Posts Tagged ‘ecology’
a closer look at bonobos, enfin
As this blog is called what it is, I’ve decided to read the entire, long, Wikipedia article on bonobos to get a more subtle and comprehensive feel for their society and how it shapes their individuality – though of course I’ll continue to write on completely different subjects. What I’m finding so far is that there are nuances, as you would expect, and as we find in human societies. And of course it would be the same with other social species – a member of the normally less dominant gender will, through proven capabilities or particular personality traits, be given a more prominent role than usual, and leadership of or status within the group is not solely based on gender. Ranking may have a degree of fluidity based on behaviour and alliances. Not all males are subordinate and not all females are bosses. Nevertheless, bonobos are definitely matriarchal – just as chimps are patriarchal, also with some fluidity.
It surprised me when I learned, some years ago, that bonobos have a ‘male philopatric’ society. The term conveys a gender distinction – the male stays ‘at home’ for mating and reproduction, while the female moves to another group for that purpose. This occurs in some human societies too. While visiting the Tiwi Islands just north of Darwin, I was told by our islander guide that he had just ‘lost’ his sister, who had moved to another tribal group to marry, meaning that their connection was permanently broken. His culture actually forbade him to have any more contact with her. So the early Catholic Church prohibitions against first, second, third and fourth cousins marrying, as described in Joseph Henrich’s historical account of the WEIRD world, as well as many long-held cultural traditions of Australasia and elsewhere, likely hark back to our hominid ancestors.
In any case, male philopatry doesn’t seem very matriarchal. There are of course good reasons for philopatry (male or female) in general, as well as good reasons for its opposite, male or female dispersal, which inevitably means that these behaviours, their causes and consequences, are widely disputed. I think I’ll return to this issue in another post.
A particularly interesting feature of bonobo culture, fairly recently recognised, is co-operation between two separate groups, or troupes. This was in the Congo’s Kokolopori Bonobo Reserve, which may, I think, represent a space between ‘the wild’ and ‘captivity’, and so may influence behaviour. From Wikipedia:
Over two years of observation, researchers witnessed 95 encounters between the groups. Contrary to expectations, these interactions resembled those within a single group. During these encounters, the bonobos engaged in behaviours such as grooming, food sharing, and collective defense against threats like snakes. Notably, the two groups, while displaying cooperative tendencies, maintained distinct identities, and there was no evidence of interbreeding or a blending of cultures. The cooperation observed was not arbitrary but evolved through individual bonds formed by exchanging favors and gifts. Some bonobos even formed alliances to target a third individual, demonstrating a nuanced social dynamic within the groups.
This contrasts importantly with the deadly clashes between groups of chimpanzees observed by Goodall and others.
Bonobos engage in tongue-kissing, the only non-human creatures observed to do so, at least thus far. And this brings us to sex, a difficult topic to write about, even in a blog nobody reads, given so many cultural and religious tabus swirling around it in human society. So, best just to be descriptive, without making comparisons to H sapiens.
Bonobos aren’t monogamous, and they engage in sexual activity from an early age. It is mostly masturbatory, and indiscriminate, with the possible exception of mothers sexually engaging with adult sons. Heightened sexual activity often occurs when rich food sources are found, in which the masturbatory sex often occurs in large groups, increasing generalised bonding. Female masturbation is helped along by the fact that their clitorises ‘are larger and more externalised than in most mammals’. Well, here, comparison with humans is instructive:
… while the weight of a young adolescent female bonobo “is maybe half” that of a human teenager, she has a clitoris that is “three times bigger than the human equivalent, and visible enough to waggle unmistakably as she walks.
All quotes here are from Wikipedia, unless otherwise stated. The most common sexual combo is female-female. Their face-to-face, body-to-body interactions are referred to as genito-genital (G-G) rubbing, which is often accompanied by loud noises, hopefully of pleasure.
So, while female-female masturbation is the most practised sexual behaviour of the species, enhancing bonding against any male threats, male-male masturbation is also a regular thing:
The most common form of male–male mounting is similar to that of a heterosexual mounting: one of the males sits “passively on his back [with] the other male thrusting on him”, with the penises rubbing together because of both males’ erections
Clearly sexual activity is encouraged and valued as the most essential feature of bonobo society, and is practised in a variety of ways – penis-fencing, rump-rubbing, genital massaging, oral sex (among males) and, as mentioned, tongue-kissing. Adult-child sex is more common in males than females, though there’s no penetration. Is this because they’re avoiding pain, or because they know the connection with pregnancy? The general scientific consensus is that non-human species engage in sex based on instinct, hormones and such – that’s to say, more or less unconsciously without being aware of possible or likely consequences. I’m not entirely convinced, especially re our closest relatives, but how can this be tested? In any case, regardless of all this sex play, bonobo birth rates are no higher than those of chimps.
Unsurprisingly bonobo social relations are just as complex as those of chimps, and perhaps also humans, with personal animosities, rivalries and close friendships within and between genders, and the fact that infanticide in bonobo society hasn’t been observed isn’t proof that it hasn’t happened – after all, we’ve only known of the existence of bonobos for a little under a century. Still, bonobos are definitely different, and in what I would call an inspiring way. You could say that sex becomes a feel-good strategy, but also a way of diminishing any sense of male ownership of offspring. As Wikipedia puts it:
The strategy of bonobo females mating with many males may be a counterstrategy to infanticide because it confuses paternity. If male bonobos cannot distinguish their own offspring from others, the incentive for infanticide essentially disappears. This is a reproductive strategy that seems specific to bonobos; infanticide is observed in all other great apes except orangutans. Bonobos engage in sexual activity numerous times a day.
Anyway, enough of sex, let’s explore violence. Chimps, as mentioned, tend to be hostile to those not in their own troupe, and even patrol their own borders, looking for trouble. Very West Side Story. And yet, to my surprise, bonobos, are more violent in general.
In the wild, among males, bonobos are more aggressive than chimpanzees, having higher rates of aggressive acts, about three times as much. Although, male chimpanzees are more likely to be aggressive to a lethal degree than male bonobos which are more likely to engage in more frequent, yet less intense squabbling. There is also more female to male aggression with bonobos than there is with chimpanzees. Female bonobos are also more aggressive than female chimpanzees, in general. Both bonobos and chimpanzees exhibit physical aggression more than 100 times as often as humans do.
All of this sounds interesting, but ‘aggression’ might be a little more difficult to define than we think. In humans, for example, accusatory or bullying language, or the sharing of images, can be used aggressively without anything physical occurring. It has even been known to cause the victim to commit suicide. We have subtler and often more effective ways to make others suffer, and ‘non-physical’ aggression may have a physical, even deadly, impact. It is also a way of getting around laws prohibiting physical violence.
In any case, surely a major reason for the supposed greater physical aggression of chimps and bonobos, and doubtless other apes, compared to humans, is how we ‘count’ aggression. Is carpet-bombing physical aggression? Nuclear warfare? The wholesale slaughter of the Jews and the Congolese? The massacres of the ‘Crusades’? How can we not count remote, push-button slaughter, or starving people to death behind walls, or burning them to death in buildings, as physical aggression? Methinks there’s need for a rethink.
So let’s turn to something less controversial. Like all the great apes, bonobos pass the self-awareness mirror test, and it’s clear that the variations in their vocalisations have meaning, though whether they rise to the standard of a proto-language is a matter of definition. They also use many meaningful hand gestures.
A famous example of a bonobo being taught to communicate using a keyboard, and to respond effectively to whole sentences, is that of Kanzi:
Kanzi’s vocabulary consisted of more than 500 English words, and he had comprehension of around 3,000 spoken English words… Kanzi is also known for learning by observing people trying to teach his mother; Kanzi started doing the tasks that his mother was taught just by watching, some of which his mother had failed to learn….
Kanzi was also taught how to make simple stone tools, though he found a method of making them in his own bonoboesque way. There seems no doubt that effective rapport between bonobos and humans will benefit both species.
Finally, there’s the ecological importance of bonobos. They’re essentially one of the two apex species of their region, the other being elephants. Both species are frugivorous, and their ecological role is vital:
It is estimated that during its life, each bonobo will ingest and disperse nine tons of seeds, from more than 91 species of lianas, grass, trees and shrubs. These seeds travel for about 24 hours in the bonobo digestive tract, which can transfer them over several kilometers (mean 1.3 km; max: 4.5 km), far from their parents, where they will be deposited intact in their faeces. These dispersed seeds remain viable, germinating better and more quickly than unpassed seeds. For those seeds, diplochory with dung-beetles (Scarabaeidae) improves post-dispersal survival.
Diplochory means two-phase seed dispersal, using more than one vector or carrier.
Anyway, I think that’s more than enough info for one post. The Wikipedia article on bonobos makes for a very solid book chapter, with 178 references, so far. And it ends nicely with informing us all of the annual World Bonobo Day, established in 2017. No prizes should be given for guessing the date!
References
https://en.wikipedia.org/wiki/Bonobo
Joseph Henrich, The WEIRDest people in the world: how the West became psychologically peculiar and particularly prosperous, 2021
fish deaths in the lower Darling – interim report
Jacinta: We wrote about this issue in a piece posted on February 11, so it’s time to follow up – an interim report came out on February 20, and a final report is due at the end of March, but my feeling is that the final report won’t differ much from this interim one.
Canto: Yes I get the feeling that these experts have largely known about the situation for a long time – unusual climatic conditions plus an increasing lack of water in the system, which would make the remaining water more susceptible to extremes of weather.
Jacinta: So here’s some of what they’re saying. There were three separate events; the first on December 15 involved tens of thousands of fish deaths over a 30km stretch of the Darling near Menindee, the second on Jan 6-7, over 45kms in the same area, involved hundreds of thousands of deaths, even millions according to some residents, and the third on Jan 28, with thousands of deaths. Likely effects on fish populations in the Darling will last for years.
Canto: And they warn that more deaths are likely to occur – though no major events have been reported since – due to low inflows and continued dry conditions in the catchment area. Monitoring has shown that there are problems of low dissolved oxygen and ‘high stratification’ at various points along the river. I presume ‘high stratification’ is self-explanatory, that the water isn’t mixing due to low flows?
Jacinta: Yes, but I think the issue is thermal stratification, where you have a warm surface layer sitting above a cooler, oxygen-depleted sub-surface layer. These are excellent conditions for algal blooms apparently. And the low flows are a natural feature of the Darling. It’s also very variable in flow, much more so than the Murray, due to its low relief, the more variable rainfall in the region, and the tributaries which create a large catchment area. I don’t know if that makes sense.
Canto: Neither do I. I note that they’ve been carefully critical of the NSW government’s ‘Barwon-Darling Water Sharing Plan 2012’, because between the draft and final implementation of the plan the number of high-flow Class C shares was reduced and the number of Class A (low flow) and Class B (medium flow) shares increased, which meant more extraction of water overall, and at lower flows. They recognise that there have been recent Federal moves to reverse this, but clearly they don’t consider them sufficient.
Jacinta: Yes and the problem goes back a way. They refer to an analysis from almost two decades ago:
The flow regime in the lower Darling has changed significantly since the completion of the Menindee Lakes storage scheme in 1968, and as a result of abstractions in the Barwon–Darling and its tributaries. It is estimated that the mean annual flow in the Darling River has been reduced by more than 40% as a result of abstractions in the Barwon–Darling (Gippel & Blackham, 2002).
Presumably ‘abstractions’ means what I think it means – though elsewhere they use the term ‘extractions’ which is confusing.
Canto: We should point out the immense complexity of the system we’re dealing with, which we can see from detailed maps that accompany the report, not to mention a number of barely comprehensible charts and graphs. Anyway the effect of ‘water management’ on native vegetation has been dire in some regions. For example, reduced inundation of natural floodplains has affected the health of the river red gums, while other trees have been killed off by the creation of artificial lakes.
Jacinta: And returning to fish deaths, the report states that ‘the influence of upstream extractions on inflows to the Menindee Lakes is an important consideration when assessing the causes of fish deaths downstream’. What they point out is that the proportion of extractions is higher in times of lower inflow, which is intuitively obvious I suppose. And extractions during 2017-8 were proportionally the second highest on record. That’s in the Northern Basin, well above the Menindee Lakes.
Canto: And the extractions have been mainly out of the tributaries above the Barwon-Darling, not those principal rivers. Queenslanders!
Jacinta: No mention of Queenslanders, but let’s not get bogged down..
Canto: Easily done when there’s hardly any water…
Jacinta: Let’s go to the provisional findings and recommendations. There are 18 briefly stated findings in all, and 20 more expansive recommendations. The first two findings are about extreme weather/climatic conditions amplified by climate change, with the expectation that this will be a continuing and growing problem. Findings 3 and 4 focus on the combined effects of drought and development. There’s a lack of updated data to separate out the effects, but it’s estimated that pre-development inflows into the Menindee Lakes were two or three times what they are now. Further findings are that the impact of diversions of or extractions from flows are greater during dry years, that extractions from tributaries are more impactful than extractions from the Barwon-Darling Rivers.
Canto: The findings related directly to fish deaths – principally findings 10 through 15 – are most interesting, so I’ll try to explain. The Menindee Lakes experienced high inflows in 2012 and 2016, which caused greater connection through the river system and better conditions for fish spawning and ‘recruitment’ (I don’t know what that means). So, lots of new, young fish. Then came the bad 2017-8 period, and releases from the Menindee Lakes were less than the minimum recommended under the water sharing plan, ‘with the intent to prolong stock and domestic requests to meet critical human needs’. So by the end of 2018, the high fish biomass became trapped or restricted between weirs, unable to move upstream or downstream. As the water heated up, significant algal blooms developed in the areas where fish had accumulated. Thermal stratification also occurred, with hypoxic (low oxygen) or anoxic (no oxygen) conditions in the lower waters, and algal blooms proliferating in the surface waters, where the fish were forced to hang out. Then conditions suddenly changed, with lower air temperatures and stormy conditions causing a rapid destratification. The low oxygen water – presumably more voluminous than the oxygenated water – dominated the whole water column and the fish had no way out.
Jacinta: Yes, you can’t adapt to such sudden shifts. The final findings are about existing attempts at fish translocation and aerating water which are having some success, about stratification being an ongoing issue, and about lack of knowledge at this preliminary stage of the precise extent of the fish deaths.
Canto: So now to the 20 recommendations. They’re grouped under 3 headings; preventive and restorative measures (1-9), management arrangements (10-13), and knowledge and monitoring (14-20). The report noted a lack of recent systematic risk assessment for low oxygen, stratification and blackwater (semi-stagnant, vegetation-rich water that looks like black tea) in the areas where the fish deaths occurred. There was insufficient or zero monitoring of high-risk areas for stratification, etc, and insufficient planning to treat problems as they arose. Flow management strategies (really involving reduced extraction) need to be better applied to reduce problems in the lower Darling. Reducing barriers to fish movement should be considered, though this is functionally difficult. Apparently there’s a global movement in this direction to improve freshwater fish stocks. Short term measures such as aeration and translocation are also beneficial. Funding should be set aside for research on and implementation of ecosystem recovery – it’s not just the fish that are affected. Long-term resilience requires an understanding of interactions and movement throughout the entire basin. Fish are highly mobile and restriction is a major problem. A whole-of system approach is strongly recommended. This includes a dynamic ‘active event-based management’ approach, especially in the upper reaches and tributaries of the Barwon-Darling, where extraction has been governed by passive, long-term rules. Such reforms are in the pipeline but now need to be fast-tracked. For example, ‘quantifying the volumes of environmental water crossing the border from Queensland to NSW…. would increase transparency and would help the CEWH [Commonwealth Environmental Water Holdings] with their planning, as well as clear the path to move to active management in Queensland’.
Jacinta: Right, you’ve covered most of the issues, so I’ll finish up with monitoring, measuring and reporting. The report argues that reliable, up-to-date accounting of flows, volumes in storage, extractions and losses due to seepage and evaporation are essential to create and maintain public confidence in system management, and this is currently a problem. Of course this requires funding, and apparently the funding levels have dropped substantially over the past decade. The report cites former funding and investment through the Co-operative Research Centre, Land and Water Australia and the National Water Commission, but ‘by the early 2010s, all of these sources of funding had terminated and today aggregate levels of funding have reduced to early 1980s levels, at a time when water was far less of a public policy challenge than it is today’.
Canto: We await the government’s response to that one.
Jacinta: And on fisheries research in particular, it has been largely piecemeal except when their was a concerted co-ordinated effort under the Native Fish Strategy, but the issue right now is to know how many fish (and other organisms) of the various affected species survived the event, which involves multi-level analyses, combined with management of Basin water balances, taking into account the ongoing effects of weather events due to climate change, in order to foster and improve the growth and well-being of fish stocks and freshwater habitats in general. Connectivity of the system in particular is a major concern of the report.
Canto: Right, so this has been a bit of a journey into the unknown for us, but a worthwhile one. It suggests that governments have been a bit dozey at the wheel in recent years, that extractions, especially in the upper reaches and tributaries, haven’t been well monitored or policed, and the connectivity of the system has suffered due to extractions, droughts and climate change. Funding seems to have dried up as much as some of the rivers have, and we’ll have to wait and see if this becomes an election issue. I suspect it’ll only be a minor one.
why are our river fish dying?
Canto: So here’s a question. Why are so many fish dying in our rivers? I believe it has something to do with oxygen, but that raises a whole heap of questions, like why do fish need oxygen, how does this relate to fish physiology, what’s the difference between freshwater and saltwater fish (is all fish physiology basically the same), and is climate change a factor in all this – or rather, how is it a factor?
Jacinta: Okay so that’s a good focussed question, or set of questions, a bit easier to deal with than the management of our river systems, which would involve inter(and intra)-state politics and the rights or wrongs of irrigators, farmers, industry and the like. I’ve heard all that is rather complicated.
Canto: Right, so we’re just going to focus on the internal and external environment of freshwater fish.
Jacinta: Well, maybe. News reports have claimed up to a million fish deaths in the Darling River, with critically endangered Murray cod being among the victims. Algal blooms ‘which can be caused by agricultural chemicals’ (sky news) are being cited as the proximal cause, but the ultimate cause, according to Menindee Lakes residents, is government mismanagement.
Canto: I would wonder whether there are so many fish in the river to begin with – and that million figure is grossly exaggerated according to various sources. The figure appears to be something between 100,000 and 200,000, still a staggering number, and I wonder about the deaths in proportion to the population, and if some species are dying more than others. We need some science here.
Jacinta: And my preliminary enquiries into the science show that it’s complex and unsettled. The most recent mass death occurred in the Menindee Lakes, south of Broken Hill, a series of lakes connected to the Darling. We know that there was very little flow-through at the time, the water levels were low and water temperature had risen. As a result, there was a large bloom of cyanobacteria, aka blue-green algae. But apparently according to an ABC Science report, the cyanobacteria weren’t exactly the problem, it was their death, caused by a cold front, and the sudden explosion of other bacteria feeding on the dead and dying cyanobacteria, and in the process depleting the water of oxygen, that caused the fish to drown.
Canto: So what we call drowning is really loss of oxygen, which fish have evolved to capture from water but we can’t. How do they do that?
Jacinta: Gills. Fish breathe through their mouths like us. And also like us they need oxygen to function and they breathe out carbon dioxide. Gills – and we could expend pages and pages on their origin, structure and function – are those organs found on each side of the pharynx or throat, and they’re made up of protein structures called filaments. Each filament has a tiny network of blood vessels, providing a large surface area for the exchange of gases. So fish suck in water, with its oxygen, and then pump it out through the gills, where all the essential gas exchange occurs. But if the water isn’t sufficiently oxygenated, then it’s goodnight, sweet fish.
Canto: So the proximal cause isn’t the blue-green algae, it’s the oxygen-consuming bacteria that feed on the algae.
Jacinta: But if the algae weren’t there in the first place, the bacteria that feed on them wouldn’t be there.
Canto: Yes, but that’s only because the algae were dying. What if there hadn’t been this sudden drop in water temperature? Do the algae themselves affect the oxygen levels?
Jacinta: Well, actually, very much so. Cyanobacteria were the first photosynthesising organisms – we wouldn’t be here without them, and they’re now incorporated, in the form of chloroplasts, in all the plants around us. They were the principal means of oxygenating the biosphere.
Canto: So does that mean it’s good to have blue-green algae in our waterways? I’m confused.
Jacinta: The answer is yes and no. The Murray Darling Basin Authority (MDBA), currently under fire from all and sundry, have a useful factsheet about what we’ll henceforth call cyanobacteria. They’re a natural part of the system, and there are a number of species, the two most prominent being Dolichospermum and Microcystis. Under certain optimal conditions for growth, they produce ‘blooms’, which can be toxic at high levels. Mostly though, they don’t affect irrigation, recreational use of the river, or drinking water, if properly treated. It’s the decay of these blooms that causes most problems…
Canto: I note that these fish deaths occurred in the Menindee Lakes, and may have been a result of low water levels, which in turn were due to drought. Lower water levels means a lower volume of water, so that the environmental temperature would more rapidly affect the water temperature than if the volume was greater – no doubt there’s an equation to account for that – which would more quickly affect the decay of the bloom and the growth of the oxygen-depleting bacteria feeding on the bloom. So it seems to me that the ultimate cause is drought, which creates a less stable environment for the fish, and other organisms. How’s that?
Jacinta: Well, it’s the beginning of an explanation, but it’s too simple. It isn’t just drought that’s affecting water levels, it’s the fact that water is drawn from the system. And that involves politics, which we were hoping to steer clear of – oh well. By the way, the fish that have died include Murray cod, golden perch, silver perch, and bony herring. I don’t have relative numbers though. The Menindee Lakes region, which is at the centre, not only of this fish death controversy, but of the entire Murray-Darwin Basin management controversy, appears to be at crisis point, and the locals aren’t happy. Here are some quotes from The Guardian on the issue:
Since the 1960s, the original Menindee Lakes have been significantly altered to serve as a major storage for water for the Murray-Darling Basin as well as the water supply for Broken Hill. The lakes are also a major fish breeding area for native fish, and critical to maintaining stocks of fish throughout the river system.
However, the NSW government has proposed shrinking the lakes and altering the way it manages the water storage, in order to reduce evaporation. It is currently building a $500m pipeline from the Murray to Broken Hill in order to provide the inland city with an alternative water supply.
But the plan is highly controversial because it will mean the government has less reason to keep the lakes full and will likely see the Lower Darling run dry more often.
Local graziers and the towns of Wilcannia and Pooncarie are up in arms about the state of the river, accusing the NSW government of sacrificing their 500km stretch of the Darling in order to benefit upstream cotton growers.
They say the current crisis is due to Water NSW’s decision to run the lakes dry despite forecasts of drought.
Canto: The MDBA, which is a federal body, presents their reasons for the fish deaths in two concise points:
- the lack of water flowing into the northern rivers
- the impact of 100 years of over-allocation of precious water resources throughout the entire Basin.
Drought and the removal of water from the system, precisely your point, Jacinta. The MDBA of course avoids blame, and says nothing about possible current over-allocation. It does, however, say, in the same information page, that ‘the Menindee Lakes are currently under the sole control of New South Wales and have been carefully managed since December 2017’, which appears to court some controversy.
Jacinta: And finally, something important to watch out for as we seek an ultimate answer to our question. An independent panel of six science worthies has been appointed by the Federal government to enquire into these deaths. Fields of expertise include catchment hydrology, fluvial geomorphology, freshwater ecology, plant ecotoxicology, aquatic ecosystem health and much much more. The team will provide a preliminary report to the Feds by February 20, and a final report should be completed by March 31. We’ll look out for it – presumably it will be released to the public.