282
P.W.Giynn
This bias is not meant to diminish the significance of organic production and
related topics, but hopefully will serve to alert workers of this deficiency.
19.2 Environmental Setting
Due to the great expanse of deep water (up to 8,200 km) separating central
Pacific and western American shores, the far eastern Pacific is perhaps the
most isolated coral reef region in the world (Dana 1975; Grigg and Hey
1992). However, evidence suggests that several Indo-Pacific shallow-water
species are capable of crossing this barrier (Scheltema 1988; Jokiel 1990;
Emerson and Chaney 1995; Lessios et al. 1998). Once central Pacific larvae
or rafting organisms in eastward flowing currents accomplish this crossing
they must settle and become established under sometimes harsh physicochemical conditions and also survive various interactions (e. g. predation
and competition) with resident eastern Pacific species. A significant factor
influencing the distribution and development of eastern Pacific coral communities and coral reefs, recognized by such notable mid-19th century
workers as James Dana and Charles Darwin, is the sea temperature climatology of the major regional current systems. Seasonal low temperatures of
18-20 °C are tolerated by most species of zooxanthellate corals, and brief
exposures to 15-16 oc during upwelling episodes also are generally nonlethal. To a large degree, the asymmetrical distribution of eastern Pacific
reef-building corals, located mostly north of the equator, reflects the flow
of the relatively cool Peru Coastal and California Currents (Fig. 19.1). The
northern-most coral reefs occur at the tip of Baja California (23.5°N) and
are found as far south as about 3°S along the Ecuadorian coast. Coral communities are common along the eastern shores of Baja California (from
about 26°N to the tip of the peninsula) and also occur abundantly throughout the eastern Pacific region slightly farther south than coral reefs, to at
least Isla Santa Clara in the Gulf of Guayaquil, Ecuador (Fig. 19.1).
Fig.l9.1. The eastern Pacific coral reef region, spanning approximately 25° latitude and
concentrated mostly north of the equator. Some of the known coastal coral reef areas are
Cabo Pulmo-Los Frailes (I); Nayarit (2) ; Huatulco (3); Los C6banos (4); Gulf ofPapagayo
(5); Cafto Island-Golfito (6); Gulf of Chiriqui (7); Gulf of Panama (8); Utria (9); Gorgona
Island (IO); Cabo San Lorenzo-Salinas (11). Arrows denote synoptic surface flow of the
major current systems. Costa Rica Coastal Current ( CRCC). Broken arrows denote the
Equatorial Under Current (EUC), which surfaces as it collides with the westernmost
Galapagos Islands. All currents vary seasonally in their velocity and extent: the NECC
and CRCC are best developed during the northern hemispheric summer
P.W.Giynn
This bias is not meant to diminish the significance of organic production and
related topics, but hopefully will serve to alert workers of this deficiency.
19.2 Environmental Setting
Due to the great expanse of deep water (up to 8,200 km) separating central
Pacific and western American shores, the far eastern Pacific is perhaps the
most isolated coral reef region in the world (Dana 1975; Grigg and Hey
1992). However, evidence suggests that several Indo-Pacific shallow-water
species are capable of crossing this barrier (Scheltema 1988; Jokiel 1990;
Emerson and Chaney 1995; Lessios et al. 1998). Once central Pacific larvae
or rafting organisms in eastward flowing currents accomplish this crossing
they must settle and become established under sometimes harsh physicochemical conditions and also survive various interactions (e. g. predation
and competition) with resident eastern Pacific species. A significant factor
influencing the distribution and development of eastern Pacific coral communities and coral reefs, recognized by such notable mid-19th century
workers as James Dana and Charles Darwin, is the sea temperature climatology of the major regional current systems. Seasonal low temperatures of
18-20 °C are tolerated by most species of zooxanthellate corals, and brief
exposures to 15-16 oc during upwelling episodes also are generally nonlethal. To a large degree, the asymmetrical distribution of eastern Pacific
reef-building corals, located mostly north of the equator, reflects the flow
of the relatively cool Peru Coastal and California Currents (Fig. 19.1). The
northern-most coral reefs occur at the tip of Baja California (23.5°N) and
are found as far south as about 3°S along the Ecuadorian coast. Coral communities are common along the eastern shores of Baja California (from
about 26°N to the tip of the peninsula) and also occur abundantly throughout the eastern Pacific region slightly farther south than coral reefs, to at
least Isla Santa Clara in the Gulf of Guayaquil, Ecuador (Fig. 19.1).
Fig.l9.1. The eastern Pacific coral reef region, spanning approximately 25° latitude and
concentrated mostly north of the equator. Some of the known coastal coral reef areas are
Cabo Pulmo-Los Frailes (I); Nayarit (2) ; Huatulco (3); Los C6banos (4); Gulf ofPapagayo
(5); Cafto Island-Golfito (6); Gulf of Chiriqui (7); Gulf of Panama (8); Utria (9); Gorgona
Island (IO); Cabo San Lorenzo-Salinas (11). Arrows denote synoptic surface flow of the
major current systems. Costa Rica Coastal Current ( CRCC). Broken arrows denote the
Equatorial Under Current (EUC), which surfaces as it collides with the westernmost
Galapagos Islands. All currents vary seasonally in their velocity and extent: the NECC
and CRCC are best developed during the northern hemispheric summer