the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Nov 2024
A 45-year hydrological and planktonic time series in the South Bight of the North Sea
Abstract. This article presents a 45-year data series (from 1978 to 2023) acquired under the IGA (“Impact des Grands Aménagements” in French; Impacts of Major Developments) program, conducted by Ifremer for EDF (Électricité de France, the French multinational electricity utility company). The IGA program was established to monitor the ecological and environmental quality of the coastal area surrounding the Gravelines Nuclear Power Plant (NPP), located in the southern bight of the North Sea. The main objective of this program is to assess medium- and long-term environmental evolution by providing means to identify possible changes in the local marine habitats. Since 1978, the IGA program has measured key parameters, including temperature, salinity, nutrient concentrations, oxygen levels, chlorophyll-a concentrations, as well as the abundance of phytoplankton and zooplankton species. These measurements have been taken at different sampling stations around the NPP, including the “Canal d’amenée” sampling station, for which hydrological and biological characteristics are considered as representative of broader coastal area of the southern bight of the North Sea. This data paper provides an overview of the main statistical characteristics of the time series, including long-term trends and shifts analysis. Despite the importance and length of this dataset, one of the longest available for this region, its application in advancing knowledge of hydrological and biological processes has been surprisingly limited. The aim of this paper is to make this valuable dataset available to the scientific community, stakeholders, and society to help decipher the local and global influence of anthropogenic activities in a world increasingly affected by climate change. Since all the main statistics and patterns are still available thanks to our analysis, the user should be able to use this data and combine it with other sources (in situ, satellite, modelling), in order to dive into deeper analyses, and to investigate new key scientific challenges as well as more specific ones.
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RC1: 'Acceptance of paper', Anonymous Referee #1, 25 Nov 2024
dear Editor
it was a pleasure to read this paper, and to see this incredibly valuable dataset be published and accessible. I have almost no issues with the text as is, other than a small comment for page1 - just after line 25. the authors say that long term plankton time series are not available - but there are some very important ones for the North Sea - and summarised in Holland et al., Holland, Matthew M., et al. "Major declines in NE Atlantic plankton contrast with more stable populations in the rapidly warming North Sea." Science of the Total Environment 898 (2023): 165505 and also summarised in Holland, Matthew M., Angus Atkinson, Mike Best, Eileen Bresnan, Michelle Devlin, Eric Goberville, Pierre Hélaouët et al. "Predictors of long-term variability in NE Atlantic plankton communities." Science of the Total Environment 952 (2024): 17579. There are also descriptions of the plankton data in the recent OSPAR biodiversity report under Quality Status Reporting. But other than that small fact, - its a well written paper, and a dataset that will be invaluable for our long term understanding of WQ and plankton change.
Citation: https://doi.org/10.5194/essd-2024-479-RC1 -
RC2: 'Comment on essd-2024-479', Anonymous Referee #2, 06 Dec 2024
Comment on essd-2024-479 by Anonymous Referee
General Comments
The authors present a long-term dataset of hydrological and planktonic observations in the South Bight of the North Sea.
These data are particularly precious and relevant as their combination represents an incredible volume of open access monitoring data. Moreover, these observations offer significant opportunities for scientific advancement, being potentially beneficial for other ecological and management applications. Hence, this study certainly meets the ESSD criteria for data availability.
The presentation of the study site, monitoring strategy and methods is well written and very detailed even if more details could be provided (as detailed below).
Specific Scientific Comments
As regards data quality no reference is made to sensors’ maintenance and calibration and possible inter-calibration of instruments as regards temperature, salinity, turbidity and oxygen concentration. For example, no reference is made to collection of discrete samples to periodically calibrate the dissolved oxygen data recorded by the sensor, as initially done with the Winkler method. The in-situ samples are needed to fulfill quality assurance standards and correct any potential bias and drift in the sensors.
Technical Comments
Line 75: “This location…” instead of “This situation…”
Line 94: “The water was analysed…” instead of “The water is analysed …”
Figure 4 appears in the main text before Figure 3 (line 268 vs line 271). Reverse the order of the figures in the manuscript to be consistent.
Line 293: “peak value...” instead of “pic value….”.
Line 294: Please check month (March or April?) and related zooplankton mean monthly abundance.
Line 324: Any two arrows or grey arrow is reported in Table 3. Please delete “….a non-monotonic trend (2: two arrows indicating a shift in the time series), or no significant trend (grey arrow)…”
Line 400: “the utility of this time series for…” instead of “the utility of this time series fir…”
Citation: https://doi.org/10.5194/essd-2024-479-RC2 -
RC3: 'Comment on essd-2024-479', Anonymous Referee #3, 08 Dec 2024
Devreker et al. presented a highly valuable in situ dataset spanning 45 years from a coastal station. The article is well-written and clearly presented. Such initiatives and open datasets are crucial for advancing ecological studies, as they provide a broader understanding of phytoplankton dynamics over the long term. I have some questions and minor corrections, detailed below:
HAB events are expected to increase in the coming decades. It would be interesting to evaluate whether there is an observed increase in the frequency of occurrences of potentially toxic phytoplankton species in large concentrations across your 45 years of data.
Line 28: “scarce” instead of “scare”
Line 29: Reword as “and are responsible for approximately 50% of global primary production” instead of “contribute to 50% of the Earth’s chlorophyll biomass.”
Line 60: The acronym “HAB” is not defined upon its first use
Line 94: what is an “oceanographic bucket”? I suggest deleting “using an oceanographic bucket” and replace “The water is analyzed” by “water samples are analyzed”
Line 95: “at every sampling” instead of “at every instance”.
Section 3.2.1: Are corrections performed to account for possible biases between different sensors? Are the sensors calibrated regularly?
Section 3.3.1: Are micro-, nano-, and pico-plankton identified during sampling? If not, please specify which size classes are considered.
Line 154: The Shannon-Weaver Index is a diversity, not a richness, index. Replace “Species richness calculations” with “Phytoplankton species diversity calculations.”
Equation 1: explain parameters used in the equation. There is an error in the H’ formula, it should be:
-sum (pi ln(pi))
Section 3.3.2: How is zooplankton sampling performed? Is it based on time intervals? Is the volume of water passing through the net quantified?
Line 217: Avoid leaving any cells empty, as this can cause issues for users working with software like MATLAB. Instead, replace empty cells with “NaN” or use a numerical code for missing data, such as “-9999.”
Line 241: “searching for data that might be”…
Line 269: Is the trend in phytoplankton diversity consistent with the observed trends in chlorophyll concentration?
Citation: https://doi.org/10.5194/essd-2024-479-RC3
Data sets
IGA-HP Gravelines dataset – Hydrology and Plankton monitoring programme at the Gravelines coastal station, France (southern bight of the North Sea) Alain Lefebvre et al. https://doi.org/10.17882/102656
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