Reports from the front line of the current mass extinction: ocean acidification, fisheries and ecocide

Jason Hall-Spencer
Professor of Marine Biology and Editor-in-Chief of Regional Studies in Marine Science, Plymouth University, PL4 8AA

T: +44 1752887075

We are now well into the Anthropocene. Since the 1950s there has been a human population explosion with widespread coastal habitat damage exacerbated by our ever increasing use of hydrocarbon reserves.  This talk uses case studies on inshore fisheries, deep-water coral reefs and ocean acidification to show that we have our work cut out if we are to achieve ‘Good Environmental Status’ anytime soon.  But, if we are sensible, we can limit on-going damage.

Within the past 100 years fishing using internal combustion engines has completely changed the ecology of coastal waters.  In the UK, we now mainly import the marine life we eat and export what we are able to catch.  Widespread use of diesel-thirsty dredges and trawls has damaged nursery areas and homogenised seabed habitats.  We have also fished-down coastal food-webs, removing large long-lived fish (like cod and hake) to the benefit of invertebrates (like scallops and cuttlefish).  Giant rays, sturgeon and halibut are now extinct over most of their preindustrial distribution. To make their fuel go farther, large Dutch beam trawlers are now using electricity to stun flatfish throughout the southern North Sea, with unknown effects on the ecosystem.

Despite this marine ecocide, I am hopeful that we can turn things around, based on experience with cold-water coral reefs. These spectacular reefs, once thought to be restricted to the tropics, occur right up into the Arctic. Colleagues and I provided EU mandarins with evidence of the widespread damage caused by trawls in 2002, advocating the rapid development of towed gear closures to regenerate and protect vulnerable offshore marine ecosystems.  Biogenic reefs are a priority for protection as they grow slowly and are easily smashed, yet they provide important habitat for a variety of fish.  We worked with industry to design closures that limited displacement of fishing effort, as we did not want to increase damage to other sensitive habitat types or force fishermen further offshore, increasing fuel costs and CO2 emissions. Several High Seas and EU closures are now in force and satellite vessel tracking data indicate that they are working effectively, with good compliance by international fleets.  

A key solution to securing Good Environmental Status is obvious: reduce the footprint of the most destructive practices to allow recovery of coastal systems.  Thankfully, the UK Government is tightening controls to ensure that areas that are protected on paper are protected in reality.  Attention has recently turned to the question of whether these efforts can really work, given that the temperature, chemistry and biology of the oceans is changing rapidly (Brodie et al. 2014).
Underwater CO2 vents show why we need to factor acidification and warming into marine management plans. These vents provide realistic insights as they affect coasts subject to other stressors (e.g. fishing, eutrophication, invasive species) allowing us to scale-up from laboratory work. Areas with abnormally high CO2 show which flora and fauna are able to thrive, forewarning those people that are reliant on aquaculture, fisheries and coastal tourism.

A new study (Jackson et al. in press) uses results from CO2 vents to examine steps needed to future-proof marine protected areas.  If emissions track the present trajectory then by 2060 over 85% of UK deep-water coral reefs will be exposed to corrosive waters, but all is not lost. Relatively shallow areas off Scotland (ca 200 m depth) stand-out as disproportionately important to the regional survival of NE Atlantic coral reefs.

We know we are causing the current planetary mass extinction – what survives will depend on how quickly we can reduce CO2 emissions and how sensible we are in protecting the resources we still have.
Brodie J, Williamson CJ, Smale DA, Kamenos NA, Mieszkowska N, Santos R, Cunliffe M, Steinke M, Yesson C, Anderson KM, Asnaghi V, Brownlee C, Burdett HL, Burrows MT, Collins S, Donohue PJC, Harvey B, FoggoA, Noisette F, Nunes J, Ragazzola F, Raven JA, Schmidt DN, Suggett D, Teichberg M, Hall-Spencer JM (2014) The future of the NE Atlantic benthic flora in a high CO2 world. Ecology and Evolution, 4, 2787-2789.

Jackson EL, Davies A, Howell KL Kershaw PJ Hall-Spencer JM (in press) Future-proofing Marine Protected Area networks for cold water coral reefs. ICES Journal of Marine Science.  doi: 10.1093/icesjms/fsu099

Molfese C, Beare D, Hall-Spencer JM (2014) Overfishing and the replacement of demersal finfish by shellfish: an example from the English Channel. PLoS ONE 9(7), e101506.