1987, 1989). In those studies the sand dollar Mellitella stokesii (as Encope stokessi) and the ophiuroid Microphiopholis geminate (as Amphipholis germinata)
appeared as regular members of those communities. This research continued until
1996, including 76 collecting dates from February 1984 until September 1996
(Vargas and Solano 2011). Using sediment cores (265.5 cm
3 ; 14 cores/date),
Vargas and Solano (2011) studied the presence of both species in an area of
400 m
2 . They found a total of 149 individuals of M. geminata and 63 of M.
stokesii. Both species had an irregular temporal pattern of abundance, with slight
increases at the end of the rainy season or during the dry seasons.
Echinoid Ecology
Caribbean
Strathmann (1981) studied the role of spines in preventing structural damage to
echinoids tests at Carrie Bow Cay and Twin Cay, Belize. He analyzed echinoid
tests by breaking them by way of dropping lead fishing sinkers on living sea
urchins submerged in sea water. He observed specimens from five species representing four echinoid orders: Eucidaris tribuloides, Diadema antillarum,
Tripneustes, Lytechinus variegatus and Echinometra viridis (Fig. 3.3). The results
suggest that spines and tissue apparently protect the test apparently by both
spreading the load and absorbing energy. He also noted breaks on podial pore
tracks are common in all the species. The breaks at sutures were common in living
specimens of E. tribuloides. In contrast, the breaks on sutures in D. antillarum,
L. variegatus, T. ventricosus, and E. viridis were often absent and comprised a
small portion when present. Thus, he suggests that tracts of podial pores are sites
of relative weakness. In addition, he evaluated the strength of the test of the
different species under impact. He found that, within species, strength appears to
increase with size. Strathmann’s (1981) observations on test strength and thickness
led him to set up a ranking of strength under impact. Eucidaris tribuloides was the
strongest, followed by E. viridis and D. antillarum, then T. ventricosus. Lytechinus
variegatus was the weakest species. Thus, it appears that, among the species
examined, the most primitive design is the strongest. He extrapolated the results
from modern echinoids to extinct classes and he argued that is speculative, because
it is difficult to determine the causes of failure of skeletons in most fossil forms.
Information about the decline and recuperation of populations of D. antillarum
in Central America is scarce because there are few records prior to the mass
mortality and only for several of localities in Belize (Hay 1984; Lewis and
Wainwright 1985); Honduras (Hay 1984), and Costa Rica (Valdez and Villalobos
1978; Cortés 1981). Post mortality information comes from Costa Rica (Cortés
1994; Fonseca 2003; Alvarado et al. 2004; Bolaños et al. 2005; Fonseca et al.
2006; Myhre and Acevedo-Gutiérrez 2007; Cortés et al. 2010), Nicaragua (Ryan
et al. 1998), Honduras (Lessios 1998), Guatemala (Fonseca and Arrivillaga 2003)
and Belize (Aronson and Precht 1997; Carpenter and Edmunds 2006).
80
J. J. Alvarado et al.
appeared as regular members of those communities. This research continued until
1996, including 76 collecting dates from February 1984 until September 1996
(Vargas and Solano 2011). Using sediment cores (265.5 cm
3 ; 14 cores/date),
Vargas and Solano (2011) studied the presence of both species in an area of
400 m
2 . They found a total of 149 individuals of M. geminata and 63 of M.
stokesii. Both species had an irregular temporal pattern of abundance, with slight
increases at the end of the rainy season or during the dry seasons.
Echinoid Ecology
Caribbean
Strathmann (1981) studied the role of spines in preventing structural damage to
echinoids tests at Carrie Bow Cay and Twin Cay, Belize. He analyzed echinoid
tests by breaking them by way of dropping lead fishing sinkers on living sea
urchins submerged in sea water. He observed specimens from five species representing four echinoid orders: Eucidaris tribuloides, Diadema antillarum,
Tripneustes, Lytechinus variegatus and Echinometra viridis (Fig. 3.3). The results
suggest that spines and tissue apparently protect the test apparently by both
spreading the load and absorbing energy. He also noted breaks on podial pore
tracks are common in all the species. The breaks at sutures were common in living
specimens of E. tribuloides. In contrast, the breaks on sutures in D. antillarum,
L. variegatus, T. ventricosus, and E. viridis were often absent and comprised a
small portion when present. Thus, he suggests that tracts of podial pores are sites
of relative weakness. In addition, he evaluated the strength of the test of the
different species under impact. He found that, within species, strength appears to
increase with size. Strathmann’s (1981) observations on test strength and thickness
led him to set up a ranking of strength under impact. Eucidaris tribuloides was the
strongest, followed by E. viridis and D. antillarum, then T. ventricosus. Lytechinus
variegatus was the weakest species. Thus, it appears that, among the species
examined, the most primitive design is the strongest. He extrapolated the results
from modern echinoids to extinct classes and he argued that is speculative, because
it is difficult to determine the causes of failure of skeletons in most fossil forms.
Information about the decline and recuperation of populations of D. antillarum
in Central America is scarce because there are few records prior to the mass
mortality and only for several of localities in Belize (Hay 1984; Lewis and
Wainwright 1985); Honduras (Hay 1984), and Costa Rica (Valdez and Villalobos
1978; Cortés 1981). Post mortality information comes from Costa Rica (Cortés
1994; Fonseca 2003; Alvarado et al. 2004; Bolaños et al. 2005; Fonseca et al.
2006; Myhre and Acevedo-Gutiérrez 2007; Cortés et al. 2010), Nicaragua (Ryan
et al. 1998), Honduras (Lessios 1998), Guatemala (Fonseca and Arrivillaga 2003)
and Belize (Aronson and Precht 1997; Carpenter and Edmunds 2006).
80
J. J. Alvarado et al.