Interrelations among rock lobsters, sea urchins, and juvenile abalone: implications for community management

2000 ◽  
Vol 57 (11) ◽  
pp. 2175-2185 ◽  
Author(s):  
Stephen Mayfield ◽  
George M Branch
Keyword(s):  
South African ◽  
Laboratory Experiments ◽  
Sea Urchins ◽  
Ecosystem Approach ◽  
Community Management ◽  
Rock Lobster ◽  
Negative Effects ◽  
Major Threat ◽  
Complex Interactions ◽  
The Relationship

Field and laboratory experiments demonstrate that juveniles of South African abalone (Haliotis midae) depend vitally on the protection from predation that they gain from living concealed beneath Cape urchins (Parechinus angulosus). Recent reports suggest that rock lobsters (Jasus lalandii) have increased substantially in the region where the commercial abalone fishery is centered. This increase has been blamed for a recorded collapse of urchin populations and dramatic reductions in the numbers of juvenile abalone. We verified the substantial increase in rock lobster abundance there. Surveys covering 200 km of coastline showed that densities of urchins were negatively correlated with those of large lobsters (>68 mm carapace length) and that densities of juvenile abalone were positively correlated with those of urchins. The indirect negative effects of rock lobsters on juvenile abalone clearly pose a major threat to the abalone industry, already under stress from poaching. Quantification of the relationship between juvenile abalone and urchins and between urchins and rock lobsters allows a forecast of the magnitude of lobster harvesting necessary to reduce them to a level at which urchins may recover and sustain juvenile abalone. The complex interactions involved emphasize the importance of an ecosystem approach for the management of these stocks.

Prey preference and the consumption of sea urchins and juvenile abalone by captive rock lobsters (Jasus lalandii )

2001 ◽  
Vol 52 (5) ◽  
pp. 773 ◽  
Author(s):  
S. Mayfield ◽  
E. de Beer ◽  
G. M. Branch
Keyword(s):  
South African ◽  
Laboratory Experiments ◽  
Carapace Length ◽  
Consumption Rate ◽  
Prey Species ◽  
Sea Urchins ◽  
Fishing Ground ◽  
Field Observations ◽  
Rock Lobster ◽  
Fishing Area

Recent studies on the diet of the South African rock lobster (Jasus lalandii) have shown an increase in the consumption of sea urchins in certain areas relative to earlier assessments. Concurrent ecological surveys have demonstrated the dependence of juvenile abalone on urchins for their survival, and a radical increase in the abundance of lobsters in the area that is the main abalone fishing ground. This paper describes laboratory experiments on the consumption of urchins by lobsters, and the preferences for different prey species. Small lobsters (<68 mm carapace length) ate no urchins. Larger lobsters ate urchins of all sizes, although small urchins were preferred. The consumption rate was easily sufficient for the lobsters to have caused the documented disappearance of urchins (and juvenile abalone) in the main abalone fishing area. Lobsters showed a strong preference for mussels over all other prey offered, and for juvenile abalone over urchins, although previous field observations and laboratory experiments have shown that urchins provide shelter for juvenile abalone. However, if black mussels were available in addition to sea urchins and juvenile abalone, consumption of sea urchins and juvenile abalone declined.

Self-Interested Giving: The Relationship Between Conditional Gifts, Charitable Donations, and Donor Self-Interestedness

2021 ◽  
Author(s):  
Matthew Chao ◽  
Geoffrey Fisher
Keyword(s):  
Decision Analysis ◽  
Experimental Evidence ◽  
Laboratory Experiments ◽  
Self Report ◽  
Negative Effects ◽  
Charitable Donations ◽  
Prosocial Motives ◽  
The Gift ◽  
Other Regarding ◽  
The Relationship

Nonprofits regularly use conditional “thank you” gifts to entice prospective donors to give, yet experimental evidence suggests that their effects are mixed in practice. This paper uses multiple laboratory experiments to test when and why thank you gifts vary in effectiveness. First, we demonstrate that although gifts often increase donations to charities that donors did not rate highly, many of the same gifts had no effects or negative effects for charities that prospective donors already liked. We replicate these findings in a second experiment that uses a different range of charity and gift options as well as different measures of participant perceptions of a charity. We also find that making gifts optional, as is common in fundraising campaigns, does not eliminate these negative gift effects. In additional experiments, we directly test for donor motives using self-report and priming experiments. We find that thank you gifts increase (decrease) the weight that donors place on self-interested (prosocial) motives, leading to changes in donation patterns. Altogether, our results suggest that practitioners may find gifts more useful when appealing to donors not already familiar with or favorably inclined to their charity, such as during donor acquisition campaigns. They may be less useful when appealing to recent donors or others who already favor the charity, in part because the gift may activate mindsets or norms that emphasize self-interested motives instead of more prosocial, other-regarding motives. This paper was accepted by Yan Chen, decision analysis.

Improving the catch efficiency of the West Coast rock lobster, Jasus lalandii

2000 ◽  
Vol 51 (6) ◽  
pp. 613 ◽  
Author(s):  
D. Loewenthal ◽  
S. Mayfield ◽  
G. M. Branch
Keyword(s):  
Weight Loss ◽  
South African ◽  
West Coast ◽  
Capture Rate ◽  
Catch Rate ◽  
Rock Lobster ◽  
The South ◽  
The West ◽  
The Relationship

The South African commercial rock-lobster industry employs an average soak time of 22 h for traps. Experiments were undertaken to test (1) the rate of bait loss with soak time and the effect that protection of the bait has on bait loss, (2) the relationship between catch rate (numbers per trap) and soak time for traps with either protected or unprotected bait, and (3) the effect of two bait types (whole maasbanker and hake heads) on the catch of rock lobsters. There were substantial losses of unprotected bait within 6 h; substantially less weight loss was observed from protected bait even after a 48-h soak time. The numbers of rock lobsters caught in traps with unprotected bait were low relative to the capture rate with protected bait. The highest capture rate occurred after 6 h for unprotected bait and 6–12 h for protected bait. There was no significant effect of bait type (maasbanker v. hake heads) on the number or size of rock lobsters. To optimize catch efficiency, the commercial industry should use protected bait and soak times as short as 6–12 h.

Symbolic Awards in Buyer–Supplier Relations

2021 ◽  
Author(s):  
Ruth Beer ◽  
Hyun-Soo Ahn ◽  
Stephen Leider
Keyword(s):  
Laboratory Experiments ◽  
Problem Definition ◽  
Practical Relevance ◽  
Negative Effects ◽  
Bottom Line ◽  
Managerial Implications ◽  
The Cost ◽  
Behavioral Mechanisms ◽  
The Relationship ◽  
High Effort

Problem definition: Giving out a symbolic “supplier of the year” or “outstanding supplier” award can be beneficial for a buyer as it may incentivize a supplier to exert higher efforts. However, when a good supplier is scarce, the award announces which supplier is particularly good and may increase the cost of building and maintaining the relationship. This paper studies both positive and negative effects of a symbolic award and offers explanations on underlying behavioral mechanisms. Academic/practical relevance: We show that symbolic awards can effectively incentivize suppliers to provide high effort, improving a buyer’s bottom line. This is particularly relevant in cases in which certain aspects of a buyer–supplier relationship are not contractible and suppliers have discretion over the quality provided. The award format significantly influences the award’s effectiveness. Methodology: We develop a game-theoretical model that captures a supplier’s utility for the award in a competitive setting and test the predictions of the model with laboratory experiments. Results: Our experimental results confirm that private symbolic awards have motivating effects and lead to higher buyer profits. When the awards are public, this profit premium diminishes as buyers pay higher prices to get the good suppliers. When the buyer is given the option to make the award public or private, buyers prefer that awards are public over private, anticipating a negative supplier response to their choice of the private award format. Managerial implications: Expressing praise or gratitude for a supplier’s efforts can be highly beneficial for a buyer. However, when there is scarcity of good suppliers, buyers should expect increased competition and accompany the award with efforts to preserve the relationship. Finally, if buyers choose to offer a distinctive award format, private recognitions may be perceived as greedy or self-interested and backfire.

scholarly journals Making management procedures operational—innovations implemented in South Africa

2007 ◽  
Vol 64 (4) ◽  
pp. 626-632 ◽  
Author(s):  
Éva E. Plagányi ◽  
Rebecca A. Rademeyer ◽  
Doug S. Butterworth ◽  
Carryn L. Cunningham ◽  
Susan J. Johnston
Keyword(s):  
South Africa ◽  
South African ◽  
Ecosystem Approach ◽  
Management Tool ◽  
Rock Lobster ◽  
Single Model ◽  
Short Term ◽  
The Past ◽  
Management Procedures ◽  
Operational Management

Abstract Plagányi, É. E., Rademeyer, R. A., Butterworth, D. S., Cunningham, C. L., and Johnston, S. J. 2007. Making management procedures operational — innovations implemented in South Africa. – ICES Journal of Marine Science, 64: 626–632. Operational management procedures (OMPs) have become an indispensable fisheries management tool in South Africa in light of their ability to consider the consequences of the main sources of assessment uncertainty. An overview is provided of the MP approaches applied to the major South African fisheries for hake, sardine and anchovy, and west coast rock lobster. As these are among the first OMPs to be implemented worldwide, some for periods longer than 10 y, they provide useful examples of some of the successes and problems encountered with the approach. Particular emphasis is given to some recent innovations and adaptations. These include moves to (i) joint two-species OMPs for the hake and sardine/anchovy resources; (ii) a reference set of weighted operating models for primary testing and tuning in preference to a single model; (iii) consideration of a “research-conditional” approach for hake to allow greater catches in the short term, conditional on research being implemented to resolve a key uncertainty; and (iv) incorporation of some ecosystem considerations by developing appropriate robustness tests (which link with moves towards an ecosystem approach to fisheries). Key lessons gained from experience over the past decade of OMP implementation in South Africa are summarized.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Retrospective analysis of the resilience of Russian regions as socio-economic systems

2019 ◽  
pp. 46-64 ◽  
Author(s):  
Vladimir V. Klimanov ◽  
Sofiya М. Kazakova ◽  
Anna A. Mikhaylova
Keyword(s):  
Panel Data ◽  
Economic Systems ◽  
Financial Indicators ◽  
Russian Regions ◽  
Integral Index ◽  
Negative Effects ◽  
Economic Resilience ◽  
Correlation Dependence ◽  
The Impact ◽  
The Relationship

The article examines the impact of various socio-economic and financial indicators on the resilience of Russian regions. For each region, the integral index of resilience is calculated, and its correlation dependence with the selected indicators is revealed. The study confirms the relationship between fiscal resilience and socio-economic resilience of the regions. The analysis of panel data for 75 regions from 2007 to 2016 shows that there are significant differences in the dynamics of indicators in different periods. In particular, the degree of exposure to the negative effects of the crises of 2008—2009 and 2014—2015 in non-resilient regions is higher than in resilient ones.

Co-creating the Psychological “White Picket Fence”: Three Gay Couples’ Relationship Reconfiguration

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Prevan Moodley ◽  
Francois Rabie
Keyword(s):  
Grounded Theory ◽  
South African ◽  
Gay Couples ◽  
Core Category ◽  
Picket Fence ◽  
Open Relationship ◽  
The Individual ◽  
The Relationship ◽  
Porous Boundaries

Many gay couples engage in nonmonogamous relationships. Ideas about nonmonogamy have historically been theorised as individual pathology and indicating relational distress. Unlike mixed-sex couples, boundaries for gay couples are often not determined by sexual exclusivity. These relationships are built along a continuum of open and closed, and sexual exclusivity agreements are not restricted to binaries, thus requiring innovation and re-evaluation. Three white South African gay couples were each jointly interviewed about their open relationship, specifically about how this is negotiated. In contrast to research that uses the individual to investigate this topic, this study recruited dyads. The couples recalled the initial endorsement of heteronormative romantic constructions, after which they shifted to psychological restructuring. The dyad, domesticated through the stock image of a white picket fence, moved to a renewed arrangement, protected by “rules” and imperatives. Abbreviated grounded theory strategies led to a core category, “co-creating porous boundaries”, and two themes. First, the couple jointly made heteronormative ideals porous and, second, they reconfigured the relationship through dyadic protection. The overall relationship ideology associated with the white picket fence remained intact despite the micro-innovations through which the original heteronormative patterning was reconfigured.

BATOMBE: WARISAN BUDAYA BANGSA DARI NAGARI ABAI PROVINSI SUMATERA BARAT

2017 ◽  
Vol 7 (2) ◽  
pp. 159
Author(s):  
Eva Krisna
Keyword(s):  
Oral Tradition ◽  
Multidisciplinary Approach ◽  
Descriptive Analysis ◽  
Community Life ◽  
Psychological Approach ◽  
Negative Effects ◽  
Great House ◽  
Close Relationship ◽  
West Sumatra ◽  
The Relationship

“Batombe” is an oral tradition of the Nagari Abai society at Sangir Batanghari Subdistrict, South Solok District, West Sumatra Province. Batombe is exchanging rhymes (berbalas pantun) which is performed as an entertainment on the wedding party (baralek). Batombe is identical with Great House (Rumah Gadang) Nagari Abai which is a unique house because it is a long traditional custom house that has many rooms. It reaches 21 rooms. The rhymes in batombe tends to deliver a feeling of lilting so the singers often drift into the atmosphere of the show. Therefore, as part of community life, batombe often cause a negative effects for the singers soul. This paper describes various things, such as: who batombe singer is; the time to perform this activity; the relationship between batombe and Great House (Rumah Gadang) at Nagari Abai; and the negative effects caused by batombe for the singers. This paper based on the fact that in oral tradition there is a close relationship between text and the speakers and text with context (place, time and atmosphere), a multidisciplinary approach is used in this paper, such as historical, sociological, anthropological, and psychological approach. The method used is descriptive analysis method.AbstrakBatombe adalah tradisi lisan masyarakat Nagari Abai, Kecamatan Sangir Batanghari, Kabupaten Solok Selatan, Provinsi Sumatra Barat. Batombe adalah tradisi berbalas pantun yang dilakukan sebagai hiburan pada pesta pernikahan (baralek). Batombe identik dengan rumah gadang Nagari Abai yang unik, yakni rumah adat dengan ruangan yang sangat panjang hingga 21 ruangan. Pantun-pantun batombe cenderung menyampaikan perasaan yang mendayu-dayu sehingga para pedendangnya sering hanyut ke dalam suasana pertunjukan. Oleh sebab itu, sebagai bagian dari kehidupan masyarakat, seringkali batombe menyebabkan efek negatif bagi (kejiwaan) para pedendangnya. Tulisan ini mendeskripsikan berbagai hal, seperti penutur batombe, waktu untuk melakukan batombe, hubungan batombe dengan rumah gadang di Nagari Abai, dan efek negatif yang ditimbulkan batombe bagi pedendangnya. Tulisan ini bertolak dari kenyataan bahwa pada tradisi lisan terdapat hubungan erat, antara lain seperti teks dengan penutur dan teks dengan konteks (tempat, waktu, dan suasana). Pendekatan multidisipliner digunakan pada tulisan ini, yakni pendekatan historis, sosiologis, antropologis, dan psikologis. Metode yang digunakan adalah metode analisis deskriptif.

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