Posts Tagged 'annelids'

Effect of ocean acidification and elevated temperature on growth of calcifying tubeworm shells (Spirorbis spirorbis): an in-situ benthocosm approach

The calcareous tubeworm Spirorbis spirorbis is a wide-spread serpulid species in the Baltic Sea, where it commonly grows as an epibiont on brown macroalgae (genus Fucus). It lives within a Mg-calcite shell and could be affected by ocean acidification and temperature rise induced by the predicted future atmospheric CO2 increase. However, Spirorbis tubes grow in a chemically modified boundary layer around the algae, which may mitigate acidification. In order to investigate how increasing temperature and rising pCO2 may influence S. spirorbis shell growth we carried out four seasonal experiments in the ‘Kiel Outdoor Benthocosms’ at elevated pCO2 and temperature conditions. Compared to laboratory batch culture experiments the benthocosm approach provides a better representation of natural conditions for physical and biological ecosystem parameters, including seasonal variations. We find that growth rates of S. spirorbis are significantly controlled by ontogenetic and seasonal effects. The length of the newly grown tube is inversely related to the initial diameter of the shell. Our study showed no significant difference of the growth rates between ambient atmospheric and elevated (1100 ppm) pCO2 conditions. No influence of daily average CaCO3 saturation state on the growth rates of S. spirorbiswas observed. We found, however, net growth of the shells even in temporarily undersaturated bulk solutions, under conditions that concurrently favored selective shell surface dissolution. The results suggest an overall resistance of S. spirorbis growth to acidification levels predicted for the year 2100 in the Baltic Sea. In contrast, S. spirorbis did not survive at mean seasonal temperatures exceeding 24 °C during the summer experiments. In the autumn experiments at ambient pCO2, the growth rates of juvenile S. spirorbis were higher under elevated temperature conditions. The results reveal that S. spirorbis may prefer moderately warmer conditions during their early life stages but will suffer from an excessive temperature increase and from increasing shell corrosion as a consequence of progressing ocean acidification.
Continue reading ‘Effect of ocean acidification and elevated temperature on growth of calcifying tubeworm shells (Spirorbis spirorbis): an in-situ benthocosm approach’

Impacts of ocean acidification on sperm develop with exposure time for a polychaete with long lived sperm

The majority of marine invertebrate species release eggs and sperm into seawater for external fertilisation. Seawater conditions are currently changing at an unprecedented rate as a consequence of ocean acidification (OA). Sperm are thought to be particularly vulnerable to these changes and may be exposed to external environmental conditions for variable periods of time between spawning and fertilisation. Here, we undertook a mechanistic investigation of sperm swimming performance in the coastal polychaete Arenicola marina during an extended exposure to OA conditions (pHNBS 7.77, 1000 μatm pCO2). We found that key fitness-related aspects of sperm functioning declined faster under OA conditions i.e. impacts became apparent with exposure time. Sperm swimming speed (VCL), the number of motile sperm and sperm path linearity all dropped significantly after 4 h under OA conditions whilst remaining constant under ambient conditions at this time point. Our results highlight the importance of sperm exposure duration in ocean acidification experiments and may help towards explaining species specific differences in response.

Continue reading ‘Impacts of ocean acidification on sperm develop with exposure time for a polychaete with long lived sperm’

Physiological and biochemical impacts induced by mercury pollution and seawater acidification in Hediste diversicolor

The present study evaluated the impacts of predicted seawater acidification and Hg pollution, when stressors were acting alone and in combination, on the polychaete Hediste diversicolor. Polychaetes were exposed during 28 days to low pH (7.5), Hg (5 μg/L) and pH 7.5 + Hg, and physiological alterations (respiration rate), biochemical markers related to metabolic potential (glycogen and protein content, electron transport system activity) and oxidative status (activity of antioxidant and biotransformation enzymes, lipid peroxidation) were evaluated. The results obtained clearly showed that polychaetes were sensitive to low pH and Hg contamination, both acting alone or in combination. Organisms used their energy reserves under stressful conditions, which decreased by up to half of the control content, probably to fuel defence mechanisms. Our findings further demonstrated that polychaetes exposed to these stressors presented increased antioxidant defence mechanisms (3 fold compared to control). However, organisms were not able to prevent cellular damage, especially noticed at Hg exposure and pH 7.5. Overall, although all the tested conditions induced oxidative stress in Hediste diversicolor, the combined effect of seawater acidification and Hg contamination did not induce higher impacts in polychaetes than single stressor exposures. These findings may indicate that predicted climate change scenarios may not increase Hediste diversicolor sensitivity towards Hg and may not significantly change the toxicity of this contaminant to this polychaete species.

Continue reading ‘Physiological and biochemical impacts induced by mercury pollution and seawater acidification in Hediste diversicolor’

Altered epiphyte community and sea urchin diet in Posidonia oceanica meadows in the vicinity of submarine volcanic CO2 vents

Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two naturally acidified sites (i.e. north and south sides of a volcanic CO2 vent) and in a control site away from the vent at the Ischia Island (NW Mediterranean Sea) significantly differed in composition and abundance. Such differences involved a higher abundance of non-calcareous crustose brown algae and a decline of calcifying polychaetes in both acidified sites. A lower epiphytic abundance of crustose coralline algae occurred only in the south side of the vents, thus suggesting that OA may alter epiphyte assemblages in different ways due to interaction with local factors such as differential fish herbivory or hydrodynamics. The OA effects on food items (seagrass, epiphytes, and algae) indirectly propagated into food provision to the sea urchin Paracentrotus lividus, as reflected by a reduced P. oceanica exploitation (i.e. less seagrass and calcareous epiphytes in the diet) in favour of non-calcareous green algae in both vent sites. In contrast, we detected no difference close and outside the vents neither in the composition of sea urchin diet nor in the total abundance of calcareous versus non-calcareous taxa. More research, under realistic scenarios of predicted pH reduction (i.e. ≤ 0.32 units of pH by 2100), is still necessary to better understand cascading effects of this altered urchin exploitation of food resources under acidified conditions on ecosystem diversity and function.

Continue reading ‘Altered epiphyte community and sea urchin diet in Posidonia oceanica meadows in the vicinity of submarine volcanic CO2 vents’

Marine gametes in a changing ocean: Impacts of climate change stressors on fecundity and the egg

In marine invertebrates, the environmental history of the mother can influence fecundity and egg size. Acclimation of females in climate change stressors, increased temperature and low pH, results in a decrease in egg number and size in many taxa, with the exception of cephalopods, where eggs increase in size. With respect to spawned eggs, near future levels of ocean acidification can interfere with the eggs’ block to polyspermy and intracellular pH. Reduction of the extracellular egg jelly coat seen in low pH conditions has implications for impaired egg function and fertilization. Some fast generation species (e.g. copepods, polychaetes) have shown restoration of female reproductive output after several generations in treatments. It will be important to determine if the changes to egg number and size induced by exposure to climate change stressors are heritable.

Continue reading ‘Marine gametes in a changing ocean: Impacts of climate change stressors on fecundity and the egg’

Impact of predicted climate change scenarios on a coral reef meiofauna community

Changes in marine communities in response to elevated CO2 have been reported but information on how representatives of the benthic lower trophic levels will be impacted remains scarce. A laboratory experiment was conducted to evaluate the impact of different climate change scenarios on a coral reef meiofauna community. Samples of the meiofauna community were collected from the coral reef subtidal zone of Serrambi beach (Ipojuca, Pernambuco, Brazil), using artificial substrate units. The units were exposed to control treatments and to three climate change scenarios, and collected after 15 and 29 d. Important changes in the meiofauna community structure were observed after 15 d of exposure. The major meiofauna groups exhibited divergent responses to the various scenarios. Although polychaetes were negatively affected after 29 d in the most severe scenario (Scenario III), harpacticoid copepods were negatively affected in Scenarios II and III after 15 and 29 d. Harpacticoid nauplii were strongly and negatively affected in all scenarios. In contrast, Nematoda exhibited higher densities in all scenarios. To the best of our knowledge, this community-based study was the first to observe how meiofauna organisms from a coral reef environment react to the synergetic effects of reductions in seawater pH and increased temperature.

Continue reading ‘Impact of predicted climate change scenarios on a coral reef meiofauna community’

Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment

Highlights

  • CO2 seeps at two coral reefs in Papua New Guinea were used as natural analogues of ocean acidification.
  • Elevated CO2 affected recruitment in marine invertebrate communities.
  • Calcified recruits of reef-dwelling Foraminifera, polychaetes, gastropods, and bivalves were vulnerable to acidification.
  • Amphipods and copepods, which are important prey taxa, were adversely affected by acidification caused by elevated CO2.


Abstract

Rising atmospheric CO2 concentrations are causing ocean acidification by reducing seawater pH and carbonate saturation levels. Laboratory studies have demonstrated that many larval and juvenile marine invertebrates are vulnerable to these changes in surface ocean chemistry, but challenges remain in predicting effects at community and ecosystem levels. We investigated the effect of ocean acidification on invertebrate recruitment at two coral reef CO2 seeps in Papua New Guinea. Invertebrate communities differed significantly between ‘reference’ (median pH 7.97, 8.00), ‘high CO2’ (median pH 7.77, 7.79), and ‘extreme CO2’ (median pH 7.32, 7.68) conditions at each reef. There were also significant reductions in calcifying taxa, copepods and amphipods as CO2 levels increased. The observed shifts in recruitment were comparable to those previously described in the Mediterranean, revealing an ecological mechanism by which shallow coastal systems are affected by near-future levels of ocean acidification.

Continue reading ‘Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment’


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Ocean acidification in the IPCC AR5 WG II

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