Reef accessibility impairs the protection of sharks (2018) Juhel et al., Journal of Applied Ecology 55
Species such as this Carribean reef shark have higher extinction risks than most fish. But how effective are our management efforts? (Image Credit: Wikipedia Commons)
The importance of sharks goes well beyond what Jaws did to Hollywood, or one week in the USA each July. In any reef ecosystem, sharks perform a key functional role, exerting top-down pressure, stabilising food webs, and improving general ecosystem functioning. They’re also ‘charismatic’ species, meaning they’re easier to raise funding for, and bring money in through tourism. Yet pressure from fishing suggests that reef shark populations may be under threat, and with high body sizes and long lifespans, their populations are more sensitive than most to overfishing, making extinction risks higher.
Yet the lack of data on shark populations means that the effectiveness of the few existing management programs is largely untested. This paper looks at Marine Protected Areas (MPAs), areas in which national or international bodies prevent fishing or even entry, to see whether or not they are an effective conservation method for shark populations.
Scientific methods of communication with the public have been evolving ever since the first Universities were opened in the 1200s. Recent times have seen communication evolve in step with the digital age. But given our lack of progress in key areas in which scientists have long known we face problems, such as climate change, biodiversity and ocean pollution, one wonders if we’re doing our job well enough.
Ian Winfield is a freshwater ecologist at the Centre for Ecology & Hydrology in Lancaster, UK. Ian has spent years working in Northern England in an effort to conserve its populations of the Arctic charr, a common environmentally-demanding fish which has seen many of its populations in the polar regions come under increasing pressure. I took the chance to sit down with Ian at the recent International Charr Symposium in Duluth, Minnesota, and we discussed his experiences using cultural anthropology to encourage ecological action outside of the scientific community.
Normally three spined sticklebacks are less likely to find a mate when they are affected with parasites, but does this change with eutrophication? (Image Credit: Sam Perrin, NTNU)
Reversed parasite-mediated selection in sticklebacks from eutrophied habitats (2010) Heuschele & Candolin, Behavioral Ecology and Sociobiology DOI: 10.1007/s00265-010-0937-9
We’ve all heard the stories of turtles choking on plastic bags, or birds swallowing sporks. Algae grows out of control due to chemicals being added to the water, which changes the native habitat. For fish like sticklebacks, where males compete for the attention of females, the loss of visibility has the potential to be a problem for the females. Male sticklebacks defend a territory, develop a bright red spot, and fight other males. The long and short of it is that the bigger, stronger, and prettier fish mate more and the weaker and uglier fish don’t. One thing that weaker males tend to have more of than stronger males are parasites, which isn’t a surprise as a parasite’s entire existence revolves around surviving at the expense of whatever organism is unfortunate enough to have them.
Understanding how eutrophication affects female choice in relation to parasites, and thus the reproductive dynamics of this system, is quite important. This paper tries to map that out, using the Baltic Sea around Southern Finland. This experiment is well-suited to the problem, as there has already been evidence for algal growth changing the dynamics of stickleback reproduction.