1,720,993 research outputs found
Impacts of Cosmetic Ingredients on Larval Barnacles: A Study & Discussion of How Cosmetic Ingredients Affect Marine Life
No full textIn recent years, scientists have discovered toxicity of active ingredients in sunscreens to marine
life such as coral reefs. While the research findings have brought about significant policy
changes in places like Hawaii and Palau, little attention has been given to the hundreds of other
ingredients that are commonly found in such cosmetics. Through 24-hour exposure studies with
barnacle larvae, this study documents toxicity and settlement inhibition of sunscreens and 5
common “inactive” ingredients. Results indicate that “inactive PDMS additives” are toxic to
barnacle larvae inhibit settlement. Sunscreens are even more potent, therefore suggesting the
combination of ingredients that makeup sunscreens pose a greater risk to marine life than
individual components. The Master’s Project products are an analysis and discussion of the
research conducted, as well as a short video translating the research for science communication
purposes
Biological and Physical Factors Affecting the Natural History and Evolution of Encapsulated Development
No full textThe evolution of reproductive strategies involves a complex calculus of costs and benefits to both parents and offspring. Many marine animals produce embryos packaged in tough egg capsules or gelatinous egg masses attached to benthic surfaces. While these egg structures can protect against environmental stresses, the packaging is energetically costly for parents to produce. In this series of studies, I examined a variety of ecological factors affecting the evolution of benthic development as a life history strategy. I used marine gastropods as my model system because they are incredibly diverse and abundant worldwide, and they exhibit a variety of reproductive and developmental strategies. The first study examines predation on benthic egg masses. I investigated: 1) behavioral mechanisms of predation when embryos are targeted (rather than the whole egg mass); 2) the specific role of gelatinous matrix in predation. I hypothesized that gelatinous matrix does not facilitate predation. One study system was the sea slug Olea hansineensis, an obligate egg mass predator, feeding on the sea slug Haminoea vesicula. Olea fed intensely and efficiently on individual Haminoea embryos inside egg masses but showed no response to live embryos removed from gel, suggesting that gelatinous matrix enables predation. This may be due to mechanical support of the feeding predator by the matrix. However, Haminoea egg masses outnumber Olea by two orders of magnitude in the field, and each egg mass can contain many tens of thousands of embryos, so predation pressure on individuals is likely not strong. The second system involved the snail Nassarius vibex, a non-obligate egg mass predator, feeding on the polychaete worm Clymenella mucosa. Gel neither inhibits nor promotes embryo predation for Nassarius, but because it cannot target individual embryos inside an egg mass, its feeding is slow and inefficient, and feeding rates in the field are quite low. However, snails that compete with Nassarius for scavenged food have not been seen to eat egg masses in the field, leaving Nassarius free to exploit the resource. Overall, egg mass predation in these two systems likely benefits the predators much more than it negatively affects the prey. Thus, selection for environmentally protective aspects of egg mass production may be much stronger than selection for defense against predation. In the second study, I examined desiccation resistance in intertidal egg masses made by Haminoea vesicula, which preferentially attaches its flat, ribbon-shaped egg masses to submerged substrata. Egg masses occasionally detach and become stranded on exposed sand at low tide. Unlike adults, the encased embryos cannot avoid desiccation by selectively moving about the habitat, and the egg mass shape has high surface-area-to-volume ratio that should make it prone to drying out. Thus, I hypothesized that the embryos would not survive stranding. I tested this by deploying individual egg masses of two age classes on exposed sand bars for the duration of low tide. After rehydration, embryos midway through development showed higher rates of survival than newly-laid embryos, though for both stages survival rates over 25% were frequently observed. Laboratory desiccation trials showed that >75% survival is possible in an egg mass that has lost 65% of its water weight, and some survival (The third study takes a big-picture approach to investigating the evolution of different developmental strategies in cone snails, the largest genus of marine invertebrates. Cone snail species hatch out of their capsules as either swimming larvae or non-dispersing forms, and their developmental mode has direct consequences for biogeographic patterns. Variability in life history strategies among taxa may be influenced by biological, environmental, or phylogenetic factors, or a combination of these. While most prior research has examined these factors singularly, my aim was to investigate the effects of a host of intrinsic, extrinsic, and historical factors on two fundamental aspects of life history: egg size and egg number. I used phylogenetic generalized least-squares regression models to examine relationships between these two egg traits and a variety of hypothesized intrinsic and extrinsic variables. Adult shell morphology and spatial variability in productivity and salinity across a species geographic range had the strongest effects on egg diameter and number of eggs per capsule. Phylogeny had no significant influence. Developmental mode in Conus appears to be influenced mostly by species-level adaptations and niche specificity rather than phylogenetic conservatism. Patterns of egg size and egg number appear to reflect energetic tradeoffs with body size and specific morphologies as well as adaptations to variable environments. Overall, this series of studies highlights the importance of organism-scale biotic and abiotic interactions in evolutionary patterns.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ecological and economic tradeoffs between herring fisheries and whale watching in New England
Get PDFThe whale-watching industry is an important component of the New England regional economy with about one million tourism visitors. Humpback whales are the most popular whale-watching targets, whose primary activity in this area is feeding that mainly on herrings. Meanwhile, the value of herring fisheries is more than $20M annually and it is the major supply for canneries and lobster bait. According to the historical document, over-harvesting of herrings may cause the dramatic depletion of humpback whale stock.
This research investigates the economic benefits and losses of the ban on the harvesting for herring in the New England area. I compare the revenue of herring fisheries and whale-watching under different herring harvest levels through integrated economic-ecological analysis. The marine ecosystem side will be modeled through EMAX food web. The socio-economical analysis focuses on the herring fisheries and whale watching market price and quantity. By comparing the two-sided benefits, this research evaluates if herring should be left in the marine ecosystem or harvested.
The result indicated that the decrease of herring harvest would not cause dramatic increase of the whale stock,, at least in the short term. Accordingly, the decline of herring landing would not significantly or equally increases the revenue from the whale watching tourism. The result suggests that the current herring fisheries landing might not have a significant impact on the whale population
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Learning to glue underwater: Inspiration from the decorator worm
No full textThe decorator worm, a sedentary predator, builds a micro-reef on the portion of its tube above the sediment, which attracts prey. When tube tops are clipped in the lab, the worm rebuilds compulsively. Glass beads and antifouling materials were used as decoration substrates to characterize bioadhesive biochemistry and adhesion to antifouling substrate. Decorator worm adhesive was largely proteinaceous with phosphate presence and a lack of glycoprotein.
The Introduction explains the scientific context for studying natural underwater adhesives, including efforts to understand conserved molecular mechanisms in underwater adhesion to further fouling prevention on boat hulls or medical implants and biomimicking natural glues for industrial or biomedical applications. The Methods provides detailed steps to test decorator worm adhesive for protein, phosphoprotein, and glycoprotein presence. This section also provides details on how to make worms decorate with antifouling substrates. The Results section shows that decorator worm bioadhesive is highly proteinaceous and has higher phosphate presence in the tube as compared to glue on glass beads. The adhesive did not contain significant glycoprotein. The decorator worm adheres mixed ion exchange resin, synthetic ion exchange resin, strongly basic anion exchange resin, aminopropyl silane modified glass particles (.5-10 μm), imitation seagrass, plastic zip ties, iPhone cases, silicone, silicone infused with octamethylcyclotetrasiloxane (D4) and silicone infused with decamethylcyclopentasiloxane (D5) to its tube.
This report details findings on the decorator worm as a novel system for studying adhesive and antifouling materials:
• Adhesive shows high protein content
• Tube adhesive shows higher phosphoprotein than adhesive on glass beads
• Adhesive shows little to no glycoprotein presence
• Decorator worms adheres all materials tested to their tubes
• Decorator worms relatively large size and readiness to adhere any material to the exterior tubes make them excellent candidates to testing antifoul release material
Spawning Biology of Female Blue Crabs, Callinectes Sapidus
No full textThis dissertation investigated spawning biology of female blue crabs, Callinectes sapidus. Females mate following the terminal molt and undertake a spawning migration seaward, producing multiple clutches of larvae. To examine lifetime reproductive potential of female crabs, individual crabs were confined in the field from terminal molt to death. Crabs produced up to 7 clutches over 1-2 spawning seasons and survived up to 394 d after the terminal molt. Time to first clutch and time between clutches were positively correlated with carapace width and best described by degree-days. Size at maturity was negatively correlated with water temperature on the day of the terminal molt. Most measurements of clutch quality and larval fitness were similar for all clutches. The percentage of embryos developing normally decreased 40% from clutch 1 to clutch 4 and clutch volume decreased 50% from clutch 1 to clutch 5. Thus, most of a crab's reproductive output is from the first few clutches. Using swimming and abdominal pumping assays, the roles of pheromones in larval release and migratory behavior were investigated. Following delivery of egg extract, bradykinin (a pheromone mimic), and trypsin (an enzyme that generates peptide pheromones), ovigerous crabs responded with increased abdominal pumping, indicating that peptide pheromones stimulate larval release in blue crabs. Ovigerous crabs responded with increased swimming following delivery of egg extract, but not following delivery of a peptide pheromone mimic or an enzyme that produces peptide pheromones. These results suggest that some substance generated from the egg mass stimulates vertical swimming, but that peptides alone do not stimulate swimming. A blend of molecules, possibly including sugars, may be the cue that stimulates swimming behavior. Endogenous rhythms in vertical swimming, a mechanism underlying migration in tidal estuaries, were examined in the laboratory under constant conditions in juvenile females, recently-molted females, and females with mature ovaries from Beaufort, NC. Rhythms were variable in each stage, though circatidal rhythms consistent with ebb tide transport were observed in juvenile females and recently-molted females. Crabs with mature ovaries typically swam around the time of high tide. Rhythms were also examined for ovigerous females collected from estuaries with three different tidal regimes: semi-diurnal, diurnal, and non-tidal. Crabs from the tidal estuaries had circatidal or circalunidian swimming rhythms with period lengths corresponding to the tidal period of their home estuary. Swimming occurred primarily on ebb tide. Crabs from the non-tidal estuary had a circadian rhythm of vertical swimming around the time of sunset. Such a rhythm has no obvious migratory significance and migration likely takes place though another mechanism.Swimming behavior was also examined in the field in one non-tidal site and three tidal sites. Crabs were tethered in the field and swimming was monitored using archival pressure tags. Crabs tethered in the non-tidal site did not swim, possibly due to the lack of necessary environmental cues. Crabs at the tidal sites swam primarily on ebb tides. Swimming was greatest at the deepest site, which also had the strongest currents. This site is known to be a migratory area for spawning blue crabs. Decreased swimming behavior was observed at the two shallower sites, including one site that is known to be habitat for all stages of blue crabs. These results indicate that swimming behavior is variable among different areas in a single estuary. In areas where swimming is reduced, crabs may continue migrating seaward by walking or may spend additional time in that area to forage. Within each site, peak swimming generally occurred during the time of the most rapid decrease in water level, suggesting that hydrostatic pressure may serve as a cue for swimming. Mark-recapture studies were conducted in three rivers (North River, South River, Adams Creek) in eastern North Carolina, and recently-molted female crabs were tagged to ensure a relatively constant time since molting. Most crabs traveled relatively short distances and were recaptured before producing a clutch of eggs. Individuals that moved substantial distances typically moved down-estuary. The Adams Creek canal, connecting Adams Creek with the Newport River estuary, functioned as a migratory corridor, as crabs from both Adams Creek and South River migrated down the canal, presumably using ebb tide transport. Many of the crabs that migrated down the canal into the Newport River were recaptured while ovigerous. Results of this study support the hypothesis that rapid long-distance migratory movements do not begin until production of the first clutch of eggs, though some down-estuary movement takes place by prior to production of the first clutch of eggs.Female blue crabs mate following the terminal molt and begin moving seaward soon thereafter by walking and swimming. Once the appropriate salinity (> 22 ppt) is reached, the first clutch of eggs is produced and migration rate rapidly increases. Blue crab spawning biology should be similar throughout the range of the species. After taking latitudinal temperature variation and other local variables into account, results presented here should be applicable not only to blue crabs in North Carolina, but in other areas as well.</p
Improving the management of the Atlantic Cod fishery by updating stock assessments and enforcing compliance
No full textManagement of Atlantic cod, Gadus morhua, has become increasingly stringent since the
implementation of the first groundfish fishery management plan (FMP) in 1977, yet overfished
stock status is evidence of ineffective management. This management relies on fish surveys and
computer models to assess the stock, and various regulations to control the level of catch. This
masters project investigates the assessment and management practices of the Unites States and
Canada (focusing on the former) and provides practical modifications to remedy errors and
improve the current Multispecies FMP.
The cod stock assessment model includes two assumptions about the species: cod are nonmigratory,
and cod natural mortality has remained the same since its last evaluation 28 years ago.
I present two studies that contradict the assumption that cod are non-migratory, and provide three
reasons that cod natural mortality has increased: heightened competition and predation, habitat
damage, and genetic modification resulting from selective harvest.
To avoid the overfishing that results, I recommend that the model equation be changed to include
migration frequency and utilize an increased value for the natural mortality parameter. Until
necessary studies to correct the model are completed, stock assessors should add an uncertainty
parameter into the equation that buffers against error resulting from inaccurate model
specification.
Prioritization of economic concerns, overconfidence in the effort-reduction program, and
ineffective monitoring have routinely produced cod landings that surpass the target total
allowable catch (TAC). Recent landings below the target TAC are due to low biomass rather
than management success. I propose four recommendations to improve the management process:
1) decrease target TACs; 2) restrict trawler vessel days-at-sea and fishing areas; 3) improve
monitoring; and 4) fund a fisher retraining service.
The status of the Atlantic cod fishery indicates the need for a different management regime. The
New England Fishery Management Council should act now to transform the cod fishery from the
best example of management failure to the best example of collapsed stock recovery. The
science and technology to implement these recommendations is ready and waiting
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