Measuring the health of marine ecosystems with IndiSeas

14 November 2018 | Story Nadia Krige. Photo Flowcomm, FLICKR Read time 10 min.

Since the industrialisation of commercial fishing started in the early 1930s, marine ecosystems around the world have been under severe pressure. While surveys and studies are nearly constantly monitoring the effects of fishing, most of them rely on information about catches gathered by fisheries themselves. For the past 13 years, the University of Cape Town has been part of a multi-institute collaboration to evaluate the health of marine ecosystems using a new set of indicators informed by independent, research-based data.

Known as IndiSeas (Indicators for the Seas), this working group consists of volunteers from all over the world who have agreed to bring their data to the table and take part in calculating indicators for determining the health of marine ecosystems.

There are already a multitude of indicators that can be used for this purpose. But to help characterise the states and trends of exploited marine ecosystems with respect to fishing activity – specifically – IndiSeas used particular criteria to select theirs, including whether the indicator reflected well-defined processes underlying fishing activity, was able to track change, and was measurable and had historical data.

What gave their work more impact was the fact that it offered a comparative framework within which to assess the health of every marine ecosystem in terms of its global counterparts.  

Dr Lynne Shannon, IndiSeas co-chair and chief researcher in the Biological Sciences Department and Marine Research (Ma-Re) Institute at UCT, recently opened The Ocean Science Days in the Cape colloquium with a presentation on IndiSeas and the completion of its first two phases.

The colloquium, held by the Ma-Re Institute and ICEMASA (International Centre for Education, Marine and Atmospheric Sciences over Africa), was an opportunity to showcase some of the work that has been done by ICEMASA, a scientific joint venture between South African and French institutions focusing on marine and atmospheric sciences. ICEMASA was initiated in 2009 by the Institut de Recherche pour le Développement (IRD) and comprises a French–South African network of more than 60 researchers and technicians across various marine- and ocean-related disciplines.  

Director of the Ma-Re Institute, Associate Professor Marcello Vichi, identified IndiSeas as one of the most comprehensive projects to come out of the many ICEMASA collaborations because it has transcended the boundaries of academic interest with real-world relevance.

A short history of IndiSeas

The first murmurings of IndiSeas started in 2004 and 2005 when Dr Philippe Cury from the IRD, one of the first ICEMASA scientists to work in South Africa, encouraged Dr Yunne Shin and Shannon to launch the project internationally. Shin and Shannon had begun collaborating in 2000 while completing their PhD studies under his guidance.

“He suggested developing an indicator dashboard for ocean health, like what’s in a car where – if there’s a problem – a little oil light goes on, that kind of thing,” Shannon explains.

They began their study with just seven marine ecosystems, and a year later, in 2006, they officially launched Phase I of the IndiSeas project, when they got 19 ecosystems onboard. Regional experts contributed their research-based data for each of these ecosystems, and from this, they identified a set of seven ecological indicators with which to assess ecosystem health. The indicators measured:

  • Fish length: scientists expect the size of fish to decrease under fishing pressure
  • Fish life span: a proxy for the turnover rate of fish species
  • The proportion of predatory fish: a measure of fish diversity
  • The proportion of sustainably fished stocks: a measure of the success (or not) of fisheries management
  • Total fish biomass: the amount of fish in an ecosystem is likely to decrease under fishing pressure
  • How high the fish being caught sit in the food web: this is likely to decrease in response to fishing, as fisheries tend to target species higher in the food web, and
  • Ecosystem stability: using a measure of change in biomass.

Once these indicators had been calculated, the information for all of the ecosystems was put into a comparative framework and interpreted by a cohort of volunteer researchers (ecosystem experts).

“Basically, the incentive here is that the whole is greater than all the little parts,” Shannon says. To be able to assess your ecosystem of interest in the context of what’s happening internationally, you have to share your data, she explains.

The comparative framework proved to be an excellent tool for understanding what could be going wrong in the ecosystems that were showing less positive results, and vice versa.

"The key finding [was] that almost 80% of the marine ecosystems that were being examined in that first phase were classified as overexploited and deteriorating."

Although there are many international analyses of the health of marine ecosystems, Shannon explains that most of these rely on catch data, which isn’t usually representative of an entire ecosystem.

“We’ve really tapped into the research survey data to capture what’s happening under the surface, as it were,” she says. “And the crux of it is that we involve regional experts to help us with the interpretation.”

Phase I of IndiSeas culminated in a special issue of the ICES Journal of Marine Science in 2010 showcasing the states and trends of ecological indicators over time in all of these ecosystems in a comparative context.

“The key finding [was] that almost 80% of the marine ecosystems that were being examined in that first phase were classified as overexploited and deteriorating,” says Shannon. “So, ecosystem health was getting progressively worse – and this was really worrying.”

Gaining ground and momentum

IndiSeas Phase II was launched in 2011 with an additional 16 marine ecosystems on board, resulting in a total of 35, and an additional six ecological indicators.

Task groups were also set up to investigate a further set of indicators relating to the environmental and human dimensions of marine ecosystems. The human-dimension indicators aim to measure the lasting benefits of fisheries to society through things like effectiveness of fisheries management, and the well-being and resilience of fishing communities.

“Interestingly, under the co-leadership of Dr Alida Bundy of Canada, we found a really strong correlation between ecosystem status and the efficiency of management and governance, and the well-being of communities,” says Shannon.

With Phase II and ICEMASA drawing to a close, the IndiSeas collaborators are setting their sights on Phase III, which they hope will be initiated under the European Union call for projects assessing the status of Atlantic marine ecosystems. This initiative will further expand the scope of IndiSeas, connecting the project with the ocean modelling undertaken by Ma-Re. It will hopefully also allow for a continuation of the fruitful ICEMASA experience.

Vichi, as the director of Ma-Re, trusts that South Africa will become the central driver of international collaboration in ocean sciences. Shannon and Vichi expect to get feedback on that later this year.

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