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There is widespread consensus among climate scientists today that global climate change is real and has anthropogenic roots. Marine species, for example, are exposed to a large array of abiotic stressors, such as warming and ocean acidification, that are linked directly to anthropogenic climate change. The general view on whether natural populations can adapt to anthropogenic change is that many species will fail to adapt to rapid climate change effects. This accelerating trend has profound effects on marine species and ecosystems, globally and the Eastern African region is no exception. Here, we provide a review that is the result of the workshop "Marine Organisms Response to Climate Change Effects-Adaptation or Extinction?" among ocean scientists actively studying the impact of climate change in the Western Indian Ocean. The review examines several key marine organisms and ecosystems in the region of the Western Indian Ocean, how these may be impacted by climate change, and the way forward for successful conservation and management.
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Hollander J.1, Linden O.1, Gudka M.2, Duncan M I.3,19, Obura D.2, James N.3,4, Bhagooli R.5
,22, Nyanapah J.6,
Onyango C.7, Duvane J.8, Louis Y.5, Ngotho D., Mvungi E.10, Mamboya F.11, George R.12, Hamad H.13, Issa
Hamisi M.14, Adeleke B.7, Ngoa E.15, Harlay J.23, Oduor, N.17, Fondo E.17, Wambiji N.17, Raharinaivo L.18,
Winkler A.19, Okemwa G.17, Karisa J.17, Madi Bamdou M.21, Mtaki K.20, Randrianandrasana J.18
*Corresponding author: World Maritime University | Global Ocean Institute, 211 18 Malmö, Sweden. E-mail
address: (J. Hollander).
Keywords: Western Indian Ocean, coral, seagrass, mangrove, ocean acidification, fish, blue economy, climate
change, anthropogenic, adaptation
There is widespread consensus among climate scientists today that global climate change is real and has
anthropogenic roots. Marine species, for example, are exposed to a large array of abiotic stressors, such as
warming and ocean acidification, that are linked directly to anthropogenic climate change. The general view on
whether natural populations can adapt to anthropogenic change is that many species will fail to adapt to rapid
climate change effects. This accelerating trend has profound effects on marine species and ecosystems,
globally and the Eastern African region is no exception. Here, we provide a review that is the result of the
workshop “Marine Organisms Response to Climate Change Effects Adaptation or Extinction?” among ocean
scientists actively studying the impact of climate change in the Western Indian Ocean. The review examines
several key marine organisms and ecosystems in the region of the Western Indian Ocean, how these may be
impacted by climate change, and the way forward for successful conservation and management.
The Biodiversity and Environment Institute, Reduit, Republic of Mauritius
Facts and opinions published in the Journal of Indian Ocean Rim Studies (JIORS) express solely the opinions of the respective
authors. This in no way represents the views of IORA. The Authors are responsible for their citing of sources and the accuracy of
their references and bibliographies. The editors cannot be held responsible for any lacks or possible violations of third parties’ right.
Journal of Indian Ocean Rim Studies, January- June 2020
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Journal of Indian Ocean Rim Studies
Global climate change has emerged as a major problem for humanity, challenging many aspects of human life
today and compromising the life of future generations. The repercussions expand beyond human welfare, with
most ecological communities on land and in the oceans, in polar, temperate and tropical areas affected. In the
marine environment, climate change alters the physio-chemical properties of the ocean, with changes in
temperature, oxygen concentrations and pH having impacts on all marine organisms (Somero 2010). The
Intergovernmental Panel on Climate Change (IPCC) predicts an increase of temperature of between 35
degrees by the end of the century. Such extreme change will unquestionably expose coastal and marine
ecosystems to environmental stress at dangerously high rates. The question is to what extent natural populations
can adapt to anthropogenic changes. Unfortunately, many scientists today predict that key species will fail to
adapt to such rapid climate change, and that many ecosystems will change fundamentally resulting into
significant loss of biodiversity (IPCC 2018).
In the Western Indian Ocean (hereafter, WIO), these problems are real and very often acute (Wilkinson et al.,
2000; Obura et al., 2002; Mahongo 2009; Ateweberhan & McClanahan 2010; Watkiss et al., 2012; George et al.
2018). Increasing human populations have also changed historical land use patterns, in the form of urbanization
of rural areas and increasing the area of cultivated land. These changes will continue to reduce the quality and
quantity of drainage water with impacts on coastal ecosystems of the WIO (e.g. IOC-UNESCO, 2016; Okuku
2007; Mvungi & Pillay 2019). Additionally, cyclone strength and frequency are increasing, influenced by
increasing Sea Surface Temperatures (SST) that add energy to the atmosphere (Mahongo et al. 2014).
Ramirez et al. (2017) identified the WIO as one of six hotspots of marine biodiversity globally that are particularly
affected by global warming, with the list of consequences growing longer each year (George et al. 2018;
Mahongo; 2011; Mahongo et al., 2014; Mvungi & Pillay, 2019). This text will focus on a few of the most important
coastal ecosystems and organism groups in the WIO which provide essential ecosystem services in the region,
and which are now facing serious stress from climate change; fish, coral reefs, seagrasses, and mangroves.
The article will describe and discuss the results of past and ongoing climate change related research. Finally,
the article will try to widen the scope and discuss climate change effects on the whole in the WIO region,
conceptual and/or infrastructural improvements, and research avenues that have been overlooked or need
further exploration. However, providing a complete review of climate change impacts is beyond the scope of this
The ideas and concepts presented below are the result of discussions at the workshop “Marine Organisms
Response to Climate Change Effects Adaptation or Extinction?” among experts, scientists and researchers
actively studying the impact of climate change in the WIO. The workshop was funded by WIOMSA and organised
in collaboration with Lund University and the World Maritime University, in Mombasa, October 2018. In relation
to this special issue on Blue Economy in the Indian Ocean, this article focuses on how the responses of marine
organisms and ecosystems to climate change may affect their ability to provide and sustain ecosystem services
that are the foundation of the blue economy. Biodiversity and ecosystem functions generate the products and
services used by people (UNECA 2016, Attri 2016, Obura 2018), so the ability of organisms and ecosystems to
adapt to or withstand climate change will fundamentally affect the level and stability of service provision into the
Key ecosystem characteristics, features and distribution
Coral reefs are perhaps the most biodiverse of ecosystems globally and among the most productive, hosting up
to one quarter of marine species at some point in their life cycle (ref). In the WIO, they are one of the dominant
shallow marine ecosystems, fringing the coasts of mainland East Africa and the islands of the region (Obura
2015). Their high productivity provides fish and other food, protects the coastlines from storms and generates a
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range of additional ecosystem services that support rural and urban population, tourism and recreation sectors
and biomedical sciences (Eliff & Silva 2017).
There are some 400 species of reef-building coral in the WIO (Obura 2012, Veron et al. 2015), and their
symbiosis with intracellular dinoflagellates, zooxanthellae, drives the coral reef ecosystem. Photosynthesis by
the zooxanthellae generates excess energy used by the coral to grow and rapidly secrete their calcium carbonate
skeleton, which over multiple generations of corals growing on the skeletons of their ancestors builds the reef
system. Corals and their symbiotic algae need clear warm tropical waters and are restricted to shallow (< 30 m)
rocky bottoms not too close to rivers that discharge turbid water and silt into the sea. The symbiosis is, however,
vulnerable to high temperatures. Whitening, or bleaching, of the coral occurs in response to exposure to
excessively high temperatures (as well as other stress factors) (Obura 2009). If the stress is not excessive the
bleached coral may recover, but if excessive, mortality occurs. Thus, corals are highly vulnerable to climatic
warming of the last decades (Hughes et al. 2018,), and WIO coral reefs have gone through two major bleaching
events in 1998 and 2016, as well as smaller events in between (Obura et al. 2017, Gudka et al. 2019,
McClanahan et al. 2014).
All countries in the WIO, both mainland and island, contain coral reefs within their territorial waters. The most
common type of coral reefs are fringing reefs which generally contain patch reefs in adjacent shallow lagoons.
There are also isolated atoll reefs around some small islands as well as barrier reefs notably in Toliara,
Madagascar and the region also has large submerged reef banks in the Mascarene Plateau (Ahamada et al.
2002). Discharge of freshwater and sediments from major rivers into shallow waters generally creates conditions
unsuitable for corals to live, leading to natural breaks in extensive coral reef formations in several countries.
Comoros Islands have a total of 430 km2 of coral reefs with at least 195 reef-building coral species (Ahamada
et al. 2008; Obura 2012). Mayotte’s lagoon covers 1500 km2 and harbours at least 249 reef-building coral
species. Kenya’s coral reefs cover an area of approximately 639 km2, and are differentiated into two regions:
the more-diverse (239 species) southern reef is an almost continuous fringing reef system from Malindi to
Tanzania and the northern lower diversity discontinuous patchy and fore reef slopes from Lamu to the border
with Somalia. Madagascar has 3450 km of coral reefs, comprising 1130 km of fringing reef, 502 km of barrier
reef, 557 km of coral banks and 1711 km of submerged reef (Cooke 2012). The northern part of Mozambique is
characterised by extensive, highly-biodiverse coral formations fringing the coastline and the surrounding island
groups. The southern half of Mozambique and the extreme north-eastern part of South Africa (approximately 40
km² reef area) consist of marginal, non-accreting coral reefs generally dominated by soft corals. Réunion, the
youngest island, has short stretches of narrow fringing reefs along southwestern coasts (Turner & Klaus, 2005)
with a total length of 25 km and an area of 12 km2. Coral reefs cover an area of approximately 1,690 km2 in the
Seychelles, with most reef areas located in the outer islands. Tanzania’s fringing coral reefs consist of at least
273 species are located along about two thirds of Tanzania’s continental shelf and surround most of the islands
(Obura 2017). Mauritius Island consists of a discontinuous fringing reef, small barrier reef and large lagoon patch
reefs and Rodrigues Island has nearly continuous fringing reefs with both islands having approximately 240 km2
of shallow reef habitats (Turner & Klaus, 2005).
Description of benefits
Coral reefs are home to and support close to a quarter of the ocean biodiversity including fish. In this way, they
support small-scale artisanal fisheries essential for the supply of protein for numerous people in the WIO. Reefs
also generate income from tourism, and they protect the coastline by reducing wave energy and wave height,
hence protecting coasts from erosion. Unfortunately, corals are sensitive to elevated temperatures and many
experts including the IPCC predict that they will be the first ecosystem to effectively become extinct as a result
of ocean warming (1.5 C IPPC report).
The impacts on coral reefs as a result of ocean warming have been studied extensively in the WIO region (Obura
2005; Gudka et al., 2019; McClanahan et al., 2007; Obura et al. 2018). Although ocean temperature increases
occur globally, in the tropics and subtropics, the rate of rising temperature can vary across regions and at local
scales (Hoegh-Guldberg et al. 2007; Hughes et al. 2017), contributing to variation in the resilience of coral reefs
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to cope with temperatures and temperature spikes (McClanahan et al. 2007). Many factors affect local variation
in temperatures and the responses of corals and their symbiotic algae, potentially imposing directional selection
and local adaptation or phenotypic plasticity (West & Salm 2003, Obura 2005, Obura 2009, McClanahan et al,
2014; Pratchett et al, 2013).
Ocean acidification causes negative impacts on calcifying species like phytoplankton, molluscs, corals and
coralline algae (Harvey et al. 2013). For species with a calcified skeleton, the lower pH will impede building a
calcium carbonate (CaCO3) structure (Doney et al. 2009). Still, these effects will be most pronounced in colder
regions than in the tropics, since warmer temperatures stimulate faster growth and development by a higher
metabolism (Byrne 2011) which may counteract the negative effects of acidification (McNeil et al. 2004; Kleypas
and Yates 2009). At the moment, the impact of sea level rise is not considered a major threat to coral reefs in
the region, as the progression of sea level rise may be within the growth rate of most corals (Anthony & Marshall
Other than direct stressors, there are several synergistic indirect stressors that are influencing corals negatively.
For example, a stressed coral reef will be more susceptible to coral diseases, which encompasses pathogenic
fungi, bacteria or viruses that may reduce growth rate, impair reproduction and cause direct mortality (Harvell
2007). Many of these diseases are still relatively unknown, but today we see strong correlations between the
appearance of such pathogens after acute stress events such as coral bleaching and tropical cyclone damages
(van Hooidonk & Huber, 2006; Randall & van Woesik, 2015; 2017). There are also processes that are often not
immediately associated with global climate change effects such as eutrophication and pollution from various
sources, that accentuate the pressure on corals and associated species. Currently in the WIO, warmer sea
surface temperatures and El Ninõ-Southern Oscillation effects are generating stronger and more frequent
cyclones and heavier storms, which also affect new geographical areas that previously have been spared from
such events (Fitchett & Grab 2014). The region also experiences greater variation in precipitation, with the
resulting run-off from land carrying solid waste such as plastics, nutrient pollution (mostly nitrogen and
phosphorus), suspended sediment and chemicals as well as metals from industry and agriculture. Finally,
increased temperatures and alterations in ocean circulation and currents cause changes in cold and warm water
areas and allow new and sometimes deleterious species to migrate and invade new areas.
Future Research Areas
Previous research in the region has largely focused on the genus Acropora (Baird et al. 2009; Meyer et al. 2011;
Mattan-Moorgawa et al. 2012; Louis et al. 2017). Certainly, more studies on additional species are required, in
particular comparative studies on temperature response, both in the laboratory and in the field. A few key genera
that have been suggested for such studies are Porites and Favia. Nevertheless, for better management of
coastal ecosystems including coral reefs, research must also focus on rare and endemic species in the region
(e.g. Anomastrea sp.) that possess a high conservation value, and need protection of their habitats, particularly
species that live in critical habitats. Better knowledge about the sensitivity and robustness of different taxa and
populations to climate warming, possible acclimatization to changing conditions and the possible existence of
unique genetic makeups with a stronger resilience towards warming are essential aspects to be considered. A
relevant question is if priority should be placed on species that are ecosystem engineers, those with higher
resistance to extreme conditions, or rare or endemic species.
Moreover, adaptations in corals to climate change is a complex process, but we know variations exist in traits
and that selection occurs. In order to understand local morphological adaptations, behavioural changes and
variation in gene expressions, long-term monitoring programs are required because adaptations can vary among
species and across populations. This research should include a focus on the symbiotic dinoflagellates, now
known to be highly variable at high levels of classification (LaJeunesse et al. 2018). This particular field provides
several new and important research directions in terms of understanding coral resilience. For example, there
may be specific micro-organisms or certain microbe communities that facilitate corals resistance against
bleaching or invasive microorganisms which can drive shifts in these unique symbiotic microbial communities,
obstructing selection towards adaptations or even make corals more vulnerable to bleaching.
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Opportunities for future work
In the WIO, there are several research groups focusing on coral research. These research groups are either
affiliated with universities, governments or various NGOs. Most of the research commenced after the serious
bleaching event that hit the region in connection with the 1997/98 El Nino event when sea surface temperatures
increased by several degrees killing up to 90% of corals on many reefs of the region (Obura, 1999; Wilkinson et
al., 1999; Goreau et al., 2000; but also CORDIO Reports 1999, 2000, 2002, 2005 and 2008). However, research
in the WIO region is challenging since there is very little local funding available. In addition, the region is large
and comprises both mainland countries and island nations, which make logistics and management demanding.
Even if it is today possible to forecast bleaching events (Donner et al. 2017), as they until now has been
associated with El-Nino-events, and substantial research has been accomplished to understand coral responses
to elevated temperatures (Hoegh-Guldberg et al. 2007; Hughes et al. 2017), there is a lack of contingency
funding which can be mobilized in the event of a new mass bleaching event. In addition, there is little knowledge
of species-specific responses to rising temperatures.
To achieve such essential knowledge, new research is required in several fields. Taxonomic research, for
example, has unfortunately been underfinanced for many years in all areas, not only in the marine realm. Still,
museums around the world provide funding for larger sampling campaigns required to identify and classify new
species. Such research is of key importance also when it comes to forecasting the ability of different species to
survive the various impacts of climate change. Without correctly identifying which organisms comprise an
existing healthy coral microbial community, the understanding of invasive/introduced species dynamics, or even
the identification of unique genetic constitutions of certain coral populations will be impossible. This would
obviously entail substantially more man hours of field research to map coral reefs around the WIO region in
detail, but also to conduct laboratory and mesocosm experiments, as well as to conduct targeted meta-
population molecular studies.
Coral reefs are complex habitats, and a change in one end of the system will cascade and produce a multitude
of consequences elsewhere. To try and understand the various changes occurring to coral reefs, the WIO needs
formal, coordinated research groups and consortiums of laboratories, which can combine and expand efforts.
One important focus of such research groups would be to prepare a strategic monitoring plan for any impending
major bleaching events in the region, as these are likely to become more common in the next few years. This
would require a funded regional contingency plan, core-funding secured for long-term monitoring, and a plan to
study pre-determined measurement indicators at sentinel sites; during pre-, peak- and post-mass bleaching
Similarly, there is a need to develop research and monitoring related to ocean acidification. The Global
Observation Ocean Acidification Network (GOA-ON) and OceAn pH Research Integration and Collaboration in
Africa (ApHRICA) are pilot projects to deploy ocean pH sensors in the WIO for the first time. The initiative aims
to improve knowledge and to provide selected teams with training and basic observation equipment, the “OA”
toolkit. However, only a few research teams up to now have received these toolkits and initiated the first
observations. Sustainable Oceans, Livelihoods and food Security Through Increased Capacity in Ecosystem
research in the Western Indian Ocean (SOLSTICE-WIO) is a project funded by the UK Global Challenges
Research Fund (GCRF) that raises awareness and transfers knowledge on climate change issues to local
researchers and students. The long-term objective of all this work is to create a local research community of
practise for ocean acidification and other stressors on the marine environment and relate the ocean acidification
observation to species and ecosystems of socioeconomic importance to make the science relevant for society.
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Table 1. Description of marine conservation biology actions and their putative impacts on key
organisms in the WIO region.
Assess local adaptations
and resilience
Fish, corals
Predictive accuracy of species responses to
climate change
Contingency funding
forecast bleaching events
Species-specific responses
mangroves, fish
Identify vulnerable or robust taxa
mangroves, fish
Protection of species that withstand extreme
conditions, and rare endemic species
Improved molecular labs
mangroves, fish
To identify population structures, species and
rare allele combination, gene expressions, and
Focus on sympodium
dinoflagellates and
associated microbes
Symbiotic microbial communities can drive coral
adaptations and resilience
Taxonomic research
Invasive species can obstruct selection
Establish baseline
mangroves, fish
Improve comparative studies before and after
extraordinary events
Improve ecosystem-based
mangroves, fish
Mitigates global climate change. Simultaneously
highlights and protect key species or
ecosystems, and improve ocean conservation
biology and biodiversity
Standardize research and
sampling methods
mangroves, fish
Improve validation and statistical power across
the region
Support for long term
monitoring studies
Corals, HABs, pH
To enable forecasting future extreme events
Develop core lab facilities
for molecular techniques
mangroves, fish
Assure the availability of expensive molecular
equipment, and support specialist training in the
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Seagrass and mangroves
Key ecosystem characteristics and features
Seagrasses in the WIO are intimately associated with coral reef habitats, growing on sandy as well as hard-
substrate bottoms, and dominating the shallow lagoons and some shallow reef slopes throughout the region.
They may also grow sub-tidally in protected bays, estuaries and semi-enclosed sites, closely associated with
mangroves that dominate the intertidal zone along these coasts. Mangroves and seagrasses are the only two
groups of vascular plants that have adapted to life in saline water. The general ecology of seagrass ecosystems
and mangroves has been well covered elsewhere (see for example: Linneweber and Drude de Lacerda 2002;
Green et al. 2003; Hemminga and Duarte 2008; Hogarth 2015). For that reason, we will mainly focus our efforts
to discuss conditions specific to the WIO.
Seagrass beds and mangrove forests are found throughout the WIO region. Of the estimated 1 million hectares
of mangroves in the WIO region, about 90% is found in Kenya, Tanzania, Mozambique and Madagascar
(UNEP/Nairobi Convention 2009). Thirteen seagrass species are reported along 12 000 km of the region’s
coastline (Gullström et al. 2013).
Description of benefits
Historically, less research has focused on the ecology and physiology of seagrasses compared to coral reefs
and mangroves. However, today the situation is changing, and research related to the ecology of seagrasses
and their role in the lifecycle of other marine organisms has increased dramatically (e.g. George et al. 2018;
Lyimo et al. 2018; Bouma & Infantes 2019; Meysick et al. 2019). Important research has also focussed on the
ability of seagrasses to adapt to climate change and the role of seagrasses in the carbon cycle e.g. the long-
term uptake of atmospheric carbon, referred to as blue carbon (Duarte et al. 2005, 2010; Kennedy et al. 2010;
Mcleod et al. 2011; Fourqurean et al. 2012; Alongi et al. 2016; Lyimo et al. 2018; Gullström et al. 2018).
Mangrove forests and seagrass meadows constitute multifunctional, high-productivity ecosystems that serve as
spawning and/or nursery habitats for a wide variety of fish and invertebrates (de la Torre-Castro & Rönnbäck
2004; Hughes et al. 2009; de la Torre-Castro et al. 2014; Nordlund et al. 2018), thus are key fishing grounds (de
la Torre-Castro & Rönnbäck 2004; Unsworth & Cullen 2010; Nordlund & Gullström 2013). In addition, some
birds, reptiles and even mammals depend on both habitats for their survival. For example, researchers have
identified 40 different fish species, 125 sessile species and 72 species of attached microalgae associated with
seagrass meadows (Moksnes et al. 2008). Mangroves and seagrasses are accordingly keystone habitats
providing ecosystems with high biodiversity (Duffy 2006; Blaustein 2008). Furthermore, these types of vegetation
along the coast can reduce wave height and energy (Lacy & Wyllie-Echeverria 2011; Manca et al. 2012) and
enhance the accumulation of sediment (Potouroglou et al. 2017). Sediment accumulation in seagrass meadows
is highly beneficial as it keeps sediment from leaving the shore (Lacy & Wyllie-Echeverria, 2011; Manca et al.,
2012; Duarte et al. 2013; Spalding et al. 2014), hence counteracting coastal erosion. The root systems of
mangroves and seagrasses bind the sediment and the shoots, while stems and leaves slow down water
movement (Ginsberg & Lowenstam 1958; Fonseca et al 1983; Saenger 2002), and protect shores from erosion.
Mangroves and seagrass meadows also have the ability to reduce turbidity, making the water clearer by lowering
the horizontal transport of suspended sediments and thus moderating sedimentation impacts on adjacent coral
reefs (Duke & Wolanski 2000; Schaffelke et al. 2005; De Boer 2007). However, human activities have increased
run-off from land and elevated water turbidity including the levels of nutrients, with negative impacts on the plants
and associated organisms (Mohammed 2002 Hamisi et al. 2004; Uku & Björk 2005; Hamisi et al. 2009; Huxham
et al. 2010). Elevated water temperatures caused by global warming have been reported to negatively influence
productivity of tropical seagrasses in the WIO region (George et al. 2018) and these negative effects are
exacerbated by local stressors e.g. eutrophication (Mvungi & Pillay, 2019). Such disturbances have also been
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shown to increase methane emission together with sulphide concentrations in the sediments (Lyimo et al., 2018),
where high levels of sulphide could enhance seagrass mortality due to sulphide toxicity.
Seagrass meadows have also been proposed as ocean acidification refugia because of their ability to respond
positively to changes in carbonate chemistry by storing more CO2 as Blue Carbon (Cyronak et al. 2018). This,
in turn, has the potential to locally reduce ocean acidification by increasing pH and aragonite saturation (e.g.
Yates et al. (2016). Such biogeochemical services provided to the coral reef system by not only seagrass
meadows but also mangrove, are highlighted particularly in Seychelles for the Indian Ocean (Camp et al. (2016)
and provide a strong conceptual framework for conservation efforts.
The protection and management of mangrove forests together with seagrass beds are categorised as one of
the most important elements of blue carbon strategies to mitigate climate change (Laffoley & Grimsditch 2009;
Nellemann et al. 2009; Duarte et al. 2013). Peat formation in mangroves comprises a substantial carbon sink
(Ong 1993), and in Kenya, seagrass beds are 4-6 times higher in sediment carbon compared with un-vegetated
controls (Githaiga et al. 2017).
Unfortunately, these habitats are today threatened (Waycott et al. 2009). The main reason for the loss of
mangrove vegetation and seagrass meadows along the coasts of the oceans is overharvesting, reclamation,
eutrophication and the use of destructive fishing techniques (Larkum et al. 1989; Stapel et al. 1996; FAO 2007;
Hamad et al. 2014). Not only does seagrass function as nurseries for a large diversity of marine species,
seagrass act as essential fish habitats contributing towards key fishing grounds (de la Torre-Castro & Rönnbäck
2004; Unsworth & Cullen 2010; Nordlund & Gullström 2013). Seagrass-based fisheries are extremely important
for coastal livelihoods as traditional small-scale fishing activities support millions of people (Barnes-Mauthe et
al. 2013; de la Torre-Castro et al. 2014). However, fishing methods such as bottom trawls, beach seines,
explosives, poisons and rakes are destructive to seagrass habitats (Nordlund et al. 2018).
With elevated sea levels, mangroves and seagrass meadows may, in suitable areas, be instrumental to mitigate
the effects of strong winds, tidal waves, sea surges, tsunamis, and shoreline erosion (Mazda et al., 2007; Godoy
& Lacerda, 2015). However, with sea-level rise, mangrove forests may be flooded and seagrass beds silted
over. On the other hand, with sufficient space, mangrove forests and seagrass beds, as well as other natural
habitats such as saltmarshes and the supralittoral zone with sand dunes may be able to migrate landward.
Unfortunately, today, the expansion of transformed urban and agricultural land further into coastal areas has led
to a coastal squeeze of these important natural habitats (Doody 2004). Consequently, in most cases the
mangrove and seagrass habitats will disappear, together with a number of associated ecosystem goods and
Future Research Areas
As elevated sea levels, temperature, altered nutrient supply, and rainfall change at rapid rates, there is a great
risk of the biogeochemical cycles (for example the water, carbon and nitrogen cycle, etc.) being altered in these
natural systems. Pore-water or submarine groundwater discharge may play a major role in the exchange and
export of dissolved inorganic and organic carbon (DIC and DOC), nutrient and micronutrient availability at inland
bays and wetlands (Burnett et al. 2003). Understanding how these potential changes in hydrological,
geochemical and biochemical processes associated with changes in climate may affect mangrove and seagrass
biomass and productivity is starting to become particularly relevant (Maher et al. 2013).
Organisms have adapted to changing environments for millions of years in order to obtain a good phenotype-
environmental match. However, the present environmental change in combination with global climate change is
probably taking place at a higher pace than any time before, which requires a much faster response (e.g.
phenotypic plasticity) from marine organisms. To develop better and more science-based coastal management
procedures when, for example, allocating space for various human activities and marine protected areas
(MPAs), we need to understand the adaptive capacity among different populations within species, as well as
potential differences between species e.g. mangrove trees and seagrasses plant species. With a better
knowledge about evolvability and adaptive capacity, it would be possible to develop models and carry out
simulations in order to more accurately forecast future changes in species distribution and community changes.
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Efforts need to be made to understand both current taxonomy and microevolutionary processes if we are to
adequately model the specific responses of continually evolving subpopulations.
Opportunities for management and conservation
For the WIO region, it is important to remember that mangroves and seagrasses provide a wide range of coastal
ecosystem services but are also highly threatened arguably by an equally extensive list of issues. This
emphasizes the urgent need for improved management and a clear idea about the road forward.
Global climate change is contributing to elevated sea levels at an accelerating trend globally and is having
profound effects on coastal and urban areas in all continents, and the WIO region is no exception (Ngusaru et
al. 2000; Masalu 2002; Almström & Larsson 2008; Shaghude et al. 2015; Shaghude et al. 2018). In order to
prevent or mitigate the impacts of coastal erosion, various methods have been tried. In most cases hard ‘grey’
structures such as groins and seawalls have been constructed (Shaghude et al. 2015). However, such structures
may result in additional problems by shifting erosion alongshore and eventually eroding sandy beaches and
dune landscapes and causing siltation in other areas. During the last few decades, various forms of “green”
infrastructure have been trialled to manage coastal erosion effectively, with the added benefit of providing
numerous ecosystem services (Jones et al. 2012; Duarte et al. 2013; Munang et al. 2013; Spalding et al. 2014;
Temmerman et al. 2014). Mangrove vegetation and seagrass meadows are an integral part of these natural
shoreline protection solutions.
One area which has lacked in-depth research previously, is the natural interactions that exist between the marine
and terrestrial environment. Seashores with a diverse set of ecosystems including seagrass, mangroves as well
as rich beds of different algae and coastal forests, lead to a higher diversity and larger biomass of different plants
and insects in the coastal area (the supralittoral) (McLachlan & Brown, 2006). Rich shoreline and shallow water
plants and algal communities create a food web that connects the marine environment with the adjacent land. It
is therefore not only an exchange of sand and sediment but also a considerably exchange of particulate and
dissolved organic matter when plants and algae are washed up onto land and when animals from both habitats
migrate between the beach and the dunes searching for food (Defeo et al., 2009; Mellbrand et al., 2011). These
synergies contribute to conserving and/or further increasing biodiversity but have been largely under-studied at
local levels in the WIO.
Mangroves and seagrass beds in the WIO offer similar research-based management challenges as discussed
for coral reefs and later for fish. Probably the single most important improvement to enhance the quantity and
quality of research in the region would be to facilitate even stronger networks and communication among
research groups across countries in the WIO. With closer interactions among researchers, knowledge transfer
would improve, and research groups could agree upon standardized methods for basic field work procedures,
such as harmonised sampling designs to enable comparisons between location and/or among regions. Such
studies also need to be transferred, preferably to an open source regional database, where geographical
coordinates together with detailed GIS maps (Geographic Information System) can be stored and viewed for
any user. CORDIO’s Marine Spatial Atlas for the Western Indian Ocean (
results/maspawio/) is a good example of how such service and interface could appear.
Key ecosystem characteristics and distribution
The coastline of the WIO is characterized by a wide diversity of habitats and biogeographic regions. The southern
extent of the WIO encompasses South Africa’s warm-temperate coastline. Here, habitats for fishes include salt
marsh and seagrass (in estuaries) as well as rocky reefs and mixed rocky and sandy shorelines. South Africa’s
east coast is classified as sub-tropical and, in this region, the southernmost mangroves and coral reefs are
found. This region is also the southernmost distribution limit for many tropical Indo Pacific fish species. The
coastlines of northern Mozambique, Tanzania, Kenya, Somalia and the island states of Comoros, Madagascar,
Reunion and Mayotte, Mauritius and Seychelles are tropical, with fringing coral reefs, extensive mangrove
forests and seagrass beds. The WIO supports a diverse fish assemblage with approximately 2200 fish species
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recorded (van der Elst et al. 2005; Kulbicki et al. 2013), representing 15% of the marine fishes found globally
(Smith & Heemstra 1986, van der Elst et al. 2005). The variety of habitats, geomorphological histories and
biogeographic regions in the WIO also gives rise to different structures of reef fish assemblages a high level of
endemism, particularly off the warm-temperate coastline of South Africa, with 13% of fish species endemic to
the WIO (van der Elst et al. 2005; Samoilys et al. 2019). Over 50% of the fish species here have an Indo-Pacific
origin (tropical), while 29% are deep sea species, 4% cosmopolitan and 3-4% Atlantic species (van der Elst et
al. 2005).
Description of benefits
The coastal zone in the WIO is rather densely populated, with an estimated three million people directly
dependent on fishing for their livelihood in this region (van der Elst et al., 2005; Temple et al. 2017). Overfishing
can reduce the adaptability of fish to climate variability and climate change (Hsieh et al. 2006) although very little
work has been done on the impact of climate change on the fish communities of the WIO, with the most data
available from South Africa (e.g. James et al., 2013, Potts et al., 2015).
A large proportion of WIO counties’ population live near the coastal zone with fisheries contributing to
employment and protein (van der Elst et al. 2005). Most of the fishers in the region are considered artisanal or
subsistence, rather than industrialized (van der Elst et al. 2005) thus generating accurate estimates of fisheries
importance is difficult but localized studies indicate their importance for livelihoods is substantial (McClanahan
et al. 2015). The high reliance on fisheries resources means that the effects of climate change on fish populations
can transcend resource productivity and result in serious food security and livelihood compromises (McClanahan
et al. 2015, Daw et al. 2009). There is thus an urgent need to accurately predict how climate change will affect
fisheries so adaptive management of the resource and the people that rely on it can be optimized (McClanahan
et al. 2015).
Impacts/threats of climate change
The effects of climate change on fish populations can be either direct or indirect (Breeggemann et al. 2016).
Direct effects of climate change on fish populations are physical changes in the ocean environment that influence
internal patterns and processes which modulate behaviour, demographic and distribution responses (Rijnsdorp
et al. 2009, Brander 2010). Changes in ocean temperature, oxygenation, and acidification are considered the
three most important direct physical environmental drivers on fish populations, and responses to these stressors
will determine resilience to future climate change (Gruber 2011, Pörtner 2012). Although direct effects of physical
environmental drivers on fish populations can often interact (e.g., Munday et al. 2009), the overarching
environmental driver is considered to be temperature because of the pervasive effect of temperature on
ectotherm physiological rates which regulate performance (Holt & Jørgensen 2014, Potts et al. 2015, Hoey et
al. 2016). Given that very little research has been conducted on the effects of climate change of fish and fisheries
within the WIO, the impacts of climate change on the fish of the WIO can mainly be inferred from global and
regional studies (Samoilys et al. 2019).
Indirect effects influence fish populations is via changes in the productivity or structure of ecosystem processes
that have cascading effects throughout ecosystem networks (Brander 2010). For example, in the northern
hemisphere, climate warming is changing the abundance and spatial distribution of zooplankton species in the
North Sea (Helaouët & Beaugrand 2007), which in turn will exert a bottom-up effect on Atlantic cod recruitment
within the same area (Beaugrand et al. 2003). In the northern Atlantic, northward movements of a number of
fishes has been recorded during the last couple of decades, involving species like mackerel, herring cod etc
(see e.g. Perry et al. 2005).
Studies investigating the effects of ocean acidification on fish suggest that the early life stages may be the most
vulnerable to ocean acidification (Melzner et al. 2009b, Baumann et al. 2012), although some species are more
tolerant than others and can emerge as “winners” (Ishimatsu et al. 2004, Munday et al. 2011). Deleterious ocean
acidification responses manifest through the negative effects on growth, development, metabolism, behaviour,
and ultimately, mortality and recruitment (Ishimatsu et al. 2008, Munday et al. 2010). In a pioneering ocean
acidification study on a South African linefish, Erasmus (2017) and Edworthy (2017) found reduced growth,
development, metabolism, and survival of post-flexion dusky kob (Argyrosomus japonicus) larvae at low pH
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levels of 7.78 predicted for the end of the century (2100). This reduced larval performance could ultimately result
in complete recruitment failure of the species if no evolutionary adaptation to low pH occurs. Direct effects of
ocean acidification on subadult and adult fishes are, however, believed to be minimal as compensatory
mechanisms can maintain intracellular acid-base balance in an acidic environment (e.g., Melzner et al. 2009a,
Haigh et al. 2015). Low oxygen zones can also affect fish populations through reductions in available habitat or
altered metabolic/physiological processes, that can ultimately result in increased mortality (Stramma et al. 2010).
Temperature and oxygen are intrinsically linked in the ocean, as rising temperatures will reduce the
concentration of oxygen while simultaneously increasing oxygen demand in organism tissues (Deutsch et al.
Habitat loss associated with climate change can also affect the composition of fish communities. Chabanet
(2002) found that two years after the 1998 coral bleaching event, fish communities on coral reefs in Mayotte
were dominated by herbivores as opposed to browsers of sessile invertebrates. An increase in the frequency
and intensity of extreme events may also result in the loss of essential nursery habitats for coastal fish such as
mangroves, seagrass and salt marsh (James et al. 2013). Mann and Pradervand (2007) in subtropical South
Africa found a close relationship between the abundance of adult fish in the marine environment and the
availability of estuarine nursery habitats, with the abundance of adults decreasing when nursery habitats were
The response of fish populations to changes in ocean temperature can be broken down into four broad
components; behaviour, phenology, distribution, and demography (Rijnsdorp et al. 2009, Potts et al. 2015,
Poloczanska et al. 2016). Behaviour modifications are often a first response to ocean temperature changes as
fish may seek to avoid unfavourable temperatures (Rijnsdorp et al. 2009). Behaviours such as swimming speed
or foraging behaviour are temperature sensitive (Brownscombe et al. 2014, Johansen et al. 2014) and fish may
seek temperatures that maximise these behavioural processes or adjust behaviours when temperatures are
sub-optimal (Freitas et al. 2015). Temperature-induced behavioural modifications can affect fish population
phenology (the timing of cyclical events), as temperature is often a cue for seasonal migrations (Sousa et al.
2016), diel migrations (Keyser et al. 2016) and spawning migrations (Sims et al. 2004). A global analysis of sea
surface temperature trends by Lima and Wethey (2012) identifies the coast off South Africa as having some of
the highest advances in seasonal warming. When temperature stressors are chronic over time, these short-term
behavioural and phenology responses can manifest into negative impacts on the abundance and productivity of
fish populations (Crozier et al. 2008).
Over longer timescales, changing ocean temperatures can drive distributional shifts in fish populations across
latitudes or depths (Pecl et al. 2017). For example, Perry et al. (2005) show that nearly two-thirds of North Sea
fishes responded to warming temperatures by shifting their distribution either deeper or to higher latitudes. In
the warm-temperate region of South Africa, James et al. (2008) reported an increased occurrence of certain
tropical fish species in temperate estuaries. Similarly, in a 19-year study of a sub-tropical reef fish community in
South Africa, Llyod et al. (2012) found a general increase in the abundance of tropical species as well as a
change in the proportion of tropical versus temperate species. These findings were attributed to warming of the
Agulhas Current. Temperature also affects demographic processes like growth, mortality and recruitment, such
that even small changes in temperature can have big impacts on population biomass and abundance (Brander
2010, Poloczanska et al. 2016). For example, temperatures that exceed the narrow thermal tolerance of fertilised
eggs may lead to faster larval development, resulting in increased mortality and reduced recruitment into
fisheries (Pankhurst & Munday 2011). Warming temperatures can also result in faster juvenile and adult growth
rates, which alter fish production (Audzijonyte et al. 2016). Ultimately these behavioural, phenological,
demographic, and distributional changes affect the abundance, productivity, and distribution of fish populations
that the human population relies on for goods and services (Brander 2007).
Future Research Areas
Much of the leading work on this subject has come from South Africa, partly because of the sharp gradients in
temperature facilitating detection of changes in distributions over short times and distances, as well as a longer
history of studies of fish species and assemblages. Research on climate impacts on fish will require complex
laboratory-based experimental studies, as well as in-situ ecological, biological and environmental data collection.
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In order to generate baseline data, long-term monitoring programmes need to be initiated, particularly in data-
poor counties and in areas situated at the boundary of species distributional ranges, to better assess the impacts
of climate change on fish assemblages. These programmes should monitor the relative abundance of fishes as
well as the stability and resilience of fish assemblages.
With a myriad of potential changes likely, an assessment of key species climate resilience, defined as the ability
to resist or recover from a climate-related stressor (Côté & Darling 2010, Hodgson et al. 2015), is also a research
priority. Determining fish population resilience to climate change has generally been studied through correlations
between environmental variables and historical population responses (Horodysky et al. 2015). Correlative
studies mostly take a “black box” approach and do not consider the underlying mechanisms that govern
population responses (Helmuth 2009), which can make forecasting responses unreliable (Horodysky et al.
2015). Furthermore, assigning biological responses of populations to climate change is challenging, given the
complexity of interacting mechanisms, variable species responses, and the potential of cascading effects
(Poloczanska et al. 2016). While it is still useful to assess past responses to climate change, incorporating
experimentally derived information on the sensitivity of underlying processes can improve inference and
forecasting accuracy (Wernberg et al. 2011).
The incorporation of physiology into the assessment of vulnerability or resilience of fishes to climate change is
relatively new but holds great promise as a method to develop a suite of more appropriate management tools
(McKenzie et al. 2016). For example, in Papua New Guinea, Rummer et al. (2014) used metabolic physiology
to identify fish species vulnerable to climate change, while Fitzgibbon et al. (2014) used metabolic physiology to
identify the most vulnerable life history stage of spiny lobster (Sagmariasus verreauxi). Another recent global
fisheries example of the incorporation of physiological research into adaptive management plans is the Fraser
River sockeye salmon (Oncorhynchus nerka) (Patterson et al. 2016). Physiological research involved identifying
the impacts of high water temperature and high river discharge in terms of thermal tolerance, energy metabolism
and respiratory capacity, which among other factors, influence successful spawning migrations, and adjusting
catch limits when appropriate (Clark et al. 2010, Eliason et al. 2011, 2013). In the WIO, future research
quantifying the biological effect of climate change on fish populations must therefore take a species-specific
process-based, physiological approach.
The way forward
We have discussed three key marine organism groups and ecosystems that are instrumental in providing
important ecosystem goods and services for local communities and coastal economies in the Western Indian
Ocean. To date, for these systems, there have been varied efforts in studying the different climate impacts
across geographies as well as thematically in terms of the types of threats.
The current evidence suggests that temperature increases due to global warming will have the widest ranging
and most immediate impact across the marine environment and is therefore justifiably the most widely studied
to date, but significant investment still needs to be made on the other climate threats e.g. acidification, to
understand their full effects. This will help identify and develop more holistic strategies and actions to mitigate
against global climate change in the region.
Although a lot of progress has been made in the last decades, a common theme raised among all research
communities, regardless of study system, is that research conducted within the WIO needs greater collaboration
and partnerships amongst universities, laboratories, institutions, research groups, NGOs, and most recently the
use of citizen science. This should enhance learning across and within fields and facilitate the transfer of
knowledge, technology, experiences and data in order to expand the scope and number of studies. Additionally,
improved standardisation of sampling designs and methodologies, in particular for studies of climate change
where monitoring studies are an important part, would not only provide important baseline data, but also enable
detection of minor changes in ecological communities. Increased collaboration could also help fill a key research
gap on the associated or cross-effects of climate effects across ecosystems (cascading impacts).
To address the numerous research areas related to climate change and provide a comprehensive study of
biological and ecological responses of organisms, the physical environment and habitat condition to these
effects, a holistic and varied number of scientific techniques will be required. This includes genetic and molecular
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analyses, laboratory experiments and in-situ observations. For instance, information about genetic variation
within populations can provide valuable insights of species and populations uniqueness and their evolvability in
order to decide if certain populations should be designated as Evolutionary Significant Units (ESU) (Conner and
Hartl 2004). Currently, it would not be feasible to establish several advanced laboratories in the WIO due to the
high financial and human capacity requirements. Core facilities that have the expertise and equipment to conduct
advanced molecular analysis should be developed at a few key locations in WIO where the infrastructure is
already relatively well developed. Exchange programs from across the WIO to these centres of excellence will
enable students to learn specialist techniques e.g. molecular tools, with the aim of establishing new or
progressively improving existing laboratories and research station facilities in their home countries
Finally, how ecosystems will be affected is not only dependent on the direct effects of the perturbations on
individual species but also on the potential unequal pressure across trophic levels which could lead to
imbalances in the trophic structure, causing trophic cascades that may change the dynamics of the ecological
community (Ober 2016). If we are to fully understand the complex effects of a changing climate, this is a key
area to consider.
The WIO has an established group of researchers in government and private research institutions working
across different geographic areas and fields. There are also active regional monitoring networks e.g. GCRMN,
associations like WIOMSA which can coordinate regional collaboration, as well as regional inter-governmental
policy frameworks e.g. UN Nairobi Convention. The marine science sector in the WIO is therefore at a point
where there is potential to significantly grow and improve with the right investment. The UN Decade of Ocean
Science starting in 2020 provides a timely opportunity for this to happen. At the same time government interest
and intention to invest in the Blue Economy requires complementary investment in monitoring and research of
ecosystems and other resources, as climate impacts will underpin the benefits that are obtained from the ocean.
This review highlights that there will most certainly be both biological and human “winners” and “losers” in certain
areas of the WIO, it is our contention that understanding, and perhaps successfully predicting, ecological
responses to global climate change will be aided greatly by a deeper investment in a multitude of research areas
such as field ecology, genetics and social science, as well as investing in mechanisms to increase collaboration
and transfer expertise across countries, institutions and subject areas.
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ahamada, s., j. bijoux, b. cauvin, a. hagan, a. harris, m. koonjul, s. meunier, and j.p. quod 2008. status of the
coral reefs of the south west indian ocean island states: comoros, madagascar, mauritius, reunion, seychelles,
in: wilkinson c (ed.), status of coral reefs of the world: 2008, australian institute of marine science, queensland.
alongi d, murdiyarso d, fourqurean j, kauffman j, hutahaean a, crooks s, lovelock c, howard j, herr d, fortes m
2016. indonesia’s blue carbon: a globally significant and vulnerable sink for seagrass and mangrove carbon.
wetlands ecology and management 24:313.
ahamada, s., bigot, l., bijoux, j., maharavo, j., meunier, s., moyne-picard, m., & paupiah, n. 2002. status of
coral reefs in the south west indian ocean island node: comoros, madagascar, mauritius, reunion and
seychelles. status of coral reefs of the world. australian institute of marine science, townsvile, 79-100.
ateweberhan, m & mclanahan, t.r. 2010. relationship between historical sea-surface temperature variability
and climate change-induced coral mortality in the western indian ocean. marine pollution bulletin 60:964970.
attri, v.n. 2016. an emerging new development paradigm of the blue economy in iora; a policy framework for
the future. indian ocean rim association (iora), university of mauritius. available at:
pdf. [accessed 10 october 2016].
audzijonyte, a., fulton, e., haddon, m., helidoniotis, f., hobday, a. j., kuparinen, a., morrongiello, j., smith, a. d.
m., upston, j. & waples, r. s. 2016. trends and management implications of human-influenced life-history
changes in marine ectotherms. fish and fisheries 17:10051028.
baumann, h., talmage, s. c. & gobler, c. j. 2012. reduced early life growth and survival in a fish in direct
response to increased carbon dioxide. nature climate change 2:3841.
beaugrand, g., brander, k. m., lindley, j. a., souissi, s. & reid, p. c. 2003. plankton effect on cod recruitment in
the north sea. nature 426:661664.
bozinovic, f. & pörtner, h. o. 2015. physiological ecology meets climate change. ecology and evolution 5:1025
brander, k. 2010. impacts of climate change on fisheries. journal of marine systems 79:389402.
brander, k. m. 2007. global fish production and climate change. proceedings of the national academy of
sciences 104:1970919714.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
breeggemann, j. j., kaemingk, m. a., debates, t. j., paukert, c. p., krause, j. r., letvin, a. p., stevens, t. m., willis,
d. w. & chipps, s. r. 2016. potential direct and indirect effects of climate change on a shallow natural lake fish
assemblage. ecology of freshwater fish 25:487499.
brown, j. h., gillooly, j. f., allen, a. p., savage, v. m. & west, g. b. 2004. toward a metabolic theory of ecology.
ecology 85:17711789.
brownscombe, j. w., gutowsky, l. f. g., danylchuk, a. j. & cooke, s. j. 2014. foraging behaviour and activity of a
marine benthivorous fish estimated using tri-axial accelerometer biologgers. marine ecology progress series
burnett, w. c., bokuniewicz, h., huettel, m., moore, w. s., & taniguchi, m. 2003. groundwater and pore water
inputs to the coastal zone. biogeochemistry 66:333.
camp e. f., suggett d. j., gendron g., jompa j., manfrino c., smith d. j. 2016. mangrove and seagrass beds
provide different biogeochemical services for corals threatened by climate change. frontiers in marine science,
3: 52. doi: 10.3389/fmars.2016.00052
chabanet, p. 2002. coral reef communities of mayotte (western indian ocean) two years after the impact of the
1998 bleaching event. marine and freshwater research 53: 107-114.
clark, t. d., sandblom, e., hinch, s. g., patterson, d. a., frappell, p. b. & farrell, a. p. 2010. simultaneous
biologging of heart rate and acceleration, and their relationships with energy expenditure in free-swimming
sockeye salmon (oncorhynchus nerka). journal of comparative physiology b 180:673684.
cooke a & brand, j, 2012. madagascar a guide to marine biodiversity. 176 pp.
cooke s. j., sack l., franklin, c. e., farrell, a. p., beardall, j., wikelski, m. & chown, s. l. 2013. what is conservation
physiology? perspectives on an increasingly integrated and essential science. conservation physiology 1:
côté, i. m. & darling, e. s. 2010. rethinking ecosystem resilience in the face of climate change. plos biology 8:
e1000438, doi: 10.1371/journal.pbio.1000438.
crozier, l. g., hendry, a. p., lawson, p. w., quinn, t. p., mantua, n. j., battin, j., shaw, r. g. & huey, r. b. 2008.
potential responses to climate change in organisms with complex life histories: evolution and plasticity in
pacific salmon. evolutionary applications 1:252270.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
cyronak, t. et al. 2018. short-term spatial and temporal carbonate chemistry variability in two contrasting
seagrass meadows: implications for ph buffering capacities. estuaries and coasts 41: 1282-1296.
dahl, m., deyanova, d., lyimo, l. d., näslund, j., samuelsson, g. s., mtolera, m. s., et al. 2016. effects of shading
and simulated grazing on carbon sequestration in a tropical seagrass meadow. journal of ecology 104:654
daw, t.; adger, w.n.; brown, k.; badjeck, m.-c. 2009. climate change and capture fisheries: potential impacts,
adaptation and mitigation. in k. cochrane, c. de young, d. soto and t. bahri (eds). climate change implications
for fisheries and aquaculture: overview of current scientific knowledge. fao fisheries and aquaculture technical
paper. no. 530. rome, fao. pp. 107-150.
de boer, w.f. 2007. seagrasssediment interactions, positive feedbacks and critical thresholds for occurrence:
a review. hydrobiologia, 591:524.
de la torre-castro m.d., rönnbäck p. 2004. links between humans and seagrassesan example from tropical
east africa. ocean & coastal management 47:361-387.
deutsch, c., ferrel, a., seibel, b., portner, h. o. & huey, r. b. 2015. climate change tightens a metabolic
constraint on marine habitats. science 348:11321136.
doody, j.p. 2004. 'coastal squeeze' - an historical perspective. journal of coastal conservation, 10: 129-138.
donner, s.d., rickbeil, g.j.m., & heron, s.f. 2017. a new, high-resolution global mass coral bleaching database.
plos one, 12: e0175490.
duarte c.m., marbà n., gacia e., fourqurean j.w., beggins j., barrón c., apostolaki e.t. 2010. seagrass
community metabolism: assessing the carbon sink capacity of seagrass meadows. global biogeochemical
cycles 24
duarte c.m., middelburg j.j., caraco n.f. 2005. major role of marine vegetation on the oceanic carbon cycle.
biogeosciences 2:18.
duke, n.c., & wolanski, e. 2000. muddy coastal waters and depleted mangrove coastlinesdepleted seagrass
and coral reefs. in oceanographic processes of coral reefs pp. 97112, crc press.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
edworthy, c. 2017. the metabolic physiology of early stage argyrosomus japonicus with insight into the
potential effects of pco2 induced ocean acidification by. rhodes university, msc thesis. 74 pp.
eliason, e.j., clark, t.d., hague, m.j., hanson, l.m., gallagher, z.s., jeffries, k.m., gale, m.k., patterson, d.a., hinch,
s.g., farrell, a.p. 2011. differences in thermal tolerance among sockeye salmon populations. science 332:109
eliason, e.j., clark, t.d., hinch, s.g. & farrell, a.p. 2013. cardiorespiratory performance and blood chemistry
during swimming and recovery in three populations of elite swimmers: adult sockeye salmon. comparative
biochemistry and physiology, part a: molecular & integrative physiology 166: 385397.
elliff, c., silva, i.r. 2017. coral reefs as the first line of defense: shoreline protection in face of climate change.
marine environmental research, 127: 148-154.
eong, j. e. 1993. mangroves a carbon source and sink. chemosphere 27: 10971107.
erasmus, b. 2017. effects of co2-induced ocean acidification on the early development, growth, survival and
skeletogenesis of the estuarine-dependant sciaenid argyrosomus japonicus. rhodes university, msc thesis. 84
fitchett, j.m., grab s.w. 2014. a 66-year tropical cyclone record for south-east africa: temporal trends in a global
context. international journal of climatology, 34: 36043615.
fitzgibbon, q. p., jeffs, a. g. & battaglene, s. c. 2014. the achilles heel for spiny lobsters: the energetics of the
non-feeding post-larval stage. fish and fisheries 15:312326.
fourqurean, j. w., duarte, c. m., kennedy, h., marbà, n., holmer, m., mateo, m. a., apostolaki, e.t., kendrick, g.
a., krause-jensen, d., krause-jensen, d., mcglathery, k. j., & serrano, o. 2012. seagrass ecosystems as a
globally significant carbon stock. nature geoscience, 5: 505509.
freitas, c., olsen, e. m., moland, e., ciannelli, l. & knutsen, h. 2015. behavioral responses of atlantic cod to sea
temperature changes. ecology and evolution 5:20702083.
george, r., gullström, m., mangora, m. m., mtolera, m. s., & björk, m. 2018. high midday temperature stress
has stronger effects on biomass than on photosynthesis: a mesocosm experiment on four tropical seagrass
species. ecology and evolution 8:45084517.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
green, e. p., short, f. t., & frederick, t. 2003. world atlas of seagrasses. university of california press.
gruber, n. 2011. warming up, turning sour, losing breath: ocean biogeochemistry under global change.
philosophical transactions of the royal society a 369:19801996.
goreau, t., mcclanahan, t., hayes, r., & strong, a. l. 2000. conservation of coral reefs after the 1998 global
bleaching event. conservation biology, 14(1), 5-15.
gudka, m., obura, d., mbugua, j., ahamada, s., kloiber, u., & holter, t. 2019. participatory reporting of the 2016
bleaching event in the western indian ocean. coral reefs, 1-11.
haigh, r., ianson, d., holt, c. a., & neate, h. e. 2015. effects of ocean acidification on temperate coastal marine
ecosystems and fisheries in the northeast pacific. plos one, 10: e0117533.
hamad m.h., mchenga s.s.i., hamisi m.i. 2014. status of exploitation and regeneration of mangrove forests in
pemba island, tanzania. global j. bio. biotechnol. 3: 12-18.
hamisi, m. i., lyimo, t. j., muruke, m. 2004. cyanobacterial occurrence and diversity in seagrass meadows in
coastal tanzania. western indian ocean journal of marine science 3:113122.
hamisi m.i, lyimo t.j., muruke m.h.s, bergman b. 2009. nitrogen fixation by epiphytic and epibenthic diazotrophs
associated with seagras meadows along the tanzanian coast, western indian ocean. aquat. microb. ecol. 57:
harvell, c.d., e. jordan-dahlgren, s. merkel, e. rosenberg, l. raymundo, g. smith, e. weil, and b. willis. 2007.
coral disease, environmental drivers and the balance between coral and microbial associates. oceanography
20: 173195.
heck jr k.l., hays c.g., orth r.j. 2003. critical evaluation of the nursery hypothesis for seagrass meadows. mar.
ecol. prog. ser. 253: 123136.
heck jr., k.l., valentine, j.f. 2006. plantherbivore interactions in seagrass meadows. j. exp. mar. biol. ecol. 330,
helaouët, p., beaugrand, g. 2007. macroecology of calanus finmarchicus and c. helgolandicus in the north
atlantic ocean and adjacent seas. marine ecology progress series 345:147165.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
helmuth, b. 2009. from cells to coastlines: how can we use physiology to forecast the impacts of climate
change? journal of experimental biology 212: 753760.
hodgson, d., mcdonald, j. l., hosken, d. j. 2015. what do you mean, ‘resilient’? trends in ecology & evolution
hoey, a., howells, e., johansen, j., hobbs, j.-p., messmer, v., mccowan, d., wilson, s., pratchett, m. 2016. recent
advances in understanding the effects of climate change on coral reefs. diversity 8: doi: 10.3390/d8020012.
hofmann, g. e., todgham, a.e. 2010. living in the now: physiological mechanisms to tolerate a rapidly changing
environment. annual review of physiology 72:127145.
holt, r.e., jørgensen, c. 2014. climate warming causes life-history evolution in a model for atlantic cod (gadus
morhua). conservation physiology 2.
horodysky, a. z., cooke, s. j., brill, r. w. 2015. physiology in the service of fisheries science: why thinking
mechanistically matters. reviews in fish biology and fisheries 25:425447.
hsieh, c.h., reiss, c.s., hunter, j.r., beddington, j.r., may, r.m., sugihara, g. 2006. fishing elevates variability in
the abundance of exploited species. nature 443: 859-862.
huey, r. b., kearney, m. r., krockenberger, a., holtum, j. a. m., jess, m., williams, s. e. 2012. predicting
organismal vulnerability to climate warming: roles of behaviour, physiology and adaptation. philosophical
transactions of the royal society b 367:16651679.
hughes a.r., stachowicz j.j. 2004. genetic diversity enhances the resistance of a seagrass ecosystem to
disturbance. proc natl acad. sci usa 101:89989002.
hughes, a.r., stachowicz, j.j., williams, s.l. 2009. morphological and physiological variation among seagrass
(zostera marina) genotypes. oecologia 159:725733. doi 10.1007/s00442-008-1251-3
hughes t.p., anderson k.d., connolly s.r., heron s.f., kerry j.t., lough j.m., baird a.h., baum j.k., berumen m.l.,
bridge t.c., claar d.c., eakin c.m., gilmour j.p., graham n.a.j., harrison h., hobbs j-p.a., hoey a.s., hoogenboom
m., lowe r.j., mcculloch m.t., pandolfi j.m., pratchett m., schoepf v., torda g., wilson s.k. 2018. spatial and
temporal patterns of mass bleaching of corals in the anthropocene. science 359:8083
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
huxham, m., kumara, m.p., jayatissa, l.p., krauss, k.w., kairo, j., langat, j., mencuccini, m., skov, m.w., kirui, b.
2010. intra-and interspecific facilitation in mangroves may increase resilience to climate change threats.
philosoph. transact. r. soc. lond. bio. sci. 365: 21272135. doi: 10.1098/rstb.2010.0094
huxham, m., waldron, s., skov, m.w., bouillon, s., mencuccini, m., lang’at, j.k., kairo, j.g. 2014. rapid losses of
surface elevation following tree girdling and cutting in tropical mangroves. plos one 10:e0118334.
ishimatsu, a., hayashi, m. & kikkawa, t. 2008. fishes in high-co2, acidified oceans. marine ecology progress
series 373:295302.
ishimatsu, a., kikkawa, t., hayashi, m., lee, k.-s., kita, j. 2004. effects of co2 on marine fish: larvae and adults.
journal of oceanography 60:731741.
ipcc, 2018. global warming of 1.5° ipcc special report on the impacts of global warming of 1.5°c above
pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the
global response to the threat of climate change, sustainable development, and efforts to eradicate poverty
[masson-delmotte, v., p. zhai, h.-o. pörtner, d. roberts, j. skea, p.r. shukla, a. pirani, w. moufouma-okia, c.
péan, r. pidcock, s. connors, j.b.r. matthews, y. chen, x. zhou, m.i. gomis, e. lonnoy, t. maycock, m. tignor, and
t. waterfield (eds.)]. in press.
james, n.c., whitfield, a.k., cowley, p.d. 2008. preliminary indications of climate-induced change in a warm-
temperate south african estuarine fish community. journal of fish biology 72:18551863.
james, n.c., van niekerk, l., whitfield, a.k., potts, w.m., gotz, a. & paterson, a. 2013. effects of climate change
on south african estuaries and associated fish species. climate research 57: 233-248.
johansen, j.l., messmer, v., coker, d.j., hoey, a.s. & pratchett, m.s. 2014. increasing ocean temperatures
reduce activity patterns of a large commercially important coral reef fish. global change biology 20:10671074.
kennedy h., beggins j., duarte c.m., fourqurean j.w., holmer m., marbà n., middelburg j.j. 2010. seagrass
sediments as a global carbon sink: isotopic constraints. global biogeochemical cycles 24: gb4026.
keyser, f.m., broome, j.e., bradford, r.g., sanderson, b., redden, a.m. 2016. winter presence and temperature-
related diel vertical migration of striped bass (morone saxatilis) in an extreme high-flow passage in the inner
bay of fundy. canadian journal of fisheries and aquatic sciences 1786:17771786.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
kulbicki, m., parravicini, v., bellwood, d. r., arias-gonzàlez, e., chabanet, p., floeter, s. r., friedlander, a.,
mcpherson, j., myers, r. e., vigliola, l., mouillot, d. 2013. global biogeography of reef fishes: a hierarchical
quantitative delineation of regions. plos one, 8: e81847.
lajeunesse parkinson, j.e., gabrielson, p.w., jeong, h.j., reimer, j.d., voolstra, c.r., santos, s.r. 2018. systematic
revision of symbiodiniaceae highlights the antiquity and diversity of coral endosymbionts. current biology, 28:
larkum, a.w., mccomb, a.j., sheppard s.a. (eds.). 1989. biology of seagrasses: a treatise on the biology of
seagrasses with special reference to the australian region, 1(2), 105-112. elsevier, amsterdam.
lima, f.p., wethey, d.s. 2012. three decades of high-resolution coastal sea surface temperatures reveal more
than warming. nature communications 3: 704. doi: 10.1038/ncomms1713.
lloyd, p., plaganyi, e.e., weeks, s.j., magno-canto, m. & plaganyi, g. 2012. ocean warming alters species
abundance patterns and increases species diversity in an african sub-tropical reef-fish community. fisheries
oceanography 21: 78-94.
lyimo, l. d., gullström, m., lyimo, t. j., deyanova, d., dahl, m., hamisi, m. i., & björk, m. 2018. shading and
simulated grazing increase the sulphide pool and methane emission in a tropical seagrass meadow. marine
pollution bulletin 134:8993.
mcleod e, chmura gl, bouillon s, salm r, björk m, duarte cm, lovelock ce, schlesinger wh, silliman br. 2011. a
blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in
sequestering co2. frontiers in ecology and the environment 9:552560.
mahongo, s.b. 2009. the changing global climate and its implication on sea level trends in tanzania and the
western indian ocean region. western indian ocean journal of marine science 8:147159.
mahongo, s.b., francis, j., osima, s.e. 2011. wind patterns of coastal tanzania: their variability and trends.
western indian ocean journal of marine science 10:107120.
mann, b.q., pradervand, p. 2007. declining catch per unit effort of an estuarine-dependent fish, rhabdosargus
sarba (teleostei: sparidae), in the marine environment following closure of the st lucia estuarine system, south
africa. african journal of aquatic science 32: 133-138.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
maher, d.t., santos, i.r., golsby-smith, l., gleeson, j., & eyre, b.d. 2013. groundwaterderived dissolved
inorganic and organic carbon exports from a mangrove tidal creek: the missing mangrove carbon sink?
limnology and oceanography 58:475488.
marin-diaz b, bouma tj, e infantes 2019. role of eelgrass on bed-load transport and sediment resuspension
under oscillatory flow. limnology and oceanography, 9999: 1-11.
mcclanahan, t.r., ateweberhan, m., graham, n.a.j., wilson, s.k., sebastián, c.r., guillaume, m.m.m.,
bruggemann, j.h. 2007. western indian ocean coral communities: bleaching responses and susceptibility to
extinction. marine ecology progress series, 337, 113.
mcclanahan, t.r., ateweberhan, m., muhando, c.a., maina, j., & mohammed, m.s. 2007. effects of climate and
seawater temperature variation on coral bleaching and mortality. ecological monographs 77:503525.
mcclanahan t.r., ateweberhan m., darling e.s., graham n.a.j., muthiga n.a. 2014. biogeography and change
among regional coral communities across the western indian ocean. plos one 9: e93385
mcclanahan t., allison e.h., cinner j.e. 2015. managing fisheries for human food security. fish and fisheries. 16:
mckenzie, d. j., axelsson, m., chabot, d., claireaux, g., cooke, s. j., corner, r. a., boeck, g. de, domenici, p.,
guerreiro, p. m., hamer, b., jørgensen, c., killen, s. s., lefevre, s., marras, s., michaelidis, b., nilsson, g. e.,
peck, m. a., perez-ruzafa, a., rijnsdorp, a. d., shiels, h. a., steffensen, j. f., svendsen, j. c., svendsen, m. b. s.,
teal, l. r., meer, j. van der, wang, t., wilson, j. m., wilson, r. w., metcalfe, j. d. 2016. conservation physiology of
marine fishes: state of the art and prospects for policy. conservation physiology 4.
melzner, f., göbel, s., langenbuch, m., gutowska, m. a., pörtner, h. & lucassen, m. 2009a. swimming
performance in atlantic cod (gadus morhua) following long-term (4 12 months) acclimation to elevated
seawater pco2. aquatic toxicology 92:3037.
melzner, f., gutowska, m. a., langenbuch, m., dupont, s., lucassen, m., thorndyke, m. c., bleich, m., portner, h.-
o. & ortner4. 2009b. physiological basis for high co2 tolerance in marine ectothermic animals: pre-adaptation
through lifestyle and ontogeny? biogeosciences 6:23131331.
meysick l, infantes e, boström c. 2019. the influence of hydrodynamics and ecosystem engineers on eelgrass
seed trapping. plos one, 14 (9): e0222020.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
moksnes, p-o. gullström, m., tryman, k., baden, s. 2008. trophic cascades in a temperate seagrass community.
oikos 117:763777.
munday, p. l., crawley, n. e. & nilsson, g. e. 2009. interacting effects of elevated temperature and ocean
acidification on the aerobic performance of coral reef fishes. marine ecology progress series 388:235242.
munday, p.l., dixson, d.l., mccormick, m.i., meekan, m., ferrari, m.c.o., chivers, d.p. 2010. replenishment of fish
populations is threatened by ocean acidification. proceedings of the national academy of sciences 107:12930
munday, p. l., gagliano, m., donelson, j. m., dixson, d. l. & thorrold, s. r. 2011. ocean acidification does not
affect the early life history development of a tropical marine fish. marine ecology progress series 423:211221.
mvungi, e. f., & pillay, d. 2019. eutrophication overrides warming as a stressor for a temperate african
seagrass (zostera capensis). plos one 14:e0215129.
nordlund lm, unsworth rk, gullström m, cullenunsworth lc. 2018. global significance of seagrass fishery
activity. fish and fisheries 19: 399-412.
obura, d. 1999. status report - kenya. in: linden, o. & sporrong, n. (eds.) coral reef degradation in the india
ocean. status reports and project presentations 1999. cordio/sarec marine science program, pp. 33- 36.
obura, d., celliers, l., machano, h., mangubhai, s., mohammed, m., motta, h., muhando, c., muthiga, n.,
pereira, m., schleyer, m. 2002. status of coral reefs in eastern africa: kenya, tanzania, mozambique and south
africa. in: wilkinson, c. (ed.), status of coral reefs of the world, 2002. global coral reef monitoring network
(gcrmn), australian institute of marine science, townsville, australia, pp. 6378.
obura, d. 2009. corals bleach to resist stress. marine pollution bulletin 58:206-212. doi
obura, d. 2012. the diversity and biogeography of western indian ocean reef-building corals. plos one 7(9):
obura, d. 2015. coral and biogenic reef habitats. in: the regional state of the coast report: western indian
ocean. chapter 6. unep-nairobi convention and wiomsa. nairobi, kenya, 71-83
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
obura d., gudka m., abdou rabi f., bijoux j., freed s., gian s.b., maharavo j., mwaura j., porter s., sola e., wickel
j., yahya s., ahamada s. 2017. coral reef status report for the western indian ocean (1992-2016). global coral
reef monitoring network (gcrmn)/indian ocean commission (ioc)/cordio east africa. 146 pp.
obura d., gudka m, abdou rabi f, bacha gian s, bigot l, bijoux j, freed s, maharavo j, munbodhe v, mwaura j,
porter s, sola e, wickel j, yahya s and ahamada s. 2017. coral reef status report for the western indian ocean.
global coral reef monitoring network (gcrmn)/international coral reef initiative (icri). pp 144.
obura, d. 2018. ocean health in the blue economy. in: a handbook on the blue economy in the indian ocean
region. editor: prof vn attri. indian ocean rim association (iora), economic and social research council, south
africa. pp 410-435.
obura, d., bigot, l., & benzoni, f. 2018. coral responses to a repeat bleaching event in mayotte in 2010. peerj, 6,
fao. 2007. the world’s mangroves 1980–2005: a thematic study prepared in the framework of the global forest
resource assessment 2005. fao forestry paper 153, rome.
pankhurst, n.w., munday, p.l. 2011. effects of climate change on fish reproduction and early life history stages.
marine and freshwater research 62:10151026.
patterson, d.a., cooke, s.j., hinch, s.g., robinson, k.a., young, n., farrell, a.p. miller, k.m. 2016. a perspective on
physiological studies supporting the provision of scientific advice for the management of fraser river sockeye
salmon (oncorhynchus nerka). conservation physiology 4: cow026. doi: 10.1093/conphys/cow026.
pecl, g. t., araújo, m. b., bell, j. d., blanchard, j., bonebrake, t. c., chen, i., clark, t. d., colwell, r. k., danielsen, f.,
evengård, b., falconi, l., ferrier, s., frusher, s., garcia, r. a., griffis, r. b., hobday, a. j., janion-scheepers, c.,
jarzyna, m. a., jennings, s., lenoir, j., linnetved, h. i., martin, v. y., mccormack, p. c., mcdonald, j., mitchell, n. j.,
mustonen, t., pandolfi, j. m., pettorelli, n., popova, e., robinson, s. a., scheffers, b. r., shaw, j. d., sorte, c. j. b.,
strugnell, j. m., sunday, j. m. & tuanmu, m. 2017. biodiversity redistribution under climate change: impacts on
ecosystems and human well-being. science 355: eaai9214. doi: 10.1126/science.aai9214.
perry, a. l., low, p. j., ellis, j. r. & reynolds, j. d. 2005. climate change and distribution shifts in marine fishes.
science 308:19121915.
perry c.t., larcombe p. 2003. marginal and non-reef building coral environments. coral reefs 22:427432.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
poloczanska, e.s., burrows, m.t., brown, c.j., molinos, j.g., halpern, b.s., hoegh-guldberg, o. 2016. responses of
marine organisms to climate change across oceans. frontiers in marine science 3:doi:
pörtner, h.o. 2012. integrating climate-related stressor effects on marine organisms: unifying principles linking
molecule to ecosystem-level changes. marine ecology progress series 470:273290.
potouroglou, m., bull, j.c., krauss, k.w., kennedy, h.a., fusi, m., daffonchio, d., angora, m.m., githaiga, m.n.,
diele, k., huxham m. 2017. measuring the role of seagrasses in regulating sediment surface elevation.
scientific reports 7:11917.
potts, w.m., götz, a. & james, n. 2015. review of the projected impacts of climate change on coastal fishes in
southern africa. reviews in fish biology and fisheries 25:603630.
ramirez, f., afan, i., davis, l.s., chiaradia, a. 2017. climate impacts on global hot spots of marine biodiversity.
science advances 3:.e1601198.
randall, c.j., van woesik, r. 2015. contemporary white-band disease in caribbean corals driven by climate
change. nat. clim. chang. 5: 15.
randall, c.j., van woesik, r. 2017. some coral diseases track climate oscillations in the caribbean. sci. rep. 7: 1
rijnsdorp, a.d., peck, m.a., engelhard, g.h., mollmann, c., pinnegar, j.k. 2009. resolving the effect of climate
change on fish populations. ices journal of marine science 66:15701583.
rummer, j.l., couturier, c.s., stecyk, j.a.w. 2014. life on the edge: thermal optima for aerobic scope of equatorial
reef fishes are close to current day temperatures. global change biology 20:10551066.
samoilys a. melita, halforda., osuka, k. 2019. disentangling drivers of the abundance of coral reef fishes in the
western indian ocean. ecology and evolution, 9: 41494167.
saenger, p. 2002. mangrove ecology, silviculture and conservation. kluwer academic publishers.
schaffelke, b., mellors, j., duke, n.c. 2005. water quality in the great barrier reef region: responses of
mangrove, seagrass and macroalgal communities. marine pollution bulletin 51:279296.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
sims, d.w., mouth, v.j.w., genner, m.j., southward, a.j., hawkins, s.j. 2004. low-temperature-driven early
spawning migration of a temperate marine fish. journal of animal ecology 73:333341.
smith, m.h., heemstra, p.c.h. 1986. smiths’ sea fishes. macmillan publishers.
somero, g.n. 2010. the physiology of climate change: how potentials for acclimatization and genetic adaptation
will determine ‘winners’ and ‘losers’. journal of experimental biology 213:912–920.
sousa, l.l., queiroz, n., mucientes, g., humphries, n.e., sims, d.w. 2016. environmental influence on the
seasonal movements of satellitetracked ocean sunfish mola mola in the northeast atlantic environmental
influence on the seasonal movements of satellitetracked ocean sunfish mola mola in the northeast atlantic.
animal biotelemetry 4: doi: 10.1186/s40317-016-0099-2.
stapel, j., t.l. aarts, b.h.m. van duynhoven, j.d. de groot, p.h.w. van den hoogen & hemminga, m.a. 1996.
nutrient uptake by leaves and roots of the seagrass thalassia hemprichii in the spermonde archipelago,
indonesia. marine ecology progress series 134: 195206.
stramma, l., schmidtko, s., levin, l. a. & johnson, g. c. 2010. ocean oxygen minima expansions and their
biological impacts. deep-sea research i 57:587595.
temple, a.j., kiszka, j.j., stead, s. m., wambiji, n., brito, a., poonian, c.n.s., amir, o.a., jiddawi, n., fennessy, s.t.,
pe´rez-jorge, s., berggren, p. 2017. marine megafauna interactions with small-scale fisheries in the
southwestern indian ocean: a review of status and challenges for research and management. reviews in fish
biology and fisheries. doi: 10.1007/s11160-017-9494-x
turner, j., & klaus, r. 2005. coral reefs of the mascarenes, western indian ocean. philosophical transactions of
the royal society a: mathematical, physical and engineering sciences. retrieved from, d. (2012). the diversity and
biogeography of western indian ocean reef-building corals. plos one, 7(9), e45013.
uku j, björk m. 2005. productivity aspects of three tropical seagrass species in areas of different nutrient levels
in kenya. estuarine, coastal and shelf science 63:407420.
uneca 2016. africa's blue economy: a policy handbook. united nations economic commission for africa, addis
ababa. isbn: 978-99944-61-86-8. p.110.
Journal of Indian Ocean Rim Studies, January- June 2020
Volume 3, Issue 1 (Special Issue on Blue Economy)
Journal of Indian Ocean Rim Studies
van der elst, r., everette, b., jiddawi, n., mwatha, g., santana afonso, p., boulle, d. 2005. fish, fishers and
fisheries of the western indian ocean: their diversity and status. a preliminary assessment. philosophical
transactions of the royal society 363: 263-284.
van hooidonk, r. & huber, m. 2006. the impact of tropical cyclones on coral bleaching and coral diseases. agu
fall meeting abstracts.
veron, j.e.n., stafford-smith, m.g., devantier, l.m., turak, e. 2015. overview of distribution patterns of
zooxanthellate scleractinia. frontiers in marine science, 1;, 119.
ward, t. d., algera, d. a., gallagher, a. j., hawkins, e., horodysky, a., jørgensen, c., killen, s. s., mckenzie, d. j.,
metcalfe, j. d., peck, m. a., vu, m., cooke, s. j. 2016. understanding the individual to implement the ecosystem
approach to fisheries management. conservation physiology 4: cow005. doi: 10.1093/conphys/cow005.
watkiss, p. pye, s., hendriksen, g, maclean, a., bonjean, m. shaghude, y, jiddawi, n, sheikh, m. a., khamis, z.
2012. the economics of climate change in zanzibar. study report for the revolutionary government of zanzibar,
climate change committee.
wernberg, t., russell, b.d., moore, p.j., ling, s.d., smale, d.a., campbell, a., coleman, m.a., steinberg, p.d.,
kendrick, g.a., connell, s. d. 2011. impacts of climate change in a global hotspot for temperate marine
biodiversity and ocean warming. journal of experimental marine biology and ecology 400:716.
whitney, j.e., al-chokhachy, r., bunnell, d.b., caldwell, c.a., cooke, s.j., eliason, e.j., rogers, m., lynch, a.j.,
paukert, c.p. 2016. physiological basis of climate change impacts on north american inland fishes. fisheries
wikelski, m., cooke, s.j. 2006. conservation physiology. trends in ecology and evolution 21:3846.
wilkinson, c. 2000. status of coral reefs of the world: 2000. australian institute of marine science, townsville,
wilkinson, c.r., lindén, o., cesar, h.s., hodgson, g., rubens, j., strong, a.e. 1999. ecological and socioeconomic
impacts of 1998 coral mortality in the indian ocean: an enso impact and a warning of future
change? ambio, 28: 188 196.
yates k. k. et al. 2016. ocean acidification buffering effects of seagrass in tampa bay. in proceedings, the sixth
tampa bay area scientific information symposium, basis (vol. 6, pp. 273-284).
... Coastal and oceanic ecosystems in the Western Indian Ocean (WIO) region sustain millions of lives and are characterised by their abundant biodiversity, which renders them immensely valuable in socio-economic and ecological terms (UNEP, 2015a). At the same time, they face various pressures related to anthropogenic activities and climate change (Diop et al., 2016;Hollander et al., 2020). Decision-makers are challenged with mitigating these pressures while settling space-use conflicts and considering the interests and needs of a diverse range of stakeholders. ...
... Generally, many researchers are motivated to share their findings, e.g., to expedite scientific advancements, for collaborative purposes, to inform and educate, to increase the impact of their work, to generate funding, or to advance their career (Schmidt et al., 2016;Figueiredo, 2017;Schwindenhammer, 2020). Such collaboration is vital to enhance research in data-poor countries, which have limited capacities to collect, process, and analyse data (Hollander et al., 2020). Local researchers and practitioners with long-standing experience are well aware of blind spots and limiting factors for data-sharing in the WIO region. ...
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Comprehensive and timely data-sharing is essential for effective ocean governance. This institutional analysis investigates pervasive data-sharing barriers in Kenya and Tanzania, using a collective action perspective. Existing data-sharing rules and regulations are examined in respect to boundaries, contextuality and incentive structures, compliance and settlement mechanisms, and integration across scales. Findings show that current institutional configurations create insufficient or incoherent incentives, simultaneously reducing and reproducing sharing barriers. Regional harmonisation efforts and strategically aligned data-sharing institutions are still underdeveloped. This article discusses proposals to increase capacities and incentives for data-sharing, as well as the limitations of the chosen analytical framework. The debate is extended to aspects beyond institutional issues, i.e., structural data-sharing barriers or ethical concerns. Key recommendations include the establishment of more compelling incentives structures for data-sharing, increased funding of capacity-building and sharing infrastructure, and further awareness creation on the importance of data-sharing.
... It is nevertheless still intriguing to re ect on the fact that these latitudes represent environmental shifts from the tropics to the subtropics, and nally the temperate zone. As the tropics and subtropics are expanding poleward, different marine organisms will struggle more or less in order to respond to the stress of climatic change, either through their ability for rapid adaption, adaptive phenotypic plasticity or migration capacity 71 . With that said, it is important to remember that the mid-latitudes (between 30 degrees N/S and 60 degrees N/S) incorporate Australia in the southern hemisphere, and North America, as well as Europe in the northern hemisphere, and the simple fact is that most research grants and research projects are concentrated to these speci c regions. ...
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Marine organisms are simultaneously exposed to anthropogenic stressors associated with ocean acidification and warming with likely interactive effects. Although new research has started to uncover how marine primary producers, herbivores, and predators are responding to climate change, we still do not have a comprehensive understanding of general patterns across trophic levels in response to multiple stressors. Yet, marine species from different trophic levels with dissimilar characteristics and evolutionary history are likely to respond differently to climatic stressors.Our study represents the first meta-analysis of multiple stressor studies to target comparisons of mean effects and identification of interaction types among marine trophic levels. The meta-analysis revealed a number of key results: (1) Predators are the most tolerant level in response to individual and combined effects of ocean acidification and warming; (2) synergistic interactions (16%) are less common than additive (40%) and antagonistic (44%) interactions; (3) interaction types vary among trophic levels, with the proportion of synergistic interactions decreasing with increasing trophic level; (4) for interactive effects, calcifying and non-calcifying species show similar patterns across trophic levels; and (5) trophic levels respond to stressors differently along a latitudinal gradient. This study emphasizes the importance of considering stressor interactions and trophic levels in conservation actions. Contrary to many predictions, which has suggested synergistic effects predominate multiple stressors, this research demonstrates that the interaction effect between ocean acidification (OA) and ocean warming (OW) can sometimes mitigate or even reduce negative effects, with additive and antagonistic interactions dominating. Our study provides new knowledge for understanding how multiple stressors may interactively affect marine trophic levels and highlighting the need for further research and a deeper understanding of multiple stressors in conservation efforts.
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Coastal vegetation is widely attributed to stabilize sediment. While most studies focused on how canopy causes flow reduction and thereby affects sediment dynamics, the role of roots and rhizomes on stabilizing the surface sediment has been less well studied. This study aims to quantify interactions between above‐ and belowground biomass of eelgrass (i.e., living Zostera marina plants and mimics) with surface sediment erosion (i.e., bed load and suspended load), under different hydrodynamic forcing that was created using a wave flume. Belowground biomass played an important role preventing bed‐load erosion, by roughly halving the amount of sediment transported after being exposed to maximal orbital velocities of 27 cm s−1, with and without canopy. Surprisingly, for suspended sediment transport, we found opposite effects. In the presence of eelgrass, the critical erosion threshold started at lower velocities than on bare sediment, including sand and mud treatments. Moreover, in muddy systems, such resuspension reduced the light level below the minimum requirement of Z. marina. This surprising result for sediment resuspension was ascribed to a too small eelgrass patch for reducing waves but rather showing enhanced turbulence and scouring at meadow edges. Overall, we conclude that the conservation of the existent eelgrass meadows with developed roots and rhizomes is important for the sediment stabilization and the meadow scale should be taken into account to decrease sediment resuspension.
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Despite knowledge that seagrass meadows are threatened by multiple global change stressors, significant gaps exist in current knowledge. In particular, little is known about the interactive effects of warming and eutrophication on seagrasses globally, or about responses of African seagrasses to global change, despite these ecosystem engineers providing critical goods and services to local livelihoods. Here, we report on laboratory experiment assessing the main and joint effects of warming and nutrient enrichment on Cape eelgrass (Zostera capensis) from the West coast of South Africa, in which morphological attributes, photosynthetic efficiency and elemental content were assessed. Results indicate that shoot density, leaf length, aboveground biomass and effective quantum yield were negatively impacted by both warming and nutrient enrichment. Growth rate, leaf density and leaf width decreased with increasing nutrient levels but not temperature. In addition, epiphytic fouling on seagrass leaves were enhanced by both warming and nutrient enrichment but with warming eliciting a greater response. Collectively, our findings indicate a stronger effect of enrichment on Z. capensis performance relative to warming, suggesting that the upper levels of coastal eutrophication upon which our experiment was based is likely a stronger stressor than warming. Our findings also highlight limited interaction between warming and nutrient enrichment on Z. capensis performance, suggesting that effects of these stressors are likely to be propagated individually and not interactively. Our findings raise awareness of susceptibility of Z. capensis to eutrophication and the need to manage nutrient inputs into coastal ecosystems to preserve meadows of this seagrass and the critical ecosystem functions they provide.
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Background High sea surface temperatures resulted in widespread coral bleaching and mortality in Mayotte Island (northern Mozambique channel, Indian Ocean: 12.1°S, 45.1°E) in April–June 2010. Methods Twenty three representative coral genera were sampled quantitatively for size class distributions during the peak of the bleaching event to measure its impact. Results Fifty two percent of coral area was impacted, comprising 19.3% pale, 10.7% bleached, 4.8% partially dead and 17.5% recently dead. Acropora, the dominant genus, was the second most susceptible to bleaching (22%, pale and bleached) and mortality (32%, partially dead and dead), only exceeded by Pocillopora (32% and 47%, respectively). The majority of genera showed intermediate responses, and the least response was shown by Acanthastrea and Leptastrea (6% pale and bleached). A linear increase in bleaching susceptibility was found from small colonies (80 cm, 33% unaffected), across all genera surveyed. Maximum mortality in 2010 was estimated at 32% of coral area or biomass, compared to half that (16%), by colony abundance. Discussion Mayotte reefs have displayed a high level of resilience to bleaching events in 1983, 1998 and the 2010 event reported here, and experienced a further bleaching event in 2016. However, prospects for continued resilience are uncertain as multiple threats are increasing: the rate of warming experienced (0.1 °C per decade) is some two to three times less than projected warming in coming decades, the interval between severe bleaching events has declined from 16 to 6 years, and evidence of chronic mortality from local human impacts is increasing. The study produced four recommendations for reducing bias when monitoring and assessing coral bleaching: coral colony size should be measured, unaffected colonies should be included in counts, quadrats or belt transects should be used and weighting coefficients in the calculation of indices should be used with caution.
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Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other ‘blue carbon’ habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.
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Disease outbreaks continue to reduce coral populations worldwide. Understanding coral diseases and their relationships with environmental drivers is necessary to forecast disease outbreaks, and to predict future changes in coral populations. Yet, the temporal dynamics of coral diseases are rarely reported. Here we evaluate trends and periodicities in the records of three common coral diseases (white-band disease, yellow-band disease, and dark-spot syndrome) that were surveyed between 1997 and 2014 at 2082 sites throughout the Caribbean. The relationship between the periodicities of disease prevalence and El Niño Southern Oscillation (ENSO) cycles was examined using cross-wavelet analyses and convergent cross mapping (CCM). The prevalence of the diseases peaked every two to four years, and matched periodicities in ENSO conditions. CCM models suggested that environmental conditions associated with recent ENSO cycles may have influenced the patterns in disease prevalence. We also found no increasing trends in disease prevalence through time. Instead, our work suggests that the prevalence of coral diseases is dynamic and complex. The gradual increase in sea-surface temperature, a consequence of increasing greenhouse gas emissions, progressively raises the modal temperature threshold of each ENSO cycle. These dynamic cycles and the increasing modal temperatures appear to influence the dynamics of coral diseases.
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Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world’s richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, the effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation.
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The inability of physiologists to effect change in fisheries management has been the source of frustration for many decades. Close collaboration between fisheries managers and researchers has afforded our interdisciplinary team an unusual opportunity to evaluate the emerging impact that physiology can have in providing relevant and credible scientific advice to assist in management decisions. We categorize the quality of scientific advice given to management into five levels based on the type of scientific activity and resulting advice (notions, observations, descriptions, predictions and prescriptions). We argue that, ideally, both managers and researchers have concomitant but separate responsibilities for increasing the level of scientific advice provided. The responsibility of managers involves clear communication of management objectives to researchers, including exact descriptions of knowledge needs and researchable problems. The role of the researcher is to provide scientific advice based on the current state of scientific information and the level of integration with management. The examples of scientific advice discussed herein relate to physiological research on the impact of high discharge and water temperature, pathogens, sex and fisheries interactions on in-river migration success of adult Fraser River sockeye salmon (Oncorhynchus nerka) and the increased understanding and quality of scientific advice that emerges. We submit that success in increasing the quality of scientific advice is a function of political motivation linked to funding, legal clarity in management objectives, collaborative structures in government and academia, personal relationships, access to interdisciplinary experts and scientific peer acceptance. The major challenges with advancing scientific advice include uncertainty in results, lack of integration with management needs and institutional caution in adopting new research. We hope that conservation physiologists can learn from our experiences of providing scientific advice to management to increase the potential for this growing field of research to have a positive influence on resource management.
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The coastal zone represents one of the most economically and ecologically important ecosystems on the planet, none more so than in southern Africa. This manuscript examines the potential impacts of climate change on the coastal fishes in southern Africa and provides some of the first information for the Southern Hemisphere, outside of Australasia. It begins by describing the coastal zone in terms of its physical characteristics, climate, fish biodiversity and fisheries. The region is divided into seven biogeographical zones based on previous descriptions and interpretations by the authors. A global review of the impacts of climate change on coastal zones is then applied to make qualitative predictions on the likely impacts of climate change on migratory, resident, estuarine-dependent and catadromous fishes in each of these biogeographical zones. In many respects the southern African region represents a microcosm of climate change variability and of coastal habitats. Based on the broad range of climate change impacts and life history styles of coastal fishes, the predicted impacts on fishes will be diverse. If anything, this review reveals our lack of fundamental knowledge in this field, in particular in southern Africa. Several research priorities, including the need for process-based fundamental research programs are highlighted.
During a multiyear fish tracking study, subadult and adult life stages of Shubenacadie River striped bass (Morone saxatilis) were detected throughout winter in the well-mixed, hypertidal waters of the Minas Passage, Bay of Fundy. Thirty-five percent of the striped bass tagged with Vemco V16 transmitters were detected by two Minas Passage receiver arrays. Transmissions were received on 82% of winter days (December to April) and by all receivers spanning the width of the passage. Tagged striped bass were detected largely within the top 20-40 m during the day. The extent of vertical migration to shallower waters at night showed a strong relationship with water temperature; however, there was no diel vertical movement pattern observed at water temperatures <1 °C. Our results demonstrate overwintering of a portion of the Shubenacadie River striped bass population in high-flow inner Bay of Fundy waters, which extends the northern limit of this species’ winter marine range. This study is also the first to describe the relationship between daily vertical migration by striped bass and low water temperatures. Both findings suggest an elevated potential risk of interaction with an in-stream tidal turbine facility in Minas Passage.