Effects of the ocean temperature on organisms of the Galapagos Islands

Posted on by Angela M. Kuhn

The ocean’s temperature has multiple direct and indirect effects on marine organisms. Metabolic rates and mortality rates usually correlate well with temperature. While this correlation doesn’t imply causation, understanding the relationship between temperature and the abundance of organisms is key to predict their response under a changing climate.

The western Galapagos Archipelago comprises two islands: Isabela and Fernandina. Two distinct shallow water biological communities have been identified in these islands: the Elizabeth region in the Bolivar Channel and the western region elsewhere (Edgar et al, 2004). These distinct communities have different responses to temperature variability (Kuhn, 2010).

Early in my career, I explored the influence of the upper water column temperature on sessile organisms, macroinvertebrates, non-commercial and commercial fish of the Galapagos Islands. In my Bachelor’s thesis, I used multivariate statistics, including principal components and cluster analysis, to elucidate these effects on non-commercial shallow water species of the western region of the islands. This region is characterized by strong topographic upwelling and is key for the survival of many endemic cold-water charismatic species, such as penguins and flightless cormorants. I found two distinct patterns of temperature dependence: 1) biological communities in a deep channel were strongly affected by vertical differences in temperature; and 2) communities close to the Equatorial Front were affected by seasonal variations in temperature (Kuhn, 2010).

Later, I collaborated on the analysis of the combined effects of fishing pressure and temperature variability on local fisheries. After accounting for the negative effects of fishing over the stocks of sea cucumber and spiny lobster, we found a positive lagged correlation between sea surface temperature and catch (Defeo et al., 2013). The spiny lobster series, for instance, can be replicated well as a bi-variate autoregressive process.

Correlations between mean annual in situ sea surface temperature and lagged catch of spiny lobster and sea cucumber in the Galapagos Islands, Ecuador (Defeo et al., 2013). Catch series from 1995 to 2011 were linearly detrended and the residuals added to the mean, to account for the effect of fishing. Encircled triangles in B and D indicate the positive effect of 1997/1998 El Niño over spiny lobster (2000) and sea cucumber (2002–2003) catches. El Niño and La Niña events were defined based on the Oceanic Niño Index (ONI) estimated by the National Oceanic and Atmospheric Administration (NOAA). **: P < 0.05; ***: P < 0.001. Catch and SST time series were provided by Galápagos National Park and Charles Darwin Foundation. Content reproduced Creative Commons Attribution-NonCommercial 4.0 International License

Defeo, O., Castrejón, M., Ortega, L., Kuhn, A., Gutiérrez, N., & Castilla, J. C. (2013). Impacts of Climate Variability on Latin American Small-scale Fisheries. Ecology and Society, 18(4).
Edgar, G. J., Banks, S., Fariña, J. M., Calvopiña, M., & Martínez, C. (2004). Regional biogeography of shallow reef fish and macro‐invertebrate communities in the Galapagos archipelago. Journal of Biogeography, 31(7), 1107-1124.
Kuhn, A.M. (2010). Influencia de la temperatura del mar sobre comunidades rocosas submareales de la Reserva Marina de Galapagos. Tesis para la obtencion del titulo de Licenciatura en Oceanografia. Escuela Politecnica del Litoral. Guayaquil – Ecuador.

Published by Angela M. Kuhn

I'm a biological oceanographer with interest in understanding the effects of the ocean's physical variability on the marine ecosystem at different scales. I use diverse statistical methods and numerical experiments to systematically combine information from observations, simple and complex numerical marine ecosystem models.