Within the scope of the international collaborative EU project SYMBIOCORE I have joined a pilot field campaign to the Abrolhos Archipelago off the coast of southern Bahia (Brazil), which represents the kick-off event of this collaborative effort in coral reef science. This particular field campaign has originally been initiated by our Brazilian (UFBA, Salvador do Bahia) and UK (UESSEX) SYMBIOCORE partners for seasonal comparative studies on scleractinian coral photophysiology with respect to turbidity levels and water depth along a gradient from near-shore to off-shore reefs. For this field trip the SYMBIOCORE partners CESAM (Portugal) and ZMT joined the team to contribute their expertise to on-going studies, establish first personal contacts, explore and document potential study sites and plan future collaborative projects in the region.
The coastal zone and shelf area of South Bahia harbours the southern-most warm-water reef ecosystems of the Atlantic Ocean. These marginal reef environments are still only poorly investigated and offer multiple approaches to study the functioning of key reef
ecosystem processes (e.g. calcification, primary production, respiration) influenced by a number of environmental factors triggered by strong seasonality (stormy seasons from May-August and dry seasons from September-April).
Stormy seasons particularly influence turbidity and sedimentation within in-shore and near-shore reefs as well as in islands further off-shore (e.g. Parcel dos Abrolhos) by enforcing sediment resuspension. Coral reef ecosystems of southern Bahia are characterized by their distinct mushroom-like morphology (“chapeirois” = “big heads”). They represent the main research target during the present expedition. In comparison to for example Indo-Pacific reef ecosystems the number of scleractinian coral species in the Abrolhos region is very low and reaches only 17, of which the endemic Mussismilia braziliensis (massive growth form) represents the most dominant and main reef-building species. In addition, 3 species of Millepora hydrocorals occur in the region. Water current velocities are generally low to moderate (during stormy season) and seasonal water temperature in the area ranges from 24 – 28 °C. Tidal range is between 2-3 m.
Travel from Caravelas back to Salvador do Bahia. Visit of RECOR (UFBA) research facilities in Salvador do Bahia and concluding exchange with SYMBIOCORE project partners.
Recovery of multiparameter probes at St. Barbara island in the morning. Transfer to station 3 (Parcels dos Abrolhos). Investigation of the study site by video recordings, deployments of Manta multiparameter probes, surface sediment sampling, live coral samples for photophysiology and water column sampling. Observations: Moderate water current in shallow depth (ca. 20 cm s-1), higher turbidity than close to St. Barbara island (Secchi depth: 10 m). Complex coral formations, protruding massive coral heads (column-like), steep drop-off to 20 m depth. High coral cover (ca. 30-40 %). High fish abundance relative to in and near-shore reefs and groups of adult parrot fish (showing undisturbed feeding). Return to St. Barbara island for sampling of carbonate sediments close to the fringing reef (collection permit from national park authority received). Transfer back to Caravelas. Unloading of boat, sample storage and night stay at local hotel.
Transfer to station 2 (Pedra de Lixa, near-mid-shore, position: S 17° 41.591’ W 38° 59.555’). Investigation of the study site by video recording, deployment of Manta multiparameter probes, sediment sampling and water sampling. As in station 1, the team members from UFBA, UESSEX and CESAM sampled live coral colonies for photophysiological measurements. Observations: Very similar to station 1, low water currents (< 5 cm s-1), relatively high turbidity (Secchi depth: 7.7 m), although generally this site is known to show lower sedimentation rates than Pedre de Leste. Swarms of fish observed (adult parrot and surgeon fish). Evening transfer to off-shore islands (i.e. Parcel dos Abrolhos). Night snorkelling at St. Barbara island (Abrolhos national park) to investigate the fringing reef of the island and to deploy 2 Manta and Pendant probes overnight. Observations: Reduced turbidity (visibility: 10+ m). Relatively high coral cover (30%) and high abundance of fish (adult parrot fish and groupers). Sighting of a logger head turtle. Night stay close to the island.
Start of pilot cruise from Caravelas. A fully equipped catamaran with sufficient space for 7 scientists and 4 crew members has been rented from a local operator. Transfer to 1. Station (Pedra de Leste, near-shore reef, position: S 17° 46.560’ W 39° 03.050’). Investigation of the reef site by photo and video documentation, deployment of Manta multiparameter probes, while live coral samples have been collected for photophysiological measurements. In addition, water samples were taken for pigment analysis. Observations: low water current (< 5 cm s-1), high turbidity (Secchi depth: 7.5 m), Millepora hydrocorals are very abundant at reef crest with strong mucus sheet production, extensive macro-algae growth in shallow depth. Many hard corals covered with fine sediment. Very few fish were present, but if, then small groups of adult parrot fish. Overnight stay at the study site.