The physiological response of fishes to the stress of intensive aquaculture in recirculation systems
No abstract available
SEARCH · Search USGS
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
No abstract available
Abstract not submitted to date
Abstract not submitted to date
Abstract not supplied at this time
No abstract available at this time
No abstract available at this time
No abstract available at this time
No abstract available at this time
The natural aging process of Chesapeake Bay and its tributary estuaries has been accelerated by human activities around the shoreline and within the watershed, increasing sediment and nutrient loads delivered to the bay. Riverine nutrients cause algal growth in the bay leading to reductions in light penetration with consequent declines in sea grass growth, smothering of bottom-dwelling organisms, and decreases in bottom-water dissolved oxygen as algal blooms decay. Historically, bay waters were filtered by oysters, but declines in oyster populations from overfishing and disease have led to higher concentrations of fine-sediment particles and phytoplankton in the water column. Assessments of water and biological resource quality in Chesapeake Bay and tributaries, such as the Potomac River, show a continual degraded state. In this paper, we pay tribute to Owen Bricker’s comprehensive, holistic scientific perspective using an approach that examines the connection between watershed and estuary. We evaluated nitrogen inputs from Potomac River headwaters, nutrient-related conditions within the estuary, and considered the use of shellfish aquaculture as an in-the-water nutrient management measure. Data from headwaters, nontidal, and estuarine portions of the Potomac River watershed and estuary were analyzed to examine the contribution from different parts of the watershed to total nitrogen loads to the estuary. An eutrophication model was applied to these data to evaluate eutrophication status and changes since the early 1990s and for comparison to regional and national conditions. A farm-scale aquaculture model was applied and results scaled to the estuary to determine the potential for shellfish (oyster) aquaculture to mediate eutrophication impacts. Results showed that (1) the contribution to nitrogen loads from headwater streams is small (about 2 %) of total inputs to the Potomac River Estuary; (2) eutrophic conditions in the Potomac River Estuary have improved in the upper estuary since the early 1990s, but have worsened in the lower estuary. The overall system-wide eutrophication impact is high, despite a decrease in nitrogen loads from the upper basin and declining surface water nitrate nitrogen concentrations over that period; (3) eutrophic conditions in the Potomac River Estuary are representative of Chesapeake Bay region and other US estuaries; moderate to high levels of nutrient-related degradation occur in about 65 % of US estuaries, particularly river-dominated low-flow systems such as the Potomac River Estuary; and (4) shellfish (oyster) aquaculture could remove eutrophication impacts directly from the estuary through harvest but should be considered a complement—not a substitute—for land-based measures. The total nitrogen load could be removed if 40 % of the Potomac River Estuary bottom was in shellfish cultivation; a combination of aquaculture and restoration of oyster reefs may provide larger benefits.
Invasive Asian Black Carp ( Mylopharyngodon piceus ) have been present in USA aquaculture facilities since the 1980s and wild Black Carp have been found in the Mississippi River Basin since the early 1990s. This study characterizes the genetic diversity and relatedness of the Basin’s Black Carp and clarifies the introduction history. Analyses focused on three mitochondrial markers (control region, cytochrome- b , and 16S) and seven nuclear microsatellite markers ( nDNA ), using aquaculture and wild-caught samples collected in the upper and lower Mississippi Basin. Of the three mitochondrial haplotypes, two were shared between the aquaculture and wild populations, while a third was only present in upper Mississippi wild-caught specimens. Due to the presence of diploid and triploid fish, microsatellite markers were scored as pseudodominant and revealed low polymorphism (N A = 4.6, N A Ave = 1.5). Nuclear Bayesian clustering analyses identified two genetically distinct groups and four subclusters, each primarily composed of a unique haplotype. Samples from three aquaculture farms were assigned to group 1, while a fourth farm included samples from both groups 1 and 2. Wild-caught fish from the upper Basin were predominantly group 1, whereas wild samples from the lower Mississippi were assigned to both genetic groups. The presence of divergent haplotypes and distinct nDNA groups, along with geographic distribution patterns, indicate that wild populations in the basin likely resulted from multiple introductions. Genetic similarities between wild and captive populations support claims that aquaculture is the introduction source, but a shortage of samples and a history of repeated transfers among facilities obscure the precise pathway.
Black Carp ( Mylopharyngodon piceus ) was imported to the USA to control aquaculture pond snails. This species has escaped captivity and occurs in parts of the Mississippi River, several tributaries, and floodplain lakes, which is concerning due to potential competition with native fishes and predation on native mussels, many of which are imperiled. However, Black Carp captures have primarily been incidental by commercial fishers, and evidence of reproduction in the wild is limited. The objectives of this study were to assess relative abundance of aquaculture-origin and wild Black Carp using ploidy and otolith stable isotope analysis, identify spatial extent of natural reproduction using otolith microchemistry, assess age distributions of wild and aquaculture-source Black Carp to infer years in which natural reproduction occurred and timing of aquaculture escapement or introductions, and estimate size and age at maturation to assess whether recruitment to adulthood has occurred. Results revealed that Black Carp are established in parts of the Mississippi River basin based on findings that: (1) non-captive Black Carp primarily consist of fertile, naturally-reproduced fish, (2) reproduction has occurred in several rivers, (3) multiple year classes of wild fish are present, and (4) wild fish have recruited to adulthood. Multiple introductions or escapements of aquaculture-source fish into the wild, including both fertile and functionally sterile individuals, were also inferred. Individual growth appears to be rapid, although considerable variation was observed among fish. Additional study is suggested to refine understanding of where and when Black Carp reproduction is occurring in the Mississippi River basin.
Relative contributions of aquaculture-origin and naturally-reproduced grass carp ( Ctenopharyngodon idella ) in the Laurentian Great Lakes have been unknown. We assessed occurrence and distribution of aquaculture-origin and wild grass carp in the Great Lakes using ploidy and otolith stable oxygen isotope (δ 18 O) data. We inferred natal river and dispersal from natal location for wild grass carp using otolith microchemistry and estimated ages of wild and aquaculture-origin fish to infer years in which natural reproduction and introductions occurred. Otolith δ 18 O indicated that the Great Lakes contain a mixture of wild grass carp and both diploid and triploid, aquaculture-origin grass carp. Eighty-eight percent of wild fish (n = 49 of 56) were caught in the Lake Erie basin. Otolith microchemistry indicated that most wild grass carp likely originated in the Sandusky or Maumee rivers where spawning has previously been confirmed, but results suggested recruitment from at least one other Great Lakes tributary may have occurred. Three fish showed evidence of movement between their inferred natal river in western Lake Erie and capture locations in other lakes in the Great Lakes basin. Age estimates indicated that multiple year classes of wild grass carp are present in the Lake Erie basin, recruitment to adulthood has occurred, and introductions of aquaculture-origin fish have happened over multiple years. Knowledge of sources contributing to grass carp in the Great Lakes basin will be useful for informing efforts to prevent further introductions and spread and to develop strategies to contain and control natural recruitment.
The rise of aquaculture has been one of the most profound changes in global food production of the past 100 years. Driven by population growth, rising demand for seafood and a levelling of production from capture fisheries, the practice of farming aquatic animals has expanded rapidly to become a major global industry. Aquaculture is now integral to the economies of many countries. It has provided employment and been a major driver of socio-economic development in poor rural and coastal communities, particularly in Asia, and has relieved pressure on the sustainability of the natural harvest from our rivers, lakes and oceans. However, the rapid growth of aquaculture has also been the source of anthropogenic change on a massive scale. Aquatic animals have been displaced from their natural environment, cultured in high density, exposed to environmental stress, provided artificial or unnatural feeds, and a prolific global trade has developed in both live aquatic animals and their products. At the same time, over-exploitation of fisheries and anthropogenic stress on aquatic ecosystems has placed pressure on wild fish populations. Not surprisingly, the consequence has been the emergence and spread of an increasing array of new diseases. This review examines the rise and characteristics of aquaculture, the major viral pathogens of fish and shrimp and their impacts, and the particular characteristics of disease emergence in an aquatic, rather than terrestrial, context. It also considers the potential for future disease emergence in aquatic animals as aquaculture continues to expand and faces the challenges presented by climate change.
Water use in Alabama was about 9,958 million gallons per day (Mgal/d) during 2005. Estimates of withdrawals by source indicate that total surface-water withdrawals were about 9,467 Mgal/d (95 percent of the total withdrawals) and the remaining 491 Mgal/d (5 percent) were from ground water. More surface water than ground water was withdrawn for all categories except aquaculture, mining, and self-supplied residential. During 2005, estimated withdrawals by category and in descending order were: thermoelectric power, 8,274 Mgal/d; public supply, 802 Mgal/d; self-supplied industrial, 550 Mgal/d; irrigation, 161 Mgal/d; aquaculture, 75 Mgal/d; self-supplied residential, 39 Mgal/d; livestock, 28 Mgal/d; and mining, 28 Mgal/d. During 2005, about 83 percent of the water used in Alabama was for thermoelectric power to generate about 114,144 net gigawatt-hours of energy. Almost all of the thermoelectric-power water use (about 8,274 Mgal/d) was from surface water; nearly all of the water (98 percent) was used for once-through cooling, and most of that water was returned to a surface-water source. Public-supply and self-supplied residential withdrawals were about 8 percent of total water withdrawals and about 50 percent of total water withdrawals for all categories excluding thermoelectric power. The combined public-supply and self-supplied residential ground-water withdrawals were about 64 percent of total ground-water withdrawals for Alabama. Public-supply deliveries to residential customers were 41 percent of total public-supply withdrawals, or about 326 Mgal/d; combined industrial and commercial deliveries were 44 percent, or about 355 Mgal/d; and public use and losses accounted for the remaining 15 percent, or about 120 Mgal/d. Self-supplied industrial (550 Mgal/d) and mining (28 Mgal/d) withdrawals were about 6 percent of total water withdrawals and about 33 percent of total water withdrawals for all categories excluding thermoelectric power. Paper and allied products accounted for the largest self-supplied industrial surface-water withdrawals (301 Mgal/d), and chemical and allied products (12 Mgal/d) accounted for the largest ground-water withdrawals. Water withdrawals for the agricultural sector-irrigation (161 Mgal/d), aquaculture (75 Mgal/d), and livestock (28 Mgal/d)-were about 3 percent of total withdrawals and about 16 percent of total withdrawals for all categories excluding thermoelectric power. About 135,800 acres of crops, nursery stock, sod, and golf courses were irrigated in 2005. About 97 percent of these acres were irrigated with sprinkler irrigation systems. The statewide average application rate was 1.33 acre-feet per acre per year. The highest application rate, 3.74 acre-feet per acre per year, was for nursery stock. The largest total water withdrawals by county occurred in Limestone, Jackson, Colbert, and Mobile Counties, and were 60 percent of the total; these withdrawals primarily were used to meet the cooling needs at thermoelectric-power plants. Excluding thermoelectric power, the largest withdrawals by county were in Morgan, Mobile, Jefferson, Talladega, and Madison Counties. Water use was estimated at the hydrologic subbasin level for all categories except aquaculture, mining, and self-supplied residential. The Middle Tennessee-Elk subregion accounted for about 53 percent (5,185 Mgal/d) of the estimated total withdrawals by subbasin of 9,816 Mgal/d. About 92 percent of the water use in the Middle Tennessee-Elk subregion was for thermoelectric power, and more than 99 percent of the water was from surface water. Gross per capita use for all offstream uses was 2,185 gallons per day (gal/d) for the estimated 4.56 million Alabama residents in 2005. Public-supply per capita use was 199 gal/d for the estimated 4.04 million residents served by a public supplier; public-supplied residential per capita use was 81 gal/d. Self-supplied residential per capita use was 75 gal/d for the estimated 0.52 million self-supplied residential population. Average residential per capita use was 80 gal/d. Total water withdrawals decreased less than 1 percent from 9,990 Mgal/d in 2000 to 9,958 Mgal/d in 2005. Surface-water withdrawals decreased less than 5 percent from 9,950 Mgal/d in 2000 to 9,467 Mgal/d in 2005. In contrast, ground-water withdrawals increased about 12 percent from 440 Mgal/d in 2000 to 491 Mgal/d in 2005. By category, increases in irrigation (118 Mgal/d, about 274 percent), thermoelectric power (84 Mgal/d, about 1 percent), and aquaculture (65 Mgal/d, 620 percent) were offset by declines in self-supplied industrial (283 Mgal/d, about 34 percent), self-supplied residential (40 Mgal/d, about 50 percent); and public supply (32 Mgal/d, about 4 percent) from 2000 to 2005. Water use for livestock and mining was not estimated in 2000.