Bryozoan epibiosis on lobster hosts is rarely reported. Here we document bryozoan fouling of the spiny rock lobster Jasus edwardsii from the Hauraki Gulf, North Island of New Zealand. The 92 lobsters ...in this study came from the Cape Rodney-Okakari Point Marine Reserve. The lobsters were measured for size and weight, sexed, scanned for epibionts, and photographed. Forty-two per cent of the lobsters were fouled by epibionts, but only 9% by bryozoans, and they were all males. The bryozoans were all cheilostome gymnolaemates. Only erect colonies were found on the dorsal carapace, and only encrusting colonies were found on the ventral surface. Two of the erect colonies were found in gaping exposed wounds through the exterior wall into the branchial chamber. In addition to host wounds, differences in frequency and location of fouling bryozoan colonies were also attributed to time since last moult and grooming. This epibiosis is interpreted as more of a one-sided commensal symbiotic relationship, perhaps best described as phoretic (i.e. hitchhiking relationship).
We propose a dedicated research effort on the determinants of settlement persistence in the ancient world, with the potential to significantly advance the scientific understanding of urban ...sustainability today. Settlements (cities, towns, villages) are locations with two key attributes: They frame human interactions and activities in space, and they are where people dwell or live. Sustainability, in this case, focuses on the capacity of structures and functions of a settlement system (geography, demography, institutions) to provide for continuity of safe habitation. The 7,000-y-old experience of urbanism, as revealed by archaeology and history, includes many instances of settlements and settlement systems enduring, adapting to, or generating environmental, institutional, and technological changes. The field of urban sustainability lacks a firm scientific foundation for understanding the long durée, relying instead on narratives of collapse informed by limited case studies. We argue for the development of a new interdisciplinary research effort to establish scientific understanding of settlement and settlement system persistence. Such an effort would build upon the many fields that study human settlements to develop new theories and databases from the extensive documentation of ancient and premodern urban systems. A scientific foundation will generate novel insights to advance the field of urban sustainability.
An endolithic lifestyle in mineralized substrates has evolved multiple times in various phyla including Bryozoa. The family Penetrantiidae includes one genus with ten extant and two fossil species. ...They predominantly colonize the shells of molluscs and establish colonies by chemical dissolution of calcium carbonate. Based on several morphological characters, they were described to be either cheilostome or ctenostome bryozoans. For more than 40 years, neither the characters of species identity and systematics nor the problem of their phylogeny was approached. Consequently, the aim of this study is to reevaluate species identities and the systematic position of the genus
Penetrantia
by analyzing at least six different species from eight regions with the aid of modern methods such as confocal laser scanning microscopy and 3D-reconstruction techniques. This study demonstrates that the musculature associated with the operculum and brood chamber shows significant differences from the cheilostome counterparts and seems to have evolved independently. Together with the presence of other ctenostome-like features such as true polymorphic stolons and uncalcified body wall, this finding supports a ctenostome affinity. Operculum morphology reveals many new species-specific characters, which, together with information about gonozooid morphology, tentacle number, and zooid size ranges, will enhance species identification. It also revealed a probable new species in Japan as well as potential cryptic species in France and New Zealand. In addition, this study increases the known distribution range of the family and its substrate diversity. Altogether, the new information collated here provides the basis for future work on a neglected taxon.
Ctenostomes are a group of gymnolaemate bryozoans with an uncalcified chitinous body wall having few external, skeletal characters. Hence, species identification is challenging and their systematics ...remain poorly understood, even more so when they exhibit an endolithic (boring) lifestyle. Currently, there are four Recent families of endolithic bryozoans that live inside mineralized substrates like mollusk shells. In particular, Penetrantiidae Silén, 1946 has received considerable attention and its systematic affinity to either cheilostomes or ctenostomes has been debated. Species delimitation of penetrantiids remains difficult, owing to a high degree of colonial and zooidal plasticity. Consequently, an additional molecular approach is essential to unravel the systematics of penetrantiids, their phylogenetic placement and their species diversity. We therefore sequenced the mitochondrial (mt) genomes and two nuclear markers of 27 ctenostome species including nine penetrantiids. Our phylogeny supports the Penetrantiidae as a monophyletic group placed as sister taxon to the remaining ctenostomes alongside paludicellids, arachnidioids and terebriporids. The boring family Terebriporidae d'Orbigny, 1847 were previously considered to be among vesicularioids, but our results suggest an arachnidioid affinity instead. Ctenostome paraphyly is supported by our data, as the cheilostomes nest within them. A Multiporata clade is also well supported, including the former victorelloid genus Sundanella. Altogether, this study provides new insights into ctenostome systematics, assists with species delimitation and contributes to our understanding of the bryozoan tree of life.
Better resolving ctenostome bryozoan systematics is crucial in understanding bryozoan evolution in general. Ctenostomes are a paraphyletic group of soft bodied bryozoans with a wide ecological diversity, including endolithic (boring) forms like Penetrantia. Consequently, this study seeks for a larger phylogenetic analysis based on data from mitochondrial genomes and nuclear ribosomal RNA.
We present a review of the published data about serpulid skeletal carbonate geochemistry, augmented with new data from the Southern Hemisphere. We know something about skeletal carbonate mineralogy ...of 15 % of extant species (
n
= 52); and about half of extant genera (
n
= 25). Serpulid worm tubes vary in their skeletal mineralogy from entirely aragonitic (about 24 % of species) to entirely high-Mg calcite (40 %) to mixtures of the two. Mg in calcite ranges from 7 to 15 wt% MgCO
3
, with a mean of 11 wt% MgCO
3
. Little mineralogical variation within individuals or species can be found in aragonitic specimens, whereas high-Mg calcitic species show somewhat more variability in both calcite and Mg content, and those with mixed mineralogies are highly variable. These three groups correspond broadly with currently accepted clades. Given this strong phylogenetic signal, we analysed the data using phylogenetically independent contrasts, a statistical approach that separates genotypic from phenotypic variability; we found that variations which might be ascribed to environment were generally weak. The mineralogy of serpulid tubes makes them particularly vulnerable to ocean chemistry changes. While some serpulids appear to be able to adjust their tube mineralogy in order to adapt to sea-water chemistry, overall strength and elasticity may be sacrificed when they do. The biodiverse reef habitat provided by serpulids in some temperate regions may be the only complex solid habitat available, and loss or compromise of these temperate reefs will most likely have deleterious flow-on effects on temperate benthic communities.
Abstract
On the continental shelf, New Zealand bryozoans dominate ecologically-important three-dimensional benthic habitat providing structural complexity which hosts a wide variety of fauna, ...including economically valuable species (e.g. oysters and blue cod). The association between these species and bryozoan-dominated biogenic habitat commonly results in trawling damage to the benthos; eliminating pressure from destructive fishing practices could support bryozoan regrowth. In 2002, a voluntary fishing restriction was designated over part of one such bryozoan-dominated biogenic habitat, but the efficacy of this ban has not been assessed. Statutory marine protected areas have been proposed in the same area; they aim to achieve bryozoan protection and recovery. A comparison of the bryozoan fauna using benthic images from 2003 and 2019 from the Otago shelf, South Island, New Zealand/Te Waipounamu, Aotearoa shows that a 17-year voluntary fishing ban has been ineffective at increasing the cover and richness of bryozoan-dominated biogenic habitat on the Otago shelf. This study provides a baseline for future monitoring and develops useful metrics for recovery, while calling for further research on the biology and ecology of habitat-forming bryozoans.
and
are two pathogens of great public health importance. Both bacteria colonize the human gastrointestinal tract where they are known to interact in ways that worsen disease outcomes. We show that ...the damage associated with
infection (CDI) releases nutrients that benefit
. One particular nutrient, heme, allows
to use oxygen to generate energy and grow better in the gut. Understanding the mechanisms of these interspecies interactions could inform therapeutic strategies for CDI.
Prior to Cassini's arrival at Saturn, the nitrogen‐rich dense atmosphere of Titan was considered as a significant, if not dominant, source of heavy ions in Saturn's magnetosphere. While nitrogen was ...detected in Saturn's magnetosphere based on Cassini observations, Enceladus instead of Titan appears to be the primary source. However, it is difficult to imagine that Titan's dense atmosphere is not a source of nitrogen. In this paper, we apply the Rymer et al.'s (2009) Titan plasma environment categorization model to the plasma environment along Titan's orbit when Titan is not present. We next categorize the Titan encounters that occurred since Rymer et al. (2009). We also produce an empirical model for applying the probabilistic occurrence of each plasma environment as a function of Saturn local time (SLT). Finally, we summarized the electron energy spectra in order to allow one to calculate more accurate electron‐impact interaction rates for each plasma environment category. The combination of this full categorization versus SLT and empirical model for the electron spectrum is critical for understanding the magnetospheric plasma and will allow for more accurate modeling of the Titan plasma torus.
Key Points
Empirical model for the plasma environment categorization along Titan's orbit
Identification of the dense plasma region as a new plasma environment category
Evidence for Titan impacting the location of Saturn's magnetopause
Rationale
Stable oxygen and carbon isotope ratios are one of the most accurate ways of determining environmental changes in the past, which are used to predict future environmental change. Biogenic ...carbonates from marine organisms are the most common source of samples for stable isotope analysis. Before they are analyzed by mass spectrometry, any organic material is traditionally removed by one of three common pretreatment methods: roasting, bleaching, or with hydrogen peroxide at various strengths and durations.
Methods
This study compares δ18O and δ13C values in a control with no pretreatment with those from five different pretreatment methods using conventional acid digestion mass spectrometry. The objectives are to: assess the impact of the most common pretreatment methods on δ18O and δ13C values from (1) taxonomically underrepresented groups in previous studies, and (2) those that precipitate a wide range of biomineralogies, in the debate of whether to pretreat or not to pretreat. We analyzed the following biomineralogically complex temperate marine organisms from southern New Zealand: four species of bryozoans, four species of molluscs, two species of arthropods, and one species each of annelid, red alga, brachiopod, and echinoderm (test plates and spines treated separately). These species precipitate aragonite, High‐, Intermediate‐, and/or Low‐Mg calcite (LMC) in their skeletons. We used linear mixed statistical models to compare the effects of the pretreatments and mineralogical composition on their δ18O and δ13C values.
Results
Roasting was the most effective pretreatment for the removal of organic matter and light H2O2 the least, but the former had corresponding impacts on isotope ratios. δ18O values were not directly affected by wt% MgCO3, but they were significantly affected by the interaction of roasting and wt% MgCO3. This same negative effect of roasting on species with higher wt% MgCO3 occurred in δ13C values, but it was much more pronounced in δ18O values. Both H2O2 pretreatments significantly and negatively affected δ18O values at higher wt% MgCO3. Neither bleaching pretreatment significantly affected δ18O values. δ13C values were most negatively affected in skeletons with high wt% MgCO3. There was also a strong negative roasting effect and more so at higher wt% MgCO3. Bleaching and H2O2 did not significantly affect δ13C values.
Conclusions
Based on these results, and when using skeletal carbonate of complex mineralogies, we recommend considering the abandonment of pretreatment of biogenic carbonate for stable isotope analysis due to confounded results from previous studies, difficulties with preparation, and/or the absence of significant effects of organic material on isotope ratios. If pretreatment is necessary, avoid roasting especially at higher temperatures and durations, use minimal bleaching, and in general avoid using High‐Mg calcite species in O and C stable isotope studies. If bleaching is used, clearly indicate the concentration and duration of exposure.
ABSTRACT
Skeletal resorption – the physiological removal of mineralised parts by an organism – is an important morphogenetic process in bryozoans. Reports of its occurrence and function across the ...phylum are patchy, however, and have not previously been synthesised. Here we show that resorption occurs routinely across a wide range of bryozoan clades, colony sizes, growth forms, ontogenetic stages, body wall types, skeletal ultrastructures and mineralogies. Beginning in the early Paleozoic, different modes and functions of resorption have evolved convergently among disparate groups, highlighting its utility as a morphogenetic mode in this phylum. Its functions include branch renovation, formation of branch articulations, excavation of reproductive chambers, part‐shedding, and creation of access portals for budding beyond previously formed skeletal walls. Bryozoan skeletons can be altered by resorption at microscopic, zooidal and colony‐wide scales, typically with a fine degree of control and coordination. We classified resorption patterns in bryozoans according to the morphology and function of the resorption zone (window formation, abscission or excavation), timing within the life of the skeletal element resorbed (primary or secondary), and scale of operation (zooidal or multizooidal). Skeletal resorption is probably greatly underestimated in terms of its utility and role in bryozoan life history, and its prevalence across taxa, especially in fossil forms. It is reported proportionally more frequently in stenolaemates than in gymnolaemates. Some modes of resorption potentially alter or remove the spatial–temporal record of calcification preserved within a skeleton. Consequently, knowledge that resorption has occurred can be relevant for some common applications of skeletal analysis, such as palaeoenvironmental interpretation, or growth and ageing studies. To aid recognition we provide scanning electron microscopy, backscattered electron scanning electron microscopy and transmission electron microscopy examples of skeletal ultrastuctures modified by resorption.
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