scholarly journals Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12280
Author(s):  
Wilson Xieu ◽  
Levi S. Lewis ◽  
Feng Zhao ◽  
Rachel A. Fichman ◽  
Malte Willmes ◽  
...  
Keyword(s):  
San Francisco ◽  
Developmental Stages ◽  
Critically Endangered ◽  
Age And Growth ◽  
Estuarine Fish ◽  
Fish Length ◽  
Life Stages ◽  
Vital Rates ◽  
Delta Smelt ◽  
And Migration

Background The application of otolith-based tools to inform the management and conservation of fishes first requires taxon- and stage-specific validation. The Delta Smelt (Hypomesus transpacificus), a critically endangered estuarine fish that is endemic to the upper San Francisco Estuary (SFE), California, United States, serves as a key indicator species in the SFE; thus, understanding this species’ vital rates and population dynamics is valuable for assessing the overall health of the estuary. Otolith-based tools have been developed and applied across multiple life stages of Delta Smelt to reconstruct age structure, growth, phenology, and migration. However, key methodological assumptions have yet to be validated, thus limiting confidence in otolith-derived metrics that are important for informing major water management decisions in the SFE. Methods Using known-age cultured Delta Smelt and multiple independent otolith analysts, we examined otolith formation, otolith-somatic proportionality, aging accuracy and precision, left-right symmetry, and the effects of image magnification for larval, juvenile, and adult Delta Smelt. Results Overall, otolith size varied linearly with fish size (from 10–60 mm), explaining 99% of the variation in fish length, despite a unique slope for larvae < 10 mm. Otolith-somatic proportionality was similar among wild and cultured specimens. Aging precision among independent analysts was 98% and aging accuracy relative to known ages was 96%, with age estimates exhibiting negligible differences among left and right otoliths. Though error generally increased with age, percent error decreased from 0–30 days-post-hatch, with precision remaining relatively high (≥ 95%) thereafter. Increased magnification (400×) further improved aging accuracy for the oldest, slowest-growing individuals. Together, these results indicate that otolith-based techniques provide reliable age and growth reconstructions for larval, juvenile, and adult Delta Smelt. Such experimental assessments across multiple developmental stages are key steps toward assessing confidence in otolith-derived metrics that are often used to assess the dynamics of wild fish populations.

A state–space multistage life cycle model to evaluate population impacts in the presence of density dependence: illustrated with application to delta smelt (Hyposmesus transpacificus)

2011 ◽  
Vol 68 (7) ◽  
pp. 1285-1306 ◽  
Author(s):  
Mark N. Maunder ◽  
Richard B. Deriso
Keyword(s):  
Life Cycle ◽  
Density Dependence ◽  
State Space ◽  
San Francisco ◽  
Anthropogenic Factors ◽  
Life Stages ◽  
Life Cycle Model ◽  
Cycle Model ◽  
Delta Smelt ◽  
The Impact

Multiple factors acting on different life stages influence population dynamics and complicate the assessment and management of populations. To provide appropriate management advice, the data should be used to determine which factors are important and what life stages they impact. It is also important to consider density dependence because it can modify the impact of some factors. We develop a state–space multistage life cycle model that allows for density dependence and environmental factors to impact different life stages. Models are ranked using a two-covariates-at-a-time stepwise procedure based on AICc model averaging to reduce the possibility of excluding factors that are detectable in combination, but not alone. Impact analysis is used to evaluate the impact of factors on the population. The framework is illustrated by application to delta smelt ( Hyposmesus transpacificus ), a threatened species that is potentially impacted by multiple anthropogenic factors. Our results indicate that density dependence and a few key factors impact the delta smelt population. Temperature, prey, and predators dominated the factors supported by the data and operated on different life stages. The included factors explain the recent declines in delta smelt abundance and may provide insight into the cause of the pelagic species decline in the San Francisco Estuary.

Retrospective determination of natal habitats for an estuarine fish with otolith strontium isotope ratios

2005 ◽  
Vol 56 (5) ◽  
pp. 655 ◽  
Author(s):  
James A. Hobbs ◽  
Qing-zhu Yin ◽  
Jessica Burton ◽  
William A. Bennett
Keyword(s):  
Laser Ablation ◽  
San Francisco ◽  
Isotope Ratios ◽  
Core Region ◽  
Strontium Isotope ◽  
Estuarine Fish ◽  
Delta Smelt ◽  
The Core ◽  
Relative Standard ◽  
Strontium Isotope Ratios

We investigated the ability of strontium isotope ratios (87Sr/86Sr) in otolith cores to record the natal habitats of juvenile delta smelt Hypomesus transpacificus from the San Francisco Estuary, USA. Young delta smelt (<60 days old) were collected during the California Department of Fish and Game 20-mm Survey in May and June of 1999 at several potential natal areas: Napa River, Suisun Marsh, West Delta, North Delta, Central Delta, South Delta and East Delta. The core region of sagittal otoliths was assayed with laser ablation-multicollector inductively coupled plasma mass spectroscopy. The laser ablation technique provided precise estimates of 87Sr : 86Sr ratios with relative standard deviation of 0.003% (one sigma). Isotope ratios ranged from 0.7065 to 0.708 and were different among natal habitats. However, natal habitats within the delta region were not discernable among each other, and reflect the mixing of the two major rivers, Sacramento River and San Joaquin River within the delta. We will therefore be able to determine natal habitats for delta smelt by assaying the core region of the otoliths. The application of strontium isotope ratios (87Sr/86Sr) in fish otoliths will greatly improve conservation efforts for this protected species.

scholarly journals Gross morphology, histology, and ultrastructure of the olfactory rosette of a critically endangered indicator species, the Delta Smelt, Hypomesus transpacificus

2021 ◽  
Author(s):  
Pedro Alejandro Triana-Garcia ◽  
Gabrielle A. Nevitt ◽  
Joseph B. Pesavento ◽  
Swee J. Teh
Keyword(s):  
San Francisco ◽  
Sensory Ecology ◽  
Critically Endangered ◽  
Future Research ◽  
Delta Smelt ◽  
Sustentacular Cells ◽  
Olfactory Ability ◽  
Receptor Neurons ◽  
Hypomesus Transpacificus ◽  
Olfactory Rosette

AbstractThe Delta Smelt (Hypomesus transpacificus) is a small, semi-anadromous fish native to the San Francisco Bay-Delta Estuary and has been declared as critically endangered. Their olfactory biology, in particular, is poorly understood and a basic description of their sensory anatomy is needed to advance our understanding of the sensory ecology of species to inform conservation efforts to manage and protect them. We provide a description of the gross morphology, histological, immunohistochemical, and ultrastructural features of the olfactory rosette in this fish and discuss some of the functional implications in relation to olfactory ability. We show that Delta Smelt have a multilamellar olfactory rosette with allometric growth. Calretinin immunohistochemistry revealed a diffuse distribution of olfactory receptor neurons within the epithelium. Ciliated, microvillous and crypt neurons were clearly identified using morphological and immunohistochemical features. The olfactory neurons were supported by robust ciliated and secretory sustentacular cells. Although the sense of smell has been overlooked in Delta Smelt, we conclude that the olfactory epithelium has many characteristics of macrosmatic fish. With this study, we provide a foundation for future research into the sensory ecology of this imperiled fish.

Population trends and migration patterns in the critically endangered Yellow-breasted Bunting (Emberiza aureola) in the Republic of Korea

2020 ◽  
Vol 27 (1) ◽  
pp. 56-63
Author(s):  
Jong-Gil Park ◽  
Chang-uk Park ◽  
Kyoung-Soon Jin ◽  
Yang-Mo Kim ◽  
Hee-Young Kim ◽  
...  
Keyword(s):  
Population Trends ◽  
Critically Endangered ◽  
Republic Of Korea ◽  
Migration Patterns ◽  
The Republic ◽  
And Migration

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals Temporal Dynamics of ‘Ca. Phytoplasma mali’ Load in the Insect Vector Cacopsylla melanoneura

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 592
Author(s):  
Valentina Candian ◽  
Monia Monti ◽  
Rosemarie Tedeschi
Keyword(s):  
Host Plants ◽  
Developmental Stages ◽  
Temporal Dynamics ◽  
Control Strategies ◽  
Vector Competence ◽  
Insect Vector ◽  
Life Stages ◽  
Candidatus Phytoplasma Mali ◽  
High Infection ◽  
Cacopsylla Melanoneura

The transmission of phytoplasmas is the result of an intricate interplay involving pathogens, insect vectors and host plants. Knowledge of the vector’s competence during its lifespan allows us to define more sustainable well-timed control strategies targeted towards the most worrisome life stages. We investigated the temporal dynamics of ‘Candidatus Phytoplasma mali’ load in Cacopsylla melanoneura in the different developmental stages in Northwest Italy. The phytoplasma load in the vector was evaluated in overwintering adults, nymphs and newly emerged adults after different acquisition access periods. Moreover, we followed the multiplication of the phytoplasma during the aestivation and the overwintering period on conifers. Our results confirmed the ability of remigrants to retain the phytoplasma until the end of winter. We also highlighted the high acquisition efficiency and vector competence, based on phytoplasma load, of nymphs and newly emerged adults. Therefore, particular attention should be paid to the management of overwintered C. melanoneura as soon as they return to the orchards, but also to newly emerged adults, particularly in orchards with a high infection rate and when the migration to conifers is delayed.

scholarly journals Starost, rast i morfometrija otolita palamide (Sarda sarda Block, 1793) iz istočnog Sredozemnog mora

2018 ◽  
Vol 59 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Mado Kotsiri ◽  
Ioannis E. Batjakas
Keyword(s):  
Growth Parameters ◽  
Eastern Mediterranean ◽  
Fork Length ◽  
Cold Season ◽  
Age And Growth ◽  
Fish Length ◽  
Thin Sections ◽  
Significant Relationships ◽  
The One ◽  
Sarda Sarda

The otoliths of the Atlantic bonito, Sarda sarda (Bloch, 1793), were examined with the aim to estimate the age and growth of the species in the eastern Mediterranean Sea and to reveal possible relationships between otolith shape or size and age. All specimens used in this study, ranging from 7.2 to 70.4 cm in fork length and from 20 to 4889 g in total weight, were caught in the Aegean and Ionian Seas during the period 1997-2010. Otolith morphometry was studied using image analysis techniques for all intact sagittae ranging in weight from 0.6 to 11.3 mg and four shape indices were calculated. No statistical significant differences between left and right otolith morphometric variables were found. The age of fish was estimated by counting the pairs of opaque and translucent bands in transversal thin sections of otoliths. The estimated ages ranged from 0+ to 7 years and the von Bertalanffy growth parameters were determined \((L∞=79.9 cm, k=0.261 and to=-1.230 years)\). The examination of the type of growth bands at the outside margin of each otolith per month showed that one translucent band is formed annually during the cold season. The results revealed statistically significant relationships between otolith morphometric variables and fish length or age. Among the variables, otolith weight was the one that showed the highest correlation with age (R=0.77). Therefore, otolith weight could represent a valuable criterion for age estimation in Atlantic bonito that is objective, economic and easy to perform compared to annuli counting method in hard parts.

scholarly journals Simulated Fishing to Untangle Catchability and Availability in Fish Abundance Monitoring

2021 ◽  
Vol 19 (3) ◽  
Author(s):  
Vanessa Tobias ◽  
Keyword(s):  
San Francisco ◽  
Water Clarity ◽  
Ecological Monitoring ◽  
Monitoring Data ◽  
Delta Smelt ◽  
Individual Based Simulation ◽  
The Relationship ◽  
True Population

In fisheries monitoring, catch is assumed to be a product of fishing intensity, catchability, and availability, where availability is defined as the number or biomass of fish present and catchability refers to the relationship between catch rate and the true population. Ecological monitoring programs use catch per unit of effort (CPUE) to standardize catch and monitor changes in fish populations; however, CPUE is proportional to the portion of the population that is vulnerable to the type of gear used in sampling, which is not necessarily the entire population. Programs often deal with this problem by assuming that catchability is constant, but if catchability is not constant, it is not possible to separate the effects of catchability and population size using monitoring data alone. This study uses individual-based simulation to separate the effects of changing environmental conditions on catchability and availability in environmental monitoring data. The simulation combines a module for sampling conditions with a module for individual fish behavior to estimate the proportion of available fish that would escape from the sample. The method is applied to the case study of the well monitored fish species Delta Smelt (Hypomesus transpacificus) in the San Francisco Estuary, where it has been hypothesized that changing water clarity may affect catchability for long-term monitoring studies. Results of this study indicate that given constraints on Delta Smelt swimming ability, it is unlikely that the apparent declines in Delta Smelt abundance are the result of changing water clarity affecting catchability.

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