Monitoreo en aguas cercanas al área marina protegida en la costa de Granada, Caribe Oriental: cobertura bentónica y poblaciones de peces

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 Marine Protected Area (MPA) along Grenada's southwest coast from 2008 through 2012. Both Point Line Intercept and Photo Quadrat methods were used to assess benthic cover along permanent 30m transects (8 in and 12 outside the area) annually. Fish and 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)(2009)(2010) and after controls were implemented (2011-2012) showed a significant increase in algal cover. The predominant algal form was macroalgae comprising 65.4% -90.8% of total algae. Live hard coral percent cover ranged from 8.7% to 21.1%. Little annual variation was observed in percent live coral cover. Branching corals (34.1% -52.3% of total living hard coral) were the most common. Of the 19 living hard coral species identified, 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 species of fish identified in the study areas 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/100m 2 outside and 0.28 to 0.10 urchins/100m 2 inside despite a stocking attempt in the area in 2011. Rev. Biol. Trop. 62 (Suppl. 3): 273-286. Epub 2014 September 01.

Long-term Shifts in Coral Communities On Shallow to Deep Reef Slopes of Curaçao and Bonaire: Are There Any Winners?

“…A few species, in particular M. mirabilis, A. lamarcki and P. astreoides, however, appear to be more resilient and their decrease in cover and abundance was less distinct (Figure 4, Table S2). This is confirmed by observations throughout the Caribbean (Green et al, 2008;Anderson et al, 2014;Perry et al, 2015). Nevertheless, these species seem to decline when the overall coral cover in the quadrat was substantially reduced.…”

Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

“…This lack of acroporids is attributed to their region-wide decline since the 1980s, with their near absence being noted in the nearby Tobago Cays in 1999 [35,36]. The percent coral cover values obtained in the present study for Grenada are slightly higher than those reported in recently published literature for the same study sites [20,21]. No significant differences in coral cover were detected between the islands.…”

“…Ocean surgeonfish grazing increased growth of P. astreoides, but parrotfish have no impact [52]. Herbivorous fish biomass in Grenada and Carriacou is 'poor' [53] and herbivorous invertebrates, such as Diadema antillarum, are also now largely absent from reef communities in Grenada [21].…”

“…Surveys were conducted at eight sites in the nearshore waters of Grenada and Carriacou in the Fall of 2014 and 2017. Four previously established study sites [19] were selected to complement a published dataset from Grenada [20,21] and four sites were also established on the nearby island of Carriacou (Figure 1, Table 1) [14,22]. The sites on Carriacou were chosen to mirror those in Grenada in that they were approximately equivalent distances from shore, found at similar depths, had benthic community assemblages that appeared similar during initial visual assessments, and were all frequented by the recreational dive industry.…”