Marine Protected Area monitoring in the nearshore waters of Grenada, Eastern Caribbean: benthic cover and fish populations
Monitoreo en aguas cercanas al área marina protegida en la costa de Granada, Caribe Oriental: cobertura bentónica y poblaciones de peces
Robert Anderson1*, Clare Morrall2*, Jonathan Jossart3*, Steve Nimrod2, Emily Bolda1, ]]>
1, Craig Berg4* & Robert Balza1
Abstract ]]>
Grenada is highly dependent on coral reefs as a source of food and to support tourism. Local and global environmental stressors threaten these reefs. Legislation was created for this MPA in 2001, permanent mooring buoys were deployed in 2009 and enforcement of fishing restrictions began in 2010. Initiatives to address point and nonpoint source pollution from the land have recently begun, aimed at reducing stress on reef area. This study documents benthic cover and fish populations associated with reefs in a ]]>
Diadema antillarum urchin relative abundance were determined based on 2m wide belt surveys along the same transects. The predominant substrate cover was algae, ranging from 41% in 2009 to 74.2% in 2011. A general trend of increasing algal cover was noted. Combined annual survey results prior (2008-2010) and after controls were implemented (2011-2012) showed a significant increase in ]]>
Porites porites (21%-23%) and Porites astreoides (20%) dominated percentage composition. Madracis mirabilis contributed 21% of total live hard coral outside the MPA but only 8.7% in the MPA. Of the 63 ]]>
Chromis spp. (71.5% - 46%) was the dominant group. Wrasse had a significant increase from 6.9% in 2008 to 21.5% in 2010 inside the MPA with a similar increase peaking in 2011 outside the MPA. There was a noticeable (though not statistically significant) increase in piscivorous fishes in the MPA in 2012. This is a promising indication that fishing restrictions in the MPA may be having an effect. Diadema antillarum
density was low, ranging from 4.58 to 0.21 urchins/100m2 outside and 0.28 to 0.10 urchins/100m2 inside despite a stocking attempt in the area in 2011.
Key words: benthic cover, reef ]]>
Resumen
Granada es muy dependiente de los arrecifes coralinos como fuente de alimento y apoyo al turismo. Factores estresantes locales y globales amenazan con estos ]]>
Diadema antillarum a través de censos visuales de 2m de ancho a lo largo de los mismos transectos lineales. La cobertura de sustrato estuvo dominada por algas con 41% en 2009 y 74.2% en 2011. Se notó una tendencia general de aumento en la cobertura algal. La combinación de los ]]>
Porites porites (21% - 23%) y Porites astreoides (20%) dominaron el porcentaje de composición. Madracis mirabilis
contribuyó en un 21% del total de corales duros fuera del MPA pero solo un 8.7% en el MPA. De las 63 especies de peces identificadas en el área de estudio Chromis spp. (71.5% - 46%) fue el grupo dominante. Los lábridos (Labridae) mostraron un aumento significativo de su abundancia de un 6.9% en 2008 a un 21.5% en 2010 dentro del MPA con un pico de incremento similar en el 2011 fuera de la MPA. Hubo un aumento notable ]]>
Diadema antillarum fue baja, osciló entre 4.58 y 0.21 erizos/100m2 fuera del MPA y entre 0.28 y 0.10 ]]>
m2 dentro del MPA a pesar de la existencia de un programa de repoblación de la especie llevado a cabo en el 2011.
Palabras clave: cubierta bentónica, peces de arrecife, monitoreo, Granada, área ]]>
The Reefs at Risk Revisited report (Burke, Reytar, Spalding & Perry, 2011) documents Grenada as a country with high exposure to reef threats and high reef dependence. Many countries have established Marine Protected Areas (MPAs) to conserve coral reef systems thereby addressing problems associated with ]]>
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Since tourism is the primary industry of Grenada and the nearshore reefs are important tourist attractions, the Grenadian government established legislation for the Moliniere-Beausejour MPA on the southwest coast of the island in 2001 (Byrne, 2007; Turner, 2009). Permanent mooring buoys were established in 2009 and in 2010 warden patrols began enforcing newly established fishing and anchoring restrictions. Annual monitoring of fish and coral communities within Grenada’s MPA and at similar coral communities ]]>
Methods and Materials
Study Area: The Moliniere-Beausejour MPA is located along Grenada’s southwest coast. Two study sites are in the MPA (Dragon Bay, 12°5’6.00”N, 61°45’45.36”W and Flamingo Bay, 12°5’30.36”N, 61°45’30.60”W) and three sites on nearby reef areas outside the MPA (Northern Exposure Shallow, 12°1’57.30”N, 61°46’14.28”W; ]]>
Methods: Both Point Line Intercept (PLI) and Photo Quadrat (PQ) methods were used to assess substrate type inside and outside the Moliniere-Beausejour MPA. Relative abundance of ]]>
Diadema antillarum were estimated based on a revision to the Crosby and Reese (1996) PLI method developed by Crosby and Bruckner in 2002. Three algal forms were identified in the sampling protocol: macro algae, turf algae and coralline algae. In addition live hard coral was grouped into branching, massive, plate and encrusting forms. Four 30m parallel permanent transects were set up at each of the five sampling sites. ]]>
D. antillarum observed within a two meter wide belt along the transect tape and throughout the water column during a 10 minute scan were recorded. In order to enhance the reliability of these observations digital photographs were taken with a Canon EOS Digital Rebel XTI, with EF-S 60mm f/2.8 Macro USM lens and dual Ikelite DS160 strobe lights each 50cm along the transect tape ]]>
Coral species encountered along transects were identified and relative abundance determined based on occurrence within 50cm by 30cm rectangles created on 2011 transect photographs using CPCe v.3.6. Scleractinian corals were identified to species level and octocorals were identified to genus unless picture quality would not allow sufficient detail for identification. Identifications were based on Humann (1993) and Sprung (1999).
Statistical Analysis: For the photo quadrat, point line intercept, and fish data a Repeated Measure Analysis of Variance (ANOVAR) with two factors, time and protection, was used to determine if the category varied by year or location (inside and outside of the MPA). All data was tested for normality, equal variance, and sphericity, and an ArcSine Root or Log transformation was used to satisfy the assumptions of normality and ]]>
Results ]]>
Substrate: Algae was the dominant substrate cover at survey sites inside and outside the MPA. Both the Point Line Intercept (PLI) and Photo Quadrat (PQ) survey methods showed a trend of increasing algal cover reaching a peak in 2011 (Fig. 1). Combining survey results prior to implementation of MPA controls (2008-2010) and comparing this to combined data after MPA controls were implemented (2011-2012) showed a significant increase in algal cover ]]>
Table 1) (T-Test, p<0.05). Algal cover ranged from 41.1% (SE=2.3, n=60) outside the MPA in 2009 to 74.2% (1.6, 40) inside the MPA in 2011 and was not significantly different (T-Test, p>0.05) inside and outside the MPA except in 2009 PQ surveys (T-Test, p<0.05). Three algal forms were identified in the sampling protocol: macro algae, turf algae and coralline algae. Macro algae dominated ranging from 65.4% (3.1, 60) to 90.8% (1.6, 40) of the total algae found (Table 2). Both ]]>
Table 3) (T-Test, p<0.05). Turf algae had significant annual variation (ANOVAR, p<0.05) with the highest percent composition of 27.2% (6.2, 60) occurring during 2009 outside the MPA. That same year turf algae was significantly less (T-Test, p<0.05) inside the MPA only reaching 8.5% (1.7, 40) of total algae found. The contribution of turf algae to total algal composition since 2009 has been less than 7% at all sites (Table 2). The combined years comparison revealed that the proportion of turf algae decreased significantly after implementation of controls ]]>
Table 3) (T-Test, p<0.05). Percent cover of coralline algae was significantly higher in 2008 and 2009 than in 2010 through 2012 (ANOVAR, p<0.05) in the PQ surveys. Percent contribution of coralline algae in the PLI surveys for 2008 and ]]>
Table 3) (Wilcoxon, p<0.05).
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Live hard coral percent cover (Fig. 1) ranged from 8.7% (0.8, 60) outside the MPA in 2011 to 21.1% (3.9, 40) inside the MPA in 2010 with little annual variation inside or outside the MPA (ANOVAR p>0.05). Percent cover for live hard coral was somewhat greater inside than outside the MPA but this difference was not significant (T-Test, p>0.05). Combined year comparisons show in both PLI and PQ results that percent live hard coral cover did not change significantly in the MPA since implementation of control ]]>
Table 1) (T-Test, p<0.05). Branching coral was the predominant form of coral found on the transects ranging from 34.1% (5.3, 40) to 52.3% (5.4, 60) of all coral. The percent composition of this coral form varied little from year to year and comprised a slightly greater portion of the hard coral outside the MPA compared to within the MPA (
Table 4). Combined annual results before and after implementation of MPA controls (Table 5) showed that the percent composition of branching coral did not change significantly (T-Test, p>0.05). Massive coral percent composition on the other hand was significantly greater inside than outside the MPA (T-Test, p<0.05) before but not after controls were implemented based on both the PLI and PQ surveys (Table 5). Massive and encrusting ]]>
Table 4). Percent composition of massive coral was significantly higher in the MPA in 2008 (T-Test, p<0.05) than outside the MPA but the difference declined somewhat through the years to the point that massive coral percent composition was higher outside the MPA in the 2012 PLI survey (Table 4).
A total of 22 coral taxa were identified (19 hard coral species and three octocoral genera) in the nearshore waters of Grenada. In the MPA Porites porites and Porites ]]>
dominated the surveys (Table 6) making up 21% (1.0, 478) and 20% (0.9, 478) of the live coral cover respectively and no significant difference in percent composition outside the MPA (Wilcoxon, p>0.05) was found. Madracis mirabilis was also a major coral species outside ]]>
Montastraea cavernosa and Siderastrea siderea occurred more frequently in the MPA (Wilcoxon, p<0.05) while Montastraea annularis and Montastraea faveolata occurred more often outside the MPA (Wilcoxon, p<0.05). Soft coral,
Pseudopterogorgia spp., was more prevalent in the MPA where it made up 11% (0.7, 478) of the total substrate cover compared to the 3% (0.4, 714) outside the MPA (Wilcoxon, p<0.05). The species Dichocoenia stokesi and Agaricia lamarcki were only found in the MPA.
Fish: Of the 63 species of fish observed along transects inside and outside the MPA (Table 8) Chromis spp. was the dominant group (Fig. 2). Through ]]>
Chromis spp. declined from 71.5% (4.2, 40) of the total fish recorded to 46.0% (4.9, 40) in the MPA. Outside the MPA Chromis spp. also declined from 2008 through 2011 but ]]>
Fig. 2). Analysis of combined annual results prior to implementation of fishing controls and after implementation showed no significant change for the major groups of fishes observed along transects inside and outside the MPA (T-Test, p>0.05). The only exception to this was a significant ]]>
Table 7).
The fish observed along transects were grouped based on their feeding habits following Sandin, Sampayo and Vermeij (2008). Planktivores, comprised mainly of Blue and Brown
Chromis as well as Bicolor Damselfish, dominated the feeding groups’ percent composition (Fig. 3). Percent composition of planktivores was significantly greater inside than outside the MPA in 2011 and significantly higher in 2008 and 2011(T-Test, p<0.05). Herbivores, made up of Parrotfishes, territorial Damselfishes, and Surgeonfishes, ranked second among the percent composition of feeding groups and were significantly greater outside the MPA in 2008 (T-Test, p<0.05) and ]]>
Table 9) (T-Test, ]]>
Diadema antillarum: Density of Diadema antillarum has been consistently greater outside than inside ]]>
m2 (2.3; 24) outside the MPA in 2008 to 0.1 urchins/100m2 (0.1; 16) in the MPA during the 2010 - 2012 surveys. There is a general decline in density across the years (Table 10).
Discussion
Nearshore coral reefs are suffering from local as well as global environmental impacts. Local impacts such as overfishing, nutrient and soil runoff from farms, municipal ]]>
The five years of data compiled in this study to date confirm concerns that Grenada’s nearshore reefs are at risk as indicated in Burke et al. (2011). The general increase in macro algal cover and low percent live coral cover are clear indicators of continued local as well as global stresses. High relative percent of macro algae compared to turf and coralline algae both inside and ]]>
Porites porites, Madracis mirabilis
, and Porites astreoides (Table 4) are not indicative of a resilient coral reef system. The predominance of planktivorous fishes and low percent composition of piscivores are likely a result of selective overfishing and nutrient loading (Knowlton & Jackson, 2008; Sandin, 2008; ]]>
Grenada’s Moliniere-Beausejour MPA encompasses an important portion of the reefs along Grenada’s southwest coast and improvement in the reef community in the MPA has the potential for improving all of the coral reef communities along the southwest shore (Angulo-Valdes & Hatcher, 2009; Crabbe, 2013; Sala et al., 2013). Fishing restrictions and required usage of permanent mooring structures have been implemented in the MPA. The MPA is ]]>
D. antillarum in 2011 (Nimrod, 2012) did not result in a detectible increase in urchin density during surveys in 2011 or 2012 (Table 10) and in fact D. antillarum density in the MPA was actually lower in 2010 through 2012 than in the previous two years. Comparison ]]>
Fig. 3,
Table 9). These results may be an indication that additional measures need to be taken to enhance the MPA. Measures implemented thus far target fishing and physical damage to the reef. Since excess nutrient runoff from shore is a potential driver of algal growth this may be an important issue to be addressed by all concerned with marine resources.
Studies of local nutrient runoff ]]>
This ongoing ]]>
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Acknowledgments
Funding for this project was provided by the Fischer Family Foundation and Gary Stimac and is greatly appreciated. Thanks are also offered to Jacob Krause, Jillian Groeschel, Kyle Foster, Svetlana Bornschlegl, Victoria Krueger, Thomas ]]>
References
]]>
Alvarado, J. J., Cortés J., Esquivel M. F., & Salas, E. (2012). Costa Rica’s Marine Protected Areas: status and perspectives. Revista de Biologia Tropical, 60, 129-142. [ Links ]
Anderson, R., Morrall C., Nimrod S., Balza R., Berg C., & Jossart, J. (2012). Benthic and fish population monitoring in the nearshore waters of Grenada, Eastern Caribbean. Revista de Biologia Tropical, 60, 71-87. [ Links ]
Angulo-Valdes, J. A., & Hatcher, B. C. (2010). A new typology of benefit derived from marine protected areas. Marine Policy, 34, 635-644. [ Links ]
Baker, A. C., Glynn P. W., & Riegl, B. (2008). Climate change and coral reef bleaching: an ecological assessment of long-term impacts, recovery trends and future outlook. Estuarine, Coastal and Shelf Science, 80, 435-471. [ Links ]
Bruckner, A.W., & Hill, R. (2009). Ten years of change to coral communities off Mona and Desecheo Islands, Puerto Rico from disease and bleaching. Diseases of Aquatic Organisms, 87, 19-31. [ Links ]
Buddemeier, R.W., Lane, D.R., & Martinich, J. A. (2011). Modeling regional coral reef responses to global warming and changes in ocean chemistry: Caribbean case study. Climatic Change, 109, 375-397. [ Links ]
Burke, L., & Maidens J. (2004). Reefs at risk in the Caribbean. Washington, D.C., USA: World Resources Institute. [ Links ]
Burke, L., Reytar, K., Spalding M., & Perry, A. (2011). Reefs at Risk Revisited. Washington, D.C., USA: World Resources Institute. [ Links ]
Byrne, J. (2007). Grenada Gap Analysis. Christiansted, St. Croix, USVI. 25: The Nature Conservancy. [ Links ]
Cantin, N. E., Cohen, A. L., Karnauskas, K. B., Tarrant, A. M., &. McCorkle, D. C. (2010). Ocean warming slows coral growth in the central Red Sea. Science, 329, 322-325. [ Links ]
Convention on Biological Diversity. (2012). Action Plan for Implementing the Convention on Biological Diversity’s Programme of Work on Protected Areas (Grenada). Retrieved from http://www.cbd.int/protected/implementation/actionplans/country/?country=gd. [ Links ]
Crabbe, M. (2013). Coral Reef Populations in the Caribbean: Is There a Case for Better Protection against Climate Change? American Journal of Climate Change, 2(2), 97-105. [ Links ]
Crosby, M. P., & Reese E. S. (1996). A manual for monitoring coral reefs with indicator species: butterfly fishes as indicators of change on the Indo-Pacific reefs. NOAA, Silver Spring, Maryland, USA: Office of Ocean and Coastal Resource Management, [ Links ]
Eakin, C. M., Morgan J. A., Heron S. F., Smith T. B, Liu G., Alvarez-Filip, L., Baca, B., Bartels, E. Bastidas, C., …, & Yusuf, Y. (2010). Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005. PLoS ONE, 5, e13969. [ Links ]
Fine, M. & Tchernov, D. (2007). Scleractinian coral species survive and recover from decalcification. Science, 315, 1811. [ Links ]
Gardner, T. A., Côte´, I. M., Gill, J. A., Grant, A., & Watkinson A. R. (2003). Long term region-wide declines in Caribbean corals. Science, 301, 958-960. [ Links ]
Graham, J. E., Barrett, N. S., & Stuart-Smith R. D. (2009). Exploited reefs protected from fishing transform over decades into conservation features otherwise absent from seascapes. Ecological Application, 19, 1967-1974. [ Links ]
Guarderas, A. P., Hacker, S. D., & Lubchenco, J. (2008). Current Status of Marine Protected Areas in Latin America and the Caribbean. Conservation Biology, 22, 1630-1640. [ Links ]
Humann, P. (1993). Reef Coral Identification (Florida, Caribbean, Bahamas). Jacksonville: New World Publications. [ Links ]
Jackson, J., Cramer, K. Donovan, M., Friedlander A., Hooten, A., & Lam, V. (2012). Tropical Americas Coral Reef Resilience Workshop - 2012. GCRMN Technical Report. Panama City, Panama: Smithsonian Tropical Research Institute. [ Links ]
Kelleher, G. (1999). Guidelines for Marine Protected Areas. IUCN - The World Conservation Union. Series 3. [ Links ]
Knowlton, N., & Jackson J. (2008). Shifting Baselines, Local Impacts, and Global Change on Coral Reefs. PLoS Biology, 6(2), e54. [ Links ]
Kohler, K. E., & Gill, S.M. (2006). Coral Point Count with excel extensions (CPCe): A visual basic program for the determination of coral and substrate coverage using random point count methodology. Computers & Geosciences, 32, 1259-1269. [ Links ]
Littler, M. M., & Littler, D. S. (2007). Assessment of coral reefs using herbivory, nutrient assays and indicator groups of benthic primary producers: a critical synthesis, proposed protocols, and critique of management strategies. Aquatic Conservation: Marine and Freshwater Ecosystems, 17, 195-215. [ Links ]
Nimrod, S. (2012). The effectiveness of Diadema in triggering a phase shift reversal. Mini-Symposia presentation 12th ICRS, Cairns, Australia. [ Links ]
Riegl, B., Bruckner, A., Coles, S., Renaud, P., & Dodge, R. E. (2009). Coral Reefs - Threats and conservation in an era of global change. Ann. NY Academic of Science, 1162, 136-186. [ Links ]
Riegl, B., Berumen, M., & Bruckner, A. (2013). Coral population trajectories, increased disturbance and management intervention: a sensitivity analysis. Ecology & Evolution, 3(4), 1050-1064. [ Links ]
Ries, J. B., Stanley S. M., & Hardie, L. A. (2006). Scleractinian corals produce calcite, and grow more slowly, in artificial Cretaceous seawater. Geology, 34, 525-528. [ Links ]
Sala, E., Costello, C., Dougherty, D., Heal, G., Kelleher, K., Murray, J., Rosenberg, A., & Sumaila, R. (2013). A General Business Model for Marine Reserves. PLoS ONE, 8(4), e58799. [ Links ]
Sandin, S. A., Sampayo E. M., & Vermeij, M. J. (2008). Coral reef fish and benthic community structure of Bonaire and Curaçao, Netherlands Antilles. Caribbean Journal of Science, 44, 137-144. [ Links ]
Selig, E. R., & Bruno, J. F. (2010). A Global Analysis of the Effectiveness of Marine Protected Areas in Preventing Coral Loss. PLoS ONE, 5(2), e9278. [ Links ]
Sokal, R. R., & Rohlf, F. J. (1995). Biometry: The principles and practice of statistics in biological research. 3rd edition. New York: W.H. Freeman. [ Links ]
Sprung, J. (1999). Oceanographic Series Corals: A Quick Reference Guide. Miami: Ricordia Publishing. [ Links ]
Turner, M. (2009). Draft Grenada Protected Area System Plan Part 1 - Identification and Designation of Protected Areas. Prepared for the Environment and Sustainable Development Unit (ESDU) of the Organization of Eastern Caribbean States (OECS) Protected Areas and Associated Livelihoods (OPAAL) Project. [ Links ]
Wiedenmann, J., D’Angelo, C., Smith, E. G., Hunt, A. N., Legiret, F. E., Postle, A. D., & Achterberg, E. P. (2013). Nutrient enrichment can increase the susceptibility of reef corals to bleaching. Nature and Climate Change, 3, 160-164. [ Links ]
1. Wisconsin Lutheran College, 8800 W. Bluemound Rd., Milwaukee, WI 53226, USA; banderson@wlc.edu, ebolda@hotmail.com, katie.musser@mail.wlc.edu, rob.balza@wlc.edu
2. St. George’s University, P.O. BOX 7, St. George’s, Grenada, West Indies; cmorrall@sgu.edu, snimrod@sgu.edu
3. University of the Virgin Islands; jossart1@gmail.com
4. Milwaukee County Zoo, 10001 W Bluemound Road, Milwaukee, WI 53226, USA; craig.berg@milwcnty.com
Received 07-IX-2013 Corrected 23-II-2014 Accepted 24-III-2014