Restoring Damaged Coral Reefs Using Mass Coral Larval Reseeding

Restoring Damaged Coral Reefs Using Mass Coral Larval Reseeding

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND TO THE STUDY

Reef corals are critically important because they build the primary reef framework, supply essential habitats for thousands of fish and other species, and provide the ecosystem with direct energy and other nutrient inputs (Gardner et al, 2003). But the loss of substantial live coral cover on reefs – fundamentally through overfishing, eutrophication and other disturbances arising from human activity – has seriously disrupted their ecology. Continued human pressures on damaged reefs lead to further Reef decline and ecosystem collapse. But this situation may be alleviated through mass reseeding with coral larvae. The aim of this study is to quantify the effectiveness of mass larval reseeding to restore damaged coral communities on reefs in Nigeria and to use this assessment as a case study for future global reef restoration management strategies.

The continuous degradation of coral reef ecosystems on a global level, the disheartening expectations of a gloomy future for reefs’ statuses, the failure of traditional conservation acts to revive most of the degrading reefs and the understanding that it is unlikely that future reefs will return to historic conditions, all call for novel management approaches. Among the most effective approaches is the “mass coral larval reseeding” concept of active reef restoration, centred, as in silviculture, on a two-step restoration process (nursery and transplantation). In the almost two decades that passed from its first presentation, the “mass coral larval reseeding” tenet was tested in a number of coral reefs worldwide, revealing that it may reshape coral reef communities (and associated biota) in such a way that novel reef ecosystems with novel functionalities that did not exist before are developed (Chen et al, 2011). Factors such as elevation of seawater temperature, extreme weather events, ocean acidification and intensifying tropical storms that cause, for example, enhanced frequency and intensity of mass coral bleaching have directly or indirectly influenced coral survival, coral growth rates, reproduction efforts, larval development and settlement, and post-settlement survivorship/development of corals, damaging reef ecosystems’ health and resilience and reducing species abundance.

Graham et al (2014) further attest to the decimation of key reef-building coral populations, to a dramatic shrinkage in global reef structural complexity and that many reefs experience phase shift phenomena in addition to reefs that are continuously changing in unprecedented ways towards new ecosystem configurations and novel reef compositions that did not exist before. As the major emerging sources of global reef degradation, such as coral bleaching, seawater acidification impacts and coral diseases, interact synergistically and also in concert with local/regional anthropogenic specific stressors, among them pollution, eutrophication, sedimentation, coastal development and overfishing, augmentation of existing climate change impacts is anticipated. Large-scale rearing of coral larvae during mass spawning events and subsequent, direct introduction of competent larvae onto denuded reefs (larval seeding) has been proposed as a low-tech and affordable way of enhancing coral settlement and hence recovery of degraded reefs.

While some studies have shown positive short-term effects on settlement, none have examined the long-term effects of larval seeding for a broadcast-spawning coral. However, this study will test whether mass larval reseeding significantly increases coral recruitment rates in the short and long term towards restoring damaged coral reefs. Mass coral larval reseeding plays a critical role in the persistence and resilience of reef coral populations (Richmond 1997) but its relative importance in coral population and community dynamics can vary according to species, habitat and reef location (Connell et al. 1997). Recent data indicate quite different patterns of reseeding and post-reseeding mortality occurring in reef crest coral communities along the length of the reef (Hughes et al. 1999). Characterizing the site-specific nature of processes and mechanisms influencing the arrival and survival of corals onto reefs is necessary for sound reef management.

1.2 STATEMENT OF THE PROBLEM

Globally, coral reef ecosystems throughout the tropics have been progressively damaged in the last century by a wide range of direct anthropogenic pressures, including over-exploitation, physical destruction, pollution, eutrophication, sediment loads from agricultural and urbanized terrestrial catchments and coastal development. On top of that, the last few decades have seen exacerbated sways of climate-change-associated impacts, such as elevation of seawater temperature, extreme weather events, ocean acidification and intensifying tropical storms that cause a number of damage to coral reefs. However, this study examines how these damaged reefs can be restored using mass coral larval reseeding.

1.3 OBJECTIVES OF THE STUDY

The following are the objectives of this study:

1. To identify the factors causing damage to coral reefs.

2. To examine the process of restoration of damaged coral reefs using mass coral larval reseeding.

3. To examine other ways by which damaged coral reefs can be restored.

1.4 RESEARCH QUESTIONS

1. What are the factors causing damage to coral reefs?

2. What processes are involved in restoring damaged coral reefs using mass coral larval reseeding?

3. What are the other ways by which damaged coral reefs can be restored?

1.5 HYPOTHESIS

HO: Damaged coral reefs cannot be restored using mass coral larval reseeding.

HA: Damaged coral reefs can be restored using mass coral larval reseeding.

1.6 SIGNIFICANCE OF THE STUDY

Based on the importance of coral reefs to production and development in the fisheries industry, findings from this study will reveal how mass larval reseeding can be used to restore damaged coral reefs. This research will contribute to the body of literature on the effect of personality traits on students’ academic performance, constituting the empirical literature for future research in the subject area.

1.7 SCOPE/LIMITATIONS OF THE STUDY

This study will cover the larval reseeding ponds specifically designed to enhance the survival of coral larval.

LIMITATION OF STUDY

Financial Constraint: Insufficient fund tends to impede the researcher’s efficiency in sourcing relevant materials, literature or information and the data collection process (internet, questionnaire and interview).

Time Constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted to the research work.

REFERENCES

Graham, N.A.; Cinner, J.E.; Norström, A.V.; Nyström, M. Coral reefs as novel ecosystems: Embracing new futures. Cur. Opin. Environ. Sustain. 2014, 7, 9–14.

Connell JH, Hughes TP, Wallace CC (1997) A 30-year study of coral abundance, recruitment, and disturbance at several scales in space and time. Ecol Monogr 67(4):461–488

Richmond RH (1997) Reproduction and recruitment in corals: critical links in the persistence of reefs. In: Life and death of coral reefs. Chapman & Hall, New York, p 175–197

Hughes TP, Baird AH, Dinsdale EA, Moltschaniwskyj NA, Pratchett MS, Tanner JE, Willis BL (1999) Patterns of recruitment and abundance of corals along the Great Barrier Reef. Nature 397:59–63

Gardner, T.A.; Côté, I.M.; Gill, J.A.; Grant, A.; Watkinson, A.R. Long-term region-wide declines in Caribbean corals. Science 2003, 301, 958–960.

Chen, I.C.; Hill, J.K.; Ohlemüller, R.; Roy, D.B.; Thomas, C.D. Rapid range shifts of species associated with high levels of climate warming. Science 2011, 333, 1024–1026.