scholarly journals Morphological, histological and behavioural change in two species of marine bivalves in response to environmental stress

2021 ◽  
Author(s):  
◽  
Dayanitha Damodaran
Keyword(s):  
New Zealand ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Behavioural Change ◽  
Disease Outbreaks ◽  
Cell Types ◽  
Fine Sediment ◽  
Salinity Treatment ◽  
Stress Markers ◽  
Overall Mortality

<p>Mass mortality events (MMEs) occur when a disproportionate part of a population dies in a single event. The frequency of MMEs is increasing globally. In the past, MMEs have been linked to starvation, changes in environmental conditions and disease outbreaks. However, it is often unclear what the underlying cause of these events are. In New Zealand several MMEs have occurred in the bivalve species Austrovenus stutchburyi (Wood 1828) and Paphies subtriangulata (Wood 1828) with little known about the cause. Both of these species are recreationally harvested for consumption in New Zealand and have cultural significance.  In order to better understand MMEs in these species we must first gain a better understanding of stress expression. Bivalves have few observable features and it is difficult to classify them as healthy or stressed without investigating immune change which can be quite costly. Some research has looked into how different cell types change in response to pollutants but few studies have researched how cell types change in response to environmental conditions. The aim of this research was to find novel ways of assessing if shellfish were healthy or stressed. Little is known about how shellfish respond to environmental stressors and this is the first study to look at several novel stress expressions simultaneously, in New Zealand shellfish.  Histological, morphological and behavioural responses were measured in both A. stutchburyi and P. subtriangulata after treatment with increased temperature, lowered salinity and increased fine sediment input for up to 5 weeks. Temperature stress was the main stressor for P. subtriangulata (85% of overall mortality occurred in the heat treatment), salinity was the main stressor for A. stutchburyi (46% of overall mortality occurred in the salinity treatment), and fine sediment stress did not seem to have an effect on either species in this study. Overall, A. stutchburyi were more robust to the treatments, but low mortality occurred in both species (≤8%). Mortality correlated with time of year and was believed to be related to spawning in P. subtriangulata (48% of overall mortality occurred from October-November). Both species had a single histological marker, in A. stutchburyi this was change in gill morphology, and in P. subtriangulata this was change in digestive gland morphology. Several individual morphological features were identified as potential stress markers in A. stutchburyi and P. subtriangulata. Additionally, when removed from aquaria P. subtriangulata had impeded foot retraction time in the salinity treatment. The differences in stress markers shows the diversity of reactions to stressors even within New Zealand bivalves. This study provides a useful baseline in investigating how P. subtriangulata and A. stutchburyi respond to environmental stress. The histological slides produced during this investigation are an invaluable resource that can be used in future studies and in comparisons with archived specimens from known MMEs. Knowing how to detect signs of stress in these bivalves will help to predict MMEs in the future and aid in implementing processes to combat these events.</p>

scholarly journals Morphological, histological and behavioural change in two species of marine bivalves in response to environmental stress

2021 ◽  
Author(s):  
◽  
Dayanitha Damodaran
Keyword(s):  
New Zealand ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Behavioural Change ◽  
Disease Outbreaks ◽  
Cell Types ◽  
Fine Sediment ◽  
Salinity Treatment ◽  
Stress Markers ◽  
Overall Mortality

<p>Mass mortality events (MMEs) occur when a disproportionate part of a population dies in a single event. The frequency of MMEs is increasing globally. In the past, MMEs have been linked to starvation, changes in environmental conditions and disease outbreaks. However, it is often unclear what the underlying cause of these events are. In New Zealand several MMEs have occurred in the bivalve species Austrovenus stutchburyi (Wood 1828) and Paphies subtriangulata (Wood 1828) with little known about the cause. Both of these species are recreationally harvested for consumption in New Zealand and have cultural significance.  In order to better understand MMEs in these species we must first gain a better understanding of stress expression. Bivalves have few observable features and it is difficult to classify them as healthy or stressed without investigating immune change which can be quite costly. Some research has looked into how different cell types change in response to pollutants but few studies have researched how cell types change in response to environmental conditions. The aim of this research was to find novel ways of assessing if shellfish were healthy or stressed. Little is known about how shellfish respond to environmental stressors and this is the first study to look at several novel stress expressions simultaneously, in New Zealand shellfish.  Histological, morphological and behavioural responses were measured in both A. stutchburyi and P. subtriangulata after treatment with increased temperature, lowered salinity and increased fine sediment input for up to 5 weeks. Temperature stress was the main stressor for P. subtriangulata (85% of overall mortality occurred in the heat treatment), salinity was the main stressor for A. stutchburyi (46% of overall mortality occurred in the salinity treatment), and fine sediment stress did not seem to have an effect on either species in this study. Overall, A. stutchburyi were more robust to the treatments, but low mortality occurred in both species (≤8%). Mortality correlated with time of year and was believed to be related to spawning in P. subtriangulata (48% of overall mortality occurred from October-November). Both species had a single histological marker, in A. stutchburyi this was change in gill morphology, and in P. subtriangulata this was change in digestive gland morphology. Several individual morphological features were identified as potential stress markers in A. stutchburyi and P. subtriangulata. Additionally, when removed from aquaria P. subtriangulata had impeded foot retraction time in the salinity treatment. The differences in stress markers shows the diversity of reactions to stressors even within New Zealand bivalves. This study provides a useful baseline in investigating how P. subtriangulata and A. stutchburyi respond to environmental stress. The histological slides produced during this investigation are an invaluable resource that can be used in future studies and in comparisons with archived specimens from known MMEs. Knowing how to detect signs of stress in these bivalves will help to predict MMEs in the future and aid in implementing processes to combat these events.</p>

The 1995 mass mortality of pilchard: no role found for physical or biological oceanographic factors in Australia

1997 ◽  
Vol 48 (1) ◽  
pp. 27 ◽  
Author(s):  
D. A. Griffin ◽  
P. A. Thompson ◽  
N. J. Bax ◽  
R. W. Bradford ◽  
G. M. Hallegraeff
Keyword(s):  
New Zealand ◽  
Environmental Stress ◽  
Western Australia ◽  
Environmental Conditions ◽  
Clinical Signs ◽  
Mass Mortality ◽  
Ocean Currents ◽  
Phytoplankton Blooms ◽  
East And West ◽  
Great Australian Bight

An unprecedented mass mortality of pilchard, Sardinops sagax, occurred in Australia in 1995, spreading east and west from the Great Australian Bight at approximately 0á5 m s-1 and 0·3 m s-1 respectively to span the 6000-km range of the species from Noosa, Queensland, to Geraldton, Western Australia. Mortalities with the same clinical signs of hypoxia also occurred in New Zealand. Upwelling and phytoplankton blooms preceded the first mortalities, leading to widely publicized speculation that environmental stress caused the mortalities. However, upwellings as strong as in February 1995 off Eyre Peninsula occur as often as once every three or four years, and environmental conditions surrounding mortalities elsewhere were normal. Phytoplankton blooms were absent through much of the range; where they did accompany mortalities they were of widely differing species. Hence, the hypothesis that environmental stress caused the mortalities is quite confidently rejected. The hypothesis that ocean currents were a vector of an aeteological agent is also rejected, since the Leeuwin and East Australian currents were both flowing strongly against the spread of mortalities. Other potential vectors exist, however, so the hypothesis that an introduced pathogen was responsible cannot be rejected.

scholarly journals Sun-Tanning Perceptions of a New Zealand Urban Population (1994–2005/6)

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
A. I. Reeder ◽  
G. F. H. McLeod ◽  
A. R. Gray ◽  
R. McGee
Keyword(s):  
New Zealand ◽  
Skin Cancer ◽  
Cancer Prevention ◽  
Urban Population ◽  
Personal Information ◽  
Behavioural Change ◽  
Skin Cancer Prevention ◽  
Age Group ◽  
Significant Change ◽  
Sun Sensitivity

Background. Sun-tanning perceptions are monitored to identify changes and help refine targeting of skin cancer prevention messages.Aim. To investigate associations between perceptions of sun-tanning and demographic factors among a New Zealand urban population, 1994–2006.Methods. A telephone survey series was conducted during summer in 1994, 1997, 1999/2000, 2002/2003, and 2005/2006. Demographic and personal information (sex, age group, skin sun-sensitivity, and self-defined ethnicity) obtained from 6,195 respondents, 50.2% female, 15–69 years, was investigated in relation to six sun-tanning related statements. A total “positive perceptions of tanning” (ProTan) score was also calculated. Regression analyses modelled each component and the ProTan score against survey year and respondent characteristics.Results. Statistically significantly higher ProTan scores were found for age group (strong reverse dose-response effect), male sex, residence (highest in Auckland), ethnicity (highest among Europeans), and sun sensitivity (ann-shaped association). There was no statistically significant change in total ProTan scores from baseline.Conclusions. The development, pretesting, and evaluation of messages for those groups most likely to endorse ProTan statements should be considered for the New Zealand skin cancer prevention program. To achieve and embed significant change, mass media campaigns may require greater intensity and reinforcement with sustained contextual support for settings-based behavioural change.

A New and Open CoiledValvata(Gastropoda) from the Pliocene Koobi Fora Formation of the Turkana Basin, Northern Kenya

2010 ◽  
Vol 84 (5) ◽  
pp. 996-1002 ◽  
Author(s):  
Henning Scholz ◽  
Matthias Glaubrecht
Keyword(s):  
New Species ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Lake Level ◽  
Shell Morphology ◽  
Koobi Fora ◽  
Northern Kenya ◽  
Turkana Basin ◽  
High Level ◽  
Stratigraphic Interval

New field collections allow the study and description ofValvata juliaenew species from the Pliocene upper Burgi Member of the Koobi Fora Formation of Kenya. The shell morphology of this species varies from trochospiral to planispiral to open coiled. The species is restricted to a short stratigraphic interval.Valvata juliaeis considered as an invader of the Turkana Basin during a lacustrine transgression event. The open coiling of the species is interpreted as an ecophenotypic response to a high level of environmental stress caused by lake level fluctuations and emergence of delta systems. These environmental conditions broughtValvata juliaeto extinction soon after it invaded the Turkana Basin.

scholarly journals Modular marvels: The ecology, evolvability, and energetics of bryozoan polymorphism

2021 ◽  
Author(s):  
◽  
Carolann Schack
Keyword(s):  
New Zealand ◽  
Community Assembly ◽  
Environmental Conditions ◽  
Environmental Filtering ◽  
Classification Systems ◽  
Energetic Cost ◽  
Developmental Constraints ◽  
Mechanical Advantage ◽  
Colony Form ◽  
Hard Substrata

<p>Modularity is a fundamental concept in biology. Most taxa within the colonial invertebrate phylum Bryozoa have achieved division of labor through the development of specialized modules (polymorphs), and this group is perhaps the most outstanding exemplar of the phenomenon. This thesis addresses several gaps in the literature concerning the morphology, ecology, energetics, and evolvability of bryozoan polymorphism.  It has been over 40 years since the last review of bryozoan polymorphism, and here I provide a comprehensive update that describes the diversity, morphology, and function of bryozoan polymorphs and the significance of modularity to their evolutionary success. While the degree of module compartmentalization is important for the evolution of polymorphism in bryozoans, this does not appear to be the case for other colonial invertebrates.  To facilitate data collection, I developed a classification system for polymorphism in cheilostome bryozoans. While classification systems exist for bryozoan colony form, the system presented here is the first developed for polymorphism. This system is fully illustrated and non-hierarchical, enabling swift classification and statistical comparisons at many levels of detail.  Understanding community assembly is a key goal in community ecology, but previous work on bryozoan communities has focused on colony form rather than polymorphism. Environmental filtering influences community assembly by excluding ill-adapted species, resulting in communities with similar functional traits. An RLQ (a four-way ordination) analysis incorporating spatial data was run on a dataset of 642 species of cheilostomes from 779 New Zealand sites, to investigate environmental filtering of colony form and zooid polymorphism. This revealed environmental filtering of colony form: encrusting-cemented taxa were predominant in shallow environments with hard substrata (200 m). Furthermore, erect taxa found in shallow environments with high current speeds were typically jointed. Surprisingly, polymorphism also followed environmental gradients. External ovicells (brood chambers) were more common in deeper, low oxygen water than immersed and internal ovicells. This may reflect the oxygen needs of the embryo or increased predation intensity in shallow environments. Bryozoans with costae (rib-like spines) tended to be found in deeper water as well, while bryozoans with calcified frontal shields were found in shallow environments with a higher concentration of CaCO₃. Avicularia (defensive grasping structures) were not related to environmental conditions, and changes in pivot bar structure with depth likely represent a phylogenetic signal. Factors influencing community assembly were somewhat partitioned by levels of organization, since colony form responds to environmental conditions, while the effects of evolutionary history, predation, and environmental conditions were not well-separated for zooid-level morphology. Finally, rootlets may have been a key innovation that allowed cementing taxa to escape hard substrata, potentially contributing to the cheilostome radiation.  Despite the diversity of life on earth, many morphologies have not been achieved. Morphology can be limited by a variety of constraints (developmental, historical, biomechanical) and comparing the distribution of realized forms in a theoretical form-space (i.e. “morphospace”) can highlight which constraints are at play and potential functions. If traits cluster around biomechanical optima, then morphology may be shaped by strong selective pressures. In contrast, a well-explored (filled) morphospace suggests weak constraints and high morphological evolvability. Here, constraints on morphospace exploration were examined for 125 cheilostome bryozoan species from New Zealand. The mandible morphospaces for avicularia (beak-like polymorphs) were visualized using Coordinate-Point Extended Eigenshape analysis. Mechanical advantage, moment of inertia, drag, peak force, and rotational work required to close the mandible were calculated for theoretical (n=47) and real mandibles (n=224) to identify biomechanical optima. The volume and surface of area of the parcel of water passed through by the closing mandible (referred to as the “domain”) was also calculated. The theoretical morphospace of avicularia is well-explored, suggesting they are highly evolvable and have relaxed developmental constraints. However, there may be constraints within lineages. A well-developed fulcrum (complete pivot bar) may be an evolutionary pre/corequisite to evolving mandibles with extreme moments of inertia such as setose and highly spathulate forms. The most common mandible shape, triangular, represents a trade-off between maximizing domain size, minimizing energetic cost (force and construction material), and minimizing the potential for breakage. This suggests that they are well suited for catching epibionts, representing the first empirical evidence for avicularian function. Tendon length and mechanical advantage are limited by tendon width, which itself is constrained by the base width of the mandible. This explains the low mechanical advantage of setose mandibles and suggests that they are unable to grasp epibionts. The calories required to close the mandible of an avicularium (estimated from rotational work) are quite small (1.24 x 10⁻¹⁶ to 8.82 x 10⁻¹¹ cal).  Overall, this thesis highlights the complexity of bryozoan polymorphism and suggests cheilostome avicularia could provide a unique evolutionary system to study due to their apparent lack of strong developmental constraints. Future studies into the ecology of polymorphism should focus on the degree of investment (polymorph abundance within a colony) rather than presence or absence.</p>

Phragmidium acuminatum.

2021 ◽  
Author(s):  
Keyword(s):  
New Zealand ◽  
Environmental Conditions ◽  
Pathogenic Fungus ◽  
Plant Pathogenic Fungus ◽  
The World ◽  
Agricultural Plants

Abstract There is little published information on this plant pathogenic fungus, which is limited to parts of Asia, Europe and New Zealand. It attacks Rubus spp., among others, and as these hosts exist in other regions of the world with similar environmental conditions, this species may pose a threat to native or agricultural plants if introduced.

Valsa sordida. [Descriptions of Fungi and Bacteria].

1998 ◽  
Author(s):  
V. P. Hayova
Keyword(s):  
Czech Republic ◽  
New Zealand ◽  
North America ◽  
South America ◽  
Environmental Stress ◽  
Geographical Distribution ◽  
Plant Diseases ◽  
Republic Of Georgia ◽  
Distribution Maps ◽  
Poplar Trees

Abstract A description is provided for Valsa sordida. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Valsa sordida is usually associated with Valsa canker of poplar twigs. Wounded trees, and trees injured by insects or attacked by other pathogens are more susceptible to infection. Development of Valsa canker is affected by environmental stress (Guyon, 1996; Tao et al., 1984). Poplar canker caused by V. sordida has been studied in different countries (CMI Distribution Maps of Plant Diseases, 1977; Worrall, 1983; Wang et al., 1981) The fungus can be often found in declining poplar stands together with another pathogen of poplar trees, Leucostoma niveum. Valsa sordida may also cause necrosis of willow twigs. HOSTS: Populus spp., Salix spp. and, more rarely, other woody angiosperms. GEOGRAPHICAL DISTRIBUTION: Africa: Morocco. Asia: Armenia, Azerbaijan, China, Republic of Georgia, India, Iran, Iraq, Israel, Japan. Kazakhstan, Korea, Russia (Tatarstan), Turkey, Turkmenia, Uzbekistan. Australasia: Australia (Victoria), New Zealand. Europe: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, France, Germany, Greece, Ireland, Italy, Netherlands, Norway, Poland, Portugal, Rumania, Russia, Slovakia, Sweden, Switzerland, UK, Ukraine, former Yugoslavia. North America: Canada (Alberta, British Columbia, Nova Scotia, Ontario, Québec, Saskatchewan). USA (California, Colorado, Michigan, Minnesota). South America: Chile. TRANSMISSION: Both conidia and ascospores are air-borne, especially under humid conditions. Yellow or orange exudation of conidia from conidiomata can be often seen after rain.

scholarly journals Bacterial Cell Wall Quality Control during Environmental Stress

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Elizabeth A. Mueller ◽  
Petra Anne Levin
Keyword(s):  
Quality Control ◽  
Cell Wall ◽  
Cell Surface ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Bacterial Cell ◽  
Cell Shape ◽  
Bacterial Cell Wall ◽  
Peptidoglycan Synthesis ◽  
Peptidoglycan Cell Wall

ABSTRACT Single-celled organisms must adapt their physiology to persist and propagate across a wide range of environmental conditions. The growth and division of bacterial cells depend on continuous synthesis of an essential extracellular barrier: the peptidoglycan cell wall, a polysaccharide matrix that counteracts turgor pressure and confers cell shape. Unlike many other essential processes and structures within the bacterial cell, the peptidoglycan cell wall and its synthesis machinery reside at the cell surface and are thus uniquely vulnerable to the physicochemical environment and exogenous threats. In addition to the diversity of stressors endangering cell wall integrity, defects in peptidoglycan metabolism require rapid repair in order to prevent osmotic lysis, which can occur within minutes. Here, we review recent work that illuminates mechanisms that ensure robust peptidoglycan metabolism in response to persistent and acute environmental stress. Advances in our understanding of bacterial cell wall quality control promise to inform the development and use of antimicrobial agents that target the synthesis and remodeling of this essential macromolecule. IMPORTANCE Nearly all bacteria are encased in a peptidoglycan cell wall, an essential polysaccharide structure that protects the cell from osmotic rupture and reinforces cell shape. The integrity of this protective barrier must be maintained across the diversity of environmental conditions wherein bacteria replicate. However, at the cell surface, the cell wall and its synthesis machinery face unique challenges that threaten their integrity. Directly exposed to the extracellular environment, the peptidoglycan synthesis machinery encounters dynamic and extreme physicochemical conditions, which may impair enzymatic activity and critical protein-protein interactions. Biotic and abiotic stressors—including host defenses, cell wall active antibiotics, and predatory bacteria and phage—also jeopardize peptidoglycan integrity by introducing lesions, which must be rapidly repaired to prevent cell lysis. Here, we review recently discovered mechanisms that promote robust peptidoglycan synthesis during environmental and acute stress and highlight the opportunities and challenges for the development of cell wall active therapeutics.

scholarly journals Mating Competitiveness of Transgenic Aedes aegypti (Diptera: Culicidae) Males Against Wild-Type Males Reared Under Simulated Field Conditions

2020 ◽  
Vol 57 (6) ◽  
pp. 1775-1781
Author(s):  
David S Kang ◽  
Joanne M Cunningham ◽  
Diane D Lovin ◽  
Dave D Chadee ◽  
David W Severson
Keyword(s):  
Aedes Aegypti ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Mating Success ◽  
Genetically Modified ◽  
Field Isolate ◽  
Larval Density ◽  
Laboratory Strain ◽  
Adult Mosquito ◽  
Male Mating

Abstract Efforts directed at genetic modification of mosquitoes for population control or replacement are highly dependent on the initial mating success of transgenic male mosquitoes following their release into natural populations. Adult mosquito phenotypes are influenced by the environmental conditions experienced as larvae. Semifield studies conducted to date have not taken that under consideration when testing male mating fitness, and have compared mating success of males reared under identical environmental conditions. We performed pairwise mating challenges between males from a genetically modified laboratory strain (BF2) versus males from a recent Trinidad field isolate of Aedes aegypti (L.), a major vector of multiple arboviruses. We utilized larval density and nutrition to simulate environmental stress experienced by the Trinidad males and females. Our results indicated that environmental stress during larval development negatively influenced the competitiveness and reproductive success of males from the Trinidad population when paired with optimum reared BF2 males. Small (0.027 m3) and large (0.216 m3) trials were conducted wherein stressed or optimum Trinidad males competed with optimum BF2 males for mating with stressed Trinidad females. When competing with stress reared Trinidad males, optimum reared BF2 males were predominant in matings with stress reared Trinidad females, and large proportions of these females mated with males of both strains. When competing with optimum reared Trinidad males, no difference in mating success was observed between them and BF2 males, and frequencies of multiple matings were low. Our results indicate that future mating competition studies should incorporate appropriate environmental conditions when designing mating fitness trials of genetically modified males.

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