Tripneustes are dark or white to bluish-purple in

Tripneustes gratilla (Linnaeus, 1758) is a
species of sea urchin under the phylum Echinodermata; class Echinoidea; order
Temnopleuroida; family Toxopneustidae. This is commonly known as collector
urchin and locally called as “sowaki” all throughout the island of Leyte. The
spines of this species are dark or white to bluish-purple in color and some specimens
have orange-tipped spines (Lyman, 1921). It is widely distributed in the Indo-Pacific Region, Hawaii and in the Red
Sea (Rahman et al., 2014). It
is usually found at 1 to 30 m depths, in shallow seagrass beds and also in
coral reef areas. The individuals are always covered with collected debris,
weeds or other subjects, hence the name collector urchin (Schoppe, 2000).Sea
urchins play a vital role in the ecosystem by controlling the population of
invasive algae in coral reefs, and have high economic value by providing food
and source of livelihood, generating up to millions of pesos per annum to the
fisher folks (Talaue-Mcmanus & Kesner, 1995). Unfortunately, edible
echinoids like T. gratilla are threatened by overexploitation (Micael et al.,
2009) and continuous rise of temperature due to climate change (Brennand et
al., 2010).

Climate
change is one of the major challenges in the present time causing stress to the
environment. From shifting weather patterns that threaten food production, to
rising sea levels that increase the risk of catastrophic flooding, and the
rising global temperature that threaten the lives of marine organisms, the
impacts of climate change worldwide is in unprecedented scale (UNEP, 2013).
According to the Intergovernmental Panel on Climate Change (IPCC) in 2014, as
much as 4°C increase in ocean temperature is predicted by the end of the
century. High levels of water temperature and CO2 concentration caused by both
natural and anthropogenic activities and processes are expected to be first experienced
in the coastal areas in the future. It has been noted that some parts of the
globe are already experiencing these phenomenon (Talmage & Gobler, 2011).
Several marine ecosystems and the living organisms in it, especially in the
intertidal and subtidal zones, are in great danger because of the continuous
increase of temperature (Sherman, 2015; Brennand et al., 2010; Nguyen et al.,
2011). One of the important abiotic components of the ecosystem that affects
the survival, growth, biological processes and distribution of organisms is
temperature (Kinne, 1964). In echinoderms, increasing temperature can induce
change in the position of its body and could greatly affect the growth and
development of the larvae due to its fragility, and because planktonic stage
depends on the water temperature and chemistry (Brennand et al., 2010).

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Fertilization
of T. gratilla is not directly affected by ocean warming and acidification
(Byrne, 2010) but the early embryonic and larval stages are said to be highly
susceptible to increased temperatures because it produces a fragile calcite
skeleton, and because this life stage has a planktonic period of days or weeks
in the water column where seawater chemistry and temperature have a major
impact on development (Brennand et al., 2010). 
Echinoplutei larvae support their body by producing calcite rods which
are also used for locomotion and feeding. Temperature has great influence on
the development of echinoplutei by shortening its planktonic stage which
decreases the risk of predation (Byrne, 2010; O’Connor et al., 2007). Calcite
rods and arm length have direct effect on the larval feeding efficiency and
vulnerability to predation (Soars et al., 2009; Allen, 2008). Information on
the development and survival of embryo and larvae particularly to high
temperature will provide insights on the impact of increasing temperature and
ultimately climate change to T. gratilla, hence this study. The information
from this research will eventually help in conservation efforts and for
aquaculture purposes.