Guest essay by Eric Worrall
Researchers testing the effects of global warming on a 2000 litre fish tank have warned that the world faces a major collapse of coastal fisheries, because some of their fish died.
Climate change could drive coastal food webs to collapse
Authors
Professor, Marine Biology, University of Adelaide
Professor, Ecology, University of Adelaide
University of Adelaide
May 1, 2017 6.01am AEST
Coastal marine food webs could be in danger of collapse as a result of rising carbon dioxide levels, according to our new research. The study shows that although species such as algae will receive a boost, the positive effects are likely to be cancelled out by the increased stress to species further up the food chain such as predatory fish.
…
Test tank
We used a self-contained ecosystem in a 2,000-litre tank to study the effects of warming and ocean acidification on a coastal food web. This approach can give us a good idea of what might happen to genuine coastal food webs, because the tank (called a “mesocosm”) contains natural habitats and a range of species that interact with one another, just as they do in the wild.
Our food web had three levels: primary producers (algae), herbivores (invertebrates), and predators (fish).
The results show that carbon dioxide enrichment can actually boost food webs from the bottom up through increased algal growth. This benefited herbivores because of the higher abundance of food, and in turn boosted the very top of the food web, where fish grew faster.
But while this effect of ocean acidification may be seen as positive for marine ecosystems, it mainly benefits “weedy” species – a definition that can be applied to some species of algae, invertebrates, and even fish.
In contrast, habitat-forming species such as kelp forests and coral reefs are more likely to disappear with rising CO₂ emissions, and with them many associated species that are deprived of their habitats and food.
Detrimental effect
Our results therefore showed that warming had a detrimental overall effect on the coastal food web we studied. Although higher temperatures boosted algal growth, herbivorous populations did not expand. Because herbivore abundances remained similar and elevated temperatures result in a higher metabolic demand, predatory fish consumed more herbivorous prey, resulting in a collapse of these prey populations.
…
Read more: http://theconversation.com/climate-change-could-drive-coastal-food-webs-to-collapse-76798
The abstract of the study;
Boosted food web productivity through ocean acidification collapses under warming
Authors
Silvan U. Goldenberg,
Ivan Nagelkerken,
Camilo M. Ferreira,
Hadayet Ullah,
Sean D. Connell
First published: 27 April 2017
Future climate is forecast to drive bottom-up (resource driven) and top-down (consumer driven) change to food web dynamics and community structure. Yet, our predictive understanding of these changes is hampered by an over-reliance on simplified laboratory systems centred on single trophic levels. Using a large mesocosm experiment, we reveal how future ocean acidification and warming modify trophic linkages across a three-level food web: that is, primary (algae), secondary (herbivorous invertebrates) and tertiary (predatory fish) producers. Both elevated CO2 and elevated temperature boosted primary production. Under elevated CO2, the enhanced bottom-up forcing propagated through all trophic levels. Elevated temperature, however, negated the benefits of elevated CO2 by stalling secondary production. This imbalance caused secondary producer populations to decline as elevated temperature drove predators to consume their prey more rapidly in the face of higher metabolic demand. Our findings demonstrate how anthropogenic CO2 can function as a resource that boosts productivity throughout food webs, and how warming can reverse this effect by acting as a stressor to trophic interactions. Understanding the shifting balance between the propagation of resource enrichment and its consumption across trophic levels provides a predictive understanding of future dynamics of stability and collapse in food webs and fisheries production.
Read more (paywalled): http://onlinelibrary.wiley.com/doi/10.1111/gcb.13699/abstract
Note: the link to the study does not work in some web browsers, I had to view it using Google Chrome
Unfortunately the full study is paywalled, but attempting to infer global consequences of increased CO2 from a toy eco-system in a 2000 litre fish tank is absurd.
On the positive side, the researchers performed an actual experiment, rather than just running a computer model.
But anyone who has ever kept fish knows how difficult it can be to keep a fish tank eco-system stable. Fish in a tank are subject to numerous stresses, even a small mistake with feeding, water contamination or filtering waste can lead to disease and death.
If the researchers had instead studied regions of the ocean with elevated CO2 levels, they would have discovered plenty of places in the ocean where CO2 levels are naturally elevated well beyond anything anthropogenic CO2 will achieve, due to natural outgassing from volcanic sources.
Many of these reefs are ridiculously healthy, despite corals and fish growing in water which is continuously totally saturated with CO2.
The existence of healthy natural reefs with populations of fish growing in regions of the ocean which are full of CO2, strongly suggests whatever killed the fish in that 2000 litre research tank had nothing to do with CO2.
Maybe somebody who has read the actual article can tell us: are there control tanks in their methods? I would surely expect real live, paid scientists to draw their conclusions from a comparison to the bathtubs where they didn’t monkey with the controls.
I did a quick back of the envelope calculation and 2,000 l is 2 cubic meters – that is a tank 2m by 1m by 1m. I was convinced that I had done this wrong – surely they couldn’t be publishing data from such a small tank? No, I have it right (as have all the other posters here – but I couldn’t visualise gallons any more than i could visualise litres) – 2 x1 x1.
And their contention is that it is predators eating all the prey fish that stuff it up? There is no room in such a tank for a predator-prey relationship to develop (nor enough time in a 2-3 month study). This shows the most appalling ignorance of ecology and food-webs, yet it was apparently published by two professors. Stunned.
2000 L is about the largest commercially available fish tank you can buy, but it is readily available for purchase from several locations, with decorative wooden stands too. You typically see them in doctors offices or office building lobbies. This isn’t even the size of the smallest of ponds. I definitely agree that it’s malfeasance to interpret anything from such a tiny sample size, especially given how easy it is to massacre your fish by accident.
Copeland, B. J. 1965. Evidence for regulation of community metabolism in a marine environment. Ecology. 46(4):562-564.
When I was in graduate school, he got algae, before current gas levels. Easy to do, called regulation, compensation, etc.
Check their appendix, someone tell me where the “acid is.” Check Table 1 for Total Alkalinity.
http://onlinelibrary.wiley.com/store/10.1111/gcb.13699/asset/supinfo/gcb13699-sup-0001-AppendixS1.pdf?v=1&s=1523f557a0fe4e890531a38aeaf166e383fdd91e
The bad thing is that these sorts of studies are used as justification for pet projects paid for by taxpayers. Got one where I live. Big fad for sequestration of nitrogen by oysters, now I hear it is good for carbon dioxide. Failure to understand laws of thermodynamics, among others. It is in “major” journals, those high in “Impact Factors.”
There are better researchers down under.
They probably filled it with a garden hose.
Here’s a similarly story/study that uses a fish tank to cook and corrode .
This appears to be an alarming discovery. After all if ocean conditions are already doing this what next?
http://www.sacbee.com/news/local/environment/article146505289.html
Sea life dissolves quickly in warming waters off California coast, UC Davis finds
Read more here: http://www.sacbee.com/news/local/environment/article146505289.html#storylink=cpy
But then if you look at the study you’ll learn that it is NOT the waters off the coast where this has happened .
https://www.ucdavis.edu/news/honeycomb-shaped-sea-creature-dissolves-under-current-warming-acidic-conditions
It’s in their lab experiments where they add the heat and acid to a tank.
“Canary in the Kelp Forest
Sea Creature Dissolves in Today’s Warming, Acidifying Waters
In the study, published in the journal Proceedings of the Royal Society B: Biological Sciences, researchers at the UC Davis Bodega Marine Laboratory raised bryozoans, also known as “moss animals,” in seawater tanks and exposed them to various levels of water temperature, food and increased acidity.
The scientists found that when grown in warmer waters and then exposed to acidity, the bryozoans quickly began to dissolve. Large portions of their skeletons disappeared in as little as two months.
“We thought there would be some thinning or reduced mass,” said lead author Dan Swezey, a recent Ph.D. graduate in professor Eric Sanford’s lab at the UC Davis Bodega Marine Laboratory. “But whole features just dissolved practically before our eyes.”
Here’s a similar fish tank study.
It appears to be an alarming discovery. After all if ocean conditions are already doing this what next?
http://www.sacbee.com/news/local/environment/article146505289.html
Sea life dissolves quickly in warming waters off California coast, UC Davis finds
Read more here: http://www.sacbee.com/news/local/environment/article146505289.html#storylink=cpy
But then if you look at the study you’ll learn that it is NOT the waters off the coast where this has happened.
It’s in their lab experiments where they add the heat and acid to a tank.
Canary in the Kelp Forest
Sea Creature Dissolves in Today’s Warming, Acidifying Waters
https://www.ucdavis.edu/news/honeycomb-shaped-sea-creature-dissolves-under-current-warming-acidic-conditions
In the study, published in the journalProceedings of the Royal Society B: Biological Sciences, researchers at the UC Davis Bodega Marine Laboratory raised bryozoans, also known as “moss animals,” in seawater tanks and exposed them to various levels of water temperature, food and increased acidity.
The scientists found that when grown in warmer waters and then exposed to acidity, the bryozoans quickly began to dissolve. Large portions of their skeletons disappeared in as little as two months.
“We thought there would be some thinning or reduced mass,” said lead author Dan Swezey, a recent Ph.D. graduate in professor Eric Sanford’s lab at the UC Davis Bodega Marine Laboratory. “But whole features just dissolved practically before our eyes.”
materials and methods from the manuscipt:
2.1 Mesocosms
Our mesocosm simulated a shallow temperate coastal ecosystem with high level of realism. Twelve circular mesocosms each with a volume of 1,800 L were maintained indoors at a research station (February–July 2015), and habitats and organisms were collected in the vicinity between 1 and 5 m depth. The mesocosms comprised a mosaic of the three principle local habitat types (Fig. S1, S2; Gulf St. Vincent, South Australia; Bryars & Rowling, 2009): (i) “artificial seagrass” with epiphytes planted into fine silica sand 6 cm deep, (ii) “open sand” composed of the same sand 6–25 cm deep, and (iii) “rocky reef” made of natural rocks including associated macrophytes and invertebrates. The two soft-bottom habitats were additionally seeded with 25 L natural sediment collected amongst seagrass meadows and including all infauna and flora. In the flow-through system, unfiltered seawater from 1.5 km off-shore (~8 m depth) continuously supplied nutrients and planktonic propagules to each mesocosm at 2,300 L/day. To simulate tidal water movement, a diffuser formed a light circular current in the mesocosms alternating direction in 6-hr intervals. A lamp was mounted above each mesocosm with a spectrum close to sunlight and an irradiance corresponding to a local water depth of ~6–7 m (14/10 light-dark cycle, 30 min dawn and dusk dimming).
2.2 Climate treatments
Ocean acidification (levels: ambient and elevated CO2) was manipulated in crossed combination with ocean warming (levels: ambient and elevated temperature), using three replicate mesocosms per treatment combination (see Table S1 for details on water parameters). We achieved a mean elevated pCO2 of 900 ppm (pH = 7.89) and temperature rise of +2.8°C, which represented the conditions predicted for the end of this century following a business-as-usual emission scenario (RCP8.5; Bopp et al., 2013). We applied an ambient temperature of 21°C, corresponding to average summer temperature based on a 5 year dataset of two local loggers (5 m depth, 2010–2015, SA Water). For the ocean acidification treatment, the incoming seawater was preconditioned to elevated pCO2 levels with pure CO2 in a header tank. Additionally, water was continuously circulated between each mesocosm and a separate bin heavily bubbled with enriched air at 1,000 ppm pCO2. Submersible titanium heaters were used in the elevated temperature treatments. Temperature and pH were measured daily and alkalinity fortnightly in each mesocosm. As typical for shallow coastal systems, community metabolism produced diurnal variability in pH and reduced pCO2 to 900 ppm due to net autotrophy.
2.3 Food web assessment
We studied a sediment-associated three-level food web including predatory fish, herbivorous invertebrates and microalgae. Longfin gobies (Favongobius lateralis) were the principle predators on the soft-bottom habitat, where they took bites at the sand to catch small invertebrates (see Appendix S1—predators). Seven juveniles caught with seine nets were introduced to each mesocosm (mean ± SD total length = 22 ± 4 mm) and first habituated to captivity for 1 month. Then, the mesocosm communities were progressively acclimatized to their respective climate treatment over 1 week and kept at treatment levels for 3.5 months. This duration was considered as sufficiently long to reach an extended level of acclimation in the predators and allowed for potentially ~1–10 (depending on taxa) herbivore and ~100 microalgae generations. Predators tripled in body mass confirming that the mesocosms provided ample food and habitat. Finally, predator production was estimated as the combined gain in mass of all gobies within each mesocosm over the entire study period.
To assess production and standing biomass of herbivores, three different sampling units were built using the bottom part of plastic vials (6.5 cm diameter, 2 cm depth): (i) covered by mesh (~5 mm mesh size) to exclude predators for measurement of production, (ii) entirely open and accessible to predators for measurement of standing biomass, and (iii) covered by an elevated mesh allowing predators to enter as a procedural control for the presence of the mesh. The units were filled with 1.5 cm of mesocosm sand, which had been washed superficially to remove any excess organic matter while retaining low levels of herbivores. Then, units were placed on the “open sand” habitat and herbivore populations allowed to grow out for 1 month at the end of study period.
Herbivores were sampled within two units per mesocosm for each production, standing biomass and the procedural control. The replicate units for each measure were then pooled prior to sample processing. Herbivores were extracted from the sand via floatation with Ludox TM colloidal solution with a specific gravity of 1.18 and collected on a 120-μm sieve. The three dominant invertebrate taxa, which also corresponded to the principle prey found in the predators’ stomachs (see Appendix S1—predators), were counted under a stereo-microscope (see Appendix S1—herbivores). A subsample of the two smaller taxa, copepods (~0.2–1 mm) and annelids (~0.6–5 mm) was photographed to determine average individual mass based on biovolume estimates, which was then applied to the count of each sample. The considerably larger tanaid shrimps (~2–5 mm) were instead weighed on a microscale (±0.1 mg). The combined wet mass of these three taxa was finally calculated (~830 individuals per sample). There was no main effect of the mesh (ANOVA: df(1,8), p = .54) or interaction between the effect of the mesh and climate treatments (ANOVA: df(1,8), p > .11 for all interactions), and thus, procedural control and standing biomass units were pooled. Finally, the estimates from the units were extrapolated to the area of the entire soft-bottom habitat resulting in one replicate of both herbivore production and standing biomass per mesocosm.
Microalgae were assessed using sampling units for production, standing biomass and the procedural control which were identical to those used for the herbivores. Prior to placement into the mesocosms, herbivores had, however, been removed from the covered units for microalgae production (n = 2 per mesocosm) using boiling water. Herbivores (and predators) were instead present in the open units for microalgae standing biomass (n = 4 per mesocosm) and the procedural control (n = 4 per mesocosm). Microalgae were allowed to recolonize the sand surface inside the units over 1 month at the end of the study period.
Chlorophyll a served as a proxy for microalgae biomass. It was extracted from each unit with 90 % acetone, measured spectrophotometrically (6,405 UV/Vis, Jenway) and its concentration calculated (Jeffrey & Humphrey, 1975). There was no interaction between the effect of the mesh and climate treatments (ANOVA: df(1,8), p > .30 for all interactions), and thus, units for standing biomass and the procedural control were pooled. For the data analysis, the average across units was calculated and then extrapolated to the area of the entire soft-bottom habitat resulting in one replicate for both microalgae production and standing biomass per mesocosm.
2.4 Predator behaviour and food demand
To assess the predators’ response to an olfactory food cue, a behavioural experiment was conducted within the mesocosm. A food cue disperser containing a food mix of various invertebrates was placed on the “open sand” habitat to start the test. Then, the surrounding area was video recorded from the top and side for 7 min (Fig. S2). A target was overlayed during the subsequent video analysis and the behaviour of each predator manually recorded using the software Solomon Coder. We interpreted the number of line crosses into and within the target as food search activity. This behavioural test was conducted on two different days in the final month of the study, each day at a different area within the mesocosm. The behaviour during all individual predator observations during both days was summed and the response variable “line crosses per minute” calculated. A procedural control preceding each trial showed identical foraging activity for all climate treatments in the absence of a food cue (Fig. S4a), suggesting that any difference in behaviour during the trials was due to the presence of the olfactory food cue.
To determine food demand, the predators were captured and starved for 20 hr (i.e. gastric evacuation). Then, before being sacrificed, they were released back into their original mesocosm to forage freely for 4 hr. The prey in their stomach was counted under a stereo-microscope and the average mass of prey organisms estimated applying the taxa-specific mass obtained from the herbivore units. The temperature sensitivity of digestion rate, however, made a direct comparison of stomach contents between levels of warming less reliable. Therefore, the predators’ attack rate at the benthos was determined by video recording an area of each mesocosm from the top for 10 min on each of 3 different days. The consumption of prey relative to the predator’s mass was calculated for each mesocosm as follows: feeding rate = attack rate of predators × average mass of prey organisms/predator mass.
2.5 Statistical analysis
Normality and homogeneity of variance were improved by transformation if appropriate, and assumptions were met for all analyses (Shapiro–Wilk test, Levene’s test and visual examination of residuals). To assess the effect of future climate on the different response variables measured, two-way ANOVAs were conducted with ocean acidification and warming as fixed factors. These were followed by Student–Newman–Keuls post hoc tests in case a significant interaction was found between the climate treatments. For a more detailed assessment of how future climate may affect the propagation of secondary to tertiary production, a linear model with ocean acidification and warming as fixed factors, herbivore production as covariate and predator production as response variable was examined. As there was no evidence for an altered relationship between secondary and tertiary production under future climate (Table S3), a final linear regression was fitted across all climate treatments. Data analyses were performed with the software package R version 3.2.3 (R Core Team, 2015).
Does the word “adaptation” mean anything to these so-called scientists? You can’t just raise the temperature all at once (or even over weeks or months) thereby bypassing the changes that adaptations provide. Charles Darwin is currently rolling over in his grave!
Well those Chinese (or is it Siamese) Fighting Fish quickly adapt to living in an ecosystem that contains nothing but the fish and water, and just 500 millilitres of that, about the size of a 60 watt light bulb.
They do fine. Well it does. But if you halve the ecosystem volume per fish, by adding a second fish, the whole system goes pear shaped.
G
We fizzed up our fish and they died /
In a fish-tank four feet on a side /
For sea we’d no room /
But we got algae bloom /
Once again, we greens bring a red tide.
what they did was relatively rapidly change the environment, a small closed system and created an imbalance. The imbalance due to CO2 injection and temp increase would destabalise the eco system, in 2000 litre tank this effect is greatly increased as natural environments fluctuate and are not solid state environments. The tank is a solid state environment.
I’ve built reefs and bred wild fish for years. Because you are dealing with a tiny closed body of water, its very easy to push that tank’s ecosystem out of balance by simply adjusting a parameter or two where in the natural environment 1. change does not happen that instantly and everywhere at once, 2. This sudden change allows for no natural adaption or such that may occur as with slow changes.
This is junk science
I agree and also noticed there was no mention of the systems having been allowed time for the nitrification bacteria to properly cycle. Throwing fish mass into water, they’ll be highly active in the warmer water, feeding hardily, so I suspect ammonia spikes were very pronounced and unusually lethal that the near neutral pH of the water. There was no mention of ammonia or nitrite levels.
Yes how they controlled this tank is of importance.
Feeding changes cause a nitrate buildup, you need a good protein skimmer too.
I’d have many questions about the experiment setup. You can easily introduce something by accident into the system too if you dont know what you are doing, there is no replacement for experience.
You can wreck any biotope by gradually increasing temperature.
Also, in an aquarium changing temperature changes O2 levels fast, that does not happen in the ocean
Even the dimensions of the tank they used matters in this experiment. Use the wrong dimensions, bad water flow, how the contents of the tank are arranged. Water changing schedule. Water testing schedule. Monitoring. What was added to the tank and when, did they use quarantine for later additions.
Then the water, did they use RO or did they actually use ocean water. Filtration system and maintenance, lighting heating and any problems and how did they address them.
I would then have a bunch of questions relating to the stock in the tank
These ocean-climate-doom-from-fishtanks studies are – unfortunately – a well worn theme. Results from fishtanks are even more unreliable than from computer simulations of climate. I remember during postgraduate oceanography studies doing a research cruise where they collected excellent depth sampled water and plankton samples using a towed undulating torpedo-like collector. We got a lot of good data including my own MSc project on mackerel larval first feeding. But they insisted on adding a fishtank study. I don’t know why – we were surrounded by real sea – the Celtic Sea to the north, Bay of Biscay to the south. Nevertheless in our tubby French trawler converted to “research vessel” we had to set up a fishtank and try to grow tiny fish larvae and feed them copepods. At least when all the larvae inevitably died they just accepted it as a noble failure and didn’t politicise it into evidence of human environmental culpability in the sea. Although I think the Plymouth (the original one in the UK) Marine Research Lab – but still called IMER back then – is much more politicized now than then.
The fact remains though that such fishtank studies are wretchedly pointless and should be outlawed in marine biology. There are many factors in tiny artificial cubes of seawater and their unstable transient ecosystems that are entirely unrelated to the actual marine environment.
I knew this was coming when schools started “dissecting” things on a computer. The dive into fantasy and the Maxtrix was not far behind.
So, how does a study like this make it through their precious peer review?
I swear that I only posted t his once.
So, how does a study like this make it through their precious peer review?
So they cooked the fish after adding salt and vinegar, not before?
Love it!
2000 Litres. that’s a box 2 metres by 1 metre by 1 metre. That’s smaller than a lot of home aquaria. Filed under “Ignore”.
You can just imagine the fish in the tank, saying “Anyone know how you drive this thing?”
These warmists are messing with the global fish tank ecosystem and the Nemos of the world will fight back with swift retribution and the attack of the killer coral spores-
http://www.adelaidenow.com.au/news/south-australia/family-of-six-hospitalised-after-being-overwhelmed-by-noxious-gases-at-aldinga-beach-home/news-story/753f3fd0e771f6830748f47cdcee791a
You mess with natural bleaching of corals and they’re coming to get us warmies and no fish tank will stop them. Doomed I tell ya, we’re all doomed!
Since this paper is from three people from University of Adelaide I propose it be ignored on the grounds that Australian Universities jumped the shark on climate science long ago and have contributed nothing enlightening or useful for years.
All of you who are dismissing the finding of these scientists are doing a great disservice to true science. I was able to replicate the results of their experiment using my 3 gallon cooking pot. I placed several live sea creatures, lobsters to be precise, in the pot, added water, put it on the stove and slowly raised the temperature of the water. Within 15 minutes all of the lobsters had died, all as a result of warming. You may laugh now, but you can’t deny the science.