Jellyfish are important components of marine food webs and form problematic blooms that negatively impact human enterprise. Jellyfish of the genus Aurelia (Class Scyphozoa) are common bloom-formers in the Gulf of Mexico (GoM). Aurelia have a multi-modal life cycle where the perennial polyp produces seasonal medusae. Abiotic tolerance ranges and limits strongly influence the distribution of marine species but are unknown for most jellyfish species. Tolerance limits for survival are crucial to understanding present polyp distribution and how distribution may change in climate change scenarios. We sampled and barcoded two Aurelia species from the GoM, namely Aurelia sp. 9 and a possible new species found offshore (Aureliasp. new). Planulae obtained from one medusa of Aurelia sp. new, and five medusae of Aurelia sp. 9 were used to establish laboratory cultures. Polyps of Aurelia coerulea, a species native to Japan but introduced in North America, Australia, and Europe, were obtained from a local aquarium, barcoded, and used to establish laboratory cultures. Using controlled laboratory experiments, we determined the temperature and salinity limits for polyp survival of the two GoM species and A. coerulea. We find that A. sp. 9 and A. coerulea were tolerant of a broad range of temperatures and salinities, but differed in tolerance limits, suggesting potential differences in habitat and resistance to climate change. A. sp. 9 was most tolerant of high temperatures and low salinities, such as those found in the estuaries of the GoM. Summer high temperatures in the coastal GoM exceed the upper thermal tolerance limit of A. sp. new and A. coerulea, suggesting that A. sp. new is an offshore species and that the coastal GoM waters may not be a suitable environment for A. coerulea. Based on the upper thermal limits identified in this study, the 4°C ocean temperature increase projected for the GoM by the next century may negatively impact Aurelia sp. 9 and Aurelia sp. new populations and is expected to deter A. coerulea from invading the GoM. This is the first account of Aurelia sp. new and the first report of temperature and salinity ranges and tolerance limits for Aurelia species.
Climate Change, Ocean Acidification, and Ocean Warming
Biodiversity loss and climate change simultaneously threaten marine ecosystems, yet their interactions remain largely unknown. Ocean acidification severely affects a wide variety of marine organisms and recent studies have predicted major impacts at the pH conditions expected for 2100. However, despite the renowned interdependence between biodiversity and ecosystem functioning, the hypothesis that the species’ response to ocean acidification could differ based on the biodiversity of the natural multispecies assemblages in which they live remains untested. Here, using experimentally controlled conditions, we investigated the impact of acidification on key habitat-forming organisms (including corals, sponges and macroalgae) and associated microbes in hard-bottom assemblages characterised by different biodiversity levels. Our results indicate that, at higher biodiversity, the impact of acidification on otherwise highly vulnerable key organisms can be reduced by 50 to >90%, depending on the species. Here we show that such a positive effect of a higher biodiversity can be associated with higher availability of food resources and healthy microbe-host associations, overall increasing host resistance to acidification, while contrasting harmful outbreaks of opportunistic microbes. Given the climate change scenarios predicted for the future, we conclude that biodiversity conservation of hard-bottom ecosystems is fundamental also for mitigating the impacts of ocean acidification.
The United States’ sustained economic and geopolitical interest in the Arctic is dependent on Congressional funding and Executive support for icebreaking vessels and improved infrastructure in United States arctic territory. The United States has an interest in the Arctic and it is demonstrated by The Arctic Research and Policy Act of 1984 (amended 1990). Through the Act, the United States initiated research and policy development, with the supposition of potential economic benefits in the future. Due to verifiable and anticipated changes in ice density in the Arctic, the region is accessible like never before, and international competition for natural resources and commercial shipping lanes in the Arctic offer enormous economic benefits. The United States is woefully behind its international competitors due to a small and decrepit fleet of icebreaking vessels and crumbling arctic infrastructure. In examining The Arctic Research and Policy Act of 1984 and multiple Arctic Strategy Plans that were published by federal agencies operating in the Arctic, it is clear—attention from Congress and the Executive must be redirected towards advancement. The first step to advancing the United States interest in the Arctic is by funding and procuring icebreaking vessels and improving arctic territory infrastructure.
Climate change is the defining environmental problem for our generation. The effects of climate change are increasingly evident and anticipated to profoundly affect our ability to conserve fish habitats and fish assemblages as we know them. Preparing to cope with the effects of climate change is developing as the central concern of aquatic resources conservation and management. Reservoirs are important structures for coping with projected shifts in water supply, but they also provide refuge for riverine fishes and retain distinct fish assemblages that support diverse fisheries. The effects of climate change on reservoirs are unique among aquatic systems because reservoirs have distinctive habitat characteristics due to their terrestrial origin and strong linkage to catchments. We review (1) the projected effects of rising temperature and shifting precipitation on reservoir fish habitats, and (2) adaptation strategies to cope with the anticipated effects. Climate warming impacts to reservoirs include higher water temperatures and shifts in hydrology that can result in reduced water levels in summer and fall, altered water residence cycles, disconnection from upstream riverine habitats and backwaters, increased stratification, eutrophication, anoxia, and a general shift in biotic assemblages including plants, invertebrates, and fishes. We suggest that what is needed to cope with these changes is a new perspective focusing on maintaining ecosystem functionality rather than on retaining a particular species composition. To that end, we offer a toolkit organized into planning, monitoring, and managing compartments, and equipped with 22 adaptation tools. The coping strategies we identify are broad and general and represent a starting line applicable for developing creative alternatives relevant to local conditions.
Ocean warming and acidification are among the greatest threats to coral reefs. Massive coral bleaching events are becoming increasingly common and are predicted to be more severe and frequent in the near future, putting corals reefs in danger of ecological collapse. This study quantified the abundance, size, and survival of the coral Pocillopora acuta under future projections of ocean warming and acidification. Flow-through mesocosms were exposed to current and future projections of ocean warming and acidification in a factorial design for 22 months. Neither ocean warming or acidification, nor their combination, influenced the size or abundance of P. acuta recruits, but heating impacted subsequent health and survival of the recruits. During annual maximum temperatures, coral recruits in heated tanks experienced higher levels of bleaching and subsequent mortality. Results of this study indicate that P. acutais able to recruit under projected levels of ocean warming and acidification but are susceptible to bleaching and mortality during the warmest months.
Previous studies have found that calcification in coral reefs is generally stronger during the day, whereas dissolution is prevalent at night. On the basis of these contrasting patterns, the diel variations of net community calcification (NCC) were monitored to examine the relative sensitivity of CaCO3 production (calcification) and dissolution in coral reefs to ocean acidification (OA), using two mesocosms that replicated a typical subtropical coral reef ecosystem in southern Taiwan. The results revealed that the daytime NCC remained unchanged, whereas the nighttime NCC decreased between the control (ambient) and treatment (OA) conditions, suggesting that carbonate dissolution could be more sensitive to OA than coral calcification. The average sensitivity of the integrated daily NCC to changes in the seawater saturation state (Ωa) was estimated to be a reduction of 54% in NCC per unit change in Ωa, which is consistent with the global average. In summary, our results support the prevailing anticipation that OA would lead to a reduction in the overall accretion of coral reef ecosystems. However, increased CaCO3 dissolution rather than decreased coral calcification could be the dominant driving force responsible for this OA-induced reduction in NCC.
The health of coastal human communities and marine ecosystems are at risk from a host of anthropogenic stressors, in particular, climate change. Because ecological health and human well-being are inextricably connected, effective and positive responses to current risks require multidisciplinary solutions. Yet, the complexity of coupled social–ecological systems has left many potential solutions unidentified or insufficiently explored. The urgent need to achieve positive social and ecological outcomes across local and global scales necessitates rapid and targeted multidisciplinary research to identify solutions that have the greatest chance of promoting benefits for both people and nature. To address these challenges, we conducted a forecasting exercise with a diverse, multidisciplinary team to identify priority research questions needed to promote sustainable and just marine social–ecological systems now and into the future, within the context of climate change and population growth. In contrast to the traditional reactive cycle of science and management, we aimed to generate questions that focus on what we need to know, before we need to know it. Participants were presented with the question, “If we were managing oceans in 2050 and looking back, what research, primary or synthetic, would wish we had invested in today?” We first identified major social and ecological events over the past 60 years that shaped current human relationships with coasts and oceans. We then used a modified Delphi approach to identify nine priority research areas and 46 questions focused on increasing sustainability and well-being in marine social–ecological systems. The research areas we identified include relationships between ecological and human health, access to resources, equity, governance, economics, resilience, and technology. Most questions require increased collaboration across traditionally distinct disciplines and sectors for successful study and implementation. By identifying these questions, we hope to facilitate the discourse, research, and policies needed to rapidly promote healthy marine ecosystems and the human communities that depend upon them.
We address the question of how to provide meaningful scientific information to support environmental decision making at the regional scale and at the temporal scale of several decades in a network of marine parks in the Kimberley region of Western Australia. Where environmental sustainability is affected by slow-dynamics climate change processes and one-off investments in large infrastructure which can affect a region for decades to come, both strategic and reactive planning is necessary and prediction becomes as urgent as standard adaptive management. At the interface between future studies, socio-economic modelling and environmental modelling, we define 18 scenarios of economic development and climate change impacts and five management strategies. We explore these potential futures using coupled models of terrestrial and marine ecosystem dynamics. We obtain a projection of the Kimberley marine system to the year 2050, conditional on the chosen scenarios and management strategies. Our results suggest that climate change, not economic development, is the largest factor affecting the future of marine ecosystems in the Kimberley region, with site-attached species such as reef fish at greatest risk. These same species also benefit most from more stringent management strategies, especially expansion of sanctuary zones and Marine Protected Areas.
The Report Card 2020 summarises the latest evidence from 26 topics regarding the physical, ecological, and social and economic impacts of climate change on UK coasts and seas. New topics for this year include oxygen, cultural heritage, and transport and infrastructure.
More than 150 scientists from over 50 leading research organisations have contributed to this year’s Report Card, producing 26 peer-reviewed scientific reports which give detailed information regarding the evidence bases on UK marine climate change impacts.
Coastal marine environments provide livelihoods as billions of people around the world depend greatly on sustainability efforts in the Blue Economy. In this study, we investigated how stakeholders from important Blue Economy sectors along the German North Sea coast perceive the impacts of climate change on their daily work life and the growth of the Blue Economy. In a two-stage approach we first conducted two stakeholder workshops with representatives from the regional sea food sector, science, NGOs and local authorities, in order to identify important issues linked to climate change affecting environment, society, economy and policy. In the second stage, we conducted semi-structured interviews with key knowledge holders from the Blue Economy, to evaluate and validate the most important issues identified during the first stage, and the impacts on the respective sectors. The workshop participants identified perceptible effects of climate change on their marine environment. Early career scientists showed that they possess a clear focus on measures for climate change adaptation, transdisciplinary approaches and knowledge transfer. The interviews revealed that the climate change effects could be perceived as both negative and positive, depending on the sector. Other issues, especially political decisions and developments are perceived to have a greater immediate impact on the Blue Economy than the slow progress of climate change effects. Additionally, increased human activities, in the form of new or intensified uses like marine renewable energy generation, have a greater influence and lead to conflicts between the Blue Economy sectors. Our study showed that economic and societal stakeholders in Germanys North Sea region are aware of climate change and already perceive its effects on their businesses. Synergies and conflicts between the sectors and political decisions might influence sustainable growth of the Blue Economy in highly contested regions, such as the North Sea basin, much stronger than the effects of climate change. This calls for a more flexible and adaptive approach to policymaking, taking into account the changing environmental, social and economic realities.