ISOMED – A Stable ISOtope database of MEDiterranean marine food web components – Nature

Introduction: Aligning Marine Ecosystem Research with Sustainable Development Goals

The study of marine food webs, which delineate energy flows and predator-prey dynamics, is fundamental to monitoring human impacts on marine environments. This research directly supports international environmental policies and contributes to achieving the United Nations’ Sustainable Development Goals (SDGs), particularly SDG 14 (Life Below Water). An ecosystem-based approach to management is critical for addressing the cumulative pressures of human activities and preserving marine ecosystem services that are essential for human well-being and sustainable economic development, such as Blue Growth (supporting SDG 8: Decent Work and Economic Growth).

Policies like the European Marine Strategy Framework Directive (MSFD) mandate the development of food-web indicators to assess environmental status. A key indicator, the Marine Trophic Index (MTI), is utilized as a proxy for SDG Target 14.2, which aims to sustainably manage and protect marine and coastal ecosystems. However, the effective implementation of these policies is hindered by the scarcity and inconsistent collection of crucial ecological data. This report details the development of ISOMED, a database designed to address this data gap and support the advancement of marine sustainability objectives.

The ISOMED Database: A Tool for Advancing SDG 14

Rationale and Objectives

The primary objective of the ISOMED project is to create a centralized, georeferenced database of carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope values for marine organisms in the Mediterranean Sea. Stable Isotope Analysis (SIA) is a powerful method for assessing the trophic position and energy sources of a wide range of taxa, providing insights that are often impractical to obtain through traditional methods. By consolidating this sparse data, ISOMED provides a unique tool for investigating trophic interactions and energy flow, thereby strengthening the scientific basis for policies aimed at achieving Good Environmental Status and fulfilling the targets of SDG 14.

Scope and Significance for the Mediterranean Region

The Mediterranean Sea is a global biodiversity hotspot, hosting over 17,000 marine species. However, it is also one of the world’s most threatened marine ecosystems, facing cumulative stressors from climate change (SDG 13: Climate Action), overfishing, and pollution. The ISOMED database is a valuable resource for researchers and policymakers in the region, enabling a more comprehensive understanding of marine ecosystem functioning. It supports the consistent implementation of the MSFD and the broader Ecosystem Approach by:

• Facilitating the assignment of species to trophic guilds.
• Enabling accurate estimates of species’ trophic positions.
• Informing the construction of food web models to assess ecosystem health and resilience.
• Providing a baseline for monitoring changes in food webs due to human-related disturbances.

Methodological Framework for Data Compilation

Data Sourcing and Selection Criteria

The ISOMED database was compiled from multiple sources, ensuring a comprehensive collection of available data. The primary sources included:

• Scientific peer-reviewed papers identified through a systematic literature search on Web of Science.
• Unpublished raw δ¹³C and δ¹⁵N data from the authors of this report.

A total of 331 papers were initially collected, from which a final selection was made based on the following criteria:

1. The study reported original data for δ¹³C or δ¹⁵N.
2. The research pertained to Mediterranean marine or brackish water food webs.
3. The methodology for sampling and isotopic analysis was described in sufficient detail to allow for a quality assessment.

Data Extraction and Standardization

Relevant information was extracted from the selected sources and consolidated into a single standardized spreadsheet. Each record in the database represents georeferenced δ¹³C and/or δ¹⁵N data for a single specimen, a group of specimens, or a sample of basal organic matter. The dataset was structured with 35 columns, including 26 dedicated to metadata and nine to isotopic characterization, to ensure consistency and usability.

Database Structure and Content

Metadata Categories

To maximize the utility of the data for ecological and policy applications, each record is enriched with detailed metadata, categorized as follows:

• Sample Identification and Biology: Includes original sample name, standardized functional category, full taxonomic classification (Phylum, Class, Order, Family, Genus, Species), and, where available, biological data such as sex, maturity, size, and weight.
• Sample Preparation: Details on the analyzed tissue, whether samples were pooled, and pre-treatment methods like delipidisation or acidification.
• Geospatial and Temporal Information: Geographical coordinates (latitude, longitude), IHO Sea Area, MSFD subregion, FAO subarea, sampling depth, year, and season of collection.
• Contextual Information: Notes on the presence of anthropogenic pressures (e.g., fish farms, pollution) or specific natural conditions at the sampling site.
• Isotopic Characterization: δ¹³C and δ¹⁵N values, associated errors and error types, and the C/N ratio where available.

Spatial and Taxonomic Coverage

The final dataset comprises 4,959 georeferenced records collected between 1983 and 2018, covering the entire Mediterranean Sea. The spatial distribution is concentrated in the Western Mediterranean (3,674 records), followed by the Adriatic Sea (619), the Aegean-Levantine Sea (431), and the Ionian and Central Mediterranean Sea (235). The database encompasses the full marine food web, with 29% of records from basal sources (e.g., organic matter, phytoplankton, macrophytes) and 71% from higher-order consumers, including invertebrates, fish, marine mammals, and birds.

Validation, Availability, and Future Directions

Quality Assurance and Technical Validation

The database underwent rigorous quality control to ensure data accuracy and consistency. This process included:

• Elimination of duplicate entries, spelling errors, and typos.
• Visual inspection and verification of isotopic data to identify and correct outliers or transcription errors.
• A peer-review process conducted by the SEANOE repository.

Data Accessibility and Contribution to Open Science

In line with the principles of open science and data sharing, which are crucial for achieving SDG 17 (Partnerships for the Goals), the ISOMED database (version V1.0) is freely accessible for download from the SEANOE repository. The data adheres to the FAIR principles (Findability, Accessibility, Interoperability, and Reusability), ensuring its value for the global research community.

Future Development and Contribution to Long-Term Monitoring

The ISOMED database is a dynamic resource that will be updated periodically with new data from recent literature and ongoing research projects. Future additions will expand its taxonomic and geographic coverage. By providing a robust, spatially explicit dataset, ISOMED will continue to support the long-term monitoring of marine ecosystems, facilitating a more comprehensive understanding of their functioning and aiding in the effective implementation of policies designed to protect marine biodiversity and achieve sustainable use of ocean resources as outlined in SDG 14.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 14: Life Below Water

  This is the primary SDG addressed. The article is entirely focused on the marine environment, specifically the Mediterranean Sea. It discusses the importance of understanding marine food webs to monitor “human impacts” and support “marine environmental protection.” The text highlights major threats to marine ecosystems, such as “climate change,” “overfishing,” and “land-derived pollution,” all of which are central concerns of SDG 14. The development of the ISOMED database is presented as a tool to “support the implementation of the ecosystem approach to protect sensitive ecosystems,” directly contributing to the conservation and sustainable use of marine resources.

• SDG 17: Partnerships for the Goals

  This SDG is relevant through the creation and dissemination of the ISOMED database. The article describes a collaborative scientific effort to gather, standardize, and share crucial environmental data. It states that the database “is freely accessible for download from SEANOE… and it adheres to the FAIR principles of Findability, Accessibility, Interoperability, and Reusability of data.” This act of creating an open-access, collaborative scientific resource to support research and policymaking (like the MSFD) embodies the principles of partnership and knowledge-sharing for sustainable development.

2. What specific targets under those SDGs can be identified based on the article’s content?

1. Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution.

   The article identifies “land-derived pollution” as one of the “major drivers” of threats to the Mediterranean Sea. The ISOMED database, by providing baseline data on food webs, can help assess the impact of such pollution on marine ecosystems, which is a crucial step for prevention and reduction efforts.

2. Target 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans.

   This target is explicitly mentioned in the article. It states that the Marine Trophic Index is proposed as a “proxy indicator’ for Target 14.2 of Sustainable Development Goal 14.” Furthermore, the entire purpose of the ISOMED database is to support the “ecosystem approach” and policies like the MSFD, which aim to achieve a “good environmental status of marine waters.”

3. Target 14.4: By 2020, effectively regulate harvesting and end overfishing, illegal, unreported and unregulated fishing and destructive fishing practices and implement science-based management plans, in order to restore fish stocks in the shortest time feasible, at least to levels that can produce maximum sustainable yield as determined by their biological characteristics.

   The article names “overfishing” as a key stressor in the Mediterranean. The data in ISOMED, particularly for calculating trophic levels and understanding food web dynamics, directly supports “fisheries management” and the assessment of fishing impacts, which are essential for regulating harvesting effectively.

4. Target 17.16: Enhance the global partnership for sustainable development, complemented by multi-stakeholder partnerships that mobilize and share knowledge, expertise, technology and financial resources, to support the achievement of the sustainable development goals in all countries, in particular developing countries.

   The article describes the creation of the ISOMED database as a collaborative effort involving multiple institutions (“Italian Institute for Environmental Protection and Research,” “Università Politecnica delle Marche,” “University of Palermo,” etc.) to compile and share scientific knowledge. Making the database “freely accessible” is a direct action that supports this target by sharing knowledge and data to achieve other sustainable development goals.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Marine Trophic Index (MTI)

  This indicator is explicitly mentioned. The article states that approaches “based on the marine trophic index (MTI) consider changes in the mean trophic level of the catches and are proposed as ‘proxy indicator’ for Target 14.2 of Sustainable Development Goal 14.” The MTI is used to measure the health and integrity of marine ecosystems, particularly in relation to fishing pressure, thus tracking progress towards sustainable management (Targets 14.2 and 14.4).

• Trophic Level of Species

  This is an implied indicator. The article emphasizes that a key use of stable isotope data is to define a “species’ trophic position or level.” The ISOMED database is designed to provide the necessary data for “accurate trophic position estimates.” Changes in the trophic levels of key species or the overall trophic structure of an ecosystem can indicate pressures from fishing or pollution, serving as a measure of ecosystem health (relevant to Target 14.2).

• Diversity and Abundance of Trophic Guilds

  This is an implied indicator. The article notes that under the MSFD, the assessment of marine food webs requires evaluating “primary criteria related to diversity and abundance of trophic guilds (namely D4C1 and D4C2).” The ISOMED database facilitates this by helping to “assign species to trophic guilds.” Therefore, measuring the diversity and abundance of these guilds serves as an indicator of the status of the marine food web and overall ecosystem health (relevant to Target 14.2).

4. Summary Table of SDGs, Targets, and Indicators

Source: nature.com