Aquatic publication review (29)

In the study of the hydrosphere and the environmental components associated with it, the topic of the effects of climate change is impossible to escape. Whether one likes it or not, the facts are that our world is changing at a rate never before recorded, which is a cause for many questions and intriguing hypotheses. Because climate change affects everything – it favors biological invasions, can remodel the soil seed bank in the Atlantic Forest, change the severity, extent and frequency of drought in the western US states, and double the rate of global ocean level rise. It also causes coral reefs to fade, which can be saved by inoculating the water with probiotic microorganisms. The question is whether they are safe for non-target organisms.

Another bane of our waters is chemical pollution. Studies on the effects of exposure of striped danio to polystyrene microplastics indicate a link between exposure to these plastics and the development of polycystic ovary syndrome. Be careful what you drink!

1. Effects of temperature and N:P ratio on the invasion success of the cyanobacterium Raphidiopsis raciborskii

Meriggi C., Johnson R.K., Laugen A.T., Drakare S., (2024) Effects of temperature and N:P ratio on the invasion success of the cyanobacterium Raphidiopsis raciborskii. Aquatic Invasions 19(3): 275-286.

Recently, there have been more and more reports of environmental problems associated with invasive plankton organisms. If not our “favorite” golden alga, then the tropical freshwater cyanobacteria Raphidiopsis raciborskii. The latter species was first recorded in Central Europe about two decades ago, and is now relatively widespread and continues to expand its geographic range. Because it forms blooms and produces toxins, an increase in its population can negatively affect local biodiversity and ecosystem services, although its behavior in the waters of different geographic regions is not recognized.

A team of Scandinavian scientists conducted a laboratory experiment to study the competitiveness of R. raciborskii in interaction with other phytoplankton taxa typically found in Scandinavian lakes (diatoms, green algae and cyanobacteria). The experimental setup included three temperature conditions (17°C; 22°C; 26°C) and three variants of nutrient conditions (N:P ratio 8:1; 16:1; 32:1).

In none of the environmental variants tested did R. raciborskii become the dominant species, but in all of them it was able to proliferate and maintain biomass, even in relatively cool water (17°C). Temperature proved to be an important factor shaping the taxonomic composition of the phytoplankton community of the Scandinavian lakes, with Raphidiopsis raciborskii proving more competitive than Planktothrix agardhii at low temperatures, but less so than Microcystis aeruginosa. The results of the study demonstrate that R. raciborskii can survive at relatively high latitudes and establish itself in ecosystems such as Scandinavian lakes.

2. water restriction alters seed bank traits and ecology in Atlantic Forest seasonal forests under climate change

Borges Diaz P., Horn Kunz S., Macedo Pezzopane J. E. et al, 2024. Water restriction alters seed bank traits and ecology in Atlantic Forest seasonal forests under climate change. Global Change Biology.

The Soil Seed Bank(SSB) is one of the key mechanisms for ensuring the sustainability of forest ecosystems. Knowledge of how projected climate change will affect this essential component of the ecology is still very limited. A team from several research centers in Brazil conducted a study to assess the germination potential, ecological attributes and selected functional characteristics of SSB in a seasonal Atlantic Forest (Atlantic Forest, port. Mata Atlântica) under different climate scenarios (current and future RCP8.5) and under different levels of irrigation (unconstrained and constrained water availability as assessed by the WHC, or water-holding capacity index).

After 5 months of SSB incubation under controlled conditions, the number of exclusive (exclusive) species ranged from 24 in the current scenario without water restrictions, 22 in the current scenario with water restrictions, 16 in the future scenario without restrictions, to only 6 in the future scenario with water restrictions. All assessed ecological attributes and functional traits (such as leaf area, biomass production, density, richness or taxonomic diversity) were significantly reduced in the future projection, especially in the scenario with water restriction.

The results indicate that water scarcity, especially in future warmer scenarios, could significantly reduce seed viability and forest regeneration capacity. The effects of climate change shown in the study could alter the overall structure of seasonal forests in the future, and result in a loss of SSB regeneration potential due to reduced seed viability and increased mortality of juvenile individuals.

3. anthropogenic warming has ushered in an era of temperature-dominated droughts in the western United States

Zhuang Y., Fu R., Lisonbee J. et al. (2024).Anthropogenic warming has ushered in an era of temperature-dominated droughts in the western United States. Sci. Adv. 10, eadn9389 (2024).

As we are on the effects of climate change, of course, there can be no missing the thread of drought, which is increasingly affecting many areas of the globe, including the United States. Historically, meteorological drought in the western states has been caused mainly by rainfall deficits. However, an analysis of National Oceanic and Atmospheric Administration (NOAA) precipitation data from 1948 to 2022, conducted by U.S. scientists at the University of California and NOAA, shows that since about 2000, rising surface temperatures and the resulting increased evaporation (evapotranspiration) have contributed more to the severity (62 percent) and extent (66 percent) of the drought in the western U.S. than the precipitation deficit. The increase is particularly noticeable in Southern California, Nevada and the Four Corners region (the four-state quadrangle of Utah, Colorado, New Mexico and Arizona).

Based on an analysis of field observations and climate model simulations, the authors conclude that the main reason for the increased severity and extent of drought in the study area is an increase in evapotranspiration, mostly caused by anthropogenic warming. An example of such a change in factors is the unprecedented drought in the western United States between 2020 and 2022, for which evaporation was responsible for 61 percent, compared to 39 percent explained by a precipitation deficit.

Climate model simulations predict that in the fossil fuel-based development scenario (SSP5-8.5), droughts such as this one will occur not with the current frequency of once every thousand-plus years, but once every 60 years by the mid-21st century and once every six years by the end of the 21st century. We wish the people of the Western U.S. much satisfaction with the development of the fossil fuel economy.

4. the rate of global sea level rise doubled during the past three decades

Hamlington B.D., Bellas-Manley A., Willis J.K. et al. The rate of global sea level rise doubled during the past three decades. Commun Earth Environ 5, 601 (2024).

As we have written in the past – when it dries up some, it floods others. The rise in global mean sea level is one of the clearest indicators of climate change. And according to satellite data, global sea levels are rising twice as fast as they were three decades ago. Between 1993 (when such measurements began) and the end of 2023, as Benjamin Hamlington of NASA’s Jet Propulsion Laboratory in Pasadena, California, and his colleagues showed, global mean sea level rose by 111 mm, and the rate of that rise increased from about 2.1 mm/year to about 4.5 mm/year.

Climate change is accelerating two processes that shape the amount of water in the seas and oceans: melting ice and increasing water volume due to heat absorption from greenhouse gas emissions (thermal expansion). Scientists predict that if this trajectory continues over the next three decades, sea levels will rise by an additional 169 mm worldwide.

5. not only for corals: exploring the uptake of beneficial microorganisms for corals by sponges

Ribeiro B., N. Garritano A., Raimundo I. et al. (2024). Not only for corals: exploring the uptake of beneficial microorganisms for corals by sponges. npj Biofilms Microbiomes 10, 125.

The phenomenon of coral fading due to destabilization of symbiosis with photosymbionts as a result of climate warming is well known and fairly well studied. One way to support corals against anthropogenic stressors is to rebuild their microbiome using so-called beneficial microorganisms for corals (BMC). An interesting issue is the interaction of BMCs and non-target organisms, such as sponges.

The researchers set out to investigate whether sponges belonging to the model species, Stylissa carteri and Callyspongia crassa, incorporate probiotic bacteria used as BMCs into their biome, and whether such inoculations can affect host health. Based on a four-week experiment conducted in three variants (no BMC inoculation, inoculation once and inoculation three times a week), the authors found that in the case of S. carteri, probiotic strains naturally populated the microbiome in low numbers, and that after BMC inoculation, the abundance of two of them (BMC-Cobetia and BMC-Pseudoalteromonas) increased. In contrast, there was no natural presence of BMC-associated bacteria in the microbiome of C. crassa, nor was it proven that this sponge could acquire these microorganisms after inoculation. The sponges were visually healthy and continued to filter water efficiently at the end of the experiment.

The results indicate that the application of BMC to nearby corals can alter the structure of the microbiome of neighboring sponges, potentially affecting them, but these effects do not impair their vital functions. These studies support the view that inoculation of corals with probiotics has potentially very limited or negligible negative effects on the fitness of non-target organisms, which is an important criterion for the safe use of probiotics under field conditions.

6. Evaluating the potential of daily intake of polystyrene microplastics via drinking water in inducing PCOS and its ovarian fibrosis progression using female zebrafish

Adhikari M., Biswas Ch., Mazumdar P. et al, (2024). Evaluating the potential of daily intake of polystyrene microplastics via drinking water in inducing PCOS and its ovarian fibrosis progression using female zebrafish. NanoImpact, 34.

It is not particularly revealing to say that consuming water contaminated with microplastics will not do us any good. Polystyrene microplastics are widely known to be endocrine and reproductive disrupting chemicals. Despite numerous reports on the reproductive and endocrine toxicity of these particles, the literature on the daily intake of polystyrene microplastics in drinking water, which promote polycystic ovary syndrome (PCOS) and lead to ovarian fibrosis, is quite sparse.

Researchers led by Prof. K. Pramanick of Presidency University in Kolkata exposed female striped danios to polystyrene microplastics in drinking water for three weeks and compared selected reproductive traits with a control group kept in clean water. In fish exposed to microplastic, the level of testosterone, naturally produced there in small amounts, increased significantly in the ovaries. In microplastic-induced PCOS, excess testosterone in the ovaries interferes with the growth and development of follicles, impeding ovulation or egg release.

The exposed fish also showed a decrease in levels of folliculotropic hormone, which plays a role in sexual and reproductive development, while body weight increased due to fat deposition in the intestines and ovaries. These features are characteristic of PCOS, including in humans. Polystyrene microplastics have played a key role in the induction of PCOS in fish, but the results in the striped danios can be extrapolated to females, which may help develop treatments.