• Michael Clores Partido State University – Caramoan Campus, Caramoan, Camarines Sur, 04429 Philippines




biomass elasticity, ecotrophic efficiency, flow to detritus, grazing, seagrass, trophic


Ecotrophic efficiency (EE) is an estimate of the proportion of production that is utilized by the next trophic level through direct predation or fishing or exported out of the ecosystem. In seagrass systems, analysis of EE provides crucial information on how biomass, when used or lost in biological functioning, affects the higher trophic levels via death or grazing relative to the energy lost via decomposition (i.e., Flow to the detritus, FTD) and exports to another ecosystem (i.e., Sum of all exports, SAE). In this study, projections on the effect of change in the EE of functional groups in seagrass systems due to the alteration of biomass were established heuristically using Elasticity Analysis. Using a previously constructed Ecopath model for a shallow Philippine seagrass meadow, the simulations of altering the biomass of seagrasses and their grazers were done to determine the change in EE, FTD, and SAE, thereby generating information on the dynamics of the grazing and detrital pathways in the seagrass ecosystem. Results showed the effects of biomass increase and decrease of grazers (herbivorous gastropods, Tripneustes gratilla, and polychaetes). If the grazers’ biomass increases, their EE tends to decrease, and biomass accumulation tends to increase. This implies that a fraction of their production used in the system is reduced even if their predators' density and feeding rate are still constant. In addition, the EE of seagrasses tends to increase, leading to a decrease in biomass accumulation at the primary producers’ trophic level. Lastly, the EE of detritus decreased because the FTD and SAE of its major contributors (the seagrasses) had also decreased. The findings contribute to the ongoing analysis of the role of herbivores versus detritivores in the energetics of seagrass habitats.


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Author Biography

Michael Clores, Partido State University – Caramoan Campus, Caramoan, Camarines Sur, 04429 Philippines

E-mail: michael.clores@parsu.edu.phmclores@gbox.adnu.edu.ph
ORCID: 0000-0002-4671-5699


Archer, S.K., Stoner, E.W., Layman, C.A. 2015. A complex interaction between a sponge (Halichondria melanadocia) and a seagrass (Thalassia testudinum) in a subtropical coastal ecosystem. J Exp Mar Bio Ecol, 465: 33-40.

Attayde, J. L., & Ripa, J. (2008). The Coupling between Grazing and Detritus Food Chains and the Strength of Trophic Cascades across a Gradient of Nutrient Enrichment. Ecosystems, 11(6), 980-990. https://doi.org/10.2307/40296419

Barbeau, M.A., Caswell, H. 1999. A Matrix Model for Short-Term Dynamics of Seeded Populations of Sea Scallops. Ecol Appl, 9(1): 266-87.

Blomberg, B.N., Montagna, P.A. 2014. Meta-analysis of Ecopath models reveals secondary productivity patterns across the Gulf of Mexico. Ocean Coast Manag; 100: 32-40

Burnell, O.W., Connell, S.D., Irving, A.D., Russell, B.D. 2013. Asymmetric patterns of recovery in two habitat forming seagrass species following simulated overgrazing by urchins. J Exp Mar Bio Ecol, 448: 114-20.

Caswell, H. 2001. Matrix population models: construction, analysis and interpretation. Sinauer Associates, Sundeland, Massachusetts, USA.

Christensen, V., Walters, C.J., Pauly, D. 2000. Ecopath with Ecosim: a user’s guide. University of British Columbia, Fisheries Centre, Vancouver, Canada and ICLARM, Penang, Malaysia.

Clores, M.A. and Cuesta, M.A. 2019. Trophic models of seagrass ecosystems in Maqueda Channel, Caramoan Peninsula, Philippines. Appl Environ Res, 41(3): 14-31.

Clores, M.A., Conde, M.A.A., Perez, J.D.V. 2020.Biomass leaching and dynamics of nutrients, microbial abundance and activity during decomposition of seagrass Cymodocea rotundata necromass. Appl Environ Res, 42(1): 1-13.

Du, J., Makatipu, P.C., Tao, L.S.R., Pauly, D., Cheung, W.W.L, Peristiwady, T, et al. 2019. Comparing trophic levels estimated from a tropical marine food web using an ecosystem model and stable isotopes. Estuar Coast Shelf Sci, 233: 106518

Fourqurean, J.W., Manuel, S., Coates, K.A., Kenworthy, W.J., Smith, S.R. 2010. Effects of excluding sea turtle herbivores from a seagrass bed: Overgrazing may have led to loss of seagrass meadows in Bermuda. Mar Ecol Prog Ser, 419: 223-32.

Gascuel, D. 2005. The trophic-level based model: A theoretical approach of fishing effects on marine ecosystems. Ecol Modell, 189(3-4): 315-32.

Gloeckner, D.R., Luczkovich, J.J. 2008. Experimental assessment of trophic impacts from a network model of a seagrass ecosystem: Direct and indirect effects of gulf flounder, spot and pinfish on benthic polychaetes. J Exp Mar Bio Ecol, 357(2): 109-20.

Hearne, E.L, Johnson, R.A., Gulick, A.G., Candelmo, A., Bolten, A.B., Bjorndal, K.A. 2019. Effects of green turtle grazing on seagrass and macroalgae diversity vary spatially among seagrass meadows. Aquat Bot. 152, 10-5.

Heymans, J.J., Coll, M., Libralato, S., Morissette, L., Christensen, V. 2014. Global patterns in ecological indicators of marine food webs: A modelling approach. PLoS One, 9 (4).

Johnson, R.A,, Hanes, K.M., Bolten, A.B., Bjorndal, K.A. 2020. Simulated green turtle grazing affects benthic infauna abundance and community composition but not diversity in a Thalassia testudinum seagrass meadow. J Exp Mar Biol, 522:151266.

Johnson, R.A., Gulick, A.G., Bolten, A.B., Bjorndal, K.A. 2019. Rates of Sediment Resuspension and Erosion Following Green Turtle Grazing in a Shallow Caribbean Thalassia testudinum Meadow. Ecosystems, 22(8): 1787-802.

Lindeman, R. L. and Lindeman, L. 2007. The Trophic Dynamic of Ecology. Ecology, 23(4): 399-417.

Lindeman, R.L. 1942. The trophic‐dynamic aspect of ecology. Ecology, 23, 399-418.

Smith, T.M. and Smith, R.L. 2009. Elements of Ecology 7th ed. San Francisco CA: Pearson Benjamin Cummings.

Ullah, M.H., Rashed-Un-Nabi, M., Al-Mamun, M.A. 2012. Trophic model of the coastal ecosystem of the Bay of Bengal using mass balance Ecopath model. Ecol Modell, 225: 82-94.

Yeager, L.A. and Layman, C.A. 2011. Energy flow to two abundant consumers in a subtropical oyster reef food web. Aquat Ecol, 45(2): 267-77.




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