly understood in the Arctic Ocean, despite their importance. Oceanographic moorings provide excellent platforms for studying larval dispersal, recruitment, and growth of organisms (Chava et al., 2021; Schiaparelli and Aliani, 2019). Instruments and floats on a mooring are deployed in the water column by design, so th