Legislating to protect the ecological function of coral reefs
Submitting InstitutionUniversity of Exeter
Unit of AssessmentBiological Sciences
Summary Impact TypeEnvironmental
Research Subject Area(s)
Environmental Sciences: Environmental Science and Management
Biological Sciences: Ecology, Other Biological Sciences
Summary of the impact
Professor Mumby's research on the impact of parrotfish grazing on the
resilience of coral reefs has had a direct impact on the management of
Caribbean reefs and fisheries. The results of his research have influenced
conservation policy across the Caribbean and have led to the Governments
of Belize and Bonaire enacting legislation to ban fishing of parrotfish.
The work has also motivated the National Marine Fisheries Service (USA)
and the Caribbean Fishery Management Council (Puerto Rico and US Virgin
Islands) to set annual catch and size limits for parrotfish caught in US
Professor Mumby (appointed to Exeter in 2002, Professor, 2006-10, and
currently on unpaid leave as an ARC Laureate Fellow at the University of
Queensland, 2010-15) and his group have been conducting research on coral
reef ecology since 1995, publishing over 112 peer-reviewed articles to
date. Their research focuses on a number of areas, including the role of
herbivorous parrotfish in maintaining reef resilience, and it is the
findings of this work that have influenced conservation and management of
coral reefs across the Caribbean. Specifically, this research has resulted
in new legislation to ban fishing of parrotfishes in two countries (Belize
and Bonaire) and new catch and size limits in US Caribbean fisheries.
The critical balance between macroalgae and corals in reef ecosystems has
been disturbed in recent years as a consequence of both natural (e.g.,
hurricanes) and anthropogenic perturbations (e.g., climate change,
over-fishing, pollution) with many Caribbean reefs experiencing a shift
from coral to macroalgal dominance. Algal-dominated reefs offer few
benefits to people and can be self- reinforcing because macroalgae
negatively impact coral recruitment, growth, and fecundity. Grazing by
herbivorous fishes and urchins limits the growth and spread of macroalgae,
and enhances the recovery of coral populations following disturbance,
leading to an overall increase in reef ecosystem resilience.
The link between conservation of herbivorous parrotfish and coral
recovery was made by Mumby's group in several steps. First, studies of
no-fishing reserves revealed that fishing effects on parrotfish abundance
heavily outweighed other controls such as natural predation . A
reduction in fishing led to a doubling of fish grazing and four-fold
reduction in macro-algal abundance. The reduction of macro-algae led to a
linear increase in the density of coral recruitment , suggesting that
coral recovery could accelerate with management of parrotfish
exploitation. This was confirmed three years later by studying the
dynamics of Bahamian coral reefs after a major disturbance; reefs with
less algae exhibited net recovery whereas those with more algae
experienced continued decline. These ecosystem-scale studies were
supported by mechanistic, experimental investigations of the effects of
algae on coral recruitment, growth and fecundity.
The empirical studies described above were used to parameterise a
simulation model of Caribbean reefs which allowed a wider range of
scenarios to be explored including pollution and climate change impacts
[3-5]. These studies have provided clear evidence that protection of
parrotfish can have long-lasting benefits despite the diversity and
intensity of external disturbances. In some cases, local conservation of
parrotfish can buy 40 years for reefs to adapt to climate change. Even the
subtleties of conserving the nursery habitat of parrotfish  can have
profound (albeit non- intuitive) benefits to reef resilience.
Subsequently, the models developed by Professor Mumby's group have been
adapted by other researchers for use in other reef ecosystems outside the
References to the research
Evidence of the quality of the research: this work has been
published in high quality peer reviewed journals.
1. Mumby, P. J., C. P. Dahlgren, A. R. Harborne, C. V. Kappel, F.
Micheli, D. R. Brumbaugh, K. E. Holmes, J. M. Mendes, K. Broad, J. N.
Sanchirico, K. Buch, S. Box, R. W. Stoffle, and A. B. Gill. 2006. Fishing,
trophic cascades, and the process of grazing on coral reefs. Science
311:98-101. Citations: 272, featured study of a
review in TREE by Hughes et al 2008.
2. Mumby, P. J., A. R. Harborne, J. Williams, C. V. Kappel, D. R.
Brumbaugh, F. Micheli, K. E. Holmes, C. P. Dahlgren, C. B. Paris, and P.
G. Blackwell. 2007. Trophic cascade facilitates coral recruitment in a
marine reserve. Proceedings of the National Academy of Science, U S A,
104:8362-8367. Citations: 129
3. Mumby, P. J. 2006. The impact of exploiting grazers (Scaridae)
on the dynamics of Caribbean coral reefs. Ecological Applications,
16:747-769. Citations: 115.
4. Mumby, P. J., A. Hastings, and H. J. Edwards. 2007. Thresholds
and the resilience of Caribbean coral reefs. Nature, 450:98-101. Citations:
5. Hoegh-Guldberg, O., P. J. Mumby, A. J. Hooten, R. S. Steneck,
P. Greenfield, E. Gomez, C. D. Harvell, P. F. Sale, A. J. Edwards, K.
Caldeira, N. Knowlton, C. M. Eakin, R. Iglesias-Prieto, N. Muthiga, R. H.
Bradbury, A. Dubi, and M. E. Hatziolos. 2007. Coral reefs under rapid
climate change and ocean acidification. Science 318:1737-1742. Citations:
982, won Thomson-Reuters award for high citation.
6. Mumby, P. J., A. J. Edwards, J. E. Arias-Gonzalez, K. C.
Lindeman, P. G. Blackwell, A. Gall, M. I. Gorczynska, A. R. Harborne, C.
L. Pescod, H. Renken, C. C. C. Wabnitz, and G. Llewellyn. 2004. Mangroves
enhance the biomass of coral reef fish communities in the Caribbean. Nature,
427:533-536. Citations: 342. Most heavily cited
paper on mangroves since 1972
Details of the impact
A major focus of Professor Mumby's research is the key role of
herbivorous parrotfish in maintaining reef resilience, and it is this work
that has had the greatest impact on the conservation and practical
management of Caribbean coral reefs. Specifically, this research has
resulted in new legislation to ban the fishing of parrotfishes in two
countries (Belize and Bonaire) and has played a significant role in the
introduction of new catch and size limits in US Caribbean fisheries.
In 2005, Professor Mumby was invited to give a presentation at the
Fisheries Department in Belize where some of the first results
highlighting the importance of grazers to reef health and reef resilience
were presented. The Chair of the Belize Fishing Cooperative attended the
meeting and requested the same presentation be given to fishermen and
women. Over 170 fishers attended the meeting and upon hearing the results
queried why parrotfish were not protected, given that they have such an
important role in reef health. The fishers voted almost unanimously to
make a recommendation to the Fisheries Department that parrotfish be
protected in Belizean waters. This recommendation, combined with the
research into the importance of parrotfish for reef health and the
Wildlife Conservation Society (WCS) programme of fisheries catch data
(section 5; source 1), led to the Government of Belize enacting
legislation to ban fishing of parrotfishes in 2009 (section 5; source 2).
Over a number of years, Professor Mumby has conducted research on the
reefs of Bonaire, Netherlands Antilles, and during his visits to the
island gave numerous outreach presentations to the Bonaire Marine Park
staff and public, with his collaborator, Prof Robert Steneck. In addition,
Professor Mumby contributed to a number of annual reports for the Bonaire
Marine Park on the state of the reefs (section 5; source 3). During these
presentations and reports, parrotfishes and their importance in enhancing
reef health and resilience were frequently discussed. Mumby's publications
that detailed how a reduction in fishing mortality of grazers could
benefit reef health were a key part of the initial proposal recommending a
ban on fishing parrotfishes in Bonaire, which was presented to the
Environment Department (section 5; source 4). These activities fed
directly into a change in policy that resulted in the Government of
Bonaire enacting legislation to ban the fishing of parrotfishes in 2010
(section 5; source 5).
In October 2011, the National Ocean and Atmospheric Administration
(NOAA), the National Marine Fisheries Service (NMFS), the Southeast
Regional Office (SERO) and the Sustainable Fisheries Division (F/SER2) of
the US Government released a Biological Opinion on the continued
authorization of the Reef Fish Fishery within the US Caribbean, Puerto
Rico and the US Virgin Islands (section 5; source 6). In assessing the
status of the reefs and the impact of the Reef Fish Fishery on reef health
in the US Caribbean, the Biological Opinion drew heavily on research
conducted by Professor Mumby and colleagues. Ten publications were cited
which detailed the links between macroalgae and reef health, fishing
mortality and parrotfish abundance, and fishing mortality, levels of
grazing and reef resilience. While the authors of the Biological Opinion
acknowledged the importance of grazers in enhancing reef health and
resilience, the decision was taken to introduce Annual Catch Limits (ACL)
for herbivorous species (including parrotfishes) within the US Caribbean,
rather than introducing an overall ban.
In January 2012, the environmental law firm, Earthjustice, on behalf of
the Center for Biological Diversity, challenged NOAA, NMFS, SERO, F/SER2
for failure to comply with the Endangered Species Act in managing the US
Caribbean Reef Fish Fishery. Earthjustice filed for a judicial review of
the 2011 Biological Opinion, which authorised the continuation of the Reef
Fish Fishery in Puerto Rico and the US Virgin Islands (albeit with catch
limits for herbivorous species). The lawsuit stated that the Biological
Opinion did not go far enough and should have recommended a ban on fishing
herbivorous fishes, in particular parrotfishes, in the US Caribbean in
order to protect critical habitat for Acropora palmata and Acropora
cervicornis (two coral species listed on the endangered species
act). In their review of the Biological Opinion, Earthjustice drew heavily
on Professor Mumby's research, highlighting the importance of parrotfishes
in enhancing the recovery and resilience of coral reefs (section 5; source
7). On 30th Sept 2013 the Federal District Court in San Juan,
Puerto Rico ruled in favour of Earthjustice (section 5; source 8).
Currently, the Caribbean Fishery Management Council is proposing to
implement size limits for parrotfish caught within US Caribbean Fisheries
(section 5; source 9). The Council drew heavily on Professor Mumby's work
in assessing the need for size limits within the fishery and it was the
main scientific study cited in a presentation to policy makers (section 5;
Sources to corroborate the impact
- Communication from the Country Director, Wildlife Conservation
- Statutory Instrument No. 49, Fisheries (Nassau Grouper & Species
Protection) Regulations, 2009, Belize.
- Steneck, R.R., Mumby P. and Arnold S. (2007) A Report on the Status of
the Coral Reefs of Bonaire in 2007 with Results from Monitoring 2003 —
- Communication from Bonaire National Marine Park Manager, Bonaire.
- Island Resolution No. 15 - Nature, The Executive Council of the Island
Territory of Bonaire, 2010.
NOAA Biological Opinion/Earthjustice Lawsuit
- Endangered Species Act — Section 7 Consultation — Biological Opinion,
NOAA, October 4th 2011. Cites Mumby p.217
- Communication from Staff Attorney, Oceans Program, Earthjustice, San
- Lawsuit document - complaint for Declaratory and Injunctive Relief,
Earthjustice, January 30th 2012. Refers to the Biological
Caribbean Fishery Management Council
- Caribbean Fishery Management Council - Public Hearings and Scoping
Meeting Agenda, July 2012.
- Powerpoint presentation detailing the case for setting size limits on
parrotfish caught within the US Caribbean.