Biomonitoring in the Maldives

Tropical marine ecology

• The project

  

  Location map showing the three investigated islands in the North Ari Atoll (Modified from Pisapia et al., 2017). In 2012 all the twelve islands were visited, in 2018 only Rasdhoo, Vihamafaaru and Mayafushi were visited. 

  We generally apply three indices: ABI (Amphistegina Bleaching Index), FI (Foram Index) and SEDCON Index (Sediment Constituent Index), to assess the health conditions and reef resilience in the Maldives (Pisapia et al., 2017; Spezzaferri et al., 2018, and several articles in preparation). We compare the ecological status in community, resort and uninhabited islands to assess the impact of different management regimes  in the context of global climate changes.

• ABI - Amphistegina Bleaching Index

  Amphistegina is a large symbiont-bearing benthic foraminifera, requiring high water quality.  Amphistegina bleaches in response to photo-inhibition resulting in symbiont loss.

  The Amphistegina Bleaching Index (Hallock et al. 2006, and references therein) provides a measure of in-situ photo-oxidative stress within coral reef environments.

   

  For more detailed information download the papers:

  Hallock, P., Williams, D. E., Fisher, E. M., Toler, S. K. (2006). Bleaching in foraminifera with algal symbionts: implications for reef monitoring and risk asessment. Anuário do Instituto de Geociências, 29(1), 108-128.

  Spezzaferri, S., El Kateb, A., Pisapia, C.,  Hallock, P. (2018). In situ observations of foraminiferal bleaching in the Maldives, Indian Ocean. Journal of Foraminiferal Research, 48(1), 75-84.

• FoRAM Index

  FoRAM Index

  The Foram Index (FI) is currently used to assess local impacts on the water quality in tropical reef environments (Hallock, 2003). Similarly to corals, symbiont-bearing foraminifera require high water-quality conditions.

  The FI is based on the relative proportions of symbiont-bearing, stress tolerant and other small foraminifera as functional groups.

   

  the FI is determined using the equation:

  FI= (10 x P_s) + (P_o) + (2 x P_h)

  where:

  P_s= N_s/T, number of symbiont bearing foraminifera over the total

  P_o= N_o/T, number of stress tolerant foraminifera over the total

  P_h= N_h/T, number of other small foraminifera over the total

   

  and:

  FI values < 2 indicate unfavourable ecological conditions for calcifying organisms that host algal symbionts

  FI values between 2-4 indicate marginal conditions

  Fi values >4 indicate favourable ecological conditions for calcifying organisms that hosts algal endosymbionts, supporting reef growth.

   

  For more detailed information download the papers:

   Hallock, P., Lidz, B. H., Cockey-Burkhard, E. M.,  Donnelly, K. B. (2003). Foraminifera as bioindicators in coral reef assessment and monitoring: the FORAM index. Environmental monitoring and assessment, 81(1-3), 221-238.

  Pisapia, C., El Kateb, A., Hallock, P., Spezzaferri, S. (2017). Assessing coral reef health in the North Ari Atoll (Maldives) using the FoRAM Index. Marine Micropaleontology, 133, 50-57.

• Sediment Constituents - SEDCON Index

  The SEDCON Index should be used in combination with the FORAM Index (FI) to assess if an environment can support reef growth (Hallock et al., 2003; Daniels, 2005).

  This index is based on the assumption that the sediment reflects the community structure and provides a measure, over an average of one year, of the integrity of the reef community. It is based on the proportion of the various sediment components.

  Coral fragments (P_c), primary reef framework builder, mixotrophic, environment suitable for calcification and algal symbiosis.

  • Symbiotic foraminifera (P_f), sediment producer, mixotrophic, calcification possible by algal symbiosis.
  • Corallinae algae (P_ah), framework builder, autotrophic, various interpretations.
  • Calcareous algae (P_ah), sediment producers, autotrophic, nutrient signal and high CaCO₃
  • Molluscs (P_ah), grazers, predators, heteroptrophic, food resources, nutrient signal.
  • Echinoid spines (P_ah), bioeroders, heterotrophic, bioerosion and nutrient signal.
  • Worm tubes (P_ah), heterotrophic, abundant food resources.
  • Other identifiable grains (P_ah), sediment producers, heterotrophic, abundant food resources.
  • Unidentifiable grains (P_u), bioerosion proxy and signal.

  SI= (10 x P_c) + (8 x P_f) + (2 x P_ah) + (0.1 x P_u)

  where :

  P_c= N_c/T, number of coral grains over the total

  P_f= N_f/T, number of symbiont bearing foraminifers over the total

  P_ah= N_ah/T, number of corallinae algae, calcareous algae and heterotroph skeletal grains over the total

  P_u= N_u/T, number of unidentifiable grains over the total

   

  and:

  SI values < 2 indicate dominance of unidentifiable grains reflecting strong bioerosion

  SI values between 2-4 indicate dominance of autotrophic and heterotrophic processes

  SI values >4 indicate dominance of calcifying organisms.

   

  For more detailed information download the paper: 

  Daniels, C. A. (2005). Coral reef assessment: an index utilizing sediment constituents.

• FOraminiferal BIo-MOnitoring (FOBIMO)

  Monitoring the quality of the ecosystems is nowadays one of the most important subject in research environments.

  Monitoring the status of marine environments has traditionally been based on macrofauna studies, as macrofaunal experts made a large effort to standardise their methods  and develop biotic indices (e.g., Grall and Glemarec, 1997; Borja et al., 2000; Rosenberg et al., 2004; Rumohr, 2004; ANSI, 2007; Rees et al., 2009).

  However, foraminifera have several advantages in comparison with macrofaunal organisms as:

  • Density (between 100 and 10000 living individuals per 100 cm² surface area sediment;
  • High variability within the same environment
  • Short life cycle that respond quickly to environmental changes
  • Test preserved in the sediment
  • Large community of active researchers

  The FOBIMO Initiative was established in 2010 to promote the use of benthic foraminifera as efficient monitoring tool.

   

  For more detailed information download the paper: 

  Schönfeld, J., Alve, E., Geslin, E., Jorissen, F., Korsun, S., Spezzaferri, S. (2012). The FOBIMO (FOraminiferal BIo-MOnitoring) initiative—Towards a standardised protocol for soft-bottom benthic foraminiferal monitoring studies. Marine Micropaleontology, 94, 1-13.

Image courtesy of Giovan Peyrotty