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Geology topics

J. Berg

Publications and source records attributed to J. Berg.

2 recordsLinked to original sources

Documentation of a Gulf sturgeon spawning site on the Yellow River, Alabama, USA

The Gulf Sturgeon Recovery Plan (USFWS, GSMFC and NMFS 1995) stressed the need to provide maximum protection to Gulf sturgeon spawning habitat. The approach employed by various Gulf sturgeon researchers, including ourselves, to document spawning has been to identify potential spawning habitat on the basis of physical characteristics and/or tracking data, collect eggs, and then raise the eggs in the laboratory until the point where the larval fish can be identified (e.g., Marchant and Shutters 1996, Sulak and Clugston 1998, 1999). However, collecting eggs in any appreciable number is usually difficult, and these eggs may not always be viable upon return to the laboratory. Molecular methods provide an alternative means of identifying the species represented by an egg. Notable examples related to sturgeon conservation include cases where molecular markers were used to verify the sources of commercially available caviar (DeSalle and Birstein 1996, Birstein et al. 1999). Parauka and Giorgianni (2002) reported that potential Gulf sturgeon spawning habitat is present in the Yellow River; however, efforts to document spawning by the collection of eggs or larvae have been unsuccessful in the past. Herein, we report on the first successful collection of eggs from a potential spawning site on the Yellow River and the verification of their identity as Gulf sturgeon by using molecular methods.

Alabama, Florida

Dual-Carbon sources fuel the OCS deep-reef Community, a stable isotope investigation

The hypothesis that phytoplankton is the sole carbon source for the OCS deep-reef community (>60 m) was tested. Trophic structure for NE Gulf of Mexico deep reefs was analyzed via carbon and nitrogen stable isotopes. Carbon signatures for 114 entities (carbon sources, sediment, fishes, and invertebrates) supported surface phytoplankton as the primary fuel for the deep reef. However, a second carbon source, the macroalga Sargassum, with its epiphytic macroalgal associate, Cladophora liniformis, was also identified. Macroalgal carbon signatures were detected among 23 consumer entities. Most notably, macroalgae contributed 45 % of total carbon to the 13C isotopic spectrum of the particulate-feeding reef-crest gorgonian Nicella. The discontinuous spatial distribution of some sessile deep-reef invertebrates utilizing pelagic macroalgal carbon may be trophically tied to the contagious distribution of Sargassum biomass along major ocean surface features.

Proceedings of the 11th International Coral Reef S