Economic Blues (Oceanic Ones)

by Patrick Shore

While many impacts of climate change can be physically seen or experienced, such as abnormal weather and storm patterns and glacial retraction, the unknown and vast nature of our ocean makes changes less visible and understandable. It does seem certain though that seemingly small oceanic changes such as rising sea levels and surface temperatures could have devastating impacts across the globe. These small changes can indirectly affect weather global weather patterns: snowpacks, rainfall, harvests, soil fertility, and storms. Aside from the physical impacts of ocean climate change, such as the flooding of coastal and lowland cities, the changes to our oceans could have more immediate, economic effects. Continue reading

The Future Distribution of Harmful Algal Blooms

by Kyle Jensen

As the climate warms, algal blooms of certain harmful species are presenting an increasing threat to many biotic communities. Their introduction is often anthropogenic, and their occurrence is driven by eutrophication and changing climates. Their range may be influenced by rising temperatures, altered salinity due to runoff caused by climate change, and increasing nutrient loads due to increased development and fertilizer use containing favorable levels of nitrogen and phosphorous. Glibert et al. (2014) used a model incorporating climatic changes to predict the future distribution of these harmful algal blooms (HABs) under climate change scenarios. The study found a general increase in the distribution and presence of these HABs, though effects varied by region. Continue reading

Elevated Temperatures Increase Toxicity of Copper but Decrease that of Oxytetracycline in a Marine Protozoan

by Emil Morhardt

One aspect of increased ocean temperatures is that they may alter the resistance of marine organisms to pollutants. In a paper just published, such was found to be case for the marine protozoan, Euplotes crassus, that lives on the ocean floor where particulate pollutants get deposited. The protozoans were exposed to two common pollutants—the organic antibiotic oxytetracycline, and the potentially toxic metal, copper—over a range of temperatures. The scientists looked at their effects on survival rate, replication rate, feeding rate (endocytosis) and general of toxic stress (measured as lysosomal membrane stability) all interrelated. Increasing the concentrations of both these toxicants decreased all four measures of protozoan well-being, but in almost all cases Continue reading

Mapping the Global Potential of Ocean Thermal Energy Conversion

A global transition to sustainable energy infrastructure will require long-lead-time research and development of myriad technologies such as ocean thermal energy conversion (OTEC). Although OTEC plants are capital-intensive installations, new technology is reducing the cost of investing in this technology. OTEC exploits the temperature difference across the thermocline to produce electricity. To explore the potential of the oceanic thermocline as a renewable energy resource on a global scale, researchers used a Geographic Information System (GIS) to map a detailed model of global climatology of oceanic stratification (Nagurny et al.2011). Nagurny and colleagues employed this information, coupled with statistics for an OTEC plant model, to estimate OTEC potential at locations worldwide, to understand the distribution of these resources, and to pinpoint locations with high potential for utilizing OTEC. This visual system enabled the researchers to estimate the potential renewable energy available in the ocean’s thermocline at any given location using a model of an OTEC installation. This model is an improvement over past thermocline studies; it yielded a worldwide distribution of power on a 1/12th degree grid across multiple time periods. It was obtained from a baseline single stage Rankine cycle design and can be simply adjusted to employ different plant designs. —Meredith Reisfield
Nagurny, J., Martel, L., Jansen, E., Plump, A., Gray-Hann, P., Heimiller, D., Rauchenstien, L.T., Hanson, H.P., 2011. Modeling global ocean thermal energy resources. Oceans, 2011, 1-7.

Nagurny and colleagues at Lockheed Martin and the National Renewable Energy Lab mapped global climatology model of ocean thermoclines based on open-source data from the Naval Research Laboratory’s (NRL’s) Hybrid Coordinate Ocean Model (HYCOM). The data for this model were gridded at 1/12th degree latitude and longitude using GIS, which improved spatial resolution over previous models. A closed cycle OTEC plant model developed by Lockheed Martin was applied to this GIS map. The nominal OTEC plant design produces 150 MW gross (100 MW net power) of electricity. The researchers chose this design because sufficient data about the plant was available, the size of the plant is feasible with existing technology, and this design produces enough power to have the potential to be economically reasonable in the near future. To calculate net power, gross power, and fixed and variable losses the researchers examined aspects accounting for major contributing and loss factors to OTEC power production. They focused on three groups of factors: gross power, cold water pipe pumping cost, all other pumping and transmission power costs. Gross power was calculated using established thermodynamic equations of a Rankine cycle. The model was formulated so that the gross power and variable loss factors were the variables that depended on oceanic conditions. Nagurny and colleagues added an algorithm that optimized the depth of the cold water source, relaxing the assumption that successfully installing an OTEC power plant would require 1-km-deep cold water. Previous global assessment of potential resources were limited by the assumption that sufficiently cold water lay 1000 m below the ocean’s surface and left out shallower regions with potential OTEC resources. The researchers chose the most shallow depth out of the bottom water, the water at a level where the temperature gradient of 3°C per km balances production and loss, and water at 1000 m (for consistency with previous studies).
The net power potential worldwide varied from 0 to 197 MWe. Large regions offer potential for net power production. Large areas of the Pacific, Atlantic, and Indian Oceans can supply 100 MWe or greater from the nominal design. Areas in the Philippines and off New Guinea where found to have the greatest potential for OTEC, with upwards of 190 MWe obtained from the 100MWe plant conditions. The higher resolution of this model and the inclusion of shallower cold water availability allowed the mapping of the Gulf Stream’s July thermocline off the U.S. east coast, the western Equatorial Atlantic, and the Central Pacific near and to the northeast of Hawaii. The study was limited by a lack of data concerning ocean currents at depth, which are needed to replace the cold water in OTEC for the power production to be sustainable, and climate change data affecting the solar heating of surface water. 

Global Fish Meal and Aquaculture Pro-duction in Response to Climate Change

Climate variability and change has the potential to alter the balance of marine systems. Global aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> systems rely on small pelagic fish populations, fisheries productivity, fishmeal supply, and fish oil production. Aquaculture is dependent on fishmeal as food to serve as a primary source of protein, lipids, minerals, and vitamins. Fishmeal is produced using small pelagic fish such as sardines, anchovies, and mackerels. These species are short lived and fast growing, so their production is highly susceptible to environmental changes. Fisheries production has stabilized over the last decade, however aquaculture has continued to increase, particularly through production of low-value freshwater fish. Prediction of changes in fisheries yield that result from climate change are important to estimate. Merino et al. (2010) used bioeconomic models at two temporal scales with the objective of investigating environmental and human induced changes to aquaculture systems. Short-term economic hypotheses were that (i) there is no relationship between aquaculture production and fishmeal consumption, given that technological advances will reduce the dependency on fishmeal production; and (ii) fishmeal demand is linearly related to aquaculture expansion. Long-term models were based on two socioeconomic scenarios until the year 2080. The World Markets scenario was estimated using prices based on recent average and highest price records while The Global Commons scenario predicted limited expansion of aquaculture and population growth. —Lauren Lambert
Merino G., Manuel B., Christian M., 2010. Climate variability and change scenarios for a marine commodity: Modelling small pelagic fish, fisheries and fishmeal in a globalized market. Journal of Marine Systems 81, 196–205.

Merino et al. expect that climate change will have a negative effect on marine resources through reduced levels of primary production. Global aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> production relies on both carnivorous and herbivorous species. The majority of carnivorous species include salmonoids from Chile and Norway, and shrimp from Thailand and China<!–[if supportFields]> XE “China” <![endif]–><!–[if supportFields]><![endif]–>. Herbivorous species, mainly from China, make up 55% of global aquaculture production. Carnivorous species are dependent on fishmeal, however the amount of fishmeal used for herbivorous species is rising because of the improved growth rates and profits. The models combine the uncertainties of future climate and market effects on global fishmeal production and consumption.      
The first model used short-term impacts over a 10-year simulation to find the annual variable production rate of individual small pelagic fish stocks aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–>. The second was long-term (2080) and estimated environmental impacts on the same stocks by using primary production predictions as proxies for carrying capacities of fish stocks. The short-term simulation investigated the consequences of short-term climate change on fish and fishmeal systems. Biological, economic, and activity/investment components were observed through this simulation. The biological component computed expected yields and was modulated by expected primary production. The economic component estimated net profits for regional production systems by combining their costs with revenue from the global market. This was driven by outputs from the biological component, activity component, fishmeal price function, transformation, and shipping costs. The parameters of the global market are price records from 15 international fish markets. Activity and investment components express exploitation patterns in terms of catchability and fishing activity of specific stocks. The results of this simulation were presented in the form of bioeconomic indicators such as global exploitation index, estimate of global small pelagic fish caught, and a measure of traded fishmeal to global markets as well as average prices.
The fish stocks show fluctuation according to random variability in fish production. In years that fish stocks decline, the costs of obtaining fish at the same yield show a slight increase, and the small pelagic and fishmeal supply remains relatively constant. As fishmeal markets expand, fish production fluctuates as a result of climate change. Through this simulation, Merino et al.found that in years with negative environmental conditions the price of fishmeal would need to be increased while production levels stay the same. At the end of the 10-year simulation, the fish stocks global indicator was 23% of optimal levels. Under these same conditions, the combination of random negative environmental impacts and increases in demand will continue to reduce the size of the fish stocks.
Long-term simulations investigated the impacts of changes in primary production under two different management scenarios. These are short and long term models that use actual data from 1997–2004 for 3 regional production systems. The import and export data from the International Fishmeal and Fish Oil Organization (IFFO) was used to estimate the size of these fish stocks, fleets, and transforming industries. The global market only works under the condition that fish stocks are currently exploited at their maximum sustainability capacity and that the differences in fishmeal production are reflective sof the difference in available fish stocks, fleets, and technology. This allows for investigation of impact of climate variability on production systems that trade products in the global commodity markets. The Global Commons management scenario showed that resulting fish biomass, exploitation levels, fish yield, and market trade are similar to present conditions. The World Market scenario shows a decline in all parameters that were tested. The model showed that production appears to be sustainable over the 10-year period, but fishmeal prices will rise. 
 The results of the long-term scenarios show changes in biomass of small pelagic fish, index of global exploitation level, total production of small pelagic fish, and quantity of fishmeal in the markets. Sustainability of small pelagic resources is more dependent on how society responds to climate change than to the magnitude of the alterations. There is a link between global climate change and aquaculture<!–[if supportFields]>XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> dynamics in relation to the demand for natural resources and limits of ecosystem services. Ecosystems are expected to respond to global warming through variations in primary production and species capacity parameters. 

The Effect of Climate Change on the Mediterranean Sea

The Mediterranean Sea is a sea with specific identifiable water masses in each sub-basin and at different depths that have been well recorded. The Mediterranean sea was chosen as the final analysis of ecosystems in this paper because of its wide biodiversity and scientific opinion of being a “miniature ocean” by physical oceanographers (Myers et al. 2000). The circulation of water through the Mediterranean is determined by incoming water from the Gibraltar straights (Atlantic water) and the sinking of waters caused by influx from the three coldest areas of the sea; the northern Adriatic, the Gulf of Lions, and the North Aegean sea. A study performed by Lejeusne et al. (2009) examined the past thirty years and discovered that the traditional flow of water in the Mediterranean Sea has been disrupted due to climate change. Deep-water temperatures from the northwestern Mediterranean have been experiencing a general warming of 0.0048 °C per year since the 1980s. The Eastern Mediterranean transient has encountered temperature and salinity increase as well as increased stratification in the water column. Further research has shown that the Eastern Mediterranean Transient has begun to affect the water circulation and species ecosystems there as well. At shallow depths two types of climate-driven effects have been observed: a warming trend and an increase in the frequency of anomalous events like storms and anomalous annual temperature spikes. Rosemary Kulp
Myers, P.G., Mittermeier, R., Mittermeier, C., Fonseca, G., Kent, J., 2000. Biodiversity hotspots for conservation priorities. Nature 403, 853–858
Lejeusne, C., Chevaldonne, P., Pergent-Martini, C., Boudouresque, C., Pe´rez, T., 2009. Climate change effects on a miniature ocean: the highly diverse, highly impacted Mediterranean Sea. doi:10.1016/j.tree.2009.10.009.

The organisms of the Mediterranean Sea are divided into three biogeographical provinces, the western basin, the eastern basin, and the Adriatic Sea, with each province subdivided along latitudinal patterns (east-west, north-south). Subtropical species are more abundant in the southern parts of these provinces while more temperate species dominate the northern parts. Increasing sea surface temperature and higher frequency of storms has lead directly to an increasing abundance of thermotolerant species and the disappearance of stenothermal species acclimated to colder temperatures. Not surprisingly the major shifts in stenothermal populations have occurred in the colder climate of the Northwestern Mediterranean, the coldest area of the Mediterranean Sea. An example of the changing biodiversity occurring in the Northwestern Mediterranean sea involves the Hemimysis speluncola, a cave-dwelling species which collapsed and re-distributed Northward under the temperature anomalies of the 1990’s. Subsequent studies confirmed a higher thermotolerance for the newly dominant H. margalefi compared to the cold stenothermal H. speluncola, unable to move north and now restricted to the cold regions of the Gulf of Lions and the northern Adriatic. An important note to consider is that current geographical context of the Mediterranean Sea makes it impossible for shallow-water temperate species already trapped in the northernmost, coldest parts of the different basins to migrate or disperse northwards to mitigate temperature changes which will lead to large scale extinction of these trapped species as the waters continue to warm. Significant range expansion is also occurring with two-thirds of the mobile species recorded, as warm loving species, like the ornate wrasse Thalassoma pavo andorange coral Astroides calycularis, found usually along the eastern and southern shores of the Mediterranean Sea, have been recently recorded distributed more north and westward over the decades (Lejeusne et al. 2009).
 The expansion of thermophiliac species from the eastern Mediterranean into the northwestern Mediterranean is important because of the additional organisms introduced through the Suez Canal from the Red Sea. Most of the species introduced into the Mediterranean are of tropical origin, and have been traditionally confined to the easternmost Levantine shores, but the warming of the Mediterranean allows them to progress westwards and northwards, through the whole eastern basin, with some now reaching the Adriatic and the western basin (Galil and Zenetos 2002). It is expected that the southern parts if the Mediterranean Sea will become more colonized by sub-tropical species from the Southern Atlantic and Red Sea, while the Northern parts of the Mediterranean will be populated by current southern and eastern native species of the Mediterranean (Lejeusne et al. 2009).
Climate change and subsequent increases in the severity and frequencies of storms and anomalous temperature spikes can exceed organisms range of thermal tolerance, which leads to diseases and mass mortality. Mediterranean temperate sessile invertebrates such as sponges and corals experienced unprecedented disease outbreaks and mass mortalities within the past decade. After being initially affected, bare skeletons become exposed and are then colonized by microorganisms and eventually macroscopic organisms. Colonized skeletons can remain attached for years, unless detached by storms, and the slow regeneration rate of corals and sponges cannot counterbalance immediate and delayed effects of disease outbreaks, dramatically altering benthic and coastal seascapes within the Mediterranean Sea (Lejeusne et al. 2009).
Since the Mediterranean operates under low levels of nutrients, the benthic ecosystems are under strong nutritional forcing with the summer season traditionally carrying the lowest levels of nutrients. With increased temperatures, the combination of thermal stress and food shortage results in mass mortality events will likely disrupt summer season benthic–pelagic coupling. Cascading effects will likely contain planktonic communities, especially copepod assemblages, which have a strong influence on pelagic ecosystem fluxes due to their role of a biological carbon pump to deeper waters. Plankton populations impact fish recruitment in Mediterranean marine ecosystems and will certainly be influenced by the arrival of new species in these ecosystems, possibly disrupting or completely altering current ecosystem functioning (Lejeusne et al. 2009).
It is important to note that marine invertebrates and fish are not the only species concerned by such expansions. The last decade has seen increasing reports of toxic dinobionts in coastal areas, with possible consequences on human pathology. These dinoflagellants are thermophiliac, exotic species like Gambierdiscus toxicus, and the main causative agent of ciguatera poisoning[1], normally has a tropical or subtropical distribution but have been recently reported from Crete (Lejeusne et al. 2009). Range expansion of the palytoxin-producing dinobiont Ostreopsis ovata in the Mediterranean have also been documented, with definite consequences on human health documented (Kermarec et al. 2008) For both cases increases in water temperature are believed to be the direct result of these species proliferation in the Mediterranean.

In all four ecosystems climate change has resulted in species endangerment with the understanding that barring genetic adaptation the biofood web range-extension northward of current mobile species will occur as stenothermal species that cannot migrate into colder water will die out and ecosystems are reconstructed with invasive themroresiliant species. Increasing sea levels are expected to invade on current real estate properties as primary plant producers and nursery grounds for many commercially valued fish and shrimp flood with sea-water. Further research is required to adequately prove these theories, but based on these analyses a clear north-south gradients is revealed with the impact of invasive species being a key factor to future ecosystem predictions. Another clear issue to consider is the implications of warmer water on the proliferation of potentially harmful bacteria pathogens and microbial ecosystems in relation to human health and commercial consumption of tropical and subtropical fish.

[1] Ciguaterra poisoning is a nonbacterial food poisoning that results from eating fish contaminated with the ciguatoxin, produced by dinoflagellates such as Gambierdiscus toxicus which live in tropical and sub-tropical waters. The toxin is believed to block acetylcholinesterase activity and characteristics of poisoning include vomiting, diarrhea, tingling or numbness of extremities and the skin around the mouth, itching, muscle weakness, pain, and respiratory paralysis. No specific treatment has been developed.

New insights into global patterns of ocean temperature anomalies: implications for coral reef health and management

In this study, Selig et al. (2010) created the Coral Reef Temperature Anomaly Database (CoRTAD) using data from the National Oceanic and Atmospheric Administration’s (NOAA) National Oceanographic Data Center (NODC) from 1985 to 2005. The data were used to calculate frequency, size, intensity, and duration of extreme thermal stress events that were associated with coral bleaching and disease. A baseline was also established to compare extreme temperature events and explore how the anomalies varied by region. Their data showed that the frequency of anomalies varied by year and region, and that 48% of coral bleaching related anomalies and 44% of disease related anomalies were smaller than 50 km2, which is a smaller resolution than most current models use. This indicates that more fine-scale models are needed to accurately predict the effects of climate change on corals, and that temperature anomalies influencing coral bleaching and disease are likely to vary significantly on smaller spatial scales producing fairly localized responses to climate change.  ¾ Rachel King
Selig, E., Casey, K., Bruno, J., 2010.  New insights into global patterns of ocean temperature anomalies: implications for coral reef health and management. Global Ecology and Biogeography 19, 397 – 411.

            The CoRTAD is a 21-year, 4-km resolution global dataset of ocean temperature anomalies that was developed with data from the Pathfinder Version 5.0 collection, produced by the NOAA’s NODC and the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. The authors derived the sea surface temperature (SST) data from an Advanced Very High Resolution Radiometer (AVHRR) sensor, which was processed to a 4.6 km resolution at the equator. A day-night average of the data was used to increase the number of observations with no significant change in the accuracy. The CoRTAD was validated against in situ temperature loggers over a variety of coral locations and depths, and was accurate at most sites to within 0.11 ºC, less than the range of accuracy for the loggers themselves (± 0.2 ºC).
            The authors focused their analysis on two metrics – one associated with coral bleaching and one associated with disease severity These two factors are important drivers of coral decline, so analysis of these areas provides a clear indicator of temperature effects on coral populations. Thermal stress anomalies (TSAs) were the metric used for coral bleaching, and is categorized as temperatures that exceed the long-term average warmest week of the year by 1 ºC or more. Weekly sea surface temperature anomalies (WSSTAs) were the metric used for analyzing temperature correlations coral disease. WSSTAs are temperatures that are 1 ºC or more than the weekly climatological value. The authors also calculated the frequency of WSSTAs and TSAs over the 21-year period and the size of the anomalies in the tropics for anomalies that overlapped areas with known coral reefs.
            The frequency of TSAs and WSSTAs varied considerably across different regions. For all the 4-km grids containing reefs, the TSA frequency ranged from 37 anomalies to 444 over the 21-year period. The authors also examined the anomaly frequency by year to determine if there were more TSAs in recent years than in past years, but found that it varied by region. Some regions had the most extreme temperatures in the 1998 El Niño/Southern Oscillation (ENSO) event, but other regions had higher anomaly frequencies during the 1987-88 ENSO or the 2005 ENSO. However, the severity of the 1998 and 2005 ENSO events was apparent by the coral bleaching anomalies in those years. The size distributions of WSSTAs and TSAs were remarkably similar considering difference in number of occurrences for the two anomalies. Most anomalies had relatively small sizes and a higher number of occurrences. Large anomalies ( > 500 km2) represented less than 10% of data, with 33% of TSAs and 29% of WSSTAs in the size category between 1 and 25 km2.
            Current models for climate change are critical in helping determine patterns for ocean warming, and therefore areas of concern for conservation. However, most of these models have very coarse resolution, which can falsely display homogenous patterns of thermal stress. The authors’ results show that over 60% of bleaching and disease related anomalies occur at smaller scales than the resolution for many models for climate change. Therefore, to adequately understand the potential effects of climate change on ocean warming and bleaching or disease related events, finer scale models may be required. Their results can also help pinpoint areas for possible coral refuges based on the frequency and magnitude of thermal anomalies, though given the uncertainties in using past temperature data to predict the effects of future warming is still difficult. Large-scale events such as the 1998 ENSO could still produce massive bleaching even in areas identified as potential refuges. As such, the importance of accurate and appropriately sized data for climate change is a necessity according to the authors, and is important in determining conservation strategies for coral reefs in the future.