RESUMO
Buildup of decaying pelagic Sargassum on the beaches and coasts of the Mexican Caribbean during the massive arrivals of 2015 and 2018 had detrimental impacts on the environment and tourist industry. To avoid ecological and economic impacts from massive beaching of Sargassum, it would be better to remove the pelagic algal masses while still at sea. However, out at sea, pelagic Sargassum rafts constitute an ecosystem with a diversified associated fauna and their removal could impact this fauna. We conducted a survey on the motile macrofauna associated to pelagic Sargassum rafts in the Puerto Morelos reef lagoon, Mexican Caribbean. Pelagic Sargassum was sampled with nets at 2â¯m, 50â¯m and 500â¯m from shore, at four sites during the months of September, October and November 2018. The 108 samples contained 10,296 individuals belonging to 32 taxa distributed over eight Phyla. The main phyla were Arthropoda (48%), Annelida (41%) and Mollusca (15%). Fish abundance was low (10 individuals) with only five species, of which three are typically associated with Sargassum rafts and two are common in seagrass meadows and coral reefs. Species composition and abundance of motile macrofauna varied with month and zone; the nearshore zone had the lowest abundance but there was no difference in the abundance of the fauna associated with rafts 50 or 500â¯m offshore. Three of the four most abundant species (together accounting for 89% of the individuals) were species typically associated with pelagic Sargassum, and the fourth was an amphipod that was only registered once near shore. Although more studies over larger time and spatial scales are required, these results suggest that the removal of pelagic Sargassum within the reef lagoon may not have a significant effect on local populations of motile macrofauna.
Assuntos
Sargassum , Animais , Região do Caribe , Recifes de Corais , Ecossistema , MéxicoRESUMO
BACKGROUND AND AIMS: Cryptic peracarids are an important component of the coral reef fauna in terms of diversity and abundance, yet they have been poorly studied. The aim of this study was to evaluate the taxonomic richness and abundance of cryptic peracarids in coral rubble in the Puerto Morelos Reef National Park, Mexico (PMRNP), and their relationship with depth. METHODS: Three reef sites were selected: (1) Bonanza, (2) Bocana, and (3) Jardines. At each site six kilograms of coral rubble were collected over four sampling periods at three depths: 3 m (back-reef), 6-8 m (fore-reef), and 10-12 m (fore-reef). RESULTS: A total of 8,887 peracarid crustaceans belonging to 200 taxa distributed over five orders and 63 families was obtained; 70% of the taxa were identified to species and 25% to genus level. Fifty species of those collected represent new records for the Mexican Caribbean Sea. Isopoda was the most speciose order while Tanaidacea was the most abundant. DISCUSSION: Cryptic peracarid taxonomic richness and abundance were related to depth with higher values of both parameters being found in the shallow (3 m) back-reef, possibly due to a higher reef development and a greater accumulation of coral rubble produced during hurricanes. Peracarid data obtained in the present study can be used as a baseline for future monitoring programs in the PMRNP.
RESUMO
We documented the prevalence of diseases, syndromes and partial mortality in colonies of the Montastraea annularis species complex on 3 reefs, and tested the assumption that a higher prevalence of these parameters occurs when reefs are closer to point-sources of pollution. One reef was isolated from the impact of local factors with the exception of fishing, 1 potentially influenced by local industrial pollutants, and 1 influenced by local urban pollution. Two reefs were surveyed in 1996 and again in 2001 and 1 in 1998 and again in 2001. In 2001, colonies on all reefs had a high prevalence of the yellow-band syndrome and a relatively high degree of recent partial mortality, while the prevalence of black-band and white-plague diseases was low although a new sign, that we named the thin dark line, had relatively high prevalence in all reefs. As no direct relationship was found between disease prevalence and local environmental quality, our results open the possibility that regional and/or global factors may already be playing an important role in the prevalence of coral disease in the Caribbean, and contradict the theory that coral disease prevalence is primarily related to local environmental degradation. Reasons that may partially explain these findings are the high level of potential pathogen connectivity within the Caribbean as a result of its circulation patterns coupled to the large land-derived pollutants and pathogens input into this Mediterranean sea, together with the surface water warming effects which stress corals and enhance pathogen activity.