Ecology

Ian Bateman and Andrew Balmford argue that land ‘sparing’ for conservation purposes is the best way to achieve conservation and food-security outcomes, by intensifying agricultural production on designated lands (Nature 618, 671–674; 2023). But to meet global biodiversity-conservation goals, land sparing needs to be combined with land sharing in a strategic and socially just way.
Competing Interests
The authors declare no competing interests. More

Bosson, J. B. et al. Nature 620, 562–569 (2023).Article 

Google Scholar 
Huss, M. & Hock, R. Front. Earth Sci. 3, 54 (2015).Article 

Google Scholar 
IPCC. Climate Change 2021: The Physical Science Basis (Cambridge Univ. Press, 2021).
Google Scholar 
Immerzeel, W. W. et al. Nature 577, 364–369 (2020).Article 
PubMed 

Google Scholar 
Stibal, M., Sabacká, M. & Zárský, J. Nature Geosci. 5, 771–774 (2012).Article 

Google Scholar 
Cauvy-Fraunié, S. & Dangles, O. Nature Ecol. Evol. 3, 1675–1685 (2019).Article 
PubMed 

Google Scholar 
Stibal, M. et al. Nature Ecol. Evol. 4, 686–687 (2020).Article 
PubMed 

Google Scholar 
Sytsma, M. L. T., Lewis, T., Bakker, J. D. & Prugh, L. R. J. Anim. Ecol. 92, 723–737 (2023).Article 
PubMed 

Google Scholar 
Alsos, I. G. et al. Sci. Adv. 8, eabo7434 (2022).Article 
PubMed 

Google Scholar 
García Criado, M. et al. Preprint at EcoEvoRxiv https://doi.org/10.32942/X2MS4N (2023).Brožová, V., Bolstad, J. S., Seregin, A. P. & Eidesen, P. B. Ecol. Evol. 13, e9892 (2023).Article 
PubMed 

Google Scholar 
Lee, J. R. et al. Glob. Change Biol. 28, 5865–5880 (2022).Article 

Google Scholar 
La Farge, C., Williams, K. H. & England, J. H. Proc. Natl Acad. Sci. USA 110, 9839–9844 (2013).Article 
PubMed 

Google Scholar 
Dullinger, S. et al. Nature Clim. Change 2, 619–622 (2012).Article 

Google Scholar 
Stewart, J. R., Lister, A. M., Barnes, I. & Dalén, L. Proc. R. Soc. B. 277, 661–671 (2010).Article 
PubMed 

Google Scholar 
McKay, D. I. A. et al. Science 377, eabn7950 (2022).Article 
PubMed 

Google Scholar 
Convention on Biological Diversity. COP15: Nations Adopt Four Goals, 23 Targets for 2030 in Landmark UN Biodiversity Agreement (2022).Cauvy-Fraunié, S. & Dangles, O. Nature Ecol. Evol. 4, 688–689 (2020).Article 
PubMed 

Google Scholar 
Black, T. & Kurtz, D. J. Glaciol. 69, 251–265 (2023).Article 

Google Scholar  More

Ian Bateman and Andrew Balmford contend that sharing land with agriculture for conservation purposes promotes only common bird and insect species, whereas judiciously sparing some lands from agriculture would be more effective for rarer species (Nature 618, 671–674; 2023). But any agricultural conservation scheme must also protect common species that are crucial for food production.
Competing Interests
The authors declare no competing interests. More

I study the environmental effects of oyster, clam and mussel farming. In this photo from April, I’m standing in the Sacca di Goro, a shallow lagoon in Italy, south of Venice. I make the 120-kilometre round trip here from the University of Ferrara every week during sampling months — April to the end of July and November to December — to study the growing oysters.Oyster farming has a smaller ecological footprint than fish farming does because oysters do not require feeding, which can cause eutrophication — an overgrowth of nutrients that chokes off marine animal life. They also do not require any drugs, disinfectants, pesticides or any form of growth additives.The oysters in these baskets — called lanterns — are between one and four centimetres in diameter. The oyster farmers in the lagoon then move the molluscs to the open sea, where they grow to roughly 10 centimetres, or commercial size. Fishers sometimes take the lanterns out of the water to mimic tides, which are not prominent in the Mediterranean Sea. Being out of water is like going to the gym for the oyster — it builds muscle meat and texture.I don’t like to eat oysters. This can be tricky because the fishers usually offer me some. But I’m excited about the potential uses for the discarded valves, or shells. For example, they can be used to build artificial reefs, be ground up to make body scrubs or be applied instead of lime to raise the pH level of agricultural soil.To calculate the environmental impact of oyster farming, I survey the fishers and map their use of fossil fuels, plastic and other resources that might harm the environment. Then I measure how much carbon the oysters capture as they grow. I focus on the valves, which are made almost entirely of calcium carbonate.I hope to prove that oyster farming absorbs more carbon than it emits. More

Pascual, U. et al. Nature https://doi.org/10.1038/s41586-023-06406-9 (2023).Article 

Google Scholar 
IPBES. Methodological Assessment Report on the Diverse Values and Valuation of Nature of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. (Balvanera, P. et al. eds) https://doi.org/10.5281/zenodo.6522522 (IPBES Secretariat, 2022).
Google Scholar 
Kolinjivadi, V., van Hecken, G., Rodríguez de Francisco, J. C., Pelenc, J. & Kosoy, N. Curr. Opin. Environ. Sustain. 26–27, 1–6 (2017).Article 

Google Scholar 
Pascual, U. et al. BioScience 64, 1027–1036 (2014).Article 

Google Scholar 
Costanza, R. et al. Ecosystem Serv. 28, 1–16 (2017).Article 

Google Scholar 
Sikor, T. (ed.) The Justices and Injustices of Ecosystem Services (Routledge, 2013).
Google Scholar 
Dowie, M. Conservation Refugees (The MIT Press, 2009).
Google Scholar 
Girard, F., Hall, I. & Frison, C. (eds) Biocultural Rights (Routledge, 2022).
Google Scholar 
Kosoy, N. & Corbera, E. Ecol. Econ. 69, 1228–1236 (2010).Article 

Google Scholar  More

Dudgeon, D. et al. Biol. Rev. 81, 163–182 (2006).Article 
PubMed 

Google Scholar 
WWF. Living Planet Report 2022 Building a Nature-Positive Society (eds Almond, R. E. A. et al.) (WWF, 2022).
Google Scholar 
van Klink, R. et al. Science 368, 417–420 (2020).Article 
PubMed 

Google Scholar 
Haase, P. et al. Nature https://doi.org/10.1038/s41586-023-06400-1 (2023).Article 

Google Scholar 
Mouillot, D., Graham, N. A. J., Villéger, S., Mason, N. W. H. & Bellwood, D. R. Trends Ecol. Evol. 28, 167–177 (2013).Article 
PubMed 

Google Scholar 
Pharaoh, E., Diamond, M., Ormerod, S. J., Rutt, G. & Vaughan, I. P. Sci. Total Environ. 878, 163107 (2023).Article 
PubMed 

Google Scholar 
Rumschlag, S. L. et al. Sci. Adv. 9, eadf4896 (2023).Article 
PubMed 

Google Scholar 
Outhwaite, C. L., Gregory, R. D., Chandler, R. E., Collen, B. & Isaac, N. J. B. Nature Ecol. Evol. 4, 384–392 (2020).Article 
PubMed 

Google Scholar 
Tickner, D. et al. BioScience 70, 330–342 (2020).Article 
PubMed 

Google Scholar  More

RESEARCH BRIEFINGS
09 August 2023

Local human-derived stressors combine with global ocean warming to threaten coral-reef persistence. Simultaneous reduction of human-derived stressors that originate on land, such as coastal run-off, and sea-based stressors, such as fishing pressure, resulted in greater coral-reef persistence before, during and after severe heat stress than did reduction of either alone. More

Large populations of fish help coral reefs to grow — but can’t protect against heatwaves.Credit: Barry Fackler/Getty

Minimizing land-based and sea-based human impacts at the same time might help reefs to recover from marine heatwaves, a study has found. But researchers warn that, in the absence of aggressive action to limit global warming, addressing impacts such as pollution and overfishing are insufficient to counter the growing threat. The findings — published this week in Nature1 — come as record ocean temperatures scorch reefs off the coast of Florida and scientists fear for the effects of El Niño on Australia’s Great Barrier Reef.Researchers analysed 20 years of reef data from a 200-kilometre stretch of coastline on Hawai’i Island. The data included an unprecedented marine heatwave in 2015, providing the researchers with a unique opportunity to explore how factors such as wastewater run-off and fishing intensity shaped the coral reef’s response. The heatwave was the strongest in 120 years of record-keeping, and saw ocean temperatures rise to 2.2 °C above normal, with a peak at 29.4 °C.A year after the heatwave, nearly one-quarter of the reefs had lost more than 20% of their coral cover. The hardest-hit reef lost close to half of its cover. But for 18% of reefs, coral cover was unaffected or even increased.Local impactsThe team used modelling to determine which factors best explained the differences in coral-cover changes.In the 12 years leading up to the heatwave, reefs with more fish — particularly herbivorous scrapers — and lower levels of wastewater pollution experienced coral growth.Scrapers “literally scrape the reef”, says Jamison Gove, an oceanographer at the Pacific Islands Fisheries Science Center at the US National Oceanic and Atmospheric Administration in Honolulu, Hawaii. “They not only remove fast-growing algae, but they clear space that allows for the settlement of crustose coralline algae, which is a precursor for coral growth,” he says.On the flipside, wastewater pollution from sewage disposal systems and run-off from urban environments damage coral health, says Gove. “It’s not only that you have this soup of virulent bacteria and other things that can cause coral disease,” he says. “You also have whatever everybody’s flushing down or putting down their sink. You have household chemicals, you have pharmaceuticals, so you have all sorts of toxins.”Modest gainsOverall, the researchers estimate that addressing land-based and sea-based human impacts on reefs simultaneously improves their chances of having higher levels of coral cover in the four years after a heatwave by three to six times, compared with addressing them independently. But lower pollution levels and more scrapers — factors that drove increases in coral cover before the heatwave — offered little protection against temperature spikes. Reefs with the lowest levels of urban run-off lost slightly less cover, but the presence of more fish — particularly scrapers — did not have a substantial effect on coral loss or survival.Gove says that the study reveals how human activity, both on land and in the sea, affects coral reefs, but stresses that these local impacts must be addressed in the context of action on climate change.“We can do all the local management you want, but in the decades to come, if we’re not aggressively curbing greenhouse-gas emissions, then climate change and marine heatwaves will most likely overwhelm any of the effects that we’ve identified within our paper,” he said.Terry Hughes, a marine biologist at James Cook University in Townsville, Australia says the study has confirmed that there are three main stressors on coral reefs: overfishing, pollution and climate change. “If you clean up the water quality and rebuild depleted populations of herbivores it does help the reef to recover. But the big, big caveat is provided they have enough time to recover,” he says. “It’s no use improving the recovery rate by managing water quality and fishing if the frequency of these bleaching events continues to increase.”Hughes gives the example of back-to-back bleaching events that struck the Great Barrier Reef in 2016 and 2017, and says that climate modelling suggests that most coral reefs will experience bleaching events every year by 2050 under a business-as-usual emissions scenario.“They don’t discriminate between well-managed reefs, or a polluted and non-polluted reef,” he says. “They all fry if the temperature is high enough.” More