Decadal increase in seagrass biomass and temperature at the CARICOMP site in Bocas del Toro, Panama

Abstract

The Caribbean Coastal Marine Productivity Program (CARICOMP) was launched in 1993 to study regional long-term interactions between land and sea, taking standardized measurements of productivity and biomass of mangroves, coral reefs and seagrasses. Since 1999 continuous measurements of seagrass (Thalassia testudinum) parameters as well as environmental data have been recorded in Caribbean Panama. Replicate stations were selected near the Smithsonian Tropical Research Institute in Bocas del Toro. Sediment cores and quadrants were placed there to estimate biomass and productivity, respectively. Mean values for productivity, standing crop, turnover rate, total dry biomass, and Leaf Area Index were 1.74gDW/m 2 /d, 66.6gDW/m 2 , 2.62%/d, 1 481 gDW/m 2 , and 4.65, respectively. Total dry biomass (shoots, rhizomes and roots) and LAI of T. testudinum increased significantly during the study period. Mean values for total rainfall, Secchi disk depth, sea surface temperature, and salinity were 3 498mm, 8.24m, 28.79°C, and 32.26psu, respectively. Sea surface temperature was the only environmental variable with a statistically significant change, increasing from 1999 to 2010. Correlation between sea surface temperature and T. testudinum parameters (total biomass and LAI) were both positive and significant. Human population has increased dramatically over the last ten years in Bocas del Toro region, increasing pressure (deforestation, runoff, wastewater) over coastal ecosystems (seagrasses, mangroves, coral reefs). Change in the abundance of T. testudinum may be linked to ocean warming, as a consequence to satisfy plant's metabolic requirements, although other local factors need to be analyzed (reduced grazing and increased eutrophication). A further warming of the ocean could have a negative effect on T. testudinum population, increasing respiratory demands and microbial metabolism.

Seagrass structural and elemental indicators reveal high nutrient availability within a tropical lagoon in Panama

“…The mean bay-wide aboveground biomass of T. testudinum (71.7 g dry mass m −2 ) was similar to other reported values at the Panama CARICOMP stations between 1999-2006 (mean: 77.4 g dry mass m −2 , ( Van Tussenbroek et al, 2014 ) and between 1999–2010 (mean: 66.6 g dry m −2 ; ( López-Calderón et al, 2013 ). Mean T. testudinum biomass from our surveys was also similar to values reported at other Caribbean CARICOMP stations ( Van Tussenbroek et al, 2014 ), see Table S4 ), however, these comparisons should be made with caution as there were generally only 2–4 sites / region in the CARICOMP program, compared to 24 sites in the current study.…”

“…In our study, no spatial pattern of seagrass nutrient content was observed, thus we did not find any nutrient gradient from the mainland to the open ocean, similar to other findings ( Carruthers et al, 2005 ), suggesting that nutrient availability across the bay is relatively homogeneous. The Bahía Almirante is relatively small, with a low tidal range (<0.5 m) and only three narrow connections with the open ocean ( Carruthers et al, 2005 ; López-Calderón et al, 2013 ), thus bay flushing is limited relative to the delivery of nutrients from the inflowing creeks.…”

“…Bahía Almirante receives moderate to high freshwater input (mean annual precipitation of approximately 3.3m) and as a result, extensive nutrient loading from the inflowing rivers ( Phillips, Rouse & Bustin, 1997 ; Carruthers et al, 2005 ). With a minimal tidal range (<0.5 m) and only three narrow connections with the ocean, the water circulation inside the bay is limited ( Carruthers et al, 2005 ; López-Calderón et al, 2013 ). A total of 24 sites were surveyed across Bahia Almirante (see Fig.…”

“…Studies of seagrass cover in Bahía Almirante are relatively limited. Through the Caribbean Coastal Marine Productivity Program ( CARICOMP, 1998 ), data on seagrass temporal variability and environmental parameters have been collected since 1998 near the Smithsonian Tropical Research Institute’s station in Bocas del Toro ( Guzmán et al, 2005 ; López-Calderón et al, 2013 ; Van Tussenbroek et al, 2014 ). However, CARICOMP was limited to two sites and may not reflect broader seagrass cover across the bay.…”

Intra and inter annual variation in a seagrass meadow on the Caribbean coast of Costa Rica: 2009-2015

“…Mean biomass of T. testudinum between 2009 and 2015 in CNP was also higher than the mean biomass reported for this species in Tobago from 1992 to 2002 (Juman, 2005) and Mexico from 1993 to 2005 (Rodríguez-Martínez et al, 2010). López-Calderón, Guzmán, Jacome, & Barnes (2013) found a mean biomass from 1999 to 2010 of 1 481 gDWm -2 for T. testudinum and an increase of this biomass with time, in Bocas del Toro (Table 5). Contrary to Fonseca et al (2007), López-Calderón et al (2013) attributes biomass increase to an increase in water temperature and nutrient availability.…”