A new perspective on the importance of marine-derived nutrients to threatened stocks of Pacific salmon (Oncorhynchus spp.)

2005 ◽  
Vol 62 (5) ◽  
pp. 961-964 ◽  
Author(s):  
Mark D Scheuerell ◽  
Phillip S Levin ◽  
Richard W Zabel ◽  
John G Williams ◽  
Beth L Sanderson
Keyword(s):  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Freshwater Ecosystems ◽  
Juvenile Salmon ◽  
Freshwater Ecosystem ◽  
Phosphorus Transport ◽  
Riparian Ecosystems ◽  
Growth And Survival ◽  
Marine Derived Nutrients

Considerable research has highlighted the important role of anadromous salmon in importing marine-derived nutrients to freshwater and riparian ecosystems. These subsidies are thought to support diverse food webs and increase the growth and survival of juvenile salmon during their freshwater residency. Quite recently, however, salmon smolts have been identified as important exporters of nutrients from freshwater ecosystems. Using a mass-balance approach, we examined the phosphorus-transport dynamics by spring/summer Chinook salmon (Oncorhynchus tshawytscha) in the Snake River basin and estimated that net phosphorus transport into the basin over the past 40 years was <2% of historical levels. Furthermore, a nonlinear relationship existed between nutrient import by adults and subsequent export by smolts, such that smolts exported proportionally more phosphorus as spawner abundance decreased. In 12% of years, smolts exported more than adults imported, resulting in a net loss of phosphorus from the ecosystem. This loss of marine subsidies may have caused a state shift in the productivity of the freshwater ecosystem, resulting in strong density-dependent survival observed in juvenile salmon. These results suggest that conserving this threatened stock of salmon requires the need to explicitly address the important role of marine-derived nutrients and energy in sustaining salmon populations.

scholarly journals Role of Water User Associations on the Restoration of the Ecosystem in Tanzania

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 141 ◽  
Author(s):  
Happyness Ngonyani ◽  
Khaldoon Mourad
Keyword(s):  
Land Use ◽  
Land Use Planning ◽  
Water Resource Management ◽  
Freshwater Ecosystems ◽  
Mitigation Strategies ◽  
Freshwater Ecosystem ◽  
Sample Population ◽  
Water User Associations ◽  
Water User

The Mkoji sub-catchment is the most populated sub-catchment in the uppermost part of the Rufiji basin in Tanzania, with critical users downstream, and it is vulnerable to water shortages. Despite the efforts made by governmental and non-governmental organizations in forming and supporting water user associations, little is known about their role on water resource management in the country. This study aimed to investigate the role of water user associations on the restoration of decreased environmental flow and degraded aquatic ecosystems in Tanzania, taking the Mkoji sub-catchment as a case study. Six water user associations were assessed, focusing on their strategies and influence on restoration, land use, ecosystem degradation, and their role in climate change mitigation strategies. Data were collected from various sources using interviews, focus group discussions and questionnaires. The Spearman correlation test was used to seek the relationship between the flow and the aquatic ecosystem. Statistical results showed that there was no correlation between the flow and rainfall, and there was a correlation between freshwater ecosystems and the flow. The results showed that 89% of the sample population accepted the decrease of the flow while 75% accepted the decrease of the fish catch in the freshwater ecosystem of the study. Based on the results obtained, the paper concluded that water user associations are doing a great job in management and restoration while politics, funding, and water permits were the main obstacles. Therefore, the government should play a role in restoring the ecosystem, bridging the gaps between farmers and animal keepers, land use planning, and developing aquaculture.

Biofilm nutrient limitation, metabolism, and standing crop responses to experimental application of salmon carcass analog in Idaho streams

2014 ◽  
Vol 71 (12) ◽  
pp. 1796-1804 ◽  
Author(s):  
Jonathan D. Ebel ◽  
Amy M. Marcarelli ◽  
Andre E. Kohler
Keyword(s):  
Nutrient Limitation ◽  
Pacific Northwest ◽  
Standing Crop ◽  
Pacific Salmon ◽  
Trophic Levels ◽  
Juvenile Salmon ◽  
Stream Metabolism ◽  
Growth And Survival ◽  
Nutrient Additions ◽  
Salmon Carcass

Dramatic declines of Pacific salmon (Oncorhynchus spp.) populations have decreased delivery of marine-derived material to Pacific Northwest streams where juvenile salmon reside. Managers use artificial nutrient additions to increase juvenile salmon growth and survival and typically assume nutrient-driven increases in biofilm production are an important pathway by which nutrients become available to higher trophic levels. To evaluate how biofilms respond to additions of salmon carcass analog, a pasteurized, processed form of nutrient mitigation materials, we quantified biofilm nutrient limitation, benthic and whole-stream metabolism, and biofilm standing crops before and following experimental additions in tributaries of the Salmon River, Idaho, USA. Biofilm nutrient limitation did not change and standing crop did not increase in response to analog additions at two different levels (low, 30 g·m−2; or high, 150 g·m−2) within 1 month of addition. In contrast, whole-stream and benthic primary productivity and respiration increased in a high-analog treated segment, but did not increase in a low-analog treated segment. Together, our results suggest that metabolism may be a more appropriate tool for assessing the ecosystem effects of nutrient additions than biofilm standing crop or nutrient limitation, which are constrained by a variety of abiotic and biotic factors like hydrology and grazing.

Challenges for Diadromous Fishes in a Dynamic Global Environment

2009 ◽  
Author(s):  
Jon M. Honea
Keyword(s):  
Life Histories ◽  
Pacific Salmon ◽  
North Pacific Ocean ◽  
Terrestrial Ecosystems ◽  
Freshwater Ecosystems ◽  
Riparian Ecosystems ◽  
Nutrient Sources ◽  
Temporal And Spatial Variability ◽  
Ecological Importance ◽  
Animal Communities

<em>Abstract</em>.-We review the current understanding of major pathways, mechanisms, and consequences of salmon-borne marine-derived nutrients (MDN) in estuarine, freshwater, and riparian ecosystems. Semelparous Pacific salmon <em>Oncorhynchus </em>spp. acquire most of their body mass while at sea before returning to spawn and die in natal streams. The annual spawning migrations transport substantial quantities of MDN from the fertile North Pacific Ocean to relatively nutrient-poor coastal freshwater and terrestrial ecosystems. People have been long aware of the importance of salmon-borne MDN for the productivity of freshwater ecosystems in western North America, and the rapidly increasing knowledge base supports this notion. Nevertheless, many details associated with nutrient pathways, cycling processes, and the ecosystem-scale consequences of MDN transfer remain to be elucidated. The collective data suggest that freshwater portions of the salmon production system, as well as the dynamics of local terrestrial plant and animal communities, are intimately linked to MDN in complex ways. At the same time, the ecological importance of MDN, relative to other major nutrient sources, is temporally and spatially dependent and influenced by the life histories and abundances of salmonid stocks. Although interactions among climate cycles, salmon, riparian vegetation, predators, and MDN flowpaths and feedbacks are complex, they also form a wonderfully integrated ecological system with a high degree of resilience and productivity. Understanding this complex system and its inherent temporal and spatial variability requires a holistic scientific perspective that values important interactions among the salmonid life cycle, the physical setting, and the numerous linkages to other ecosystem components.

Costs of living for juvenile Chinook salmon (Oncorhynchus tshawytscha) in an increasingly warming and invaded world

2012 ◽  
Vol 69 (10) ◽  
pp. 1621-1630 ◽  
Author(s):  
Lauren M. Kuehne ◽  
Julian D. Olden ◽  
Jeffrey J. Duda
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Multiple Stressors ◽  
Freshwater Ecosystems ◽  
Smallmouth Bass ◽  
Interactive Effects ◽  
Physiological Indicators ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Rapid environmental change in freshwater ecosystems has created a need to understand the interactive effects of multiple stressors, with temperature and invasive predators identified as key threats to imperiled fish species. We tested the separate and interactive effects of water temperature and predation by non-native smallmouth bass ( Micropterus dolomieu ) on the lethal (mortality) and sublethal (behavior, physiology, and growth) effects for juvenile Chinook salmon ( Oncorhynchus tshawytscha ) in seminatural stream channel experiments. Over 48 h trials, there was no difference in direct predation with warmer temperatures, but significant interactive effects on sublethal responses of juvenile salmon. Warmer temperatures resulted in significantly stronger and more variable antipredator responses (surface shoaling and swimming activity), while physiological indicators (plasma glucose, plasma cortisol) suggested suppression of physiological mechanisms in response to the combined stressors. These patterns corresponded with additive negative growth in predation, temperature, and combined treatments. Our results suggest that chronic increases in temperature may not increase direct predation over short periods, but can result in significant sublethal costs with negative implications for long-term development, disease resistance, and subsequent size-selective mortality of Pacific salmon.

Nutrient export from freshwater ecosystems by anadromous sockeye salmon (Oncorhynchus nerka)

2004 ◽  
Vol 61 (9) ◽  
pp. 1582-1589 ◽  
Author(s):  
Jonathan W Moore ◽  
Daniel E Schindler
Keyword(s):  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Large Body ◽  
Freshwater Ecosystems ◽  
Nutrient Export ◽  
Nitrogen And Phosphorus ◽  
Bristol Bay ◽  
Fresh Waters

Anadromous and semelparous salmon transport nutrients from the ocean to fresh waters when they return to spawn and die, a process inspiring a large body of research on the role of salmon-derived nutrients in coastal ecosystems. However, salmon also transport nutrients out of fresh waters when they migrate to the ocean as smolts. Using a total of 76 years of age-specific smolt-migration and adult-escapement data, we calculated the amounts of nitrogen and phosphorus that sockeye salmon (Oncorhynchus nerka) imported and exported from four major systems in Bristol Bay, Alaska. Smolts removed an average of 16% of the phosphorus and 12% of the nitrogen that their parents transported into fresh waters. The percentage of parental nutrients that smolts exported varied through time and among sites, ranging from 1% to 65% of the phosphorus and from less than 1% to 47% of the nitrogen. In systems where smolts were larger, they exported a higher percentage of nutrients. Depending on the strength of density-dependence, smolts could theoretically export more nutrients than their parents import to freshwater ecosystems at low spawning densities. Ignoring nutrient export by outgoing smolts will consistently lead to overestimation of nutrient import by Pacific salmon to freshwater ecosystems.

scholarly journals The fate of marine-derived nutrients: tracing δ13C and δ15N through oligotrophic freshwater and linked riparian ecosystems following salmon carcass analog additions

2017 ◽  
Vol 74 (1) ◽  
pp. 41-55 ◽  
Author(s):  
David P. Richardson ◽  
Andre E. Kohler ◽  
Million Hailemichael ◽  
Bruce P. Finney
Keyword(s):  
River Basin ◽  
Riparian Vegetation ◽  
Pacific Salmon ◽  
Trophic Levels ◽  
Limiting Factor ◽  
Riparian Ecosystems ◽  
Δ13c And Δ15n ◽  
Salmon River ◽  
Salmon Carcass ◽  
Marine Derived Nutrients

The oligotrophic condition of salmon-bearing catchments in the Columbia River Basin is a potential limiting factor for the recovery of Pacific salmon (Oncorhynchus spp.). To address this issue, nutrient supplementation programs attempt to mitigate for reduced marine-derived nutrients (MDN). We examined the assimilation of MDN in the biota of tributaries of the Salmon River Basin, Idaho, USA, following the addition of salmon carcass analogs (SCA). We measured carbon (C) and nitrogen (N) stable isotopes from biofilm, macroinvertebrate, salmonid fish, and riparian vegetation samples and found significant 15N enrichment and substantial assimilation of SCA material in all aquatic trophic levels and in riparian vegetation. Our results suggest that SCA are incorporated primarily through indirect pathways and provide a source of MDN to multiple trophic levels in freshwater and linked riparian ecosystems.

scholarly journals Can late stage marine mortality explain observed shifts in age structure of Chinook salmon?

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247370
Author(s):  
Kaitlyn A. Manishin ◽  
Curry J. Cunningham ◽  
Peter A. H. Westley ◽  
Andrew C. Seitz
Keyword(s):  
Age Structure ◽  
Chinook Salmon ◽  
Late Stage ◽  
Marine Mammals ◽  
Potential Role ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Yukon River ◽  
Abrupt Shifts

Chinook salmon (Oncorhynchus tshawytscha) populations have experienced widespread declines in abundance and abrupt shifts toward younger and smaller adults returning to spawn in rivers. The causal agents underpinning these shifts are largely unknown. Here we investigate the potential role of late-stage marine mortality, defined as occurring after the first winter at sea, in driving this species’ changing age structure. Simulations using a stage-based life cycle model that included additional mortality during after the first winter at sea better reflected observed changes in the age structure of a well-studied and representative population of Chinook salmon from the Yukon River drainage, compared with a model estimating environmentally-driven variation in age-specific survival alone. Although the specific agents of late-stage mortality are not known, our finding is consistent with work reporting predation by salmon sharks (Lamna ditropis) and marine mammals including killer whales (Orcinus orca). Taken as a whole, this work suggests that Pacific salmon mortality after the first winter at sea is likely to be higher than previously thought and highlights the need to investigate selective sources of mortality, such as predation, as major contributors to rapidly changing age structure of spawning adult Chinook salmon.

CD100/Plexin-B1 interactions sustain proliferation and survival of normal and leukemic CD5+ B lymphocytes

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1962-1969 ◽  
Author(s):  
Luisa Granziero ◽  
Paola Circosta ◽  
Cristina Scielzo ◽  
Elisa Frisaldi ◽  
Stefania Stella ◽  
...  
Keyword(s):  
B Cells ◽  
B Lymphocytes ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Follicular Dendritic Cells ◽  
Growth And Survival ◽  
High Affinity Receptor ◽  
Activated T Lymphocytes ◽  
Affinity Receptor

Growth and survival of chronic B-cell tumors are favored by the malignant cell's capacity to respond to selected microenvironmental stimuli provided by nontumoral bystander cells. To investigate which mechanisms operate in these crosstalks and whether they are malignancy-related or reproduce the mechanisms used by normal B cells we have studied the expression and functional role of semaphorin CD100 (now called Sema4D) in chronic lymphocytic leukemia (CLL) cells and normal CD5+ B cells. We demonstrate here that (1) leukemic and normal CD5+ B lymphocytes uniformly express CD100; (2) the CD100 high-affinity receptor Plexin-B1 is expressed by bone marrow stromal cells, follicular dendritic cells, and activated T lymphocytes, and is thus available to CD100+ lymphocytes in different specific microenvironments; and (3) upon interaction between CD100 and Plexin-B1 both CLL and normal CD5+ B cells increase their proliferative activity and extend their life span. These findings establish that Plexin-B1 is an easily accessible receptor for CD100 within the immune system. The encounter of CD100+ leukemic cells with Plexin-B1 may promote the proliferation and survival of malignant cells. The crosstalk operated by the CD100/Plexin-B1 interaction is not malignancy related but reproduces a mechanism used by normal CD5+ B cells.

The effect of porcine somatotropin on growth, and survival in seawater of Atlantic salmon (Salmo salar) parr

1976 ◽  
Vol 54 (4) ◽  
pp. 531-535 ◽  
Author(s):  
M. P. Komourdjian ◽  
R. L. Saunders ◽  
J. C. Fenwick
Keyword(s):  
Growth Hormone ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Hormone Treatment ◽  
Hormone Treatment ◽  
Control Fish ◽  
Growth And Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Porcine Somatotropin

The effects of porcine growth hormone on growth and salinity tolerance were studied in Atlantic salmon (Salmo salar) parr. Fish were held in freshwater at 11.5 °C during June and July under a photoperiod with light to dark periods opposite to the prevailing natural conditions. Fish treated with 1.0 μg/g body weight of growth hormone preparation on alternate days were significantly longer (P <.05), after 4 weeks, than placebo-injected controls. All hormone-injected fish survived transfer to seawater, 30‰ salinity. But under the same conditions, placebo-injected control fish showed a high mortality rate. Growth-hormone treatment caused a darkening of fin margins and a yellowing of the operculae and fin surfaces. The silvering which normally accompanies smoltification was not observed. The role of growth hormone in eliciting these actions and its possible role in the parr–smolt transformation are discussed.

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