Posts Tagged 'South Pacific'

Kon-Tiki2 expedition 2015-2016: scientific cruise report

The Kon-Tiki2 Expedition was partly an anthropogenic exploration and partly an interdisciplinary oceanic and atmospheric research expedition. As a research expedition it was unique for three reasons: 1) The type of vessel used, 2) the timing of the expedition, and 3) the geographical location. The scientific program was run onboard the ancient design balsa rafts, powered by solar power only, with almost no possibility of stopping the raft, during a year with the strongest El Niño recorded in human history, in the midst of the center of that El Niño, namely in the area between Peru, Easter Island and the Chilean mid-latitudinal coast.

The scientific expedition planned and organized as a cooperation between the NIVA and NTNU in Norway. It was divided in two legs: the transect from Peru to Easter island and from Easter Island until the expedition concluded with the organized evacuation of the rafts. Instruments were brought on board the rafts and procedures were specifically developed for this cruise to study 1) climate change and ocean acidification, 2) marine litter, 3) El Niño and operational weather forecasting and 4) marine life.

The rafts were built following the designs of archeological studies on an Ecuadorian maritime culture known as the Manteno. They were built in Peru, with help from volunteers from all over the world as well as from the national Peruvian Navy. Building efforts were delayed by logistic issues, but Leg 1 departed Callao on November 7th 2015 and reached the Easter Island as planned 6 weeks later, on December 19th 2015. After a change of crew and a full overhaul of the rafts and equipment in Easter Island, Leg 2 departed Easter Island January 6 and ended March 17 2016.

The crew was multinational, gender-mixed, synergetic and multidisciplinary experienced. Each raft on each leg had 7 members on board. Only four members were present during both legs. There was a one scientist on board on each leg representing either of the organizing institutions.

Both rafts were instrumented for research. Each had an electrical installation with capacity calculated according to the payload of instruments that would be operated from it. Wind was the main source of energy to transport the vessels while photovoltaic cells transformed solar into electric energy for the electronics onboard.

The sensor payloads can be classified into three categories: atmospheric, oceanographic and ecological. Optical sensors to measure light, together with physical sensors to measure atmospheric conditions were combined with crew observations to describe the meteorological situation in the raft. A combination of echosounders and cameras were used to describe the macrofauna biodiversity present around the rafts. DNA and Chlorophyll a filtering aimed to study the microdiversity. The physical parameters like temperature, salinity, pH, levels of carbon dioxide described the climatic conditions in the region were the cruise sailed. Finally, both conventional and state-of-the-art technology were used to observe macro and micro plastics in this remote area of the world oceans.

Currently, the material collected on the cruise is subject of analysis in different laboratories. Kon-Tiki2, due to its unique nature, has been the subject of interest to a wide range of audiences. In addition to the general scientific interest, the expedition has given a much louder voice to the oceans than any regular research expedition could have given. For instance, the expedition coincided with the Climate Summit in Paris in December 2015 (COP21), a coincidence that we utilized to its fullest. The outreach efforts of the expedition participants have raised awareness about the science as well as about the expeditions sponsors. Most importantly, it has promoted cultural awareness across many state borders.

The Kon-Tiki2 Expedition combined science with adventure and challenge. Its organization was not simple, however, the outcome is of highest value, both from a professional scientific point of view, for the originator and sponsors of the expedition idea and for each and every project participant.

Kon-Tiki2 aimed to double-down on Thor Heyerdahl’s Kon-Tiki voyage (1947) by sailing two rafts from South America to Polynesia and then back. No one has done this in modern history. Kon-Tiki2 was an unparalleled voyage of survival, science and exploration. Although one of the strongest El Niño ever recorded stopped us from sailing all the way to South America, Kon-Tiki2 substantiates the ancient Pacific pathway for both Polynesians and South Americans. We know both cultures had rafts. Polynesians probably used their superior double hulled canoe for exploration and rafts for migrations. Kon-tiki2 showed how Polynesians could have sailed to South America and back, and how South Americans could have done the same in the opposite direction.

Continue reading ‘Kon-Tiki2 expedition 2015-2016: scientific cruise report’

Effects of elevated carbon dioxide and temperature on locomotion and the repeatability of lateralization in a keystone marine mollusc

Recent work has shown that the behaviour of marine organisms can be affected by elevated pCO2, although little is known about the effect of multiple stressors. We therefore investigated the effect of elevated pCO2 and temperature on locomotion and behaviour during prey searching in the marine gastropod Concholepas concholepas, a predator characteristic of the southeastern Pacific coast. Movement duration, decision time, route finding and lateralization were measured using a T-maze tank with a prey positioned behind a barrier. Four treatments, representing present day and near-future scenarios of ocean acidification and warming were used in rearing the individuals for 6 months. Regardless of the treatment, no significant differences were found in relative and absolute lateralization before and after exposure for 6 months. However, relative lateralization was not repeatable for animals tested after 6 months at elevated pCO2 at both experimental temperatures, whereas it was repeatable in individuals kept at the present day level of pCO2. We suggest that these effects may be related to a behavioural malfunction caused by elevated pCO2. Movement duration, decision time and route finding were not repeatable. However, movement duration and decision time increased and route finding decreased in elevated pCO2 (at 15°C), suggesting that elevated pCO2 has negative effects on the locomotor and sensory performance of C. concholepas in the presence of a prey odour, thereby decreasing their ability to forage efficiently.

Continue reading ‘Effects of elevated carbon dioxide and temperature on locomotion and the repeatability of lateralization in a keystone marine mollusc’

Adult exposure to ocean acidification is maladaptive for larvae of the Sydney rock oyster Saccostrea glomerata in the presence of multiple stressors

Parental effects passed from adults to their offspring have been identified as a source of rapid acclimation that may allow marine populations to persist as our surface oceans continue to decrease in pH. Little is known, however, whether parental effects are beneficial for offspring in the presence of multiple stressors. We exposed adults of the oyster Saccostrea glomerata to elevated CO2 and examined the impacts of elevated CO2 (control = 392; 856 µatm) combined with elevated temperature (control = 24; 28°C), reduced salinity (control = 35; 25) and reduced food concentration (control = full; half diet) on their larvae. Adult exposure to elevated CO2 had a positive impact on larvae reared at elevated CO2 as a sole stressor, which were 8% larger and developed faster at elevated CO2 compared with larvae from adults exposed to ambient CO2. These larvae, however, had significantly reduced survival in all multistressor treatments. This was particularly evident for larvae reared at elevated CO2 combined with elevated temperature or reduced food concentration, with no larvae surviving in some treatment combinations. Larvae from CO2-exposed adults had a higher standard metabolic rate. Our results provide evidence that parental exposure to ocean acidification may be maladaptive when larvae experience multiple stressors.

Continue reading ‘Adult exposure to ocean acidification is maladaptive for larvae of the Sydney rock oyster Saccostrea glomerata in the presence of multiple stressors’

Ocean acidification and kelp development: Reduced pH has no negative effects on meiospore germination and gametophyte development of Macrocystis pyrifera and Undaria pinnatifida

The absorption of anthropogenic CO2 by the oceans is causing a reduction in the pH of the surface waters termed ocean acidification (OA). This could have substantial effects on marine coastal environments where fleshy (non-calcareous) macroalgae are dominant primary producers and ecosystem engineers. Few OA studies have focused on the early life stages of large macroalgae such as kelps. This study evaluated the effects of seawater pH on the ontogenic development of meiospores of the native kelp Macrocystis pyrifera and the invasive kelp Undaria pinnatifida, in south-eastern New Zealand. Meiospores of both kelps were released into four seawater pH treatments (pHT 7.20, extreme OA predicted for 2300; pHT 7.65, OA predicted for 2100; pHT 8.01, ambient pH; and pHT 8.40, pre-industrial pH) and cultured for 15 d. Meiospore germination, germling growth rate, and gametophyte size and sex ratio were monitored and measured. Exposure to reduced pHT (7.20 and 7.65) had positive effects on germling growth rate and gametophyte size in both M. pyrifera and U. pinnatifida, whereas, higher pHT (8.01 and 8.40) reduced the gametophyte size in both kelps. Sex ratio of gametophytes of both kelps was biased towards females under all pHT treatments, except for U. pinnatifida at pHT 7.65. Germling growth rate under OA was significantly higher in M. pyrifera compared to U. pinnatifida but gametophyte development was equal for both kelps under all seawater pHT treatments, indicating that the microscopic stages of the native M. pyrifera and the invasive U. pinnatifida will respond similarly to OA.

Continue reading ‘Ocean acidification and kelp development: Reduced pH has no negative effects on meiospore germination and gametophyte development of Macrocystis pyrifera and Undaria pinnatifida’

Spatio-temporal environmental variation mediates geographical differences in phenotypic responses to ocean acidification

Phenotypic plasticity is expected to play a major adaptive role in the response of species to ocean acidification (OA), by providing broader tolerances to changes in pCO2 conditions. However, tolerances and sensitivities to future OA may differ among populations within a species because of their particular environmental context and genetic backgrounds. Here, using the climatic variability hypothesis (CVH), we explored this conceptual framework in populations of the sea urchin Loxechinus albus across natural fluctuating pCO2/pH environments. Although elevated pCO2 affected the morphology, physiology, development and survival of sea urchin larvae, the magnitude of these effects differed among populations. These differences were consistent with the predictions of the CVH showing greater tolerance to OA in populations experiencing greater local variation in seawater pCO2/pH. Considering geographical differences in plasticity, tolerances and sensitivities to increased pCO2 will provide more accurate predictions for species responses to future OA.

Continue reading ‘Spatio-temporal environmental variation mediates geographical differences in phenotypic responses to ocean acidification’

Effects of ocean acidification on the potency of macroalgal allelopathy to a common coral

Many coral reefs have phase shifted from coral to macroalgal dominance. Ocean acidification (OA) due to elevated CO2 is hypothesised to advantage macroalgae over corals, contributing to these shifts, but the mechanisms affecting coral-macroalgal interactions under OA are unknown. Here, we show that (i) three common macroalgae are more damaging to a common coral when they compete under CO2 concentrations predicted to occur in 2050 and 2100 than under present-day conditions, (ii) that two macroalgae damage corals via allelopathy, and (iii) that one macroalga is allelopathic under conditions of elevated CO2, but not at ambient levels. Lipid-soluble, surface extracts from the macroalga Canistrocarpus (=Dictyota) cervicornis were significantly more damaging to the coral Acropora intermedia growing in the field if these extracts were from thalli grown under elevated vs ambient concentrations of CO2. Extracts from the macroalgae Chlorodesmis fastigiata and Amansia glomerata were not more potent when grown under elevated CO2. Our results demonstrate increasing OA advantages seaweeds over corals, that algal allelopathy can mediate coral-algal interactions, and that OA may enhance the allelopathy of some macroalgae. Other mechanisms also affect coral-macroalgal interactions under OA, and OA further suppresses the resilience of coral reefs suffering blooms of macroalgae.

Continue reading ‘Effects of ocean acidification on the potency of macroalgal allelopathy to a common coral’

How ocean acidification can benefit calcifiers

Reduction in seawater pH due to rising levels of anthropogenic carbon dioxide (CO2) in the world’s oceans is a major force set to shape the future of marine ecosystems and the ecological services they provide 1 and 2. In particular, ocean acidification is predicted to have a detrimental effect on the physiology of calcifying organisms [3]. Yet, the indirect effects of ocean acidification on calcifying organisms, which may counter or exacerbate direct effects, is uncertain. Using volcanic CO2 vents, we tested the indirect effects of ocean acidification on a calcifying herbivore (gastropod) within the natural complexity of an ecological system. Contrary to predictions, the abundance of this calcifier was greater at vent sites (with near-future CO2 levels). Furthermore, translocation experiments demonstrated that ocean acidification did not drive increases in gastropod abundance directly, but indirectly as a function of increased habitat and food (algal biomass). We conclude that the effect of ocean acidification on algae (primary producers) can have a strong, indirect positive influence on the abundance of some calcifying herbivores, which can overwhelm any direct negative effects. This finding points to the need to understand ecological processes that buffer the negative effects of environmental change.

Continue reading ‘How ocean acidification can benefit calcifiers’

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Ocean acidification in the IPCC AR5 WG II

OUP book