329 resultados para Biology, Ecology|Biology, Oceanography
Resumo:
Venomous Indo-Pacific lionfish (Pterois miles and P. volitans) are now established along the Southeast U.S.A. and parts of the Caribbean and pose a serious threat to reef fish communities of these regions. Lionfish are likely to invade the Gulf of Mexico and potentially South America in the near future. Introductions of lionfish were noted since the 1980s along south Florida and by 2000 lionfish were established off the coast of North Carolina. Lionfish are now one of the more numerous predatory reef fishes at some locations off the Southeast U.S.A. and Caribbean. Lionfish are largely piscivores that feed occasionally on economically important reef fishes. The trophic impacts of lionfish could alter the structure of native reef fish communities and potentially hamper stock rebuilding efforts of the Snapper –Grouper Complex. Additional effects of the lionfish invasion are far-reaching and could increase coral reef ecosystem stress, threaten human health, and ultimately impact the marine aquarium industry. Control strategies for lionfish are needed to mitigate impacts, especially in protected areas. This integrated assessment provides a general overview of the biology and ecology of lionfish including genetics, taxonomy, reproductive biology, early life history and dispersal, venom defense and predation, and feeding ecology. In addition, alternative management actions for mitigating the negative impacts of lionfish, approaches for reducing the risk of future invasions, and directions for future research are provided.
Resumo:
ENGLISH: In 1952 and 1953, during the course of a study of the abrupt decline and apparent disappearance from the Gulf of Nicoya of the population of anchovetas (Cetengraulis mysticetus), an important tuna bait fish, considerable material was collected on the taxonomy, biology, and ecology of the several anchovies and the herrings inhabith1g the Gulf. The Gulf of Nicoya, approximately 50 miles long and varying in width from about 5 to 35 miles, is located on the Pacific coast of Costa Rica. The family Engraulididae is represented by four genera comprising fourteen species, and nine species were identified as members of eight genera of the family Clupeidae. All of the species inhabit other coastal areas of the tropical Eastern Pacific. SPANISH: En 1952 Y 1953, durante el curso de un estudio sobre la declinación abrupta y la aparente desaparición en el Golfo de Nicoya de la población de anchovetas (Cetengraulis mysticetus) un pez de importancia para la pesca del atún, se recolectó material considerable relacionado con la taxonomía, biología y ecología de las diversas especies de anchoas y arenques que habitan dicho Golfo. El Golfo de Nicoya, que mide aproximadamente 50 millas de largo y varía en su anchura entre 5 y 35 millas, se encuentra en la costa del Pacífico de Costa Rica. La familia de los Engráulidos está representada por cuatro géneros que comprenden catorce especies, y otras nueve fueron identificadas como miembros de ocho géneros de la familia Clupeidae. Todas estas especies habitan otras áreas costeras del Pacífico Oriental tropical. (PDF contains 144 pages.)
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This annotated bibliography of selected literature on Olney's three7square (Scirpus olneyi Gray )compiled basically for two reasons: 1) to assist a task force in its pursuit of an explanation for the substantial reduction in marsh acreage at the Blackwater National Wildlife Refuge in Dorchester County, Maryland, and 2) to serve as the author's foundation for the initiation of ecological research on this species as partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Botany Department of the University of Maryland. Both purposes are directly related in that the Author's research will be of use to the task force, along I with its other technical information and research results, in under-standing and possibly correcting the marshland loss problem at the Refuge. (PDF contains 100 pages)
Resumo:
Rangia and marsh clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, occur in brackish waters along México’s eastern coast from the northern State of Tamaulipas to the southern State of Campeche. The clams were important to the prehispanic people in the southern part of the State of Veracruz, where they were used as food and as construction material. In modern times, they are harvested for food. The fishermen wade in shallow water and harvest the clams in soft sediments by hand. Annual landings of whole clams during a recent 5-yr period, 1998–2002, were 1,139–1,695 t. The only area with a substantial ongoing clam fishery is in the Lower Papaloapan River Basin, including Alvarado Lagoon, where as many as 450 fishermen are licensed harvesters. This fishery for the Rangia and marsh clams is the most important clam fishery along México’s Gulf Coast.
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The northern quahog, Mercenaria mercenaria, ranges along the Atlantic Coast of North America from the Canadian Maritimes to Florida, while the southern quahog, M. campechiensis, ranges mostly from Florida to southern Mexico. The northern quahog was fished by native North Americans during prehistoric periods. They used the meats as food and the shells as scrapers and as utensils. The European colonists copied the Indians treading method, and they also used short rakes for harvesting quahogs. The Indians of southern New England made wampum from quahog shells, used it for ornaments and sold it to the colonists, who, in turn, traded it to other Indians for furs. During the late 1600’s, 1700’s, and 1800’s, wampum was made in small factories for eventual trading with Indians farther west for furs. The quahoging industry has provided people in many coastal communities with a means of earning a livelihood and has provided consumers with a tasty, wholesome food whether eaten raw, steamed, cooked in chowders, or as stuffed quahogs. More than a dozen methods and types of gear have been used in the last two centuries for harvesting quahogs. They include treading and using various types of rakes and dredges, both of which have undergone continuous improvements in design. Modern dredges are equipped with hydraulic jets and one type has an escalator to bring the quahogs continuously to the boats. In the early 1900’s, most provinces and states established regulations to conserve and maximize yields of their quahog stocks. They include a minimum size, now almost universally a 38-mm shell width, and can include gear limitations and daily quotas. The United States produces far more quahogs than either Canada or Mexico. The leading producer in Canada is Prince Edward Island. In the United States, New York, New Jersey, and Rhode Island lead in quahog production in the north, while Virginia and North Carolina lead in the south. Connecticut and Florida were large producers in the 1990’s. The State of Campeche leads in Mexican production. In the northeastern United States, the bays with large openings, and thus large exchanges of bay waters with ocean waters, have much larger stocks of quahogs and fisheries than bays with small openings and water exchanges. Quahog stocks in certifi ed beds have been enhanced by transplanting stocks to them from stocks in uncertified waters and by planting seed grown in hatcheries, which grew in number from Massachusetts to Florida in the 1980’s and 1990’s.
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Ecosystem-based management is one of many indispensable components of objective, holistic management of human impacts on nonhuman systems. By itself, however, ecosystem-based management carries the same risks we face with other forms of current management; holism requires more. Combining single-species and ecosystem approaches represents progress. However, it is now recognized that management also needs to be evosystem-based. In other words, management needs to account for all coevolutionary and evolutionary interactions among all species; otherwise we fall far short of holism. Fully holistic practices are quite distinct from the approaches to the management of fisheries that are applied today. In this paper, we show how macroecological patterns can guide management consistently, objectively, and holistically. We present one particular macroecological pattern with two applications. The first application is a case study of fisheries from the Baltic Sea involving historical data for two species; the second involves a sample of 44 species of primarily marine fish worldwide. In both cases we evaluate historical fishing rates and determine holistic/systemic sustainable single-species fishing rates to illustrate that conventional fisheries management leads to much more extensive and pervasive overfishing than currently realized; harvests are, on average, over twenty-fold too large to be fully sustainable. In general, our approach involves not only the sustainability of fisheries and related resources but also the sustainability of the ecosystems and evosystems in which they occur. Using macroecological patterns accomplishes four important goals: 1) Macroecology becomes one of the interdisciplinary components of management. 2) Sustainability becomes an option for harvests from populations of individual species, species groups, ecosystems, and the entire marine environment. 3) Policies and goals are reality-based, holistic, or fully systemic; they account for ecological as well as evolutionary factors and dynamics (including management itself). 4) Numerous management questions can be addressed.
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The Indo-Pacific lionfishes, Pterois miles and P. volitans, are now established along the U.S. southeast coast, Bermuda, Bahamas, and are becoming established in the Caribbean. While these lionfish are popular in the aquarium trade, their biology and ecology are poorly understood in their native range. Given the rapid establishment and potential adverse impacts of these invaders, comprehensive studies of their biology and ecology are warranted. Here we provide a synopsis of lionfish biology and ecology including invasion chronology, taxonomy, local abundance, reproduction, early life history and dispersal, venomology, feeding ecology, parasitology, potential impacts, and control and management. This information was collected through review of the primary literature and published reports and by summarizing current observations. Suggestions for future research on invasive lionfish in their invaded regions are provided.
Resumo:
The Indo-Pacific lionfishes, Pterois miles and P. volitans, are now established along the Southeast U.S. and Caribbean and are expected to expand into the Gulf of Mexico and Central and South America. Prior to this invasion little was known regarding the biology and ecology of these lionfishes. I provide a synopsis of chronology, taxonomy, local abundance, reproduction, early life history and dispersal, venomology, feeding ecology, parasitology, potential impacts, and possible control and management strategies for the lionfish invasion. This information was collected by review of the literature and by direct field and experimental study. I confirm the existence of an unusual supraocular tentacle phenotype and suggest that the high prevalence of this phenotype in the Atlantic is not the result of selection, but likely ontogenetic change. To describe the trophic impacts of lionfish, I report a comprehensive assessment of diet that describes lionfish as a generalist piscivore that preys on over 40 species of teleost comprising more than 20 families. Next, I use the histology of gonads to describe both oogenesis and reproductive dynamics of lionfish. Lionfish mature relatively early and reproduce several times per month throughout the entire calendar year off North Carolina and the Bahamas. To investigate predation, an important component of natural mortality, I assessed the vulnerability of juvenile lionfish to predation by native serranids. Juvenile lionfish are not readily consumed by serranids, even after extreme periods of starvation. Last, I used a stage-based, matrix population model to estimate the scale of control that would be needed to reduce an invading population of lionfish. Together, this research provides the first comprehensive assessment on lionfish biology and ecology and explains a number of life history and ecological interactions that have facilitated the unprecedented and rapid establishment of this invasive finfish. Future research is needed to understand the scale of impacts that lionfish could cause, especially in coral reef ecosystems, which are already heavily stressed. This research further demonstrates the need for lionfish control strategies and more rigorous prevention and early detection and rapid response programs for marine non-native introductions.
Resumo:
Nile perch (Mputa), Lates niloticus was introduced into Lakes Victoria and Kyoga from lake Albert to increase fish production of these lakes by feeding on and converting the small sized haplochromines (Nkejje) which were abundant in these lakes into a larger table fish. It was, however, feared that Nile perch would prey on and deplete stocks of the native fishes and affect fish species diversity. Nile perch became well established and is currently among the three most important commercial species. It is presently the most important export fish commodity from Uganda. Considerable changes have taken place in fishery yield, and in life history characteristics of the Nile perch itself since the predator got established in Lakes Victoria and Kyoga.
Resumo:
Food and feeding, condition factor, breeding periods, growth and size at first maturity of a small pelagic cyprinid Rastrineobola argentea (P.) in Lake Victoria are determined. Fishing gears and methods that have been used in the exploitation of the species and could be harmful to the fishery are outlined. Management measures leading to possible sustainable exploitation of the fishery are suggested. Adult R. argentea feed on zooplankton during daytime. Juveniles feed on planktonic early instars of lakefly larvae. Although the species breeds throughout the year, two breeding peaks were observed during the drier months of August and December January. Least breeding was observed in the rainy months of April-May and October November. Fishes from the open water station at Bugaia showed higher numbers of breeding individuals than those from inshore areas. The mean monthly condition factor of fish from Napoleon Gulf confirmed breeding peaks as obtained from the number of fish with ripe gonads. The species showed a mean instantaneous growth rate (K) of 1.75 and attains length infinity (Lx) of 54mm. Females of the species in these waters show a reduced size at maturity as compared to ten years ago when exploitation of the species was at minimal levels. The males have however not changed much.
Resumo:
Rastrineobola argentea, local name.s Mukene (Uganda) Omena (Kenya) and Dagaa (Tanzania) occurs in lakes Victoria, Kyoga and Nabugabo (Greenwood 1966). Until the decline of the native fishes especially the haplochromines, R. argentea was of little economic importance to the fisheries of these lakes. The stocks of this species have now increased and commercial catches on Lake Victoria account for over 30%. Fishing for R. argentea is currently still restricted to inshore areas and within the fringing islands of Lake Victoria. This fishery is not yet established on Lakes Kyoga and Nabugabo although the species is quite abundant in these lakes (Proude 1963). On moonless nights, kerosene pressure lamps are exposed on the lake to attract the fishes. These fishes are then fished out using fine meshed seine, lampara or lift nets