Skip to main content

Iain Caldwell

James Cook University, ARC Centre of Excellence Coral Reef Studies, Post-Doc

I am currently a Research Associate at the ARC Centre of Excellence for Coral Reef Studies, focused on Quantitative Social-Ecological Systems. I grew up in Canada where I completed my BSc (Mount Allison University), MSc (Dalhousie University), and a PhD focused on “Habitat use, movement, and vulnerability of sedentary fishes in a dynamic world” (The University of British Columbia). I then spent several years as a postdoctoral researcher in the United States, associated with the Hawaii Institute of Marine Biology (University of Hawaii), University of California Santa Barbara, and Stanford University. I am broadly interested in why fish and other marine organisms end up where they do and what that can mean for their future, and the future of people that depend on those organisms, given predicted changes in global climate and increasing human impacts to many of the world’s coastal ecosystems. Trained as a quantitative ecologist and interested in intersections among ecology and social sciences (in particular behavioural economics), I use a variety of analytical approaches to (1) understand what drives distribution and movement of organisms across time and space, (2) predict what changes in those drivers could mean for future biodiversity and food security, and (3) improve management and conservation strategies to minimize negative effects on ecosystems and the people that depend on them.

less

59 Followers 57 Following 12 Co-authorsTotal Views1 Public Mention

Papers

Potential impacts of climate change on agriculture and fisheries production in 72 tropical coastal communities

Nature Communications

Climate change is expected to profoundly affect key food production sectors, including fisheries ... more Climate change is expected to profoundly affect key food production sectors, including fisheries and agriculture. However, the potential impacts of climate change on these sectors are rarely considered jointly, especially below national scales, which can mask substantial variability in how communities will be affected. Here, we combine socioeconomic surveys of 3,008 households and intersectoral multi-model simulation outputs to conduct a sub-national analysis of the potential impacts of climate change on fisheries and agriculture in 72 coastal communities across five Indo-Pacific countries (Indonesia, Madagascar, Papua New Guinea, Philippines, and Tanzania). Our study reveals three key findings: First, overall potential losses to fisheries are higher than potential losses to agriculture. Second, while most locations (> 2/3) will experience potential losses to both fisheries and agriculture simultaneously, climate change mitigation could reduce the proportion of places facing that...

Global risk of deadly heat

Nature Climate Change, 2017

Seahorse (Hippocampinae) population fluctuations in the Ria Formosa Lagoon, south Portugal

Journal of fish biology, 2015

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (... more Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001-2002, 2008-2009 and 2010-2013) revealed significant population fluctuations in at least one of the two seahorse (Hippocampinae) species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001-2002 v. 2008-2009), long-snouted seahorse Hippocampus guttulatus populations increased significantly between 2008-2009 surveys and new 2010-2013 surveys. There were no significant differences in H. guttulatus populations between the 2001-2002 and 2010-2013 surveys. In contrast, there were no significant differences in short-snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttul...

RESEARCH ARTICLE Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and so... more Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7 % by 2100 under “business as usual ” (represen-tative concentration pathway [RCP] 8.5), suitable growing days will actually decrease glob-ally by up to 11 % when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience losse...

Habitat use, movement, and vulnerability of sedentary fishes in a dynamic world

Multiple feedbacks due to biotic interactions across trophic levels can lead to persistent novel conditions that hinder restoration

Plant invasions: the role of biotic interactions

Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that mor... more Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to...

The influence of vector-borne disease on human history: socio-ecological mechanisms

How vector-borne disease shaped the course of human history

Using Encyclopedia of Life’s TraitBank to identify plant traits associated with vulnerability

Certain biological traits seem to predispose some species to greater extinction risk than others ... more Certain biological traits seem to predispose some species to greater extinction risk than others and, when vulnerability information is limited, could be used as proxies to identify understudied species likely in need of protection. In the past, identifying broadly applicable traits associated with extinction risk has been hampered by the difficulty of collecting information for a broad range of species (both geographically and taxonomically), with most comparative analyses focusing on regional and/or taxon specific patterns. However, efforts to collect and compile existing trait information from regional and taxon specific datasets into a single repository are making it possible to analyze patterns between traits and vulnerability on ever broader scales. We compared trait information from one such repository, the Encyclopedia of Life (EOL) TraitBank, to information on threat status from the International Union for the Conservation of Nature (IUCN) Red List to determine whether such...

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

PLoS biology, 2015

Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and so... more Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7% by 2100 under "business as usual" (representative concentration pathway [RCP] 8.5), suitable growing days will actually decrease globally by up to 11% when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience ...

Global risk of deadly heat

by Coral Bielecki, Iain Caldwell, Marie McKenzie, and Alessandra Shea

Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–... more Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–6. Although numerous studies report increased mortality associated with extreme heat events 1–7 , quantifying the global risk of heat-related mortality remains challenging due to a lack of comparable data on heat-related deaths 2–5. Here we conducted a global analysis of documented lethal heat events to identify the climatic conditions associated with human death and then quantified the current and projected occurrence of such deadly climatic conditions worldwide. We reviewed papers published between 1980 and 2014, and found 783 cases of excess human mortality associated with heat from 164 cities in 36 countries. Based on the climatic conditions of those lethal heat events, we identified a global threshold beyond which daily mean surface air temperature and relative humidity become deadly. Around 30% of the world's population is currently exposed to climatic conditions exceeding this deadly threshold for at least 20 days a year. By 2100, this percentage is projected to increase to ∼48% under a scenario with drastic reductions of greenhouse gas emissions and ∼74% under a scenario of growing emissions. An increasing threat to human life from excess heat now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced. Sporadic heat events, lasting days to weeks, are often related to increased human mortality 1,2 , raising serious concerns for human health given ongoing climate change 1–3,8–16. Unfortunately, a number of challenges have hampered global assessments of the risk of heat-related death. First, heat illness (that is, severe exceedance of the optimum body core temperature) is often underdiagnosed because exposure to extreme heat often results in the dysfunction of multiple organs, which can lead to misdiagnosis 2,3,5,17. Second, mortality data from heat exposure are sparse and have not been analysed in a consistent manner. Here we conducted a global survey of peer-reviewed studies on heat-related mortality to identify the location and timing of past events that caused heat-related deaths. We used climatic data during those events to identify the conditions most likely to result in human death and then quantified the current and projected occurrence of such deadly climatic conditions. Hereafter, we use 'lethal' when referring to climatic conditions during documented cases of excess mortality and 'deadly' when referring to climatic conditions that are projected to cause death. We make this distinction to acknowledge that climatic conditions which have killed people in the past are obviously capable of causing death, but whether or not they result in human mortality in the future could be affected by adaptation. We do not quantify human deaths per se because the extent of human mortality will be considerably modified by social adaptation (for example,

Dredging in the Spratly Islands: Gaining Land but Losing Reefs

by Charles Birkeland and Iain Caldwell

PLoS biology, 2016

Coral reefs on remote islands and atolls are less exposed to direct human stressors but are becom... more Coral reefs on remote islands and atolls are less exposed to direct human stressors but are becoming increasingly vulnerable because of their development for geopolitical and military purposes. Here we document dredging and filling activities by countries in the South China Sea, where building new islands and channels on atolls is leading to considerable losses of, and perhaps irreversible damages to, unique coral reef ecosystems. Preventing similar damage across other reefs in the region necessitates the urgent development of cooperative management of disputed territories in the South China Sea. We suggest using the Antarctic Treaty as a positive precedent for such international cooperation.

Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement

Landscape Ecology, 2013

Advances in tagging syngnathids, with the effects of dummy tags on behaviour of Hippocampus guttulatus

by Miguel Correia, Iain Caldwell, Jorge Palma, and Amanda Vincent

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

by Brandon Genco, Iain Caldwell, and Micah Fisher

Seahorse (Hippocampinae) population fluctuations in the Ria Formosa Lagoon, south Portugal

by Iain Caldwell, Miguel Correia, Heather Koldewey, and Jorge Palma

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (... more Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001–2002, 2008–2009 and 2010–2013) revealed significant population fluctuations in at least one of the two seahorse species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001–2002 v. 2008–2009), long-snouted seahorse Hippocampus guttulatus populations increased significantly between 2008–2009 surveys and new 2010–2013 surveys. There were no significant differences in H. guttulatus populations between the 2001–2002 and 2010–2013 surveys. In contrast, there were no significant differences in short-snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttulatus densities were positively correlated with the percentage of holdfast coverage, but with none of the other environmental variables tested. These results highlight the importance of holdfast availability in maintaining stable seahorse populations. While population fluctuations are certainly more promising than a consistent downward decline, such extreme fluctuations observed for seahorses in the Ria Formosa Lagoon could still leave these two species vulnerable to any additional stressors, particularly during low density periods.

A sedentary fish on the move: effects of displacement on long-snouted seahorse (Hippocampus guttulatus Cuvier) movement and habitat use

by Amanda Vincent and Iain Caldwell

Environmental Biology of Fishes, Jan 1, 2012

Revisiting two sympatric European seahorse species: apparent decline in the absence of exploitation

by Amanda Vincent and Iain Caldwell

Aquatic Conservation: Marine and …, Jan 1, 2012

ABSTRACT 1. Seahorses are marine fish with several life history characteristics hypothesized to m... more

Advances in tagging syngnathids, with the effects of dummy tags on behaviour of Hippocampus guttulatus

by Iain Caldwell and Amanda Vincent

Journal of Fish …, Jan 1, 2011

Artificial marking and tagging techniques have been used to study movement, population dynamics, ... more Artificial marking and tagging techniques have been used to study movement, population dynamics, behaviour, ecology, survival and growth of at least 25 syngnathid species. External necklace-style tags and injection of visible implant elastomer have been the most used techniques, uniquely identifying hundreds of individual syngnathids to study population dynamics, mortality, behaviour, ecology and growth in at least 13 and 12 species, respectively. Only two studies, both on larger syngnathid species, have tested the use of internal or electronic tags. This new case study reveals that dummy tags, weighing up to 6% of individual body mass, have minimal effect on normal ex situ behaviour of the long-snouted seahorse Hippocampus guttulatus, a smaller syngnathid. In paired aquarium trials, tags did not affect movement, holdfast use or general behavioural state, and only had a short-term effect (1 day) on vertical orientation. Tagged H. guttulatus gained more mass during the 5 day trials, a result which warrants further exploration but indicates that tags did not reduce feeding. This study shows promise for using electronic tagging to study H. guttulatus and similarly sized syngnathids in the wild.

The importance of seahorses and pipefishes in the diet of marine animals

by Iain Caldwell and Amanda Vincent

Reviews in Fish Biology …, Jan 1, 2011

Potential impacts of climate change on agriculture and fisheries production in 72 tropical coastal communities

Nature Communications

Climate change is expected to profoundly affect key food production sectors, including fisheries ... more Climate change is expected to profoundly affect key food production sectors, including fisheries and agriculture. However, the potential impacts of climate change on these sectors are rarely considered jointly, especially below national scales, which can mask substantial variability in how communities will be affected. Here, we combine socioeconomic surveys of 3,008 households and intersectoral multi-model simulation outputs to conduct a sub-national analysis of the potential impacts of climate change on fisheries and agriculture in 72 coastal communities across five Indo-Pacific countries (Indonesia, Madagascar, Papua New Guinea, Philippines, and Tanzania). Our study reveals three key findings: First, overall potential losses to fisheries are higher than potential losses to agriculture. Second, while most locations (> 2/3) will experience potential losses to both fisheries and agriculture simultaneously, climate change mitigation could reduce the proportion of places facing that...

Global risk of deadly heat

Nature Climate Change, 2017

Seahorse (Hippocampinae) population fluctuations in the Ria Formosa Lagoon, south Portugal

Journal of fish biology, 2015

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (... more Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001-2002, 2008-2009 and 2010-2013) revealed significant population fluctuations in at least one of the two seahorse (Hippocampinae) species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001-2002 v. 2008-2009), long-snouted seahorse Hippocampus guttulatus populations increased significantly between 2008-2009 surveys and new 2010-2013 surveys. There were no significant differences in H. guttulatus populations between the 2001-2002 and 2010-2013 surveys. In contrast, there were no significant differences in short-snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttul...

RESEARCH ARTICLE Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and so... more Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7 % by 2100 under “business as usual ” (represen-tative concentration pathway [RCP] 8.5), suitable growing days will actually decrease glob-ally by up to 11 % when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience losse...

Habitat use, movement, and vulnerability of sedentary fishes in a dynamic world

Multiple feedbacks due to biotic interactions across trophic levels can lead to persistent novel conditions that hinder restoration

Plant invasions: the role of biotic interactions

Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that mor... more Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to...

The influence of vector-borne disease on human history: socio-ecological mechanisms

How vector-borne disease shaped the course of human history

Using Encyclopedia of Life’s TraitBank to identify plant traits associated with vulnerability

Certain biological traits seem to predispose some species to greater extinction risk than others ... more Certain biological traits seem to predispose some species to greater extinction risk than others and, when vulnerability information is limited, could be used as proxies to identify understudied species likely in need of protection. In the past, identifying broadly applicable traits associated with extinction risk has been hampered by the difficulty of collecting information for a broad range of species (both geographically and taxonomically), with most comparative analyses focusing on regional and/or taxon specific patterns. However, efforts to collect and compile existing trait information from regional and taxon specific datasets into a single repository are making it possible to analyze patterns between traits and vulnerability on ever broader scales. We compared trait information from one such repository, the Encyclopedia of Life (EOL) TraitBank, to information on threat status from the International Union for the Conservation of Nature (IUCN) Red List to determine whether such...

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

PLoS biology, 2015

Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and so... more Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7% by 2100 under "business as usual" (representative concentration pathway [RCP] 8.5), suitable growing days will actually decrease globally by up to 11% when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience ...

Global risk of deadly heat

by Coral Bielecki, Iain Caldwell, Marie McKenzie, and Alessandra Shea

Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–... more Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–6. Although numerous studies report increased mortality associated with extreme heat events 1–7 , quantifying the global risk of heat-related mortality remains challenging due to a lack of comparable data on heat-related deaths 2–5. Here we conducted a global analysis of documented lethal heat events to identify the climatic conditions associated with human death and then quantified the current and projected occurrence of such deadly climatic conditions worldwide. We reviewed papers published between 1980 and 2014, and found 783 cases of excess human mortality associated with heat from 164 cities in 36 countries. Based on the climatic conditions of those lethal heat events, we identified a global threshold beyond which daily mean surface air temperature and relative humidity become deadly. Around 30% of the world's population is currently exposed to climatic conditions exceeding this deadly threshold for at least 20 days a year. By 2100, this percentage is projected to increase to ∼48% under a scenario with drastic reductions of greenhouse gas emissions and ∼74% under a scenario of growing emissions. An increasing threat to human life from excess heat now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced. Sporadic heat events, lasting days to weeks, are often related to increased human mortality 1,2 , raising serious concerns for human health given ongoing climate change 1–3,8–16. Unfortunately, a number of challenges have hampered global assessments of the risk of heat-related death. First, heat illness (that is, severe exceedance of the optimum body core temperature) is often underdiagnosed because exposure to extreme heat often results in the dysfunction of multiple organs, which can lead to misdiagnosis 2,3,5,17. Second, mortality data from heat exposure are sparse and have not been analysed in a consistent manner. Here we conducted a global survey of peer-reviewed studies on heat-related mortality to identify the location and timing of past events that caused heat-related deaths. We used climatic data during those events to identify the conditions most likely to result in human death and then quantified the current and projected occurrence of such deadly climatic conditions. Hereafter, we use 'lethal' when referring to climatic conditions during documented cases of excess mortality and 'deadly' when referring to climatic conditions that are projected to cause death. We make this distinction to acknowledge that climatic conditions which have killed people in the past are obviously capable of causing death, but whether or not they result in human mortality in the future could be affected by adaptation. We do not quantify human deaths per se because the extent of human mortality will be considerably modified by social adaptation (for example,

Dredging in the Spratly Islands: Gaining Land but Losing Reefs

by Charles Birkeland and Iain Caldwell

PLoS biology, 2016

Coral reefs on remote islands and atolls are less exposed to direct human stressors but are becom... more Coral reefs on remote islands and atolls are less exposed to direct human stressors but are becoming increasingly vulnerable because of their development for geopolitical and military purposes. Here we document dredging and filling activities by countries in the South China Sea, where building new islands and channels on atolls is leading to considerable losses of, and perhaps irreversible damages to, unique coral reef ecosystems. Preventing similar damage across other reefs in the region necessitates the urgent development of cooperative management of disputed territories in the South China Sea. We suggest using the Antarctic Treaty as a positive precedent for such international cooperation.

Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement

Landscape Ecology, 2013

Advances in tagging syngnathids, with the effects of dummy tags on behaviour of Hippocampus guttulatus

by Miguel Correia, Iain Caldwell, Jorge Palma, and Amanda Vincent

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

by Brandon Genco, Iain Caldwell, and Micah Fisher

Seahorse (Hippocampinae) population fluctuations in the Ria Formosa Lagoon, south Portugal

by Iain Caldwell, Miguel Correia, Heather Koldewey, and Jorge Palma

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (... more Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001–2002, 2008–2009 and 2010–2013) revealed significant population fluctuations in at least one of the two seahorse species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001–2002 v. 2008–2009), long-snouted seahorse Hippocampus guttulatus populations increased significantly between 2008–2009 surveys and new 2010–2013 surveys. There were no significant differences in H. guttulatus populations between the 2001–2002 and 2010–2013 surveys. In contrast, there were no significant differences in short-snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttulatus densities were positively correlated with the percentage of holdfast coverage, but with none of the other environmental variables tested. These results highlight the importance of holdfast availability in maintaining stable seahorse populations. While population fluctuations are certainly more promising than a consistent downward decline, such extreme fluctuations observed for seahorses in the Ria Formosa Lagoon could still leave these two species vulnerable to any additional stressors, particularly during low density periods.

A sedentary fish on the move: effects of displacement on long-snouted seahorse (Hippocampus guttulatus Cuvier) movement and habitat use

by Amanda Vincent and Iain Caldwell

Environmental Biology of Fishes, Jan 1, 2012

Revisiting two sympatric European seahorse species: apparent decline in the absence of exploitation

by Amanda Vincent and Iain Caldwell

Aquatic Conservation: Marine and …, Jan 1, 2012

ABSTRACT 1. Seahorses are marine fish with several life history characteristics hypothesized to m... more

Advances in tagging syngnathids, with the effects of dummy tags on behaviour of Hippocampus guttulatus

by Iain Caldwell and Amanda Vincent

Journal of Fish …, Jan 1, 2011

Artificial marking and tagging techniques have been used to study movement, population dynamics, ... more Artificial marking and tagging techniques have been used to study movement, population dynamics, behaviour, ecology, survival and growth of at least 25 syngnathid species. External necklace-style tags and injection of visible implant elastomer have been the most used techniques, uniquely identifying hundreds of individual syngnathids to study population dynamics, mortality, behaviour, ecology and growth in at least 13 and 12 species, respectively. Only two studies, both on larger syngnathid species, have tested the use of internal or electronic tags. This new case study reveals that dummy tags, weighing up to 6% of individual body mass, have minimal effect on normal ex situ behaviour of the long-snouted seahorse Hippocampus guttulatus, a smaller syngnathid. In paired aquarium trials, tags did not affect movement, holdfast use or general behavioural state, and only had a short-term effect (1 day) on vertical orientation. Tagged H. guttulatus gained more mass during the 5 day trials, a result which warrants further exploration but indicates that tags did not reduce feeding. This study shows promise for using electronic tagging to study H. guttulatus and similarly sized syngnathids in the wild.

The importance of seahorses and pipefishes in the diet of marine animals

by Iain Caldwell and Amanda Vincent

Reviews in Fish Biology …, Jan 1, 2011