Pawson and Miller (1988) describe, with specimens of Thyone tanyspeira
(Phyllophoridae), collected in Honduras, Colombia and Trinidad. The specimens
were collected during the expedition of the RV Pillsbury in 1969 and 1971 into the
Caribbean.
Pacific
Bakus (1974) compared the toxicity of holothurianss in order to test the hypothesis
that toxicity in holothurians is inversely related with latitude and that this phenomenon is in part a reflection of fish predation. He conducted the study at Cocos
Island (Costa Rica), Bahía de Bacochibampo (México), Santa Catalina Island
(California), and Friday Harbor (Washington). Six of the seven species of holothurians at Cocos Island were toxic to fishes, three of six holothurians were toxic to
fish in Mexico, while one of two were toxic to fish in California and three of
twelve species in Washington were mildly toxic to fish. At Cocos Island the toxic
species were Holothuria theeli, H. atra, H. impatiens, H. sp. 1, H. sp. 2 and
Bohadschia sp. The body wall, viscera, and Cuverian tubules (in H. theeli and
H. sp.2) were the most toxic to fishes.
3.2.2 Grazing and Bioerosion
Caribbean
In the Miskitos Cays, Nicaragua, Vadas et al. (1982) studied the abundances,
feeding and reproductive activities of the sea urchin Lytechinus variegatus on a
seagrass bed (Thalassia testudinum). Intermediate (2–4 m) and deeper (4–8 m)
depths contain fewer urchins and have higher plant diversities. Although highest
plant diversities were correlated with intermediate grazer densities (*5 ind m
-2 ).
The diet of these urchins appears to be governed primarily by availability and the
palatability of food items. Detrital T. testudinum and sediment were the two major
food items in the diet (40 and 25 %, respectively). This feeding strategy minimizes
the impact of urchin grazing on the structure and the viability of T. testudinum and
the algal-seagrass community. Over 68.5 % of the volume of the gut contents of
L. variegatus consisted of particle sizes in the 0.5–3.0 mm category. Intestinal
tract pH ranged from 6.0 in the esophagus and 6.5–7.0 in mid-stomach. The
average dry weight of the gut contents was 113 mg cm
-3 . Of this 68 % was
CaCO 3 . Food passage in the gut averaged 0.22 cm
3 ind
-1 h
-1 for the first 14.5 h,
then values decreased rapidly. The consumption rates of L. variegatus that was
taken from T. testudinum was 0.6 g dry wt day
-1 .
Hay (1984) compared the pattern of fish and urchin grazing on overfished and
less fished reefs in Haiti, Saint Croix, Saint Thomas, Belize, Honduras and Panama. In Belize he worked at Carrie Bow Cay and Lighthouse reefs and in
86
J. J. Alvarado et al.
(Phyllophoridae), collected in Honduras, Colombia and Trinidad. The specimens
were collected during the expedition of the RV Pillsbury in 1969 and 1971 into the
Caribbean.
Pacific
Bakus (1974) compared the toxicity of holothurianss in order to test the hypothesis
that toxicity in holothurians is inversely related with latitude and that this phenomenon is in part a reflection of fish predation. He conducted the study at Cocos
Island (Costa Rica), Bahía de Bacochibampo (México), Santa Catalina Island
(California), and Friday Harbor (Washington). Six of the seven species of holothurians at Cocos Island were toxic to fishes, three of six holothurians were toxic to
fish in Mexico, while one of two were toxic to fish in California and three of
twelve species in Washington were mildly toxic to fish. At Cocos Island the toxic
species were Holothuria theeli, H. atra, H. impatiens, H. sp. 1, H. sp. 2 and
Bohadschia sp. The body wall, viscera, and Cuverian tubules (in H. theeli and
H. sp.2) were the most toxic to fishes.
3.2.2 Grazing and Bioerosion
Caribbean
In the Miskitos Cays, Nicaragua, Vadas et al. (1982) studied the abundances,
feeding and reproductive activities of the sea urchin Lytechinus variegatus on a
seagrass bed (Thalassia testudinum). Intermediate (2–4 m) and deeper (4–8 m)
depths contain fewer urchins and have higher plant diversities. Although highest
plant diversities were correlated with intermediate grazer densities (*5 ind m
-2 ).
The diet of these urchins appears to be governed primarily by availability and the
palatability of food items. Detrital T. testudinum and sediment were the two major
food items in the diet (40 and 25 %, respectively). This feeding strategy minimizes
the impact of urchin grazing on the structure and the viability of T. testudinum and
the algal-seagrass community. Over 68.5 % of the volume of the gut contents of
L. variegatus consisted of particle sizes in the 0.5–3.0 mm category. Intestinal
tract pH ranged from 6.0 in the esophagus and 6.5–7.0 in mid-stomach. The
average dry weight of the gut contents was 113 mg cm
-3 . Of this 68 % was
CaCO 3 . Food passage in the gut averaged 0.22 cm
3 ind
-1 h
-1 for the first 14.5 h,
then values decreased rapidly. The consumption rates of L. variegatus that was
taken from T. testudinum was 0.6 g dry wt day
-1 .
Hay (1984) compared the pattern of fish and urchin grazing on overfished and
less fished reefs in Haiti, Saint Croix, Saint Thomas, Belize, Honduras and Panama. In Belize he worked at Carrie Bow Cay and Lighthouse reefs and in
86
J. J. Alvarado et al.