Nutrient Subsidies from Iteroparous Fish Migrations Can Enhance Stream Productivity

Abstract Fisheries independent surveys support science and fisheries assessments but are costly. Evaluating the efficacy of a survey before initiating it could save costs. We used the NORWECOM.E2E model to simulate Northeast Atlantic mackerel and Norwegian spring spawning herring distributions in the Norwegian Sea, and we ran vessel transects in silico to simulate acoustic-trawl surveys. The simulated data were processed using standard survey estimation software and compared to the stock abundances in the ecosystem model. Three existing real surveys were manipulated to demonstrate how the simulation framework can be used to investigate effects of changes in survey timing, direction, and coverage on survey estimates. The method picked up general sources of biases and variance, i.e. that surveys conducted during fish migrations are more vulnerable in terms of bias to timing and changes in survey direction than during more stationary situations and that increased effort reduced the sampling variance.

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Intense storms and the delivery of materials that relieve nutrient limitations in mangroves of an arid zone estuary

Functional Plant Biology ◽

10.1071/fp11027 ◽

2011 ◽

Vol 38 (6) ◽

pp. 514 ◽

Cited By ~ 35

Author(s):

Catherine E. Lovelock ◽

Ilka C. Feller ◽

Maria Fernanda Adame ◽

Ruth Reef ◽

Helen M. Penrose ◽

...

Keyword(s):

Stable Isotopes ◽

Tropical Cyclones ◽

Arid Zone ◽

Leaf Tissue ◽

Nutrient Limitations ◽

N Supply ◽

Use Efficiency ◽

Nutrient Subsidies ◽

Negative Impacts ◽

Arid Coast

Tropical cyclones can be devastating to ecosystems, but they can also result in pulses of fresh water and sediments delivered in floodwaters to the coastal zone. In the arid zone the pulses provided by cyclones may be particularly important for the maintenance of productivity. We examined the impacts of Cyclone Pancho on growth and nutrient limitations to growth in mangroves on the arid coast of Western Australia. We found that growth of trees was enhanced after the cyclone, more than doubling their rates of stem extension. Fertilisation studies showed that before the cyclone tree growth was nutrient limited. After the cyclone fertilisation treatments had no significant effect on growth, indicating nutrients had been delivered during the storm. Additionally, before the cyclone the efficiency of resorption of phosphorus and nitrogen from senescent leaves was higher than after the cyclone, suggesting that nutrient availability was enhanced. Analysis of stable isotopes of leaf tissue indicated that the cyclone was associated with small changes in water use efficiency, consistent with decreased soil salinity associated with the cyclone. There was, however, significant reductions in δ15N indicating enhanced N supply potentially from a new source. We conclude that in the arid zone, floodwater associated with cyclones is important for the delivery of nutrient subsidies that stimulate mangrove growth and that predicted future reductions in the frequency of cyclones will have negative impacts on the productivity of these ecosystems.

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Guano-Derived Nutrient Subsidies Drive Food Web Structure in Coastal Ponds

PLoS ONE ◽

10.1371/journal.pone.0151018 ◽

2016 ◽

Vol 11 (3) ◽

pp. e0151018 ◽

Cited By ~ 18

Author(s):

Salvatrice Vizzini ◽

Geraldina Signa ◽

Antonio Mazzola

Keyword(s):

Food Web ◽

Food Web Structure ◽

Web Structure ◽

Nutrient Subsidies

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Non-physical barriers to deter fish movements

Environmental Reviews ◽

10.1139/a2012-001 ◽

2012 ◽

Vol 20 (1) ◽

pp. 71-82 ◽

Cited By ~ 113

Author(s):

Matthew R. Noatch ◽

Cory D. Suski

Keyword(s):

Management Approach ◽

Fish Movements ◽

Fish Stocks ◽

Physical Barriers ◽

Boat Traffic ◽

Single Method ◽

Fish Migrations ◽

Anthropogenic Modifications ◽

Best Fit ◽

Case Basis

Anthropogenic modifications to aquatic ecosystems have altered connecting pathways within, and in some cases, between watersheds. Human structures, such as hydroelectric facilities, often impede fish migrations and may inflict heavy mortality on fish that become impinged or entrained. Conversely, an increase in connectivity between two waterways (e.g., through the construction of shipping canals, increased boat traffic) often results in an elevated risk of invasive species introductions. Non-physical barriers, which obstruct fish from an undesirable location without influencing the waterway, are one management approach to protecting valuable fish stocks and deterring biological invasions. Because many methods of behavioral deterrence have been employed against fish, there is a need to summarize and compare existing and developing technologies. This review details the use and application of electrical, visual, acoustic, chemical, and hydrological deterrence techniques that may be used to prevent fish movements. Site requirements are discussed, and a critical assessment of benefits and limitations to each technique are given. Because no single method of fish deterrence is “one size fits all”, this review to non-physical fish barrier technology will benefit managers and researchers attempting to develop a best-fit strategy on a case-by-case basis.

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