Diversity in immature-shark communities along a tropical coastline

2015 ◽  
Vol 66 (5) ◽  
pp. 399 ◽  
Author(s):  
Peter M. Yates ◽  
Michelle R. Heupel ◽  
Andrew J. Tobin ◽  
Stephen K. Moore ◽  
Colin A. Simpfendorfer
Keyword(s):  
Life History ◽  
Spatial Ecology ◽  
Population Level ◽  
Interspecific Variation ◽  
Eastern Coast ◽  
Life History Stage ◽  
Shark Species ◽  
Life History Stages ◽  
Young Of The Year ◽  
Effective Conservation

Effective conservation and management of shark populations is complicated by our limited understanding of their spatial ecology. For example, there are scarce data on diversity in community structure and nursery function across broader geographic scales (e.g. across multiple inshore systems) and the implications of this diversity for shark populations. Accordingly, fishery-independent surveys were undertaken to investigate shark communities along ~400km of the tropical eastern coast of Australia (18.1–20.6°S, 146.0–148.8°E). A variety of shark species were encountered, with 19 species of Carcharhiniformes contributing 99.2% of the total shark catch. Of the 1806 sharks captured, 567 were immature, including 336 young-of-the-year individuals. Immature sharks from 18 species were present; however, interspecific variation in the proportions of life-history stages was apparent. Multivariate analyses identified significant spatial heterogeneity in immature-shark communities. Results also highlighted the importance of tropical coastal habitats for numerous shark species, and indicated community-wide spatial structuring of sharks on the basis of body size rather than life-history stage. In addition to building on traditional shark-nursery paradigms, these results demonstrated that data on nursery function from restricted areas may not accurately portray patterns occurring over broader geographic scales, and this diversity may provide population-level benefits for sharks.

scholarly journals Effects of life history stage and climatic conditions on fecal egg counts in plains zebras (Equus quagga) in the Serengeti National Park

2020 ◽  
Vol 119 (10) ◽  
pp. 3401-3413
Author(s):  
Peter A. Seeber ◽  
Tetiana A. Kuzmina ◽  
Alex D. Greenwood ◽  
Marion L. East
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
National Park ◽  
Climatic Conditions ◽  
Life History Stage ◽  
Gastrointestinal Parasite ◽  
Serengeti Ecosystem ◽  
Life History Stages ◽  
Lactating Females ◽  
Host Life

Abstract In wildlife, endoparasite burden can be affected by host life history stage, environmental conditions, host abundance, and parasite co-infections. We tested the effects of these factors on gastrointestinal parasite infection in plains zebras (Equus quagga) in the Serengeti ecosystem, Tanzania, using fecal egg counts of two nematode families (Strongylidae and Ascarididae) and the presence/absence of cestode (Anoplocephalidae) eggs. We predicted higher egg counts of Strongylidae and Ascarididae, and increased likelihood of Anoplocephalidae infection in individuals (1) during energetically costly life history stages when resource allocation to immune processes may decrease and in young zebras after weaning because of increased uptake of infective stages with forage, (2) when climatic conditions facilitate survival of infective stages, (3) when large zebra aggregations increase forage contamination with infective stages, and (4) in individuals co-infected with more than one parasite group as this may indicate reduced immune competence. Strongylidae egg counts were higher, and the occurrence of Anoplocephalidae eggs was more likely in bachelors than in band stallions, whereas Ascarididae egg counts were higher in band stallions. Strongylidae and Ascarididae egg counts were not increased in lactating females. Strongylidae egg counts were higher in subadults than in foals. Regardless of sex and age, Ascarididae infections were more likely under wet conditions. Co-infections did not affect Strongylidae egg counts. Ascarididae egg counts in adult females were higher when individuals were co-infected with Anoplocephalidae. We present evidence that parasite burdens in plains zebras are affected by life history stage, environmental conditions, and co-infection.

Juvenile production variation in salmonids: population dynamics, habitat, and the role of spatial relationships

1998 ◽  
Vol 55 (S1) ◽  
pp. 191-200 ◽  
Author(s):  
John F Kocik ◽  
C Paola Ferreri
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Spatial Ecology ◽  
Spatial Scales ◽  
River System ◽  
Habitat Characteristics ◽  
Life History Stage ◽  
Growth And Survival ◽  
Juvenile Atlantic Salmon ◽  
Spatial Positioning

Anadromous Atlantic salmon (Salmo salar) exhibit a complex life history that requires the use of habitats that span several different temporal and spatial scales. While fisheries scientists have investigated the various elements of habitat and how they affect Atlantic salmon growth and survival, these studies typically focus on requisite requirements for a single life history stage. Current advances in our understanding of salmonid populations in lotic systems indicates that ignoring the spatial positioning of different habitats and dispersal capabilities of fish between them may affect estimates of habitat quality and production of juvenile Atlantic salmon. Using the concepts of juxtaposition and interspersion, we hypothesize that discrete functional habitat units (FHU) occur within river systems and that the spatial structure of FHU affects fish production. We present a method to delineate FHU using habitat maps, fish ecology, and spatial habitat characteristics. Utilizing a simulation model, we illustrate how modeling FHU structure of spawning and rearing habitat in a river system can improve our understanding of juvenile Atlantic salmon production dynamics. The FHU concept allows a flexible approach to more comprehensive analyses of the impacts of habitat alterations, seasonal habitat shifts, and spatial ecology of salmonids at various scales.

Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

2003 ◽  
Keyword(s):  
Life History ◽  
North America ◽  
Ecosystem Function ◽  
Pacific Salmon ◽  
Life History Stage ◽  
High Productivity ◽  
Life History Stages ◽  
Ecosystem Effects ◽  
Precipitous Decline ◽  
Northwestern North America

<em>Abstract.</em>—Pacific salmon <em>Oncorhynchus </em>spp. are important components of numerous food webs throughout their life history, yet we know very little about the historic and current abundance of these life history stages. We used past cannery records, recent harvest and hatchery records, and salmon life history information drawn from the literature to construct a simple bioregional model of historic and recent salmon abundance at egg, fry, smolt, ocean adult, and spawning stages for five species of Pacific salmon from Alaska to California. We found a historic-to-recent bioregional decline in salmon biomass in all life history stages. Recent salmon egg, fry, smolt, ocean-going adult, and escapement biomass estimates for northwestern North America are 74%, 55%, 59%, 86%, and 35%, respectively, of historic levels. Recent high productivity in Alaskan waters, however, masks a precipitous decline south of Alaska, where recent egg, fry, smolt, ocean-going adult, and escapement biomass levels are 34%, 23%, 50%, 40%, and 15% that of historic levels. Adult production and harvest levels are no longer sufficient measures of salmon management success. Researchers need to quantify and elucidate the ecosystem effects of historic biomass changes in life history stages of Pacific salmon on a watershed basis. Fisheries managers must set and meet specific targets for salmon life history stage abundance—from egg to spawning adult—to restore and maintain ecosystem function.

scholarly journals Organization of vertebrate annual cycles: implications for control mechanisms

2007 ◽  
Vol 363 (1490) ◽  
pp. 425-441 ◽  
Author(s):  
John C Wingfield
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Environmental Variation ◽  
Life History Stage ◽  
Control Mechanisms ◽  
Phenotypic Flexibility ◽  
Endocrine Control ◽  
Annual Cycles ◽  
Life History Stages ◽  
The Individual

The majority of vertebrates have a life span of greater than one year. Therefore individuals must be able to adapt to the annual cycle of changing conditions by adjusting morphology, physiology and behaviour. Phenotypic flexibility, in which an individual switches from one life history stage to another, is one way to maximize fitness in a changing environment. When environmental variation is low, few life history stages are needed. If environmental variation is large, there are more life history stages. Each life history stage has a characteristic set of sub-stages that can be expressed in various combinations and patterns to determine state at any point in the life of the individual. Thus individuals have a finite number of states that can be expressed over the spectrum of environmental conditions in their life spans. Life history stages have three phases–development, mature capability (when characteristic sub-stages can be expressed) and termination. Expression of a stage is time dependent (probably a minimum of one month), and termination of one stage overlaps development of the next stage. It follows that the more life history stages an individual expresses, the less flexibility it will have in timing those stages. Having fewer life history stages increases flexibility in timing, but less tolerance of variation in environmental conditions. To varying degrees it is possible to overlap mature capability of some life history stages to effectively reduce ‘finite stage diversity’ and maximize flexibility in timing. Theoretical ways by which this can be done, and the implications for neuroendocrine and endocrine control mechanisms are discussed. Twelve testable hypotheses are posed that relate directly to control mechanisms.

scholarly journals Environmental change effects on life history traits and population dynamics of anadromous fishes

2019 ◽  
Author(s):  
P. Catalina Chaparro-Pedraza ◽  
André M. de Roos
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Environmental Change ◽  
Population Level ◽  
Fish Population ◽  
Breeding Habitat ◽  
Energetic Cost ◽  
Life History Stages ◽  
History Of ◽  
The Individual

AbstractMigration, the recurring movement of individuals between a breeding and a non-breeding habitat, is a widespread phenomenon in the animal kingdom. Since the life cycle of migratory species involves two habitats, they are particularly vulnerable to environmental change, which may affect either of these habitats as well as the travel between them. In this study, we investigate the consequences of environmental change affecting older life history stages for the population dynamics and the individual life history of a migratory population. In particular, we use a theoretical approach to study how increased energetic cost of the breeding travel and reduced survival and food availability in the non-breeding habitat affect an anadromous fish population. These unfavorable conditions have impacts at individual and population level. First, when conditions deteriorate individuals in the breeding habitat have a higher growth rate as a consequence of reductions in spawning that reduce competition. Second, population abundance decreases, and its dynamics change from stable to oscillations with a period of four years. The oscillations are caused by the density-dependent feedback between individuals within a cohort through the food abundance in the breeding habitat, which results in alternation of a strong and a weak cohort. Our results explain how environmental change, by affecting older life history stages, has multiple consequences for other life stages and for the entire population. We discuss these results in the context of empirical data and highlight the need for mechanistic understanding of the interactions between life history and population dynamics in response to environmental change.

scholarly journals Habitat Use Throughout a Chondrichthyan's Life

2021 ◽  
Author(s):  
◽  
Melissa Marquez
Keyword(s):  
Risk Assessment ◽  
Life History ◽  
New Zealand ◽  
Habitat Use ◽  
Fish Distribution ◽  
Life History Stage ◽  
Nursery Ground ◽  
Data Set ◽  
Life History Stages ◽  
Species Vulnerability

<p>Over the last few decades, much effort has been devoted towards evaluating and reducing bycatch in marine fisheries. There has been a particular focus on quantifying the risk to chondrichthyans, primarily because of their relatively high vulnerability to overfishing. A key part of risk assessment is evaluating the distributional overlap of the fish with the fisheries, where fish distribution is influenced by habitat use. I synthesised published observations of habitat use for different life history stages of chondrichthyans and hypothesised the associated catch composition in terms of fish sex, size, and maturity. I then searched for these catch compositions, and thereby locations, using New Zealand research vessel catch data. Results show that some life history stages and habitats for certain species can be identified, whereas others could not. Pupping ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), and Hydrolagus bemisi (GSP); nursery ground criteria were met for Callorhynchus milii (ELE), mating ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), Hydrolagus bemisi (GSP), and Harriotta raleighana (LCH); lek-like mating criteria were met for Hydrolagus novaezealandiae (GSH). For those life-history stage habitats not found, this may be because these are outside of the coverage of the data set (and likely also commercial fisheries), or because they do not actually exist for some chondrichthyans. On the basis of results, I propose to change the order of species in the New Zealand qualitative (Level 1) risk assessment, and rise the relative risk for Hydrolagus bemisi (GSP), given the species vulnerability of pupping grounds.</p>

Detection of population trends in threatened coho salmon (Oncorhynchus kisutch)

2001 ◽  
Vol 58 (2) ◽  
pp. 375-385 ◽  
Author(s):  
Katriona Shea ◽  
Marc Mangel
Keyword(s):  
Life History ◽  
Statistical Power ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Life History Stage ◽  
Vital Rates ◽  
Life History Stages ◽  
Observational Uncertainty ◽  
Two Parameters ◽  
Management Recommendations

Populations of coho salmon (Oncorhynchus kisutch) in California are listed as threatened under the U.S. Endangered Species Act. Such listings refer to adult populations, but often, juvenile life history stages are censused, so it is important to understand what affects the relationship between true adult and observed juvenile numbers. We present models to address how observational uncertainty, census length, and autocorrelation in vital rates affect our ability to observe trends. We ask two questions about our ability to detect declines in one life history stage from censuses of another. First, given an observed decline in parr numbers, what is the chance that this reflects a decline in adults? Second, given that adult numbers are declining, what is the chance that we see that decline in parr? Our results indicate that statistical power decreases with increasing observational uncertainty and decreasing census lengths and demonstrate how these two parameters interact. Power increases as the level of autocorrelation in mortality rates increases. Management recommendations include obtaining more accurate estimates of autocorrelation in mortality and of observational uncertainty.

scholarly journals Conservation of coastal stingrays: seasonal abundance and population structure of the short-tailed stingray Dasyatis brevicaudata at a Marine Protected Area

2012 ◽  
Vol 69 (8) ◽  
pp. 1427-1435 ◽  
Author(s):  
A. Le Port ◽  
S. Lavery ◽  
J. C. Montgomery
Keyword(s):  
Population Structure ◽  
Life History ◽  
Protected Area ◽  
Marine Protected Area ◽  
Marine Reserve ◽  
Conservation Strategy ◽  
Seasonal Abundance ◽  
Management Tools ◽  
Life History Stages ◽  
Effective Conservation

Abstract Le Port, A., Lavery, S., and Montgomery, J. C. 2012. Conservation of coastal stingrays: seasonal abundance and population structure of the short-tailed stingray Dasyatis brevicaudata at a Marine Protected Area. – ICES Journal of Marine Science, 69: . Elasmobranch (shark, ray, and skate) populations around the world are in decline, and effective conservation measures are urgently needed. Marine Protected Areas (MPA) placed in locations important for key life-history stages may form part of an effective conservation strategy. In this context, we examined the seasonal abundance and population structure of the short-tailed stingray (Dasyatis brevicaudata) at an offshore MPA in northeastern New Zealand, and the reported use of this location as a mating ground. Diver surveys were conducted from 2004 to 2007 at the Poor Knights Islands Marine Reserve (PKIMR). During this time, we observed: (i) a substantial increase in adult and subadult numbers, particularly females during the suggested breeding season, and a corresponding increase in females bearing fresh mating scars; and (ii) large numbers of smaller (probably immature) D. brevicaudata individuals of both sexes from spring to autumn. These results suggest that the PKIMR acts as both a mating aggregation location and a nursery for this species. We suggest that for coastal stingrays such as D. brevicaudata, small MPAs may be effective at protecting key life-history stages, but that as movements outside of reserve boundaries also occur, additional management tools may also be necessary.

scholarly journals Experimental heating reveals nest temperature affects nestling condition in tree swallows ( Tachycineta bicolor )

2008 ◽  
Vol 4 (5) ◽  
pp. 468-471 ◽  
Author(s):  
Jonathan H Pérez ◽  
Daniel R Ardia ◽  
Elise K Chad ◽  
Ethan D Clotfelter
Keyword(s):  
Life History ◽  
Body Mass ◽  
Body Condition ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Life History Stage ◽  
Delayed Effects ◽  
Life History Stages ◽  
Treatment Status ◽  
Carry Over

Investment in one life-history stage can have delayed effects on subsequent life-history stages within a single reproductive bout. We experimentally heated tree swallow ( Tachycineta bicolor ) nests during incubation to test for effects on parental and nestling conditions. Females incubating in heated boxes maintained higher body condition and fed nestlings at higher rates. We cross-fostered nestlings and found that young nestlings (4–7 days old) incubated in heated nests had higher body condition and body mass, regardless of treatment status of their rearing parent. However, older nestlings which were fed by heated females maintained higher condition and body mass regardless of treatment status of their incubating parent. These results indicate that investment in one life-history stage can have multiple pathways of carry-over effects on future life-history stages.

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