Current Biology
Magazine but I would prefer to say that “honest science is a holy obligation”. Mistakes will quickly be left at the scientific wayside, especially if we can set aside feelings of shame in admitting to honest errors. Fallibility is an inevitable part of the scientific process. Most great scientists were right about one or two things, and hilariously wrong about many others. Galileo dismissed Kepler’s elliptical planetary orbits; Rutherford regarded the quest for nuclear energy as moonshine; and Newton predicted that the Final Judgment would take place in 1867. What is the best piece of advice you have been given? Norma Graham, a woman with three children who is in the National Academy of Sciences, told me: “Never drift. Focus each day on what is important for you”. It is easy, especially once you have a laboratory and kids, to spend a lot of time just keeping up with the daily to-do list, making sure everyone (graduate students included) has underwear that isn’t hopping off their bums with funkiness. Norma’s advice helped me make sure my husband and I shared childcare equally, instead of falling into the trap of making a series of tiny daily concessions that cumulatively would have had quite an impact on my career. It is perfectly reasonable to take a career hit for your family; children do need a ridiculous amount of attention to thrive. But it is important to make mindful decisions about how to juggle career and family, rather than drifting along from day to day, being a little less productive than you need to be to achieve what you want from life. I utterly loathe the expression ‘work– life balance’. It implies that somehow, if only you knew how to ‘balance’ things correctly, it would be possible to glide serenely along, rather than lurching constantly from family crisis to lab neglect. Being a scientist with small children is fiendishly difficult. If your children have any kind of special needs or your partner isn’t doing half the work it will be unbelievably grueling. Eventually, with a little bit of luck, it should get better. This new generation actually seem to share family chores much more equally (hooray!) so this is advice for young scientists of all genders. What advice would you offer to someone starting a career in R746
neuroscience? Don’t be afraid of failure. Remember, only your successes will be listed on your curriculum vitae. If you ask a scientist with a great funding record about their secret, they are likely to say that they apply for a lot of grants. The review process for high-profile journals can be ugly, brutal and is almost never short, but you will never get your article into Current Biology unless you submit it. In science, failures will always outnumber successes. Innate ability, skills and sheer luck are important. But so is determination — that ability to hurl a coffee cup against the wall, announce to your husband that you are quitting this f***** career tomorrow, suck down three G&Ts, wake up with a thick head to start on the revision the next morning. There may well be more mature strategies for dealing with the many low-points of a scientific career, but this one has always worked for me. I have not yet managed to get an article into Current Biology (does this count?) but I remain wildly optimistic. Why the moustache? Research shows that wearing a moustache results in a surprising number of career advantages. You will be thought to be more competent, and your work viewed as more interesting. You’ll be more likely to be invited to write a piece for, or have an article published in, Nature. Moustaches also result in bigger salaries, more office and laboratory space, and more research funding. Besides, it suits me and my husband likes the tickly sensation. Last words? On promotion to Professor, I decided to give up feeling guilty for being imperfect. My students wait too long for manuscripts to be turned around, some of my articles are more interesting than others, my kids get peanut and jelly sandwiches in their lunchboxes so often that I’m stunned they don’t look like little peanuts, and I snarl at my husband for no good reason on a regular basis. Accepting my many imperfections has made me happier, and made it easier to apologize when I do fall short of my new lax standards. I suspect this has made other people a little bit happier as well. University of Washington, Department of Psychology, Guthrie Hall, Seattle, WA, 98195-1525, USA. E-mail:
[email protected]
Current Biology 26, R739–R755, August 22, 2016 © 2016 Elsevier Ltd.
Quick guide
Mangrove forests Daniel A. Friess What is a mangrove forest? Mangroves are a coastal intertidal wetland forest composed of halophytic tree and shrub species. While definitions of a true mangrove species are still debated, mangroves contain approximately 70 vegetation species in 40 genera. Associated with this vegetation are a plethora of coastal and terrestrial fauna, including fish, crustaceans, snakes and mammals. Mangroves fringe the world’s subtropical and tropical coastlines, reaching as far north as Florida (~29°N) and southern Japan (~31°N), and as far south as the south coast of Australia (~38°S); at these high latitudes, mangroves intergrade into temperate intertidal habitats such as saltmarshes. Globally, mangroves covered an estimated 137,760 km2 in 2001. The largest proportion of mangrove is found in Southeast Asia, with Indonesia alone holding more than one fifth of the world’s mangrove in 2001. Mangroves persist in a dynamic and physiologically stressful environment that changes over hourly to decadal time scales, and repeatedly experience disturbances such as pest infestations, lightning, storm surges and tropical storms. Mangroves are generally found in calm hydrodynamic locations that encourage the deposition of fine sediments — mangroves themselves are key geomorphic agents that interact with these tides and sediments, so they are important models with which to study physical environment–ecological interactions. What unique adaptations do mangroves have for surviving in the coastal environment? Mangrove forests are located in the intertidal zone — a dynamic and physiologically stressful location that experiences fluctuations in water level, hydrodynamic energy, salinity, nutrient availability and anoxia (Figure 1). To exist in this stressful location, mangrove flora have evolved a range of unique and novel adaptations to physiological stress. Based on phylogenetic reconstructions,
Current Biology
Magazine Species-specific adaptations and responses to physiological stress in many settings can create a distribution of species assemblages along a shallow-sloping seaward–landward gradient of tidal flooding, with a small number of pioneer species able to tolerate extreme conditions at the seaward edge, with more biodiverse assemblages appearing towards land, as tidal flooding and associated physiological stress decrease.
Figure 1. Mangrove forests. Top, a member of the iconic Rhizophora genus, Johor, Malaysia. Bottom, mangroves co-exist in the intertidal zone with other ecosystems such as seagrass, Ouvea atoll, New Caledonia.
it is estimated that mangroves such as those in the family Rhizophoraceae diverged from their terrestrial forest relatives approximately 64 million years ago. Because of the adaptations required to persist in the stressful and dynamic coastal environment, only select terrestrial lineages were able to make the evolutionary jump, accounting for the very low species diversity of the mangrove ecosystem today, compared with other tropical terrestrial forest systems. In an intertidal environment that is alternately dry and flooded, only a small window of opportunity may be available for establishment. Thus, some species have developed (crypto) vivipary, where seeds germinate while on the tree in order to accumulate carbohydrate reserves (for example, in the Rhizophoraceae) and to allow rapid rooting. Once established, different mangrove species have adapted to soil anoxia and tidal inundation through the creation of above-ground root structures that allow gaseous exchange above the soil. Particular species have also adapted to tolerating a saline or brackish environment by excluding salt from the roots, or excreting salt through glands or leaf loss.
Why are mangrove forests important? In addition to their unique biodiversity value, mangroves are important habitats due to the ecosystem services they provide to human populations. Mangroves have long been known for their tangible provisioning ecosystem services to local coastal populations, such as timber, charcoal, non-timber forest products and fish/ shellfish. Mangroves also regulate key processes such as hydrodynamic wave attenuation — the potential role of this regulating ecosystem service in coastal protection largely drove the replanting and rehabilitation of mangroves in Southeast Asia in the late 2000s. More recently, carbon sequestration has attracted increasing interest as an important regulating ecosystem service, as a potential tool to mitigate a proportion of anthropogenic carbon dioxide emissions. Often neglected are the variety of cultural ecosystem services that mangroves provide to populations. These range from the tangible, such as tourism, recreation and education, to the
abstract, such as spiritual and aesthetic values. Importantly, the broad range of ecosystem services provided by mangroves benefit multiple human populations from local to regional scales. Mangrove forests are a threatened ecosystem The shallow-sloping coastal zone is a location of rapid change — a confluence of rapid urban development (with population densities substantially higher than the average of interior areas) and agricultural expansion to provide economic gain and food security for tropical nations. Thus, mangroves are often considered one of the most threatened ecosystems globally. While the dominant threat to mangroves differs nationally and regionally, aquaculture has traditionally been a leading cause of deforestation throughout the tropics. More recently, the expansion of oil palm plantations has been an under-recognised threat to mangroves, accounting for 16% of their loss in Southeast Asia between 2000 and 2012. While loss in Southeast Asia is largely due to direct land cover conversion, in regions such as Africa, indirect causes of degradation dominate. This includes the direct threat of harvesting for charcoal and construction materials (Figure 2), and indirect ecosystem stressors such as organic pollution from rapidly expanding peri-urban areas. Sea level rise is a largely invisible threat to mangroves, though is projected to have major impacts on mangrove survival in the future. Recent analyses of geomorphological processes in the
Figure 2. Mangroves under threat. Left, mangrove forests experience substantial harvesting pressure for firewood and construction materials in southwest Madagascar. Right, mangrove wood is in high demand in some countries for charcoal production.
Current Biology 26, R739–R755, August 22, 2016
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Current Biology
Magazine Indo-Pacific suggests that large swathes of mangroves are threatened with submergence under the higher IPCC sea level rise scenarios by the year 2100. For the minerogenic mangrove systems that dominate in the Indo-Pacific, mangrove resilience to sea level rise is determined largely by external sediment input, which drives soil surface accretion to allow mangroves to keep pace with rising sea levels. Sea level rise vulnerability may be exacerbated by human management decisions such as river damming, which could substantially reduce external sediment input from fluvial sources such as the Mekong river (Vietnam), Chao Phraya river (Thailand) and the Ayeryawady river (Myanmar).
Mangrove rehabiliation can offset some losses, and major efforts have occurred in some regions such as Southeast Asia. However, success rates vary wildly, often because mangrove species are planted in locations (such as mudflats) that do not fit their physiological tolerances to physical processes such as tidal inundation. Integrated coastal zone management that is able to balance the tradeoffs between economic development and mangrove conservation, while restoring degraded ecosystems, may improve the future outlook of this important coastal ecosystem. Where can I find out more?
What is the future outlook for mangrove forests? The good news is that deforestation rates in some parts of the world have decreased over the last decade. For example, while in the 1970s–1990s it was assumed that mangroves in Southeast Asia were being lost at a rate of approximately 1% per year, recent analyses suggest that this has decreased to approximately 0.2% annually. However, this regional view hides substantial rates of deforestation at local and national scales. Deforestation rates may also increase due to government plans in many countries to increase agricultural commodity production (such as fish/shrimp aquaculture, rice and oil palm) to increase economic and food security. Oil palm in particular is expected to increase and threaten mangroves in Indonesia (especially the Provinces of Papua and West Papua) and West Africa. Mangroves have traditionally been incorporated into protected areas for their conservation. New conservation mechanisms, such as Payments for Ecosystem Services (PES), also hold promise for mangrove conservation. PES schemes that pay for the carbon stored in mangroves are gaining particular attention at the international level through forums such as the IUCN Blue Carbon Initiative, and pilot studies are being established in Kenya and Madagascar, with carbon credits sold on the voluntary carbon market. We can expect mangrove PES to increase further in the future, though substantial concerns regarding land tenure, benefit sharing and market volatility remain. R748
Alongi, D.M. (2008). Mangrove forests: resilience, protection from tsunamis, and responses to global climate change. Estu. Coast. Shelf Sci. 76, 1–13. Donato, D.C., Kauffman, J.B., Murdiyarso, D., Kurnianto, S., Stidham, M., and Kanninen, M. (2011). Mangroves among the most carbon-rich forests in the tropics. Nat. Geosci. 4, 293–297. Duke, N.C., Meyneke, J.O., Dittman, S., Ellison, A.M., Anger K, Berger, U., Cannicci, S., Diele, K., Ewel, K.C., Field, C.D., et al. (2007). A world without mangroves? Science 317, 41–42. Friess, D.A., Krauss, K.W., Horstman, E.M., Balke, T., Bouma, T.J., Galli, D., and Webb, E.L. (2012). Are all intertidal wetlands naturally created equal? Bottlenecks, thresholds and knowledge gaps to mangrove and saltmarsh ecosystems. Biol. Rev. 87, 346–366. Giri, C., Ochieng, E., Tieszen, L.L., Zhu, Z., Singh, A., Loveland, T., Masek, J., and Duke, N. (2011). Status and distribution of mangrove forests of the world using earth observation satellite data. Glob. Ecol. Biogeo. 20, 154–159. Krauss, K.W., Lovelock, C.E., McKee, K.L., LopezHoffman, L., Ewe, S.L., and Sousa, W.P. (2008). Environmental drivers in mangrove establishment and early development: a review. Aqua. Bot. 89, 105–127. Lewis, R.R. (2005). Ecological engineering for successful management and restoration of mangrove forests. Ecol. Engin. 24, 403–418. Lovelock, C.E., Cahoon, D.R, Friess, D.A., Guntenspergen, G.R., Krauss, K.W., Reef, R., Rogers, K., Saunders, M.L., Sidik, F., Swales, A., et al. (2015). The vulnerability of Indo-Pacific mangrove forests to sea-level rise. Nature 526, 559–563. Polidoro, B.A., Carpenter, K.E., Collins, L., Duke, N.C., Ellison, A.M., Ellison, J.C., Farnsworth, E.J., Fernando, E.S., Kathiresan, K., Livingstone, S.R., et al. (2010). The loss of species: mangrove extinction risk and geographic areas of global concern. PLoS One 5, e100095. Richards, D.R., and Friess, D.A. (2016). Rates and drivers of mangrove deforestation in Southeast Asia, 2000-2012. Proc. Natl. Acad. Sci. USA 113, 344–349. Walters, B.B., Ronnback, P.B., Kovacs, J.M., Crona, B., Hussain, S.A., Badola, R., Primavera, J.H., Barbier, E.B., and Dahdouh-Guebas, F. (2008). Ethnobiology, socio-economics and management of mangrove forests: a review. Aqua. Bot. 89, 220–236.
Department of Geography, National University of Singapore, 1 Arts Link, Singapore 117570. E-mail:
[email protected]
Current Biology 26, R739–R755, August 22, 2016 © 2016 Elsevier Ltd.
Primer
Prosociality Keith Jensen Prosociality refers to behaviours that are intended to benefit others. This definition appears to be so straightforward that it hardly bears mentioning: like certain forms of adult entertainment, we know it when we see it. Yet, determining what counts as prosocial is not as simple as it first appears. There are numerous behaviours that appear prosocial but, on scrutiny, may not have been intended and motivated for the wellbeing of others. Consider a banal scenario: a seated passenger on a crowded bus stands up and someone takes his seat. Did the person standing up intend that someone else take the seat? Perhaps he was getting off the bus at the next stop and did not care if anyone sat there. But what if he remained standing for several stops, or made an overt gesture such as waving his hand toward the seat? In that case it is more likely that he intended for someone to have his place on the bus. But what about his underlying motives? Maybe he was putting himself in a better position to pick the pocket of the person sitting down. Less sinister possibilities include trying to impress the person who took his seat — trying to improve his reputation, his social standing, as it were. Or maybe, just maybe, he intended for another passenger to sit comfortably, to increase the happiness of a stranger, with no ulterior motives. Prosocial behaviours can come in various forms. These include informing, comforting, sharing and helping. Informing involves providing information that someone else needs, such as warning someone of danger and pointing out the location of food. Comforting involves decreasing the distress of someone else, such as hugging them when they are sad. For sharing, a resource is given up, for example offering a piece of food to someone who is hungry. Helping requires recognising the goals of other individuals and working to see those goals achieved, such as opening a door for someone who is unable to
