An initiative of Earthwatch Institute

Dr. Dave Schoeman answers your questions

August 2013

Dr Dave Schoeman
Dave is a marine biologist who researches the ways in which marine critters respond to climate change. This has allowed him the opportunity to work in South Africa, the UK, and now Australia. Dave is particularly interested in bringing together the threads of knowledge to provide a broad view of climate-change impacts, to identify ways in which these views can be tested, and to figure out how we can use this knowledge to improve our approaches to marine conservation.

Q1: Jane asked, "Hi, I'd love your feedback regarding the inundation of krill and wild krill products saturating the market.  Surely the oceans will soon be all but depleted of krill, putting immense strain on the whole marine network.  Am I correct in being concerned?"

Dave answered, "I'm no expert on krill, but there are advantages in fishing shellfish like these: their populations can be very productive, and support large fisheries. The problem is that krill is not only useful to humans, but to many other organisms in polar food webs. So damaging their populations can have knock-on effects. The key is therefore to manage fisheries to avoid over-exploitation. Science can provide advice on this, but whether or not politicians implement this advice is largely dependent on public opinion. So expressing your concerns, as you have here, is important."

Q2: MJ asked, "I live close to a number of beaches near Yeppoon in Central Queensland, and one of my hobbies is photography. I have one series of photos that I call ‘Dead things on the beach”. I have noticed that more sea creatures, especially Jellyfish, seem to wash up at certain times of the year. I have only been here a short time, but there appears to be a definite pattern. Is such a thing part of a normal cycle, dependent upon tidal patterns; or could it have some relationship to climactic changes?"

Dave answered, "Beaches are fantastic sieves, filtering all sorts of things out of coastal waters. You are seeing the larger objects (dead critters), but there are many smaller particles, too. These all contribute to fuelling food webs that centre on beaches. In terms of patterns, you will see more animal carcasses after storms. Some of these will be ripped from reefs by big waves; others will be birds that ran out of energy trying to fly against strong winds; and others, still, will be jellies of various types that are largely at the mercy of wind-driven surface currents. Strong onshore winds will drive many of these things ashore. Although climate change is thought to be changing wind patterns, the picture is not simple, and I don't think that what you're seeing is related to these changes. Instead, I think you're seeing the results of short-term cycles in storms and onshore winds, which vary seasonally and quite predictably. Keep observing, though, and keep careful notes, because these sorts of records can be very useful in identifying patterns that scientists don't see!"