During the past century, anthropogenic forces changed the composition of water in coastal aquifers. These changes were brought about by excessive mining of coastal groundwater, dredging and pier construction, wetland draining, and hard surface expansion. These forces caused an increase of salinity in the subterranean estuary, which led to a series of biogeochemical reactions. These changes continue today.
To contribute to the assessment of global biodiversity, this paper reviews available information on the cave-dwelling anchialine sponge fauna worldwide.
Stable isotope composition of soft tissues and carbonate tubes of the serpulids F. enigmaticus and M. cavatica were used to estimate their food sources. Comparison of isotope fingerprints of adjacent estuarine and anchialine cave serpulids showed that they consume predominantly particulate organic matter of terrestrial origin.
Ways of deducing information on physicochemical characteristics of anchialine caves from measurements of sedentary biota are investigated. First, photographs of Ficopomatus enigmaticus from two different anchialine caves are used to draw qualitative conclusions on water circulation patterns and organic loads of the two caves. Next, the ability of bioenergetic models to quantify average conditions in anchialine caves from information on abundance, distribution, morphological characteristcs, and individual growth rates of F. enigmaticus is discussed, and a development of a bioenergetic model is suggested.
The Amphipoda (Crustacea) found in subterranean brackish waters (subterranean estuaries) in Crna Gora (Montenegro) is represented by 12+ species belonging to the families Bogidiellidae, Gammaridae, Hadziidae, Melitidae, Niphargidae, Pseudoniphargidae and Salentinellidae.
Mixed gas rebreathers allowed divers to explore the shelf edge of the Bermuda sea mount at depths from 60 to 136 m to search for potential refugia of anchialine taxa during Pleistocene periods of sea level regression. Divers discovered karst and sea level features including a remnant natural bridge cave, drowned coral reefs, wave-cut notches and high relief escarpments.
In the framework of our research, this study was focused on crustaceans in the anchihaline caves along the Eastern Adriatic coast. From August 2002 to June 2006 we collected 99 samples in 39 anchihaline caves. A total of 33 crustacean taxa were identified. Affinities were found in the rare, endemic or ecologically restricted crustaceans recorded in fewer than 10 caves, belonging to copepods, isopods and amphipods. A high species richness was recorded in the Central Adriatic threshold and the South Adriatic Basin. Stratified caves rich in organic matter or even heavy metals had the highest species richness. The cave Medvjeđa špilja on Lošinj Island was detected as a hot spot with 12 recorded taxa.
The anchialine system at Bundera sinkhole, Australia, exhibits pronounced hydrogeochemical structure through depth that is reflected in the composition and distribution of the fauna. It is a strongly structured microbial ecosystem the components of which also change with depth and which is dominated by sulfur bacteria and chemolithotrophic microbial classes.
Recent cave diving explorations in Cenote Crustacea have led to discoveries of several undescribed annelids inhabiting sediments that lie within the halocline and marine layers. Taxonomic and genetic evaluations support their placement within Acrocirridae and Flabelligeridae, establishing new records from anchialine systems for these families. This study highlights the need for continued exploration and investigations of these mysterious labyrinths.
The invasive species Ficopomatus enigmaticus (Annelida, Polychaeta) colonized the anchialine cave Jama pod Orljakom (Krka River estuary, Croatia) seven years ago. This study examines the thermal regime of the cave and its water connection to the estuary. The results show that the cave is well connected to the Krka River estuary, but despite the good connectivity, limited water exchange can occur – especially in the surface layer. Since levels of dissolved oxygen and rates of food supply are heavily influenced by the water exchange rates, a weak exchange can determine limiting conditions on the growth and population density of F. enigmaticus in the cave.