Click
here to close Hello! We notice that
you are using Internet Explorer, which is not supported by Echinobase
and may cause the site to display incorrectly. We suggest using a
current version of Chrome,
FireFox,
or Safari.
The sea urchin Lytechinus variegatus lives close to the upper thermal limit for early development in a tropical lagoon.
Collin R
,
Chan KY
.
???displayArticle.abstract???
Thermal tolerance shapes organisms'' physiological performance and limits their biogeographic ranges. Tropical terrestrial organisms are thought to live very near their upper thermal tolerance limits, and such small thermal safety factors put them at risk from global warming. However, little is known about the thermal tolerances of tropical marine invertebrates, how they vary across different life stages, and how these limits relate to environmental conditions. We tested the tolerance to acute heat stress of five life stages of the tropical sea urchin Lytechinus variegatus collected in the Bahía Almirante, Bocas del Toro, Panama. We also investigated the impact of chronic heat stress on larval development. Fertilization, cleavage, morula development, and 4-armed larvae tolerated 2-h exposures to elevated temperatures between 28-32°C. Average critical temperatures (LT 50) were lower for initiation of cleavage (33.5°C) and development to morula (32.5°C) than they were for fertilization (34.4°C) or for 4-armed larvae (34.1°C). LT 50 was even higher (34.8°C) for adults exposed to similar acute thermal stress, suggesting that thermal limits measured for adults may not be directly applied to the whole life history. During chronic exposure, larvae had significantly lower survival and reduced growth when reared at temperatures above 30.5°C and did not survive chronic exposures at or above 32.3°C. Environmental monitoring at and near our collection site shows that L. variegatus may already experience temperatures at which larval growth and survival are reduced during the warmest months of the year. A published local climate model further suggests that such damaging warm temperatures will be reached throughout the Bahía Almirante by 2084. Our results highlight that tropical marine invertebrates likely have small thermal safety factors during some stages in their life cycles, and that shallow-water populations are at particular risk of near future warming.
Figure 2. Data (A, C) and logistic regression (B, D) for temperature dependence of development from the heatblock assay of early development (A, B) and heatblock assay of 3–4 day old larvae (C, D). Each point represents the % survival of 60 embryos or 10–20 larvae counted from a single vial in one of nine replicate trials that placed 10 vials across the temperature gradient. Fertilization success (green triangles); initiation of cleavage (red squares); successful development to morula (blue diamonds), and larval survival (black ovals). Points on regression lines indicate 10%, 25%, and 50% mortality and horizontal lines extending from the points indicate the 95% confidence intervals (when visible).
Figure 3. Relationship between culturing temperature and larval survival compared with days after fertilization. The number of larvae is the total number from two pooled 10‐mL samples. Temperatures (standard deviations) of the treatments are as follows. Experiment 1: 23.4°C (0.3), 25.3°C (0.1), 28.3°C (0.2), and 31.9°C (0.1). Experiment 2: 22.8°C (0.4), 25.2°C (0.2), 28.0°C (0.1), 29.0°C (0.2), 30.8°C (0.3), and 31.7°C (0.4). Experiment 3: 27.6°C (0.2), 28.9°C (0.2), and 30.5°C (0.4). Experiment 4: 27.3°C (0.2), 29.9°C (0.2), and 30.3°C* (0.1). *This treatment drifted over time with an average temperature of 30.8°C for the first 2 days and 30.0°C thereafter.
Figure 4. Relationship between culturing temperature and total length (from posterior end to the top of the oral hood), stomach length and total length of postoral arms (from posterior end to tip of postoral arm, averaged for both sides). Larvae from Experiments 1 and 2 were photographed on Day 4 after fertilization. Dots represent individual measurements and lines show the best fit quadratic, which strongly indicates a reduction in size above 29°C. In all cases, ANOVA analysis showed a significant effect of temperature on size and the results of the post hoc Tukey HSD tests indicated that larvae reared at 31.9°C in Experiment 1 and at 30.8°C and 31.7°C in Experiment 2 had significantly smaller body lengths and stomach length than larvae raised at 26–29°C.
Bozinovic,
Physiological ecology meets climate change.
2015,
Pubmed
Byrne,
Temperature, but not pH, compromises sea urchin fertilization and early development under near-future climate change scenarios.
2009,
Pubmed
,
Echinobase
Byrne,
Global change ecotoxicology: Identification of early life history bottlenecks in marine invertebrates, variable species responses and variable experimental approaches.
2012,
Pubmed
Clusella-Trullas,
Climatic predictors of temperature performance curve parameters in ectotherms imply complex responses to climate change.
2011,
Pubmed
Clusella-Trullas,
Lizard thermal trait variation at multiple scales: a review.
2014,
Pubmed
Deutsch,
Impacts of climate warming on terrestrial ectotherms across latitude.
2008,
Pubmed
Farley,
The role of jelly coats in sperm-egg encounters, fertilization success, and selection on egg size in broadcast spawners.
2001,
Pubmed
,
Echinobase
Hamdoun,
Embryo stability and vulnerability in an always changing world.
2007,
Pubmed
Huey,
Predicting organismal vulnerability to climate warming: roles of behaviour, physiology and adaptation.
2012,
Pubmed
Moritz,
Integrating phylogeography and physiology reveals divergence of thermal traits between central and peripheral lineages of tropical rainforest lizards.
2012,
Pubmed
Munday,
Predicting evolutionary responses to climate change in the sea.
2013,
Pubmed
Nguyen,
Upper temperature limits of tropical marine ectotherms: global warming implications.
2011,
Pubmed
Polgar,
Gross mismatch between thermal tolerances and environmental temperatures in a tropical freshwater snail: climate warming and evolutionary implications.
2015,
Pubmed
Ritz,
Toward a unified approach to dose-response modeling in ecotoxicology.
2010,
Pubmed
Schiffer,
Temperature tolerance of different larval stages of the spider crab Hyas araneus exposed to elevated seawater PCO2.
2014,
Pubmed
Sherman,
Can sea urchins beat the heat? Sea urchins, thermal tolerance and climate change.
2015,
Pubmed
,
Echinobase
Simon,
Upper thermal tolerance plasticity in tropical amphibian species from contrasting habitats: implications for warming impact prediction.
2015,
Pubmed
Somero,
Linking biogeography to physiology: Evolutionary and acclimatory adjustments of thermal limits.
2005,
Pubmed
Stillman,
A comparative analysis of the upper thermal tolerance limits of eastern Pacific porcelain crabs, genus Petrolisthes: influences of latitude, vertical zonation, acclimation, and phylogeny.
2000,
Pubmed
Summers,
The orientation of first cleavage in the sea urchin embryo, Lytechinus variegatus, does not specify the axes of bilateral symmetry.
1996,
Pubmed
,
Echinobase
Sunday,
Global analysis of thermal tolerance and latitude in ectotherms.
2011,
Pubmed
de Vries,
Development and application of a species sensitivity distribution for temperature-induced mortality in the aquatic environment.
2008,
Pubmed
