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.

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.

scholarly journals Modeling Delta Smelt Distribution for Hypothesized Swimming Behaviors

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Edward Gross ◽  
Josh Korman ◽  
Lenny Grimaldo ◽  
Michael MacWilliams ◽  
Aaron Bever ◽  
...  
Keyword(s):  
San Francisco ◽  
Three Dimensional ◽  
San Francisco Estuary ◽  
Spawning Migration ◽  
Delta Smelt ◽  
Low Salinity ◽  
Particle Tracking Model ◽  
Tracking Model ◽  
Hypomesus Transpacificus ◽  
Suisun Bay

Delta Smelt, Hypomesus transpacificus, is an endangered pelagic fish native to the San Francisco Estuary. The distribution of Delta Smelt in the estuary shifts landward from low-salinity habitat to freshwater habitat before spawning. This spawning migration often coincides with the first substantial freshwater inflow to the estuary during winter. To accomplish this landward shift in distribution, Delta Smelt are believed to use the tides by swimming to faster-moving currents during flood tides and then repositioning themselves to slower-moving currents to reduce seaward movement on ebb tides. Studies have hypothesized that the swimming behavior of Delta Smelt during this period is influenced by environmental conditions such as salinity and turbidity. The details of these swimming behaviors—including the extent to which flows, salinity, and turbidity affect behaviors and distributions—are uncertain. The spawning migration is of management interest because an increase in observed counts of Delta Smelt at the South Delta water-export facilities has coincided roughly with the spawning migration in many years. In this study, we investigated a range of hypothesized swimming behaviors using a three-dimensional particle-tracking model for water year 2002 during the spawning migration, and compared the predicted distributions of Delta Smelt to distributions inferred from catch data. Our goal was to improve understanding of the influence of Delta Smelt swimming on distribution, and, ultimately, to develop a modeling tool to help management agencies identify conditions associated with entrainment losses. Predictions of Delta Smelt distributions and entrainment varied greatly among behaviors. Without swimming, Delta Smelt would be rapidly transported seaward of Suisun Bay, while continuous tidal migration would move them deep into the interior Delta. These behaviors and a simple turbidity-driven behavior model predicted distributions inconsistent with observations, while more complex behavior rules allowed improved predictions.

scholarly journals Salinity Changes the Dynamics of Pyrethroid Toxicity in Terms of Behavioral Effects on Newly Hatched Delta Smelt Larvae

Toxics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 40
Author(s):  
Amelie Segarra ◽  
Florian Mauduit ◽  
Nermeen R. Amer ◽  
Felix Biefel ◽  
Michelle L. Hladik ◽  
...  
Keyword(s):  
San Francisco ◽  
Global Climate ◽  
Salinity Gradient ◽  
Aquatic Organisms ◽  
Behavioral Effects ◽  
Early Life Stages ◽  
Pyrethroid Insecticides ◽  
Delta Smelt ◽  
Risk Of Exposure ◽  
Hypomesus Transpacificus

Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases with increasing salinity, potentially increasing the risk of exposure for aquatic organisms at higher salinities. In the San Francisco Bay Delta (SFBD) estuary, pyrethroid concentrations increase during the rainy season, coinciding with the spawning season of Delta Smelt (Hypomesus transpacificus), an endangered, endemic fish. Furthermore, salinity intrusion in the SFBD is exacerbated by global climate change, which may change the dynamics of pyrethroid toxicity on aquatic animals. Therefore, examining the effect of salinity on the sublethal toxicity of pyrethroids is essential for risk assessments, especially during the early life stages of estuarine fishes. To address this, we investigated behavioral effects of permethrin and bifenthrin at three environmentally relevant concentrations across a salinity gradient (0.5, 2 and 6 PSU) on Delta Smelt yolk-sac larvae. Our results suggest that environmentally relevant concentrations of pyrethroids can perturb Delta Smelt larvae behavior even at the lowest concentrations (<1 ng/L) and that salinity can change the dynamic of pyrethroid toxicity in terms of behavioral effects, especially for bifenthrin, where salinity was positively correlated with anti-thigmotaxis at each concentration.

scholarly journals The transcriptome-wide effects of exposure to a pyrethroid pesticide on the Critically Endangered delta smelt Hypomesus transpacificus

2015 ◽  
Vol 28 (1) ◽  
pp. 43-60 ◽  
Author(s):  
KM Jeffries ◽  
LM Komoroske ◽  
J Truong ◽  
I Werner ◽  
M Hasenbein ◽  
...  
Keyword(s):  
Critically Endangered ◽  
Delta Smelt ◽  
Pyrethroid Pesticide ◽  
Hypomesus Transpacificus

scholarly journals Modeling Delta Smelt Distribution for Hypothesized Swimming Behaviors

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Edward Gross ◽  
Josh Korman ◽  
Lenny Grimaldo ◽  
Michael MacWilliams ◽  
Aaron Bever ◽  
...  
Keyword(s):  
San Francisco ◽  
Three Dimensional ◽  
San Francisco Estuary ◽  
Spawning Migration ◽  
Delta Smelt ◽  
Low Salinity ◽  
Particle Tracking Model ◽  
Tracking Model ◽  
Hypomesus Transpacificus ◽  
Suisun Bay

Delta Smelt, Hypomesus transpacificus, is an endangered pelagic fish native to the San Francisco Estuary. The distribution of Delta Smelt in the estuary shifts landward from low-salinity habitat to freshwater habitat before spawning. This spawning migration often coincides with the first substantial freshwater inflow to the estuary during winter. To accomplish this landward shift in distribution, Delta Smelt are believed to use the tides by swimming to faster-moving currents during flood tides and then repositioning themselves to slower-moving currents to reduce seaward movement on ebb tides. Studies have hypothesized that the swimming behavior of Delta Smelt during this period is influenced by environmental conditions such as salinity and turbidity. The details of these swimming behaviors—including the extent to which flows, salinity, and turbidity affect behaviors and distributions—are uncertain. The spawning migration is of management interest because an increase in observed counts of Delta Smelt at the South Delta water-export facilities has coincided roughly with the spawning migration in many years. In this study, we investigated a range of hypothesized swimming behaviors using a three-dimensional particle-tracking model for water year 2002 during the spawning migration, and compared the predicted distributions of Delta Smelt to distributions inferred from catch data. Our goal was to improve understanding of the influence of Delta Smelt swimming on distribution, and, ultimately, to develop a modeling tool to help management agencies identify conditions associated with entrainment losses. Predictions of Delta Smelt distributions and entrainment varied greatly among behaviors. Without swimming, Delta Smelt would be rapidly transported seaward of Suisun Bay, while continuous tidal migration would move them deep into the interior Delta. These behaviors and a simple turbidity-driven behavior model predicted distributions inconsistent with observations, while more complex behavior rules allowed improved predictions.

Fullerton Virtual Twin Study

2006 ◽  
Vol 9 (6) ◽  
pp. 963-964 ◽  
Author(s):  
Nancy L. Segal
Keyword(s):  
San Francisco ◽  
Social Relations ◽  
California State University ◽  
Future Research ◽  
State University ◽  
Collaborative Project ◽  
Similarities And Differences ◽  
Current Sample ◽  
The University ◽  
Mz Twins

AbstractVirtual twins (VTs; same-age unrelated siblings reared together from early infancy) have been studied at California State University (CSU), Fullerton since 1991. The current sample includes over 130 pairs. Past and current research have research have focused on siblings' similarities and differences in general intelligence and body size. Future research in these areas will continue as new pairs continue to be identified. These studies will be supplemented by analyses of personality, social relations and adjustment using monozygotic (MZ) twins, dizygotic (DZ) twins, full siblings and friends, as well as new VTs, who have participated in Twins, Adoptees, Peers and Siblings (TAPS), a collaborative project conducted between CSU Fullerton and the University of San Francisco, from 2002 to 2006.

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.

Sign in / Sign up

Export Citation Format

Share Document