scholarly journals Exploitation and recovery of a sea urchin predator has implications for the resilience of southern California kelp forests

2015 ◽  
Vol 282 (1799) ◽  
pp. 20141817 ◽  
Author(s):  
Scott L. Hamilton ◽  
Jennifer E. Caselle
Keyword(s):  
Sea Urchin ◽  
Life Histories ◽  
Southern California ◽  
Size Structure ◽  
Marine Reserves ◽  
Minimum Size ◽  
Kelp Forests ◽  
Positive Effects ◽  
Management Measures ◽  
History Of

Size-structured predator–prey interactions can be altered by the history of exploitation, if that exploitation is itself size-selective. For example, selective harvesting of larger sized predators can release prey populations in cases where only large individuals are capable of consuming a particular prey species. In this study, we examined how the history of exploitation and recovery (inside marine reserves and due to fisheries management) of California sheephead ( Semicossyphus pulcher ) has affected size-structured interactions with sea urchin prey in southern California. We show that fishing changes size structure by reducing sizes and alters life histories of sheephead, while management measures that lessen or remove fishing impacts (e.g. marine reserves, effort restrictions) reverse these effects and result in increases in density, size and biomass. We show that predation on sea urchins is size-dependent, such that the diet of larger sheephead is composed of more and larger sized urchins than the diet of smaller fish. These results have implications for kelp forest resilience, because urchins can overgraze kelp in the absence of top-down control. From surveys in a network of marine reserves, we report negative relationships between the abundance of sheephead and urchins and the abundance of urchins and fleshy macroalgae (including giant kelp), indicating the potential for cascading indirect positive effects of top predators on the abundance of primary producers. Management measures such as increased minimum size limits and marine reserves may serve to restore historical trophic roles of key predators and thereby enhance the resilience of marine ecosystems.

Effects of marine reserves on predator-prey interactions in central California kelp forests

2020 ◽  
Vol 655 ◽  
pp. 139-155
Author(s):  
DC Yates ◽  
SI Lonhart ◽  
SL Hamilton
Keyword(s):  
Species Interactions ◽  
Size Structure ◽  
Marine Reserves ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Negative Effects ◽  
Central California ◽  
Invertebrate Predators ◽  
Predatory Fishes ◽  
Density And Biomass

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.

scholarly journals Protection of large predators in a marine reserve alters size-dependent prey mortality

2017 ◽  
Vol 284 (1847) ◽  
pp. 20161936 ◽  
Author(s):  
Rebecca L. Selden ◽  
Steven D. Gaines ◽  
Scott L. Hamilton ◽  
Robert R. Warner
Keyword(s):  
Size Structure ◽  
Sea Urchins ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Size Dependent ◽  
Predator Size ◽  
Top Predators ◽  
Large Predators

Where predator–prey interactions are size-dependent, reductions in predator size owing to fishing has the potential to disrupt the ecological role of top predators in marine ecosystems. In southern California kelp forests, we investigated the size-dependence of the interaction between herbivorous sea urchins and one of their predators, California sheephead ( Semicossyphus pulcher ). Empirical tests examined how differences in predator size structure between reserve and fished areas affected size-specific urchin mortality. Sites inside marine reserves had greater sheephead size and biomass, while empirical feeding trials indicated that larger sheephead were required to successfully consume urchins of increasing test diameter. Evaluations of the selectivity of sheephead for two urchin species indicated that shorter-spined purple urchins were attacked more frequently and successfully than longer-spined red urchins of the same size class, particularly at the largest test diameters. As a result of these size-specific interactions and the higher biomass of large sheephead inside reserves, urchin mortality rates were three times higher inside the reserve for both species. In addition, urchin mortality rates decreased with urchin size, and very few large urchins were successfully consumed in fished areas. The truncation of sheephead size structure that commonly occurs owing to fishing will probably result in reductions in urchin mortality, which may reduce the resilience of kelp beds to urchin barren formation. By contrast, the recovery of predator size structure in marine reserves may restore this resilience, but may be delayed until fish grow to sizes capable of consuming larger urchins.

scholarly journals Southward decrease in the protection of persistent giant kelp forests in the northeast Pacific

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Nur Arafeh-Dalmau ◽  
Kyle C. Cavanaugh ◽  
Hugh P. Possingham ◽  
Adrian Munguia-Vega ◽  
Gabriela Montaño-Moctezuma ◽  
...  
Keyword(s):  
Baja California ◽  
Marine Reserves ◽  
Fold Increase ◽  
Kelp Forests ◽  
Giant Kelp ◽  
Central California ◽  
Northeast Pacific ◽  
The Face ◽  
High Resolution Satellite Imagery ◽  
Northeast Pacific Ocean

AbstractKelp forests are globally important and highly productive ecosystems, yet their persistence and protection in the face of climate change and human activity are poorly known. Here, we present a 35-year time series of high-resolution satellite imagery that maps the distribution and persistence of giant kelp (Macrocystis pyrifera) forests along ten degrees of latitude in the Northeast Pacific Ocean. We find that although 7.7% of giant kelp is protected by marine reserves, when accounting for persistence only 4% of kelp is present and protected. Protection of giant kelp decreases southerly from 20.9% in Central California, USA, to less than 1% in Baja California, Mexico, which likely exacerbates kelp vulnerability to marine heatwaves in Baja California. We suggest that a two-fold increase in the area of kelp protected by marine reserves is needed to fully protect persistent kelp forests and that conservation of climate-refugia in Baja California should be a priority.

A comparative study of the life histories of Nematodirus battus and N. filicollis, nematode parasites of sheep

Parasitology ◽  
1959 ◽  
Vol 49 (3-4) ◽  
pp. 374-386 ◽  
Author(s):  
R. J. Thomas
Keyword(s):  
Life History ◽  
Intestinal Mucosa ◽  
Related Species ◽  
Life Histories ◽  
Basic Pattern ◽  
Culture Methods ◽  
Closely Related Species ◽  
Nematode Parasites ◽  
History Of ◽  
Comparative Description

1. The life history of N. battus is described, and a comparative description of the life history of N. filicollis is given.2. The life histories of these two species are compared with those of N. spathiger and N. helvetianus, two closely related species, and are shown to follow the same basic pattern, with minor variations in timing which appear to be specific in nature, and not related to differences in culture methods or host species.3. The pathogenesis of Nematodirus species is discussed and related to the migration of larvae into the intestinal mucosa during development.

III.—The Life-history and Cytology of Didymium nigripes Fr.

1932 ◽  
Vol 57 (1) ◽  
pp. 93-142 ◽  
Author(s):  
Elsie J. Cadman
Keyword(s):  
Life History ◽  
Life Histories ◽  
Important Research ◽  
Great Work ◽  
Animal Kingdom ◽  
History Of ◽  
Natural Groups

Since 1860, in which year De Bary published his great work Die Mycetozoen, the investigation of the life-history of members of the Mycetozoa has aroused a considerable amount of interest, and a great deal of important research has been carried out in this connection. The group of organisms is particularly interesting, because it lies on the borderline between plant and animal kingdoms, and it is very possible that a detailed investigation of several species of the Mycetozoa might be of considerable assistance in elucidating certain obscure points in the life-histories of higher members of both the great natural groups. The term “Mycetozoa,” which we owe to De Bary, will be used throughout in preference to the older term “Myxogastres” invented by Fries (32, p. 2), and that of “Myxomycetes” first employed by Link (32, p. 2). “Mycetozoon,” or “fungus-like animal,” is a very appropriate description of a member of the group, since during part of its life-history it exhibits distinctly animal-like characters, and the individuals move rapidly by means of flagella, whilst later, during the development of the sporangium, a plant-like form is assumed. The combination of plant and animal characters has given rise to much discussion as to the position of the Mycetozoa in plant or animal kingdom, and the group has been claimed by both zoologists and botanists.

A Cultural History of Education in the Modern Age

2020 ◽  
Keyword(s):  
Cultural History ◽  
Life Histories ◽  
History Of Education ◽  
Political Transformation ◽  
Modern Age ◽  
History Of ◽  
Children And Childhood ◽  
Essential Resource ◽  
Literature Culture ◽  
The Many

The twentieth century brought profound and far-reaching changes to education systems globally in response to significant social, economic, and political transformation. This volume draws together work from leading historians of education to present a tapestry of seminal and enduring themes that characterize the many educational developments since 1920. An essential resource for researchers, scholars, and students in history, literature, culture, and education, A Cultural History of Education in the Modern Age presents essays that examine the following key themes of the period: church, religion and morality; knowledge, media and communications; children and childhood; family, community and sociability; learners and learning; teachers and teaching; literacies; and life histories.

scholarly journals The application of life history information to the conservation management of Chrysoritis butterflies (Lepidoptera: Lycaenidae) in South Africa

Koedoe ◽  
2004 ◽  
Vol 47 (1) ◽  
Author(s):  
R.F. Terblanche ◽  
H. Van Hamburg
Keyword(s):  
South Africa ◽  
Life History ◽  
Life Histories ◽  
Host Plants ◽  
Conservation Management ◽  
Aesthetic Value ◽  
Wing Patterns ◽  
In The Wild ◽  
History Of ◽  
Voucher Specimens

Due to their intricate life histories and the unique wing patterns and colouring the butterflies of the genus Chrysoritis are of significant conservation and aesthetic value. Thisoverview probes into practical examples of butterfly life history research applicable to environmental management of this relatively well-known invertebrate group in South Africa. Despite the pioneer work on life histories of Chrysoritis in the past, more should be done to understand the life history of the butterflies in the wild, especially their natural host plants and the behaviour of adults and larvae. A system of voucher specimens of host plants should be introduced in South Africa. Although various host plant species in nature are used by the members of Chrysoritis, including the Chrysoritis chrysaor group, the choice of these in nature by each species is significant for conservation management and in the case of Chrysoritis aureus perhaps even as a specific characteristic.A revision of the ant genus Crematogaster will benefit the conservation management of Chrysoritis species since some of these ant species may consist of a number of specieswith much more restricted distributions than previously thought. Rigorous quantified tudies of population dynamics of Chrysoritis butterflies are absent and the introductionof such studies will benefit conservation management of these localised butterflies extensively.

Syphilitic General Paralysis

1893 ◽  
Vol 39 (165) ◽  
pp. 217-224
Author(s):  
M. J. Nolan
Keyword(s):  
Life Histories ◽  
The Other ◽  
Fin De Siecle ◽  
Short Life ◽  
General Paralysis ◽  
Generic Term ◽  
Fin De Siècle ◽  
History Of ◽  
Vexed Question

At the present time, when our fin de siècle knowledge of “general paralysis” enables us to recognize under that generic term many types of the disorder, and when the relation between it and syphilis continues a rather vexed question, little apology is needed for introducing to notice the following cases. They illustrate unmistakably some of the instances in which syphilis is solely responsible for what. Is termed by Dr. Savage” A process of degeneration which ultimately produces the ruin we recognize as general paralysis.”∗ Whatever may be hereafter formulated from the present evolutionary crisis in the history of the disorder there can be but little doubt that syphilis will be one of its most intimate and important relations. The story of its methods is briefly sketched in the following two short life-histories—in one asserting itself in the offspring of its victims by right of impure heredity, in the other carrying death direct into the vital centres by the force of its malignant virus.

Evolution and environment in the late Silurian-early Devonian: the rise of the pteridophytes

1985 ◽  
Vol 309 (1138) ◽  
pp. 147-165 ◽  
Keyword(s):  
Vascular Plants ◽  
Preliminary Report ◽  
Life Histories ◽  
Early History ◽  
Flora Of Australia ◽  
Early Devonian ◽  
The World ◽  
History Of

A brief review of the major advances since 1979 in Silurian and Devonian palaeobotany is followed by a preliminary report on a Gedinnian assemblage from the Welsh Borderland. This is dominated by rhyniopsids and includes several species of Cooksonia and Salopella . Spores have been isolated from a number of taxa. The assemblage is used to illustrate the problems of recognition and classification of early vascular plants. Parallel sedimentological and palaeogeographical studies permit speculation on the ecology and life histories of the plants that colonized the Old Red Continent. It is concluded that the lack of well preserved and independently dated assemblages from elsewhere in the world (an exception being the Baragwanathia flora of Australia) prevents the detection of any provincialism in the late Silurian and early Devonian and makes generalizations on the early history of vascular plants premature.

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