Possible Fossil Echinoid Mass Mortality Detected in Holocene Lagoons, Belize

Abstract

The development of benthic foraminiferal assemblages during the past 6,000 yrs was investigated in Holocene sediment cores from three carbonate platforms (Turneffe Islands, Lighthouse Reef, and Glovers Reef) Based on cluster analyses, seven benthic foraminiferal assemblages are distinguished during the Holocene.The three platforms exhibit characteristic differences in benthic foraminiferal fauna and diversity, which are controlled by their respective environments during the last 6,000 yrs. Turneffe Islands has four benthic foraminiferal assemblages, which are typical for restricted lagoons with fluctuating salinity. Lighthouse Reef is inhabited by two benthic foraminifera associations, which are characteristic of high water exchange with the surrounding ocean and clear waters. Glovers Reef is characterized by two benthic foraminiferal assemblages, which occur in deeper lagoons with slow water circulation. In general, during the Holocene, the highest mean diversity, evenness, and richness of benthic foraminifera were found in the Turneffe Islands and the lowest occurred at Glovers Reef. The foraminiferal faunas of the Lighthouse and Glovers Reefs had been in a "Diversification Stage" since 6,000 yrs, whereas the foraminiferal fauna of the Turneffe Islands reflects the development from a "Colonisation" (~4,000 yrs BP) to a "Diversification Stage" (~2,000 yrs to present time).Lagoonal depth, water circulation, substrate, and BW-temperature have higher influence on foraminiferal diversity as compared to lagoonal size and age. The negative correlation between diversity and lagoonal depth is based on differences in light intensity and substrate. In contrast to Lighthouse Reef, the Turneffe Islands and Glovers Reef show decreasing diversity of benthic foraminifera with increasing lagoon depth, due to finer sediment, turbid waters and/or dense mangrove growth, which reduce the light intensity and the number of species. Water Circulation also affected the benthic foraminifera modes of living and their diversity during the last 6,000 yrs.

A 3000 year record of Caribbean reef urchin communities reveals causes and consequences of long‐term decline in Diadema antillarum

“…A4, A5), b) no relationship exists between total Diadema spine abundance and accretion rate (Cramer et al 2017a), c) the greatest abundance of Diadema spines was not found in the most recent parts of the record (Fig. 2), and d) urchin subfossils (primarily spines) previously collected from atoll lagoon cores in Belize were dominated by Diadema (Gischler 2010). Third, because Diadema can be patchily distributed (Bauer 1976, Lessios 1988a, our coring locations could have sampled microhabitats not frequented by this species.…”

Quaternary reef response to sea‐level and environmental change in the western Atlantic

“…The loss of this grazer has been proposed as a major cause of the increase in macro‐algal cover on Caribbean reefs (Perry, ). Data from lagoons in Belize suggest that similar die‐offs have occurred during the Holocene, 6·4 to 6·1 kyr, 4·0 kyr and 1·3 kyr bp (Gischler, ); however, more data from fossil reefs are needed in order to decipher whether such turnovers as those in acroporids and in echinoids are unprecedented or not.…”

Reefs in Space and Time: Recognizing David Stoddart's Contribution to Coral Reef Science

“…An analysis of the distribution of the grazer Echinometra viridis showed, however, that its abundance correlated positively with fleshy algal abundance. The study by Gischler (2010b) on fossil Diadema and Echinometra die-outs in cores from Belize atoll lagoons showed that at least three previous events had probably happened during 6.4-6.1 kyrs BP and around 4 kyrs BP and 1.3 kyrs BP. McClanahan et al (2000McClanahan et al ( , 2001 experimented with artificial algae reduction on patch reefs in Glovers Reef, which resulted in the increase of certain fish taxa due to increased accessibility, net production, and palatability of early succession turf algae.…”