Accelerating loss of seagrasses across the globe threatens coastal ecosystems

Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 square kilometers per year since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% per year before 1940 to 7% per year since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth.

Kommentar zum Worm-et-al.-Artikel„Impacts of Biodiversity Loss on Ocean Ecosystem Services“: erschienen im Wissenschaftsmagazin Science, Vol. 314, am 3. November 2006

Folgende Kernbehauptungen bzw. Hypothesen werden in dem Worm-et-al.-Artikel aufgestellt: -Der Verlust an Biodiversität (Artenzahl) in einem Meeresgebiet reduziert tief greifend seine Produktivität und seine Stabilität in Stressperioden, hervorgerufen u.a. durch Überfischung und Klimaänderung. -Die Zahl der kollabierten Arten nimmt zu. Dieser Trend projeziert den Kollaps aller wildlebenden Arten und Bestände, die gegenwärtig befischt werden, auf das Jahr 2048. -Diese Entwicklung ist zum gegenwärtigen Zeitpunkt reversibel, denn das Meer besitzt noch ein großes Potential sich zu regenerieren. Dazu ist aber mehr Umweltschutz notwendig.

Artisanal canoe fishing industry of the Rivers State: its economic viability and investment potentials

Consequent upon the present national call in Nigeria for all to go back to agriculture including fishing, most retrenched workers and unemployed youths from the riverine areas are taking up fishing as a legitimate and gainful livelihood. To sustain this tempo and attract more investment, the economic viability of such projects must be known. This study is an attempt to document the profitability and investment potential of artisanal canoe fishing. Socio-economic information including catches, operational cost and returns were obtained through a personal interview questionnaire survey of 240 randomly selected artisanal canoe fishermen from Bonny, Brass and Degema Local Government Areas (LGA) of the State and analyzed. With an investment cost of about 8,135, 8,490 and 6,571 and operation cost of 750, 776 and 627, the analysis showed an average monthly gross income of 1,869, 3,221 and 1,775 for the three local government areas respectively. A benefit-cost-ratio of 1:8, net present value of 400, 603 and internal rate of return greater than 50% were obtained. Since capital invested in fisheries is not tied up for long before benefits start flowing, coupled with the high IRR, it is concluded that artisanal canoe fishing would be an economically viable venture if well managed

Fishing systems: viability in Nigeria

Following an outline of the various fishing systems in Nigeria, considering both the marine and freshwater environment, details are provided of those around which viable sustainable fisheries may be developed

Aspects of the fishing industry and an overview of artificial reefs and fish aggregating devices for increasing fisheries output and viability in Nigeria

Aspects of the Nigerian fishing industry are outlined to explain the concept of fishing systems viability which is often influenced by a combination of factors including biological productivity, as well as technical, economic and social factors. The productivity of the aquatic environments can be increased by the construction and installation of artificial reefs and fish aggregating devices. These man-made structures provide shelters, food and breeding grounds for fin fish and shell fish. The habitat enhancement techniques are appropriate, efficient, cheap and simple strategic options for increase in fish production. Recommendations for effective utilization and long term management are outlined.

Bacterial production of nitrate in aquatic systems: progress report. Nitrate-loss processes in raw water

This short interim progress report builds on previous progress reports which have described the quantification of the process both within and between lakes of different degrees of eutrophication. These data indicated that slight changes in methodology, particularly when investigating sediment deposits, could grossly affect the measured activity. The aim of the present research was an attempt to rationalize these differences. If this could be achieved it would enable meaningful interpretation of published data obtained using different methods and therefore enlarge the available database. In addition some observations have been made on the production of nitrite by Grasmere profundal sediment slurries sampled during the circulation period.

Nitrates - loss processes in raw water

This project investigated the production of nitrate (nitrification) by bacteria in lakes. The work was undertaken as nitrification is a key process in the nitrogen cycle and previous estimates of rates of nitrification were unreliable. When different methods were used to estimate rates of nitrification within sediment deposits different results were obtained. Investigation' of specific aspects of these methodologies has allowed some rationalization of these observations and also enabled comparisons of previously published data which, beforehand, was not possible. However, it was not clear which methods gave the most reliable rate estimates. Calculation of a nitrate budget for Grasmere lake indicated that the use of methods which involved the mixing of surface sediments (and therefore disrupted preformed nutrient gradients) overestimated the rate of nitrification. The study concludes that slight changes in the method used to prepare sediment slurries can result in large changes, in the measured nitrifying activity. This makes comparisons between studies, using different methods, extremely difficult. Methods to study sediment nitrification processes which do not disrupt preformed substrate gradients within the sediment provide the most reliable rate estimates.

Viability of seeds in food products proposed for field trips in Galapagos

Seeds of 14 plant species extracted from food products proposed for field trips in Galapagos were tested for viability. Strawberry Fragaria ananasa and Blackberry Rubus glaucus jams (Snob and Gustadina brands) contained no viable seeds. Schullo brand granola contained inviable Sesame Sesamum indicum seed, but Sesame in granolas prepared in Galapagos was viable. Sesame seed in bread was viable but Flax Linum usitatissimum seed in bread was not. Brown Rice Oryza sativa and Sunflower seeds Helianthus annuus were both viable. Fresh Apple Malus domestica, Naranjilla Solanum quitoense, Cucumber Cucumis sativus, Pineapple Ananas comosus, Pear Pyrus communis, Bell Pepper Capsicum annuum, Tomato Solanum lycopersicum, Grape Vinis vinifera all contained viable seeds. We recommend prohibiting any product with viable seeds from field trips to uninhabited areas. CDF Contribution Number 1009.

Accelerating loss of seagrasses across the globe threatens coastal ecosystems

Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 square kilometers per year since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% per year before 1940 to 7% per year since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth.

Modeling the effect of striped bass (Morone saxatilis) on the population viability of Sacramento River winter-run chinook salmon (Onchorhynchus tshawytscha)

We estimated the impact of striped bass (Morone saxatilis) predation on winter-run chinook salmon (Oncorhynchus tshawytscha) with a Bayesian population dynamics model using striped bass and winter-run chinook salmon population abundance data. Winter-run chinook salmon extinction and recovery probabilities under different future striped bass abundance levels were estimated by simulating from the posterior distribution of model parameters. The model predicts that if the striped bass population declines to 512,000 adults as expected in the absence of stocking, winter-run chinook salmon will have about a 28% chance of quasi-extinction (defined as three consecutive spawning runs of fewer than 200 adults) within 50 years. If stocking stabilizes the striped bass population at 700,000 adults, the predicted quasi-extinction probability is 30%. A more ambitious stocking program that maintains a population of 3 million adult striped bass would increase the predicted quasi-extinction probability to 55%. Extinction probability, but not recovery probability, was fairly insensitive to assumptions about density dependence. We conclude that winter-run chinook salmon face a serious extinction risk without augmentation of the striped bass population and that substantial increases in striped bass abundance could significantly increase the threat to winter-run chi-nook salmon if not mitigated by increasing winter chinook salmon survival in some other way.

Phosphate treatment of frozen prawns. Pt. 1. Screening of various phosphates for prevention of drip loss

Various phosphates and their mixtures were screened for their efficiency of preventing drip loss in frozen prawns. The effectiveness of the phosphates decreased in the following order: Sodium tripolyphosphate — Sodium pyrophosphate — Sodium hexametaphosphate Sodium metaphosphate — Sodium dihydrogen phosphate; the last two being ineffective. Even though thaw drip loss was reduced by the above treatments the organoleptic quality of the thawed as well as cooked products was unsatisfactory, discoloration being the major defect. A solution of a mixture of 12% sodium tripolyphosphate and 8.6% sodium dihydrogen phosphate or 2% citric acid in water when used as dip prevented thaw drip loss, improved cooked yield and organoleptic quality without adversely affecting the biochemical characteristics. Commercial scale trials showed that the results are highly reproducible.

Effect of decapsulation on viability and hatching performance of Artemia cysts at different salinity levels

Artemia cysts were produced from the traditional solar salt works of Bangladesh through different fertilization treatments were tested for viability and hatching performance in different forms, such as processed and preserved, processed and decapsulated and unprocessed and undecapsulated. Decapsulated cysts performed maximum hatching (86.0%) in 20ppt salinity during 48 hours of incubation. The hatching percentage by the unprocessed and undecapsulated cysts were very low (12.0- 18.7%) in all the tested salinity grades.

Colossal loss of shell and fin-fish larvae during collection of Penaeus monodon (Fab.) fry in the rivers of Satkhira

This study was conducted in five river-estuaries of Satkhira from January to December '96. It was found that during the collection of each Peneaus monodon) post larva (PL), about 45 larvae of other shrimps, 12 individuals of fin-fishes and 530 macro-zooplankters were mercilessly destroyed. It was also recorded that about 11.6 million of P. monodon PLs were harvested annually from the study area. The sh1dy implies that colossal loss of shell and fin-fishes and other plankton resources is done by tiger shrimp fry collectors, and such massive destruction adversely affect the natural productivity and ecological balance of the coastal environment.

Investigations on wooden floating materials: the loss of buoyancy under continuous immersion in water and the rate of its redemption by drying

A wooden fishing float under immersion in water for long periods is liable to absorb water, the quantity of water absorbed possibly being dependent upon the physical factors like the specific gravity and the inherent property of the material, the time of soaking and the pressure acting on it. Consequently a wooden float is likely to become heavy and loss its original buoyancy. However, when the float is removed from water and dried, the lost buoyancy is regained on complete drying. The present paper is an attempt to elucidate these two important characteristics of some of the chief wooden floating materials used on the West Coast of India.