Search for: All records

Positive interactions are underrepresented in marine ecology but have a substantial impact on biodiversity and ecosystem stability. Here, we showcase a previously undescribed commensal relationship between two temperate rocky reef fishes in sandy bottom habitats: the rock wrasse ( Halichoeres semicinctus) and round stingray (Urobatis halleri). Using snorkel surveys in Big Fisherman’s Cove on Santa Catalina Island, we showed that rock wrasse abundances were positively associated with the presence of round stingrays and that round stingrays significantly altered rock wrasse behavior. Specifically, rock wrasse within a 1 m radius of a feeding round stingray spent approximately 40% and 35% more time feeding compared to rock wrasse in proximity of a resting round stingray or a sandy bottom control, respectively. The positive effect of feeding round stingrays on rock wrasse feeding behavior is in response to stingrays disturbing sand as they eat, uncovering small invertebrates for the wrasses to prey on. As round stingrays are one of the most common fishes in southern California, they may impact the fitness of rock wrasses. 

Foundation species, which help maintain habitat and ecosystem functioning, are declining due to anthropogenic impacts. Within the rocky intertidal ecosystem, studies have investigated the effects of foundation species on community structure and some resource fluxes; however, how intertidal foundation species loss will affect multiple facets of ecosystem functioning in concert remains unknown. We studied the direct and indirect effects of foundation species loss of mussels Mytilus californianus and surfgrass Phyllospadix spp. on community structure, fluxes (light, temperature, dissolved oxygen [DO], dissolved inorganic nutrients, pH T ), and ecosystem metabolism (net ecosystem calcification [NEC] and net ecosystem production [NEP]) in central Oregon using in situ tide pool manipulations. Surfgrass loss increased microalgae cover, increased average maximum light by 142% and average maximum temperature by 3.8°C, increased DO and pH T values, and indirectly increased NEP and NEC via increased maximum temperature and pH T respectively. Mussel loss increased microalgae cover, increased average maximum light by 5.8% and average maximum temperature by 1.3°C, increased DO and pH T values, and indirectly increased NEP via increased producer cover. Shifts in baseline nutrient concentrations and temperature values from coastal upwelling influenced ecosystem metabolism in pools with intact foundation species. Our results indicate that as communities respond to foundation species loss, ecosystem functioning depends on the dominant community present and biologically or physically driven shifts in biogeochemistry. This study highlights the importance of the connection between community and ecosystem ecology in understanding the magnitude of changes occurring with anthropogenically-driven intertidal foundation species loss.