Effect of sampling frequency on detection of natural variability in phytoplankton: unattended high-frequency measurements on board ferries in the Baltic Sea

In the 1980s and 1990s prior to 1995, massive blooms of the diazotrophic cyanobacterium Nodularia spumigena occurred in the Baltic Sea Proper but never extended into the central and eastern Gulf of Finland. The absence of nitrogen-fixing cyanobacteria blooms in parts of the Baltic Sea with a high N:P ratio (e.g. Gulf of Finland) has been explained by their reduced competitive advantage in conditions of P limitation. Starting with the summer of 1995, massive blooms of N. spumigena occurred in the central and eastern Gulf of Finland, as detected by both satellite sensors and in situ monitoring. We propose that the eastward expansion of N. spumigena blooms was triggered by the 1993 saltwater inflow into the Baltic. With the arrival of the saline and oxygen-depleted waters in the Gulf of Finland in 1995, stratification in the bottom layers increased, oxygen concentrations decreased, and increased amounts of phosphate were released from the sediments. The subsequent decrease in the N:P ratio may have caused the reoccurring N. spumigena blooms.KEY WORDS: Cyanobacteria · Nodularia · Nutrients · Gulf of Finland · Baltic SeaResale or republication not permitted without written consent of the publisher

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“…Every week, 24 water samples were collected for phytoplankton species counts and fluorometric chlorophyll a analysis (Rantajärvi et al 1998).…”

Section: Methodsmentioning

confidence: 99%

Cyanobacteria blooms in the Gulf of Finland triggered by saltwater inflow into the Baltic Sea

Kahru

Leppänen²,

Rud³

et al. 2000

Mar. Ecol. Prog. Ser.

106

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“…A combination of three factors can justify this occurrence: (i) high natural variability of phytoplankton (Rantajärvi et al, 1998); (ii) phytoplankton dynamics are ruled by complex set of factors difficult to simulate in dynamic ecological models, such as species succession (Arhonditsis et al, 2007); and (iii) the model outputs represent an uniform value for a box, thus cannot account for the variability in that area. With regard to phosphate, the data did not indicate a particular pattern, and in general the model overestimated observed phosphate concentrations.…”

Section: Standard Simulationmentioning

confidence: 99%

Assessment of coastal management options by means of multilayered ecosystem models

Nobre

Ferreira

Nunes

et al. 2010

Estuarine, Coastal and Shelf Science

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This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of its main forcing functions such as catchment loading and aquaculture activities. This modelling approach was developed as a tool for the sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed together with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay still exceed the thresholds for poor quality according to the Chinese seawater quality standards.There are still other management options to be considered given that for any of the scenarios there is still a moderate high to high portion of nutrient loads from the catchment and fish cages that can be reduced. The model predicts that overall, shellfish production decreases using any of these development scenarios (less 10% to 28%). Main reason is that shellfish growth is being sustained by the substances to be reduced for improvement of water quality. To counteract this effect the model outcomes indicate that zoning of shellfish aquaculture should be implemented at the ecosystem level to optimize productivity ratios. The present case study exemplified the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and maybe particularly useful for the application of coastal management regulation, such as in implementing the European Marine Strategy Directive.3

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“…This can be difficult to attain adequately using a conventional in situ point-scale sampling approach, particularly for study domains of large size (Rantajarvi et al 1998;Kutser 2004). Strategic planning of sampling intervals based on some prior spatial realizations of the system is an important consideration for successful measurement and characterization of horizontal variability.…”

mentioning

confidence: 99%

Physical controls on the spatial evolution of a dinoflagellate bloom in a large lake

Antenucci

Hipsey

et al. 2011

Limnology & Oceanography

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A set of satellite images of chlorophyll a concentration for Lake Kinneret (Israel) from the period February to April 2007 captured the temporal evolution of horizontal patchiness that developed during the typical spring bloom of the dinoflagellate Peridinium gatunense. Narrow bands of high concentration located adjacent to the shoreline at the start of the bloom were followed by progressive propagation of this high-concentration region from the shoreline toward the center of the lake as the bloom proceeded. A three-dimensional (3-D) hydrodynamic numerical model and an analytical model for a flat-bottomed elliptical basin together explain the observed phenomenon. The spatial structure of Kelvin waves, which were demonstrated to most likely be present in February and April due to resonance, produced regions of high velocity gradient, contributing to horizontal dispersion close to the shoreline. This region of high dispersion was narrow and close to the shoreline at the start of the bloom when the Burger number was relatively small, but it widened over the course of the season as the Burger number increased due to increasing stratification. In addition, an increase in the dispersion rate with time in the lake interior was inferred from numerical simulation due to increasing wind speeds and a thinner surface layer. Physical processes, in this case, horizontal dispersion as a result of both Kelvin waves and wind, can play an important role in governing the dynamics and spatial evolution of dinoflagellate blooms in lakes.

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Effect of sampling frequency on detection of natural variability in phytoplankton: unattended high-frequency measurements on board ferries in the Baltic Sea

Cited by 80 publications

References 8 publications

Cyanobacteria blooms in the Gulf of Finland triggered by saltwater inflow into the Baltic Sea

Cyanobacteria blooms in the Gulf of Finland triggered by saltwater inflow into the Baltic Sea

Assessment of coastal management options by means of multilayered ecosystem models

Physical controls on the spatial evolution of a dinoflagellate bloom in a large lake

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